6" Mc Laren road Loco build by Andy Smith
Mclaren Build Diary Part 1
First of all a big thank you to Colin
Dix for a) getting me started on this project b) for all the help
and friendship and finally for offering to host the build diary on
the Bailey Steam site.
So where did it all start and how did
I get myself into this mess? Like many others I have more than enough
projects on the go in the workshop already! 2004 was the year we returned
our 6” Wallis to the rally field after and absence of 15 years
or so and thoughts turned to missing our Aveling & Porter 5 ton
GND tractor 7898 that we owned up until 1997. With the escalating
cost of another full size engine out of reach thoughts turned to the
possibility of building a half size 3 speed road loco.
There are now many good steam sites on
the Internet and one good one that I came across was the Bailey Steam
Services Site run by Colin Dix up near Ross on Wye. I had spent many
a lunch break following Colin’s construction diary of his own
engine so decided to give him a call, after a long chat Colin invited
me up to see his engine however it did come with a warning! “if
you come up and see it you will fall in love with it and want to build
That fateful visit was to be the start
of so many things (little did I know at the time), we were made most
welcome by Colin, Julie and the boys and enjoyed viewing the engine
in the workshop over a cup of tea and cakes etc. Colin provided me
with an overview of his build costs and I plugged in my own numbers
with updated prices from Double B who supply the castings for this
engine in 3”, 4” and 6” scales. Colin provided me
costs for machining that was outside my equipments scope as this was
an essential factor in whether the project got the green light!
Jan 04 – The fateful first visit to Bailey Steam!
The build so far has not been straightforward
and I nearly gave up early on out of sheer frustration at not being
able to get castings. On return from Colin’s we ordered a set
of drawings from Double B and when these duly arrived I immediately
made the regulator lever as this was the first bit we made for the
6” Wallis. Many nights were spent studying the drawings
and we decided to go ahead ordering the rolling’s for the chimney,
smokebox and front wheel rims and all the castings for the front end
of the engine in May 2004. It became clear early on that casting supply
was going to be an issue so I busied myself making the smokebox door
hinge, lamp brackets, perch bracket assembly etc.
The first part “Regulator lever”
The project effectively then went on
hold waiting for castings, chasing the castings almost on a weekly
basis before being finally promised castings just before Christmas
only to be put off yet again. At this point I was close to scrapping
the whole project. Colin came to my rescue again with an offer to
come up over Christmas to steam his 6” Mac and go for a road
run around the local villages. This was just the tonic I needed and
with renewed vigour and after some more chasing we got a date of 17th
Jan to collect the first batch of castngs, exactly one year to the
day of my first visit to Colin’s. The trip was once again on
and off right up until the last minute and even on my arrival having
driven some 140 miles to Sudbury we were told all the castings are
not here! There had been a mistake by the foundry as they had cast
the front hubs without any coring out but on the plus side there were
lots of other castings available so we cleared out all the 6”
scale stock in one foul swoop.
The Front end rollings July 04
Castings delivery to the Workshop!
The Double B casting supply issue seemed
to resolve itself once the new foundry came on line and the castings
were come thick and fast and my bank account was shrinking at an alarming
We now have 95% of the castings although
I still do not have a cylinder block, this being the last real key
casting. The front end is now nearing completion and will be ready
to stand on her wheels once I have finished off the last bit of machining
on the hub.
The hubs are effectively cones with 9
degree angle faces so allow the spokes to come straight out without
bending at the hub. I did consider machining them conventionally but
the hub inners and outers are cast with the angles on them leaving
insufficient material to clean up flat and still support the spokes.
Machining the hubs has had its challenges
in that there was insufficient travel on the top slide of the lathe
to do it in one pass so we had to take two bites at it. Ideally the
hub inners and outers should be machined at the same setting but this
was not possible so careful setting up was key to success!
The hub outers came from two different
foundries and one pair were glass hard and even tip tools did not
want to cut! This was eventually overcome but added to the problems.
The next problem is how to machine the slots for the spokes on the
cones. Colin machined his by packing up his rotary table at 9 degrees
but this was a precarious set up that could have moved part way through
machining. I have devised a more solid set up with a tilting machine
vice and an indexing head. This will allow the hub to be clocked up
in the flat and then tipped up and clocked in exactly before machining
six slots in each face. I set it all up on the big mill at work with
a digital read out only to find that there is insufficient clearance
under the head! Believe it or not my small Taiwanese mill at home
has much more clearance so the set up should work there?
Front Hub machining setup
Front hubs prior to spoke slotting
The final drive gears and pinions are
all 12 module and I have no way of cutting the teeth or machining
the big gears as they weigh near on a 1cwt each. I machined the two
pinions and delivered them along with the raw castings for the two
spur wheel to Colin. Colin machined the spur wheels although once
again the curse of the foundry struck again with a large “slag”
inclusion being found at the rim that only showed itself after machining
was nearly finished. This of course was the one from the “old”
foundry but to Double B’s credit they replaced it with a new
casting in a couple of weeks. The 12 module gears were cut at AG Prout
Engineering as this was outside the scope of Colin’s gear cutting
The two small pinions have been cut but the larger ones were delayed
as they have to be cut as a pair and with one defect casting this
has slowed things down.
Finished final drive pinion with square drive hole cut
Final drive spur wheel prior to machining
I have deliberated over the chimney as
no clear clues are available as to whether Mclaren’s had lapped
and riveted or but strap and double riveted chimney’s or even
if they were riveted at all ?
A friend of mine Richard Morris who I
met through this project is restoring 8HP 3 speed Mclaren No 1295
and he traveled over to South America to photograph the sister engine.
Fortunately this is still fitted with its original chimney and clearly
shows a double riveted butt jointed chimney with rivets at a larger
than “normal” pitch so I have copied this. I now have
to decide whether to fit a spun brass cap or go for a more original
cast iron version that sits down inside the chimney?
