1/4 Scale Mc Donald tractor.

[George Punter]

I have just started a new project, well at least working in a feasibility study as that gives a way out if nothing materialises ! The new project is to be a working 1/4 scale model of a 1934 Mc Donald Australian tractor. The full size tractor has a bore of 9.25” and. stroke of 10” and is a 2 stroke single cylinder diesel with reed valve air induction. I am lucky as the full size tractor is only 17km away and I have access to photograph and measure it up. So far I have taken about 60 photographs and spent 6 hours on sketches. I have also started to make the cylinder/crankcase pattern as I needed to check some external details with the full size tractor. As part of the exercise I have gathered information on the history of McDonald and a copy of the owners manual . The photographs show the early stages of the pattern that has yet to be rubbed down and painted with spray big.
George.

 

[George Punter]

What a difference a couple of days make - some rubbing down and a few coats of spray bog on the engine crankcase /cylinder barrel pattern. I now have to make the core box to create the internal space inside the engine and that entails engage brain into negative thinking!
If any one our there has information / plans of the gearbox and the cylinder head it would be appreciated. I have a plan of the gearbox but no side elevation to show the position of the reverse gear and shaft. The photo shows the full size Mc Donald (1934) tractor.
George.

 

[Moper361]

View attachment 109590 View attachment 109591 View attachment 109589 What a difference a couple of days make - some rubbing down and a few coats of spray bog on the engine crankcase /cylinder barrel pattern. I now have to make the core box to create the internal space inside the engine and that entails engage brain into negative thinking!
If any one our there has information / plans of the gearbox and the cylinder head it would be appreciated. I have a plan of the gearbox but no side elevation to show the position of the reverse gear and shaft. The photo shows the full size Mc Donald (1934) tractor.
George.

George that is an impressive task to take on .I am familiar with the McDonald tractor as i grew up on a wheatfarm in central wheatbelt of WA .It was and still is a running tractor in a small museum now on loan .I will be following this thread with much interest as they are one of my favourite vintage tractors. I cant still remember the starting sequence of our McDonald .check all fluid levels then unscrew the relief plug on side of the cylinder head give it a few turns by hand .Then screw the relief plug back in while heating the bulb .Give the oiler box a few turns by hand .Wait for the heat bowl to heat up cherry red .Give a the injector a good squirt by hand then start rocking flywheel and bang she would pop into life usually the wrong way haha .Once it was running if you could slow it down and get the engine to fire back the other way if you were quick on the throttle .
All the best with the build and id love to see pictures along the way to show my father
Regards Nat

 

[George Punter]

Thanks Nat

for the comments relating to the Mc Donald tractor and model. I am fortunate it that the full size tractor is situated only 17 kms away from my home and is one of a pair owned by the same family. These two tractors have consecutive engine numbers yet both came originally from different parts of Australia. I have spent about nine hours so far measuring up and photographing and quite some time making the crankcase pattern. I now designing the cores for this pattern to create the empty space inside and as this is a two stroke engine that poses problems with the water cooling and transfer ports! It’s a case of thinking in the negative and trying to work out how they will be made. The photographs show progress so far. The composite cores will need to be made in separate parts and then glued together. Did you or the museum by any chance have a spare parts or owners manual for your tractor? I am trying to find out what shape is inside the cylinder head at the combustion chamber.
Regards,
George.

