Casting an Olds Type "R" - at 62.5% Scale

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Staff member
HMEM Supporting Member
Global Moderator
Jul 2, 2021
Reaction score
MidSouth, USA
I have seen several Olds Type "R" hit and miss engines at various engine shows, and more recently some really nice Briesch Olds kit builds here, and the tulip-top water hopper caught my attention, as well as the simplicity of the 1.75 hp Type "R".

I decided to source some Briesch Olds castings, but no luck finding any 1/2 scale castings.
Supposedly some 200 sets of 1/2 scale Olds Type "R" castings were made.

I found some 1/4 scale Olds Type "R" castings for sale online, but the dreaded "Out of Stock" button popped up.

There was an incomplete set of 1/4 scale Olds castings for sale on ebay a few days ago, and they went for over $400.00, which is somewhat surprising since those same castings go for about 1/2 of that (if they were in stock).

I considered finding some Olds drawings for sale, either from the original 1/2 Briesch kit, or from the 1/4 kit, but the problem with those drawings is that it is impossible to assume they are accurate, and there are some conflict of interest issues that could arise if using other's copyrighted drawings.

So the only viable route forward is to just build an Olds Type "R" as Olds himself would have built it, ie: by making one pattern at a time.
The dimensions of this engine will be unique to the world, but should be fairly close to a scaled full sized Olds Type "R".

I will use a few photos I found of existing full sized engines online, and a video I found, along with a couple of original Olds brochures that I found for sale on ebay.
I think I can get reasonably close to the look and feel of the original Olds "R", just using the photos and brochures.

I like a slightly larger engine size, since my eyesight is not that good, and I don't like dealing with small fasteners and their associated small taps, which tend to break off at the worst possible time.

The scale will be an odd 62.5%, and that is derived from using a 10" diameter flywheel.
I don't feel like I need to adhere to a round number scale, since there is no real reason to do so, other than "everybody else adheres to typical scales".
All I can say is I am not "everybody else".
The gears will be designed in Solidworks, 3D printed, and then cast with the teeth on them. I will use the lost wax process on these parts if necessary.

Looks like this engine will end up about 17" long, and 11" tall, before mounting it on skids.

So here is tonight's start on the flywheel, which I think came out pretty well.
Lofted ellipsoidal spokes.
The fillets were relatively well behaved. Sometimes they don't work well with compound surfaces that occur on this flywheel.

There are some subtle features on this flywheel that can be seen in the photos, such as the rim details, etc.

So off we go to building our own Olds Type "R", and when I say "build", I mean 3D print our own patterns, and then cast all the various parts in gray iron in the backyard.







Split flywheel patterns will look similar to this.
I have not added the coreprints, draft angle on the outside of the rim, and machining allowances yet.

The 3D model has been created full size, so if we want to cast a full sized engine, we can (assuming your crucible is large enough, or do a double-pour).
Or the 3D model can be scaled down and 3D printed to any scale.





I got the water hopper roughed-out.
This item was a lot more tricky than the flywheel, given that there is a vertical parting line down the long axis of the engine, which means there is a crown at the front and back of the hopper.
The crowned area is due to draft angle when the shape is extruded, and without the draft angle, the part probably will not pull cleanly from the sand mold.

It is much easier to draw square/flat shapes/parts, but that is not how patterns are made.

The downside to adding draft angle on many of the pieces is that it tends to throw off the fillet command.
For this hopper, I will have to manually fill in a bit between the top funnel shape and the hopper, since that fillet won't work in Solidworks.

This is not a bad start on the hopper.






Your 62.5% is 5/8 and fractional scales like that are quite common. For example there is the JD at 3/8 and the R&V at 5/16 which spring to mind as well as others.

Also for those of us that work in metric that is also very close to the 1/16" on the original to 1mm on the model that I often use
Sounds like it turned out somewhat common by mistake, but I will take that.

I put the shadowed letters on the water hopper.
They are raised slightly, and so they will show up in the casting.

Were the Olds always red? Most of the ones in the videos are red.



I did not think the Olds had the letters cast in, that is why they are painted with a drop shadow to make them stand out more.

The Olds is not listed on the paint colour page I usually use Paint Color Codes
Thanks for that.
I have never seen that chart.

Yes, I would guess the "Olds" was painted on; it would appear that way.

The raised parts on my model could be easily sanded off if desired, or used as a guide when painting the name on the hopper.

I traced over an old brochure, and got the "L" off to the right a bit too much.
I hate noticing things like that, but I can fix it.

The trend around the net these days seems to be people from around the world posting 3D models on GrabCad, or similar places.
I have not posted any 3D models on GrabCad, but it does sort of beg the question "Should we be making some sort of open-source library somewhere for 3D models for model engines/engineers?".