The stainless double riveted chimney, final riveting
will take place after the chimney cap is fixed in place
The summer season does not usually leave
much time for model engineering and the summer of 2005 was to be no
exception although we had no idea what lay ahead! We attended the
Welland rally with the Wallis during the last weekend in July, this
is an excellent friendly 3 day rally set to the backdrop of the Malvern
Hills and run by the Ross-on-Wye club. The Friday started off well
with the ground drying nicely and a normal day of ring events and
running around. Instead of Saturday dawning dry and bright per the
forecast we were awoken by the sound of rain on the tent roof, and
the day remained wet with the ground turning into a sea of mud that
was to last well into Sunday. Despite all this we had a wonderful
weekend with friends camped alongside the Dix family with “Hogwart”.
This was the first time that the two engines had met and the Mac is
certainly a big engine somewhat dwarfing the Wallis despite them both
being 6” scale.
“Hogwart” and “Tiger” at Welland before the
We were scheduled to attend the Kemble
rally the following weekend but this was not to be as my mum sadly
passed away on the Friday following a long battle with cancer. Mum
was a great support to my late father Les Smith and attended early
Andover rallies with him in the late fifties and early sixties with
various models and always supported our engine activities both full
size and modeling. Needless to say all engine activities came to a
grinding halt for several months. Colin came to my rescue again with
the offer of having “Hogwart” for a couple of days at
he GDSF and we did not need to be asked twice! We had a wonderful
time trundling around the play pen and it really made me glad that
I am building the Mac, it truly is a fabulous powerful engine.
We left off last time pondering the chimney cap and things went from
bad to worse! I had settled on a brass cap from Double B per the 4”
version and again after lots of chasing they eventually turned up
but made of copper instead of brass and to completely the wrong shape!
Action was clearly required so with help from Richard Morris who provided
a drawing of a proper Mac cap and my friend Mark Money in Tasmania
who provided a template from his 10HP road loco we were able to validate
the shape. My dad always considered the cap as the crowning glory
of any engine and so many models are spoilt by ugly appendages that
bear no resemblance to there full size counterparts, I was therefore
determined to get it right. The 6” drawing was provided to Double
B and about three weeks later the caps turned up, I am delighted with
the final result and it really sets the chimney off.
Finished chimney cap and chimney
October turned out to be a busy month as the cylinder
block was also successfully cast by Crayford Castings in Kent. Despite
being fully cored out it came in at 185kgs and took two of us to
lift it out of the car!
The Cylinder block with ports cast in
A couple of week’s vacation was
followed by news that the boiler was complete and tested ready for
collection. The boiler was made by Bell boilers near Stonehouse in
Gloucestershire and I planned to co-ordinate the collection with Colin
so that we could take it up to Alan Prout’s yard and machine
of the stay ends on his Kearn’s borer to ensure a nice flat
parallel surface to bolt the hornplate’s to.
Colin machining the side stays on the Kearn’s borer
The allotted day dawned cold, frosty
and foggy and we set of early to collect the boiler at 9:00, it took
about 2 hours and the windscreen washers had just about thawed out
by the time we got there. The boiler was loaded without issue and
then we headed off to Alan’s where the job went smoothly but
I have never been so cold in my life, it took a least a day to thaw
out properly! The boiler was safely unloaded with an engine crane
but it was certainly on its limit!
The cylinder block was dropped of at
Colin’s at the same time as the boiler stay machining ready
to go up on the big Kearn’s borer at Alan Prout’s. The
block was completed and collected just before Christmas 2005 and is
now somewhat lighter as I was able to lift out of the car on my own!
Clupet piston rings have also now been sourced but I am still trying
to figure out how they make them!
“The finish machined Cylinder Block”
Other work has been the machining of
the trunk guides and final drive gears. The Trunk guides needed a
lot of cleaning up and many hours of careful filing to put the radiuses
on the edges of the trunk guides to blend in nicely. The foundry fettler
had also been a little over zealous and this required additional cleaning
Much thought and discussion took place
over the crankshaft to determine the best method to produce ranging
from fabrication, machine from solid or SG iron casting? After much
review the machined from solid option was chosen as this is a very
powerful engine and with a 1cwt flywheel hanging on the end it just
didn’t feel right as a casting, an order was placed with Custom
Crank and Engineering in Wolverhampton.
Some feverish work over the Christmas
holidays saw the building of the front wheels completed and this enabled
the whole front end to be assembled on New Year’s Day, quite
a moment and a good feeling for how big it all really is.
“The front end all assembled on New Year’s day 2006!
Next job was the hornplates, belly tank brackets
and ashpan brackets. The hornplates were laser cut with all the
bearing housing bracket holes but still heavy and awkward to mark
out and drill al the dummy rivet / stay holes. The third shaft bearings
and back axle bearings were also machined and bronze oilite bushed
fitted ready to ensure alignment when fitting the hornplates to
the boiler sides.
“Hornplate ready for riveting”
The rear wheel rims have sat in the garage
since the summer and just looking at them did not seem to make them
any smaller or lighter! The first job was to grind the welds on the
T rings back ready for filling after vulcanizing the tyres on. The
brake rings were supplied un-welded so these were fitted, welded and
then welded into the rims on the inside of the rim. The rear hubs
are substantial to say the least and the double lobe hub is just about
as much as I can carry when fully assembled. Colin lent me his wheel
building jig and fly press for bending the spokes and this was used
on the front wheel as well. The rear rim was lifted up onto the jig
with an engine crane and the whole wheel has to be moved around and
turned over using this as it’s the only safe way.
“The first rear wheel completed 12” wide x 39 ¾”
One rear wheel is now finished and the
second one is on the jig and I have started to fit the spokes. All
the wheels will have to be dismantled for the tyre vulcanizing as
it sends everything red rusty. The wheel rims are shot blasted after
vulcanizing so will need a coat of primer before reassembly and riveting.
The finished crankshaft was collected in March and I am very happy
with the results.