 

[Moper361]

Hi George .If you are not in a hurry i will be back in Australia next month on holidays as i do not residide in Ozz at the momment as i work overseas .I do not have a parts manual myself but have a few contacts still from various vintage tractor clubs as i was a avid restorer in my yoinger day and possibly know someone with a parts book i could copy .The cylinder head doeas have some shape internally as i have had ours apart before but to be exact i could not say just now .Also the piston i can say has quite a dome ontop to help sweep the air ..I will be down in july so will have a call round and see what i can find .
When i first looked at your crank case my first thoughts were how would you create the tranfer port and water jackets .This will take some creativity but very doable im sure .
Regards Nat

 

[George Punter]

Hi Nat,
I don’t intend to start the actual construction of the model tractor until the end if the year as I have another project to complete first. I am still gathering information and any help will be very much appreciated. I do have a reprint of a booklet that has two section drawings of the crankcase and also the gearbox ( top view only) but a side view of the gearbox would be very useful as I need to see how reverse gear works. I did notice that there are two types of piston - one is domed and the other has a deflector and I have opted for the domed version. I also read that the engine does not have high a compression as the hot bulb is the point of ignition. Having designed the cores for the engine the next part is to work out do I actually make the core boxes !
Regards,
George.

 

[Moper361]

Hi George
Im back in perth on holidays just now i have done some hunting around for MCdonald manual and there was one forsale but by the time i called it had sold .However when talking to the guy he gave me details off were he purchased it from as it is still Available as a reprint from a web sight called rallybages online .ive attached a couple of screen shots with details on .I hope this helps .Im ofto take a look at a boxford lathe now .
Regards Nat

 

[George Punter]

Thanks Nat for the information on the Mc Donald tractor manuals etc. I will make contact with the seller soon with a view to ordering the most suitable book. I think a phone call will give me the opportunity to discuss the content of the books and my needs. I appreciate the help. I was pleased to hear you are about the purchase a lathe - is that with a view to taking up model engineering? I have been making some progress on the development of the engine, focusing on the cores for the inside of the cylinder and crankcase. As the cylinder and exhaust port are set at ten degrees to the horizontal and the outside of the port is vertical there is a twist in the actual rectangular port opening. I plotted all of this on CAD and then produced a split core box on the 3D printer. That’s technology for you - makes life a great deal easier! I will add to this post as and when I develop the next stage.
Regards,
George.

 

[Moper361]

Thanks Nat for the information on the Mc Donald tractor manuals etc. I will make contact with the seller soon with a view to ordering the most suitable book. I think a phone call will give me the opportunity to discuss the content of the books and my needs. I appreciate the help. I was pleased to hear you are about the purchase a lathe - is that with a view to taking up model engineering? I have been making some progress on the development of the engine, focusing on the cores for the inside of the cylinder and crankcase. As the cylinder and exhaust port are set at ten degrees to the horizontal and the outside of the port is vertical there is a twist in the actual rectangular port opening. I plotted all of this on CAD and then produced a split core box on the 3D printer. That’s technology for you - makes life a great deal easier! I will add to this post as and when I develop the next stage.
Regards,
George.

Hi George
My situation at the moment is I work overseas and live in Thailand with my family and have done so for past 15 years .I have a mill ,Lathe and quite a lot of tooling and arbors etc I've made over the years since there that I use for hobby machining now and plan to keep it all there .But as time moves on I'm looking at setting up a small hobby shop here in Perth with the thought of moving back in the future .So I was looking around at the Chinese lathes and mills and stumbled across a boxford AUD with mill attachment and a trailer load of tooling to go with it so thought I'd take a look at it .the lathe has been owned from new and looks to be in quite good condition and would fit in my limited room .It would be a good start to setting up a small hobby shop if it's as discribbed .Ive been out of the loop in Australia for so long I really don't know what it's all worth at this stage .

 

[George Punter]

Nat what area of model engineering are you interested in ? As a teacher in the UK before I came to Australia our workshops were equiped with Boxford lathes but later I taught in a large comprehensive school and that was equiped with Colchester Student lathes and also had the luxury of a Senior milling machine. As at that time my home workshop consisted of a Myford ML 7 and a Black and Decker portable drill the school workshop became a real asset! I don’t know what value you put on the machinery you are looking at as it depends on condition. The competition is also that Taiwan makes some good lathes at reasonable cost. Hare and Forbes ( in Queensland ) carry a wide range in both size and cost and it may be worth looking them up on the net to give you any idea of value.