“The finished crankshaft machined from a solid billet”
Having completed the wheels it was time
to consider the options on rubbering them, fork lift tyres were considered
but in the end vulcanizing direct onto the rims was chosen. Colin
was also looking to get the full size Ruston wheels done at the same
time and we found a company in Birmingham who offered a very competitive
price compared to some of the other quotes we received along with
a 4 week delivery. I decided to strip the wheels down and just send
the rims up as they have to go into an autoclave to cure the rubber
and its sends everything red rusty. The rims were shipped up to Leakes
and they were as good as their word and they were ready for collection
four weeks later. I am very pleased with the results and now have
three wheels back together again ready for riveting.
“The finished front wheels”
“A finished rear wheel”
Unfortunately things have taken a turn
for the worse on the work front as we have had to move offices and
have lost the use of the big mill in the workshop “how inconsiderate
of them”! This meant some feverish activity to try and get all
the big machining done and out of the way before the opportunity was
lost. This has however diverted me away from target of getting her
up on her wheels. I have now purchased a large mill for the workshop
at home along with a phase converter so hopefully this loss has now
“Gear blanks all machined ready for gearcutting”
I have finished machining all the gear
blanks and delivered them to Colix at the end of June to have the
teeth cut and the squares broached in and these were collected from
Colin at the Midlands ME Exhibition in October
“Some of the completed gears”
“ Machining on the chamfers on the rear axle carrier”
The pile of bits in the workshop is now
building fast and some assembly is planned over the Christmas holiday
to reduce this pile and have something that starts to look like an
With a couple of weeks off over Christmas
2006 it was planned to start assembling the ever increasing pile of
bits in the workshop onto the boiler in the garage. I don’t
know about you but I find that however much space I have it seems
to get filled up with “stuff”. The arrival of the full
size Ruston project has not helped matters but it’s a good job
that it came flat packed “IKEA style”. Space is tight
in the garage with the 6” Wallis in there but this is all part
of the challenge!
The boiler was already set up on blocks
in the garage ready to receive the hornplates and although the hornplates
were all finished I still needed to fit the dummy rivets. The drawings
show ¼” rivets but as they would have been at least ¾”
in full size I opted to go for 3/8”. Richard Morris had already
provided me the pitching info to allow the holes to be positioned
correctly which was a great help. Although I had a large bag of ½”
long 3/8 rivets they all needed to be shortened and with several hundred
to do it was very boring time consuming job.
I elected to do the riveting in the mornings
so as to cause minimal disruption to the neighbours. The belly tank
mounting brackets and ashpan brackets also had to be riveted on at
the same time. I cannot believe how heavy / awkward ½ size
hornplates are to move around on the rivet dolly and swinging that
hammer really was an arm acher. My wife informed me that she could
hear the banging over the television from the workshop which is about
140 feet away down the garden………………
The boiler side stays had already been
machined flat and parallel so I thought fitting them would be a doddle,
how wrong I was! I started with the flywheel side as it has cutouts
for the injector clack and two washout plugs. The hornplate was clamped
on and lined up with the cutouts, bottom of the firebox and checked
for squareness with the throatplate and boiler crown. The holes were
spot marked through and then the hornplate removed to check alignment
with the 8 large stays needed to be drilled and tapped, all were nice
and central so they were drilled and tapped. The hornplate was then
bolted on with button headed cap screws (the allen key holes will
be filled before final painting to simulate stays). All the bearing
housings were then bolted onto both hornplates before offering up
the second hornplate.
The second shaft and rear axle carrier
were fitted to ensure alignment before clamping the hornplate in position.
It did not seem to matter where I fitted it either one would line
up or then they would’nt, the drain plug bosses were holding
it off so it was take it all off and then back down the workshop with
the hornplate (now even heavier with all the bearings
fitted) and get it up onto the mill to open out the holes to clear
the bosses and allow more adjustment. It did’nt help that the
hornplates were not dead flat but by clamping the front and spectacle
plates in postion I managed to get it all set up correctly but a much
longer job than originally envisaged and not helped by the cramped
working conditions. It was a case of check, adjust, check again etc
“The hornplates bolted on”
The weather over the Christmas period
can only be described as “wet” so I could not get the
Wallis out enable the front end to be fitted, this was rather frustrating
as it was all ready to fit on. I decided that to ease the working
conditions and allow more maneuverability I would fit some heavy duty
castors on the back end so I busied myself fitting those in anticipation
and hope of some dry weather.
The smokebox and front end had already been assembled so once the
smokebox was on it would be fairly quick to build up the rest. The
smokebox is quite heavy and I knew it would be a tight fit, the spacer
ring was fitted onto the boiler with countersink caphead screws so
that I could drive the smokebox on. The chimney base was left on as
guide to squareness / level and it had to be adjusted several times
during the fitting as I did’nt want a “wonky” chimney!
Like all rollings it was not truly round so I had to revert to a hydraulic
ram to open it out to get it started on and drive it on with a hardwood
block and sledge hammer, it really is a good fit. After a double check
for squareness half a dozen holes were drilled and rivet bolts now
hold it in place.
The addition of the perch bracket, axle,
wheels and chimney only took an hour after that and it was a great
feeling to see it start to look like an engine, I had to wait another
week for the weather to improve before rolling her out on the drive
to get a look in daylight.
“JYNX” meets “TIGER”
It’s such a huge boost to your
enthusiasm to see it all start to come together and for several evenings
I just had to go and keep looking at it in the garage.
I have now fitted the spectacle plate
and cross stays that go between the hornplates on a Mclaren, fitted
the firehole door and machined the crankshaft and secondshaft bearings.
The crankshaft was dropped in and rotates freely without any play
or adjustments to the bearings so I guess hornplate fit cannot be
too bad. The secondshaft and three speed gearing on the crankshaft
and second shaft were fitted on Sunday, first gear was engaged and
it turns over very sweetly without an ounce of backlash in the gearing.
The pile of bits in the workshop is also definitely much smaller now!
“The Crankshaft and second shaft installed”
We have not even steamed the Wallis this
year and our first rally is not until Kemble in August as I just have
not had the time with heavy travel / work commitments etc.
We have despite all the above made some
significant progress since the last update. The next process was to
finish off the diff assembly and 3rd shaft gearing and then the two
final drive assemblies. Things are all getting a bit big now and I
am really glad of that extra 6” in the mill table length as
the third shaft only just fitted to mill the square on the end. The
length and diameter of the shaft would not fit in my lathe and we
don’t have a steady for the lathe at work (will have to fix
that!). Colin came to my rescue again by allowing to use his lathe
to centre and face each end and then turn down the diameter and put
in the retaining groove, a round trip of 160 miles but a good chance
for a chat and Ruston discussions …………….
over a cuppa.
Machining the square on the 3rd shaft
The diff gears and bevel pinions were
already cut so to finish the diff assembly I just needed to make the
pinion shafts and drill the mounting bolt holes for the gear ring
and put in the oil pipe hole etc, the finished assembly along with
the final drive pinion are quite a lump but it was very rewarding
to see it all come together and more importantly fit the shaft I machined
up at Colin’s. The assembly is held on the shaft by a split
collar that drops into a groove in the shaft so this was made and
fitted next. My measurements on the length of the shaft worked out
perfectly so when the square was cut it all fitted perfectly with
just a small amount on end float.
The assembled diff unit
The winding drum and final drive centre
had already been machined so again just needed final assembly and
the bearings made and fitted. The offside gear bolts directly to the
rear of the hub so both gears were put up on the mill and the holes
pitched out and then transferred to the hub / drive boss followed
by reaming for fitted bolts. I could not lift the assembly off the
mill so had to assemble on the floor, more big bits ready to be fitted
on once the rear axle goes in.
Final Drive spur gear / rear hub backplate
The cylinder block has also now been
finished off with all the stud holes etc being added and all the covers/
trunk guides fitted. Drilling the valve chest stud cover holes proved
to be a real challenge as the block would not fit under the quill
on the mill. Mr Heath Robinson was called in and we overcame the problem!
Mr Heathrobinson at work!
I have also had lasercuts made for the
belly tank ends, rear spring hangers and gear change sliders, this
process works on steel up to 14mm thick and saves a tremendous amount
of time. While on belly tanks I decided to have a pattern made for
the water lifter hose bracket and this was done along with several
castings by Alan Davenport, Richard Morris lending his original to
help get it right even down to the casting number, the end result
is very pleasing. Colin also decided to build a toolbox for the belly
tank so we did two with Colin getting these folded up. Richard Morris
once again came to the rescue with pictures and dimensions from his
full size version.
Water lifter hose brackets (pattern and castings)
Laser cut / folded bellytank ends
Folded toolbox prior to welding
The finished toolbox with owners plate
With the block all finished it was time for assembly,
the following pictures sum up the current build status as of July
The finished cylinder block
Lifting on the cylinder block
Starting to look like a proper engine!
Diary Update 15/08/2007
None of the two 6”Macs finished
so far have been fitted with rear spring gear although Colin did make
most of the components ready to fit on his engine. Having driven Colin’s
engine on numerous occasions it really is not necessary and only has
very limited movement anyway but in an engine of this scale I felt
that I should include it.
The drawings are a bit sketchy in this
area so I went ahead and produced some ACAD drawings of the springs
and associated parts and these were used by the laser cut company
to make some of the parts although the “T” pieces were
CNC flame cut.
“T” piece flame cuts
I decided to get the actual leaf springs made professionally as they
need to be hardened and tempered to maintain there “spring”
in use. I sent the drawings out for quote with numerous responses
ranging from not interested to extortionate ……….!
Laser cuts for the spring gear
I finally found a company in the midlands who were recommended and
at a fair price so got these underway while I was making the rest
of the parts. The springs were duly delivered as agreed and I have
to say I was really disappointed when I opened the parcel. The leaves
were all different leaves, the centre buckle looked like it had been
hewn with an axe and then they were dipped in what I can only describe
as tar! To be fair the vendor did offer to collect them and remake
at their cost but by this time my confidence in their ability to do
them to an acceptable standard had evaporated so we agreed a large
partial refund of the cost and I got on with putting them right! This
involved stripping each spring and re-machining the centre buckles
and then adjusting the length of every leave, the worst job was actually
get the black tar off as it seemed to get everywhere!
Finished rear spring assemblies ready
The spring troughs and stirrups were fairly easy fabrication work
with the laser cuts saving a huge amount of time. The “T”
pieces were machined and the oil and stud holes put in ready for a
trial assembly. This is where it all started to go wrong again as
the leading edge of the “T” pieces fouled on the fire
hole door hinge and the back head while the stirrups fouled on the
rear boiler washouts! A bit of investigation with Colin revealed that
he had similar issues with his “T” pieces but he had not
encountered the washout problem having never fitted the rest of the
spring gear. Another builder I am in contact with reported that he
had exactly the same issues as me so at least I was not alone.
Assembled onto the engine
I have overcome the problem by machining the front of the “T”
pieces away on both sides, adding a radius to the door hinge and dropping
the stud size down to ½” as there is no longer room for
¾” nuts. The reduced stud size has also provided clearance
for the washout plugs but this makes access extremely difficult with
the spring gear on.
- Progress Update 04/09/2007 -
With the spring gear done and fitted
I decided the next task is to get the cylinder block finished off.
All the machining has already been done and covers temporarily attached
etc but I had been putting off making all the studs as it is such
a boring job.
Another one of my pet hates is studs sticking out of nuts all different
lengths and not finished off nicely on the ends so I have made sure
that all the studs were identical and the finished result is very
pleasing. At the same time as the studs I have also finished off glands
for the regulator, slide valves and piston rods, all went smoothly
with the exception of the HP slide valve as the flange of the gland
fouls on the trunk guide. The trunk guide is machined off flat on
one side anyway as per full size to I just need to adjust the gland
to allow it to fully enter the block
Pictures of block with studs fitted.