Regards,
George.

 

[Moper361]

Nat what area of model engineering are you interested in ? As a teacher in the UK before I came to Australia our workshops were equiped with Boxford lathes but later I taught in a large comprehensive school and that was equiped with Colchester Student lathes and also had the luxury of a Senior milling machine. As at that time my home workshop consisted of a Myford ML 7 and a Black and Decker portable drill the school workshop became a real asset! I don’t know what value you put on the machinery you are looking at as it depends on condition. The competition is also that Taiwan makes some good lathes at reasonable cost. Hare and Forbes ( in Queensland ) carry a wide range in both size and cost and it may be worth looking them up on the net to give you any idea of value.

Regards,
George.

Mainly interested in Small engines George .I have made a couple of Air and steam engines now and looking at starting on a webster ic engine soon .I make a lot of my own tooling and am set up to machine gears ets and have done so in the past .My work shop in Thailand is quite well set up with qite a lot of equipment .A 12x36 lathe ,zx47 mill with indexing head and a load of welders and tooling .The lathe i am looking at here in Perth is to start setting up a small hobby machine shop in our house in Perth .You may ask why i want a machine shop in Thailand and one in Perth the reason being is that over the next few years i can see myself bouncing back and forth between the two as my work slows down and also for my daughtets schooling etc as she gets older .

Here is some pictures of the lathe and tooling .The price seems reasonable for the lathe and tooling .the guy wants about the same money for the boxford with tooling as what it would cost me for a slightly larger AL 250g lathe from hare and fores with no tooling .The chinese lathe is slightly larger in chuck and spindle bore size .

 

[George Punter]

Over the last few weeks I have been thinking of the best way to cast the cylinder crankcase unit. While I have made many four stroke engines this is the first attempt at a fuel injected hot bulb two stroke water cooled unit. The water cooling adds to the problem as I am not sure if I will use a wet or dry liner. The problem with a wet liner is creating a good seal that prevents the water leaking into where the liner meets the ports. The liner will be cast iron or 4140 steel and the casting will in aluminium alloy and the problem is the expansion of the different materials when hot. A dry liner would eliminate this problem but would be more difficult to cast. I shall ponder on gathering as much information as possible from books etc before I make a decision. For me problem solving is all part of our hobby!
George.

 

[George Punter]

Well I am now back in action having spent some time overseas and also having cataracts removed from both eyes. It gave me time to think about the problem I had with the design of the cylinder for the tractor engine. Having spent some time looking at water cooled motorcycle and our board motors I have decided that the engine will be of the dry liner type. I now have to work out the shape of the core and how it will be made. I have also located a Mc Donald stationary engine that has had the cylinder head removed and will enable me to see inside both the cylinder and the hot bulb head. The material for the rear wheels has been ordered from the local laser cutter but I am still in the process of designing the front wheel as the hubs pose a real problem. As I still have to complete my 5” gauge diesel loco but expect to have that completed by Christmas and the it will be full on with the tractor.
George.

 

[stevehuckss396]

That is good news. I was looking forward to seeing this build. Glad your health is also improved.

 

[Moper361]

Mainly interested in Small engines George .I have made a couple of Air and steam engines now and looking at starting on a webster ic engine soon .I make a lot of my own tooling and am set up to machine gears ets and have done so in the past .My work shop in Thailand is quite well set up with qite a lot of equipment .A 12x36 lathe ,zx47 mill with indexing head and a load of welders and tooling .The lathe i am looking at here in Perth is to start setting up a small hobby machine shop in our house in Perth .You may ask why i want a machine shop in Thailand and one in Perth the reason being is that over the next few years i can see myself bouncing back and forth between the two as my work slows down and also for my daughtets schooling etc as she gets older .

 

[Moper361]

Good to hear your well George I was wondering where you had disappeared to .
Glad your back into the build and have a few issues sorted out in regards to design and a plan in place as im following with interest .