It’s really nice now that as I
make bits they can be fitted straight onto the engine. With the trunk
guide studs all done and the oil pump sitting in the drawer it was
tempting to make the mounting bracket and get that on as well. Having
studied all the pictures the 8HP engines seem to have the lubricators
mounted directly above the HP valve chest on studs but this is all
cored out on the 10HP engines leaving no area for the studs so they
seem to have them fitted on the top of the trunk guides. Armed with
pictures on Boadicea’s mounting bracket we had this knocked
up in short order along with the threaded fitting for the block. I
have not fitted the pipe yet as I am going to fit a secondary non-return
valve in the line.
Picture of the fitted oil pump.
The purpose of pushing on with the block
is to enable me to get it permanently fitted to the boiler, I do mine
by assembling the connecting rods / crossheads / pistons to line everything
up and check for free rotation as well as allowing for boiler expansion
(calculated to be 0.080” in this case). So with this in mind
the crossheads and piston rods were next on my list. Having read Colin’s
build diary and the need to add bronze slippers I was very careful
in measuring everything and it became clear that the crossheads have
very little machining allowance on the diameter that fits in the crosshead.
I also decided to deviate from the drawings at this point as the single
cross pin to take the load / drive did not seem adequate. On full
size Mclaren’s the crosshead is screwed onto the piston rod
and then fitted with a locknut. The piston rod is cross drilled through
the crosshead and long dome headed bolt and nut are fitted.
The crosshead castings were carefully
set up in the four jaw chuck and faced / drilled and tapped for the
piston rod. The piston rods were then made up over length and the
crossheads fitted on and the locknuts tightened. I machined the OD
to fit in the crosshead like this to ensure that the diameters remain
concentric. Once the desired fit was achieved and checked on the engine
I drilled the cross holes to ensure that they would always go back
in the same place after finishing off the other machining operations.
Picture of turning the crossheads
The crossheads were then removed from
the rods and had the side cheeks milled and the little end holes put
in, then the rears were machined and the inside cheeks cleaned up
as well as the two locking bolt holes that prevent the little end
pins from rotating in the crossheads. Another measure up once assembled
to determine the finished piston rod length and the job is completed,
pistons and slide valves are next on the list!
Pictures of finished crossheads.
- Progress Update 25/09/2007 -
The slide valves on the Mac are supplied
as gunmetal castings all nicely cored out to allow free steam movement
but like all things in life nothing is that simple! The ports on the
Mac block are all cast in and if the sand cores move during assembly
of the mold or during the actual casting process then the ports can
move. This was the case with my block but being worse on the HP side,
needless to say that after squaring up they don’t match the
drawing dimensions on either side! Fortunately the slide valve castings
are on the small side internally so I have after discussion with Colin
opened them up on the inside to ensure that the ports are not blocked
/ obstructed and just cleaned up the outside edges. I may have to
adjust these once we get to setting the valve timing. The rest of
the slide valve machining is very straight forward.
Picture of slide and valve rod
I positioned the slide valves in the
block and then inserted a piece of ½ dia bar with a pointed
end on through the gland / block to mark the position of the hole.
The hole is then drilled oversize on the rod to allow some float to
let the valve move off the face in the event of priming.
The assembled slide valve in the block
I have made the valve rods from ½
dia stainless and left them over length until I have made the rest
of the valve gear, the locknuts will allow easy adjustment of the
valve timing at ether end of the valve rods.
The block with fitted crosshead and slide valves
- Progress Update 15/10/2007 -
They say a little of what you fancy is
good for you! So instead of pushing on with the connecting rods I
decided I fancied building the belly tank as I have been looking at
the laser cut and bent ends sitting in the corner of the workshop
since the summer. I had already sourced some strip to roll up for
the radius flange so I rolled this up to just sit on the edge of the
radius leaving a natural weld prep. Now welding is not one of my strengths
but I have to say it came out quiet well and after dressing back the
result was pleasing. I had some off cuts of 1 ¼” diameter
boiler tube left over from the 6” Wallis and these were cut
to make fill in pieces for the corners and once again after welding
and dressing back to leave a perfect 5/8 corner radius.
Picture of welded up belly tank end
The strengthening pad that also provides
the fixing at the front was also welded in at the same time and I
will mark this out and drill the fixing holes once the belly tank
is trial fitted after assembly. I clamped the rear belly tank end
onto the engine to mark the position of the mounting holes. The end
was adjusted to be both central and level to the horn plates before
marking the holes, the positions were then checked for position and
one set of holes drilled before remounted to double check before drilling
the other side.
Picture of trial fitting for fixing holes
I deliberated on how to make the wrapper
as it’s a big piece of steel to bend as per original plus the
need for access to the inside to rivet it. I eventually decided to
leave the boiler radius as a separate panel (as per Colin did) but
to fit a separate flat base again as per original with a central manhole
in the underside for access. The company that laser cut and bent the
ends were also able to fold the wrapper ends and laser cut base with
manhole rings so I provided them with a finished end to act as e template
and the results are excellent.
Picture of laser cut bits
Before starting to drill any holes I
assembled the pieces to see what it would all look like and check
for any major errors in my plan!
Picture of mock-up
The drawings called for ¼ rivets
at 13/16” pitch but once again after mocking up this did not
look right. Richard Morris once again came to my aid confirming rivet
sizes in full size of ½ “ and 1 7/8” pitch making
¼” and 15/16” pitch. The two end wrappers were
carefully marked out and the pitching worked out perfectly avoiding
a rivet right on the corner where it would be almost impossible to
get to. The holes were all piloted before opening up to ¼”
dia and I am now putting in all the holes for the water lifter, toolbox,
hose bracket etc before the mass riveting exercise begins. I have
enlisted the help of a friend to help with manoeuvring the tank around
and we will have to pick a weekday to do this to minimise the impact
on the neighbours with all that banging!
Picture of drilled belly tank end
The fitting of the ends is now complete
and all the fittings are made and fitted prior to assembly. Unfortunately
my plan for help went wrong as he decided to go away for the weekend
at the very time I was ready for riveting so my son was enlisted to
help along with an engine crane and I was able to do this on my own
once it was all set up!
Picture of fitted up tank end
The ends were riveted first with the
bolts holding everything in line and these were removed once enough
rivets were in place to hold things tight and I only had to remove
one rivet that got misaligned on the snap leaving a nasty unsightly
mess. The corners dressed nicely in as well once the rivets had pulled
the joint in and I am very pleased with the results so far.
Picture of riveted belly tank end
Picture of riveting setup
I have decided to fit a separate bottom
plate to the tank (once again as per original) and the removable top
section allowed this as it would be very difficult if not impossible
to rivet without this access. I have also added in the manhole and
strengthening angle iron brackets where the steering brackets are
mounted. The bottom edges of the ends need to be “scarfed”
down to a knife edge to allow the bottom to fit snugly so these were
ground back and pull up nicely with bolts but this will need careful
attention when riveting up.
Picture of belly tank prior to fitting the base.
Picture of bottom assembled prior to riveting in position.
- Progress Update 29/11/2007 -
Having fitted up all the bottom of the
tank, bolted in place and drilled / positioned the strengthening plates
it was time for my favourite job of welding! The bottom was removed
and the strengthening ring and steering shaft supports bolted up tightly
and after careful tacking all still looked good, that is until I had
finished the welding and the based had bent like a banana! Time for
a cuppa but having left it all to cool down it did not look any better!
Careful bolting down soon pulled everything into line and I could
at least sleep knowing I only had several hundred rivets to put in.
Picture of Finished tank bottom
I had a tidy up / move round in the workshop
until the belly tank could be sat over a sturdy bench at waist height
with the rivet set in a suitable vice and by careful adjustment of
the support blocks the belly tank could be levered up and the manoeuvred
over the snap. This et up worked well but I found I needed a third
hand at times and I only managed to drop the tank with my finger between
the snap and the tank a couple of times! I had to have several goes
at the riveting spread over a couple of evenings as it was noisy work
and I didn’t want to upset the neighbours. The end result is
very pleasing and it was great to be able to bolt all the bits back
on and see what it looked like although I still have the top section
to roll and fit.
Picture of bits bolted back on the tank
I decided to do the steering brackets
next as I had already fitted the bolts in the tank and it would be
easier to set up with the tank off the engine. The castings were not
as easy to machine as they would not fit in the vice on the mill so
I had to add an angle plate and some clamps for additional; support.
The steering shaft comes through at an angle in a split bearing on
the 10HP engines which are different to the 8HP and smaller engines.
The cap is part of the casting and needs to be sawn off before machining
and then refitted with studs to put the shaft hole in and a bronze
bearing. I had been up at Richard Morris’s the weekend before
and he very kindly provided a couple of large 3/8 split pins for the
ends of the shaft, this seems to be a Mclaren special as despite having
the worm wheel keyed in place it still has the split pin at right
angles to the key.
Picture of steering shaft machining
Picture of shaft fitted to tank
The steering brackets and shaft fitted
straight onto the tank so it was now almost ready to fit onto the
engine. I made up two hardwood spacers ½” thick that
slip in between the tank and the mounting brackets on the horn plates
to allow the tank to slide up into the front mounting bracket. It
was necessary to get the engine out to fit the tank and it was a simple
job to slide the tank under the boiler on a trolley and then pack
up with wooden blocks until the correct height was found and the bolt
holes lined up. The pre fitting obviously worked as the tank bolted
straight on and is nice and square so now I just have to fit the front
Picture of belly tank being fitted
Having got the tank on and subsequently fitted the
shaft underneath it seemed sensible to make the steering shaft and
fit the worm and the steering wheel, only problem was I could not
find the casting! After a bit of searching it was located and also
realised that I have very few castings left to machine now. A study
of the drawings also showed me how many are complete now so I guess
I must be making some progress.
The steering wheel is a straight forward
machining operation but how I hate those over zealous foundry fettlers
who had attacked the rim! The handle was turned up from stainless
and both ends of the shaft turned to fit the bearing, worm and wheel
with the final length being determined by a test fitting. I cannot
make the top bearing yet as it bolts on to the gear case and I may
have to machine a little off the top of the steering shaft bearing
housing to lift the assembly up as it comes a bit to close to then
final drive pinion.
Picture of the steering wheel fitted
I really must get on with those connecting rods next!
- Progress Update 08/01/2008 -
When I originally did the major machining
on the front plate I deliberately left out the two outer holes for
the gear change shafts thinking it would be easier to mark them in
position from the engine. Having fitted the gear change castings it
became clear quite early on that one side lined up perfectly and the
other side was miles out! I have been pondering this for a while as
to how to overcome it as the shaft really has to go through the centre
of the boss to both look right and line up with the gear change pin.
I made up a marker from a piece of 9/16” dia bar with a nice
cone turned on the end, simple to pop this in the housing and then
tap the end to mark the hole position. The near side marked dead centre
but the offside really was about 3/16” out of position so the
only choice was to machine part of the bear cap / gear change housing
and move it all over as far as I could and make a spacer up to sort
the gap this generated.
Picture of middle gear change
While the front plate was off for machining
the holes I put in the drain cock and simpling valve holes and drilled
and tapped the back of the regulator stand for the pressure gauge
support. I had already machined the middle gear change so this just
needed the two 3/8” stud holes drilling and tapping. The gear
and racks have different numbers of teeth in different positions these
were first sorted out into sets per gear and then machined to length
/ turned down to allowing fitting of the selectors. The selectors
had previously been laser cut so just needed a clean up and marking
/ drilling for the fitting hole and lubrication holes.
Picture of low speed gear change
The actual gears had the selector grooves
left out at the original machining as we were concerned about cracking
during the broaching process for the drive squares so each of the
three gears had to be set up and clocked in before adding in the grooves,
this was straight forward on low and top but on the middle speed the
casting has the ring left off of it to allow it out of the sand as
a straight pull for casting. This requires the outer square to be
turned down and then the selector ring / groove either shrunk or loctited
into position. I favoured the shrink fit option so having turned down
the casting a ring was machined up 0.001” per inch dia undersize,
this was then gently warmed and dropped on and it won’t be coming
off in a hurry! Even though it was only 0.003” shrink fit it
closed down the square so that it no longer fitted onto the shaft
but a bit of careful fitting soon overcame that problem
Picture of middle gear change
This now leaves the three actuating handles to complete the gear change
so I am hoping to get these finished off over the Christmas break
Picture of all three completed gear changes
Having completed the belly tank my attention now turned
to sorting out the laser cutting / bending for the tender so this
could be going on in the background while I worked on the gear change.
Both Colin and Ken Knight kindly provided me with the electronic drawings
for the tender and I modified these to suit my own needs and then
sent them out as dxf files to the laser cutter which saves both time
and money. The parts were collected about a week later and once again
I am really pleased with the results.
Picture of the tender bits
Picture of drawbar laser cuts prior to welding
I have already fitted the brake shaft
casting and drilled all the fixing holes and have fitted the manhole
and put in the rivet holes for the floor and front tank fixing, next
job is to finish off the angle and fit them to the horn plates to
transfer all the bearing mounting holes.
Picture of the floor angle fixing
I guess those connecting rods are going to have to wait!
- Progress Update 22/02/2008 -
Progress on the tender has gone very
smoothly with riveting the angle iron onto the tender sides and I
found I could do this on my own by careful balancing of the tender
side on the rivet set! It was a fairly easy job to clamp each tender
side onto the horn plates using the rear axle bearing housing as the
location and ensuring all was square, that is until one slipped off
and landed on my big toe!
Picture of finished tender side
I followed the same process as I used
on the belly tank ends and welded in infill pieces for the corner
radius and then dressed back with the angle grinder. The tender floor
is in two pieces allowing removal for internal access so an angle
framework needs to be welded in place to support this in the middle
and at the front and rear. I drilled and tapped all the holes in the
plates first and assembled the tender and then tacked the joints before
removing the plates for final welding ensuring everything remained
nice and square.
I already had the steel pre-cut for the
coal tubs. Which just needed rolling into shape, I say just but it
was damn hard work! I managed to get some off cuts of angle for the
tender from our local fabrication company and when I was there spied
a nice set of rolls in the corner so asked if they could roll the
coal tubs? They quickly agreed and I delivered the steel planning
to collect it a few days later but after several visits and no activity
I concluded it was not going to happen! Colin again very kindly and
probably foolishly allowed me to go up and use his while at the same
time borrowing his lathe to bore the ends of the brake shaft tube
as we did not have a steady for the lathe at work. I went up for the
day between Christmas and New Year despite not feeling my best as
I was really not very well. After several hours of winding the handle
of the rolls between us in cold weather we got the job done and they
have come out superbly so thank you Colin, we were both exhausted
at the end of it though and I had muscle aching for several days after
Picture of the tender with coal tubs on
The coal tub bases were made in the same
way with a rolled ring welded onto laser cut disc and then dressed
back to give a nice radius. The drawings called for ¼”
rivets but these just did not look right so I changed them to 3/16”
and increased the spacing on the top strengthening ring and they now
look spot on compared to the original photos that I have. The brake
gear was tackled next and I decided to drop the brake hand wheel down
inside the coal tub to allow two people to comfortably drive the engine,
not quite correct but a case of practicality over authenticity and
it works really well on “Hogwart”. Ken Knight very kindly
donated a length of square 4TPI threaded rod for the brake shaft that
was left over from his build so this was an easy job for a change!
Picture of fitting the tender on
With everything on the tender completed
it was time to wait for some nice weather to get the engine out and
fit the tender on. We did not have to wait very long and took advantage
of the fine dry weather last weekend. The tender fitting went without
a hitch other than one rogue rivet that prevented the tender from
sliding into place on one side. Some quick work with the angle grinder
soon solved that and to my delight all the holes lined up perfectly
with the only exception being the offside 3rd shaft bearing housing
where there is not room for the fixing bolt heads so I will have to
modify the diff bevel wheel to provide some clearance.
Picture of the fitted tender
Starting to look like a real engine now!
Another momentous event happened just
before Christmas with the arrival of the spark arrestor which had
been on order for almost three years. The good news is it’s
a superb job, fits the chimney perfectly and looks really good. I
have also collected the 6” scale transfers from Richard Morris
and they are absolutely superb, Richard has made a fantastic job of
these and they will really finish the engine off.
- Progress Update 01/04/2008 -
With the tender now on space in the garage
has become a premium and with all the big bits done its time to start
working on the details. I personally find this the hardest time to
keep enthusiasm going on any project as it feels like you do a lot
of work and don’t have much to show for it. The rear axle carrier
had to come out to fit the tender so I decided to do the rear axle
oilers as these have long pipes that are threaded into the carrier
so a good time to get this done while it was all dismantled. The original
oilers have tapered cocks allowing you to turn them on and off and
stop the oil siphoning out of the oilers when the engine is standing.
Richard Morris kindly lent me one of his full size ones for me to
copy and it was simple enough job to make these up along with the
pipes and they both fitted nicely on the engine.
Picture of finished rear axle oilers
I had been putting off making the three
gear change levers for a while but these also needed doing and I managed
to find some suitable rectangular bar. I milled the main profile and
bored / reamed the main holes in the flat stock as it was easier to
hold and the use of the digital readout on the mill made this really
easy to get all the profiles equal around the centre hole. The handle
section was a simple turning job between centres and then the radius
profiles and fixing bolt holes added to complete. I have not put the
flats on the shafts yet and won’t until I finally get the gear
changes all set up properly.
Picture of finished gear change levers
The water gauge frames have been sitting
in the drawer for a while so I decided these should go on next. The
boiler has bosses welded in place to accommodate the frame extensions
so these needed to be drilled out and tapped to suit the extensions
(this would have been much easier to do with the horn plates off).
The extensions were made from some large section hexagonal steel bar
suitably relived in the middle and are screwed straight into the bosses.
Picture of fitted gauge frame
I have decided to start work on finishing
off the crankshaft and needed to fit the middle speed gear, centre
balance weigh and all the eccentrics. The balance weight had already
been machined earlier in the build and I had successfully managed
to thread it over the crank webs for a test fitting but it still needed
the large U bolt and special nuts that clamp it into place. I worked
out the length on the U bolt and threaded both ends of a piece of
5/8 diameter bar. The bar was then heated to red heat and bent around
a piece on 3” bar, it sounds easy but it took numerous heats
to finally get it into shape and also not damage the thread but we
got there in the end.
Picture of U bolt and special nuts
I have had the steel ready for the eccentric
sheaves for a while and these are different from the HP to the LP
and also on a 10HP Mclaren the pump drive comes of the rear of one
of the LP eccentrics, this eccentric being extra wide. The sheaves
themselves are a straight forward turning job with the holes being
bored in with the offset in the four jaw chuck.
The straps took much longer that I originally
though and some tricky machining to get the fits just right, all the
special studs and fixing bolts along with the oilers but they are
now done and ready for fitting onto the crankshaft. The eccentric
rods are rather delicate and again different lengths from HP to LP
so I have decided to machine these from the solid from 2 ¾”
dia bar but to save time I am having these CNC turned for a very reasonable
cost leaving me the ends to machine and the offsets to complete.
Picture of finished eccentrics
- Progress Update 11/05/2008 -
While waiting for the eccentric rod blanks
to arrive I decided to remove the crankshaft from the engine and fit
the balance weight, eccentrics and gears etc. I had already machined
the balance weight and fitted it on the crankshaft (this is no easy
job as it needs to be jiggled over the crank webs) so it was an easy
job to fit the pre made U bolt and then drill and tap into each crank
web for the two additional bolts and spacers that secure it . The
next job was to fit the dummy shield to the middle speed gear and
add keyway clearance and a nice radius to allow it to fit snugly against
the crank web. This gear is keyed in place and a tight fit on the
shaft to careful fitting was required. The eccentrics were only fitted
loosely in place as I will be coming back to the timing once the rest
of the motion has been fitted.
Picture balance weight and eccentrics installed on crankshaft
The crankshaft is no light weight but
I was able to lift it out on my own and carry it down to the workshop.
Its reinstallation was somewhat different the added bits (especially
the balance weight) make it really heavy so required a trolley to
transfer it back to the garage. My son was enlisted to help lift it
back in position and it is great that he is both willing and able
to help now its getting so big and heavy.
Picture of finished crankshaft assembly installed in the engine
The reversing lever was next on my list
of jobs to do. The drawings leave a lot to be desired in this area
so armed with dimensions and pictures (again from Richard Morris)
I have been able to create an accurate version of Mclaren’s
distinctive reversing lever. The actual quadrant was laser cut but
everything else being machined from solid including the bottom latch
with its distinctive shape.
Picture of fitted reversing lever
The eccentric rods arrived last week
so I now have these on the mill machining the rectangular sections
at either end prior to slotting and putting the pin holes in. The
rods are different lengths each side as the HP eccentrics are smaller
than the LP ones and each end has a different offset so will definitely
need to measure twice and cut once!
Picture of eccentric rod machining
- Progress Update 26/06/2008 -
The eccentric rods are now finished after
a lot of machining and the dustbin man was seen limping away after
emptying the bins with swarf! The rods are quite delicate on the ends
and I am really glad that I machined them from the solid. I carefully
reamed all the pin holes 3/8” diameter only to find that the
holes in the link are oversize so they will need to be opened out
a little and the pins made oversize although the die block holes are
spot on 3/8 so not sure what went on there. The rods have been fitted
onto the engine and they line up nicely on the HP side and as per
drawing the LP side will need to be bent to line up with the link
so allowed this in the length before putting the pin hole in. I will
carry out the bending once the block and motion bracket have be finally
positioned and fixed down.
Picture of eccentrics rods with links
The lifting link arms are quite a visual
feature on a Mclaren being turned from round bar with a nice taper
and spherical balls on both ends and it is important that all three
are exactly the same length so as not to affect valve timing. It seemed
like and ideal test piece for the new CNC XYZ lathe at work! After
a test piece was done I ended up with three identical arms on a nice
stub ready to hold in the dividing head to put the flats on holes
in. Once completed the only remaining job was to put in the clamp
screw holes and broach in the keyways.
Picture of machining lifting arms
The lifting links on a Mac are just flat
rectangular bar section so easy to make and then with spacers on spindles
with nuts on each end. Colin had machined his lifting links from solid
with the spacers with the view that this would give a larger bearing
surface and be less affected by wear but it was not until Richard
Morris sent me some pictures of his stepped spindles that I figured
out how it goes together! The spindle is a larger diameter where it
passes through the link so the spacers and lifting links are effectively
clamped up against the shoulder on the shaft so they are solid with
the shaft. In this instance the oversize holes in the link allowed
me to follow full size practice and I just need to add in the split
pin holes in the nuts before I harden the shafts!
Picture of lifting link assembly
The motion bracket had already been machined
but it is amazing just how much finishing off work there still is.
The weyshaft is located sideways by two annular grooves and clamp
bolts so these were drilled and tapped along with the two boiler stud
mounting holes and the four bolt holes that locate it onto the end
of the trunk guides. The weyshaft spindle itself was turned up and
the annular grooves and keyways added in., slots broached in the lifting
arms, valve spindle guides and bushes made and fitted and the whole
lot assembled ready to go back on the engine.
Picture of assembled motion bracket
I have now set myself a target to get
her running on air and have generated a to do list of 48 items which
I am slowly crossing off as I make progress! Some of the jobs are
not really related to running but the need to fit the flywheel etc
is driving the need to get the rear axle and wheels on as the weight
is so heavy now the castors are becoming ineffective and it is almost
impossible to move around! A couple of smaller jobs to help this has
been the machining of the rear axle spacer and steam manifold. I have
also added in two holes to the face of the flywheel to simulate those
cast into the original for faceplate mounting as they will both look
correct and make suitable lifting points when fitting the flywheel
Picture of axle spacer and steam manifold
"And yes the connecting rods are now underway as well so watch
Aye, likely story Maaaatttteeee?
Call back later to see how Andy's Mac is progressing!
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