I keep hearing from numerous folks who sell castings that getting castings made keeps going up steeply, and the quality in general often goes down.
Casting availability often seems to be an issue with companies that sell castings.
Many nice old kits have gone by the wayside.

Seems like there could be maker-spaces for engine builders, where you can select the engine you want to build, 3D print the patterns, and then cast them at the makers-space.

One trend is for kit companies to offer ready-to-run engines, but I wonder about the next generation of engine builders who come along and who have lost the machining and other technical skills required to build engines in this smart-phone world.

The old days of shop classes are gone, although I did see one technical college a few years ago that required all students in one CNC class to create their own hit-and-miss models with CNC, and then assemble them and make them run.
I walked into this lab (I was meeting a friend of Bob Pearson....the Cretors guy) to buy some stuff, and there were perhaps 20 hit-and-miss models on all the tables, all running at the same time.
What a sight, and all young folks in their 20's. I do lament that they were not doing manual lathe and mill work though, but better CNC than nothing.

If you have ever attended NAMES, you can see we desperately need to usher in a next generation of model builders.
Most of the folks at NAMES I saw are in the same boat as me, ie: we are not spring chickens anymore.

I am open-sourcing every set of drawings I make, and hope to recreate some of the great old kits, or at least the drawings for them.
As far as a 3D model library, I would be open to that as long as it was open-sourced to all, and remained free.
Last edited:
i also feel that a lot of kits have castings for casting sake. I did a few patterns the other week and questioned the person why they were making "simple" parts as castings when they could easily have been done with a rotary table or even easier with the growing number of CNC machines that we are seeing in the home workshop. Four flanges that will probably want cleaning up all over anyway so why cast if they can be cut from a bit of CI or steel bar?


If kit suppliers did not need to have so many parts cast or hold stock of them it would make it more viable and less of a finantial risk to provide kits with the minimum amount of castings.

As an example I'm currently making a steam engine base don the Stuart Real but only bought the cylinder and flywheel castings as the rest can be made quite easily and for a lot less. Take for example the base casting which is nothing more than a rectangle with rounded corners and a bit of draft angle. To buy this is going to set you back £41GBP but a piece of metal to make it from less than £10GBP and you can add some shape to it if you want and end up with a better looking engine. The shaping from stock is also more satisfying than just flattening a casting and adding some holes and if like me you enjoy the machining you get more shop time for your money

Buying just the critical castings is a pretty efficient way to build an engine, in my opinion, and I agree, I think a lot of kits have "complete" castings, but many are more like blobs of metal. I think it is sort of a marketing thing.

I remember seeing some of the first casting kits I ever saw, and remember thinking "You gotta be kidding".

There are some superb casting kits out there though, no doubt.
I bought some Ball Hopper Monitor castings from Maury just before he sold his kit company, and those iron castings are the cat's meow.
They are basically like investment castings, almost.
I am not sure exactly how they got that sort of quality in small iron castings, but I suspect it had to be resin-bound sand with ceramic mold coat.

I have seen some make ceramic shell trees from wax pieces, and then pour an entire tree of parts that are extremely accurate.
For mass production, you can make a lot of parts quickly using the wax/ceramic shell/iron casting method.

I don't use the ceramic shell method because it requires a lot of special equipment (such as a wax injection machine, burnout oven, dip tank, vacuum chamber?, etc), and is a multi-step process. The slurry has a pretty short shelf life too as I understand it, perhaps under a year.
And you have to make the mold to inject the wax into first.
But assuming you were set up to do lost wax, you could do a large number of parts all at the same time.

My thoughts as far as individuals making their own castings are to sort of pool resources, so one person does not have to foot the entire bill.
This is the way many locomotive clubs operate; ie: everyone contributes to the club.

Maker's Places operate sort of like this, but I think a club dedicated to model engines would be better than a general maker's space.

A club could perhaps buy a small induction furnace, and iron castings could literally be made in perhaps 20 minutes or less.

CNC helps avoid the need for castings for everything, but I am still partial to 3D printing and making castings.
Everyone has their favorite methods, and these are often hybrid approaches.
No one size really fits all people.

Last edited:
I worked on the base today.
I had to go back and look at how I approached the base for the Galloway, since I was a bit stumpted by this part.

On previous engine 3D models, I was trying to model them basically using any method that worked.

On this particular engine, I am paying very close attention to parting lines, since that is what determined whether you can pull the pattern from the sand.

So having parting lines means having draft angle, and having draft angle on some of the surfaces greatly complicates the 3D model.

Since castings are suppose to have a uniform wall thickness, then the shell function becomes critical so that the wall thickness is maintained along the draft angle.

Untimately it becomes a matter of making compromises, but I am starting with the correct draft angles, and then correcting problems that are caused by that.

I got the base started, and I think it looks ok so far.
Still have to add water passages, bearing bosses, bosses for the various cams/gears/shafts, etc.

There is more than one variant of these engines, as I see in a few photos found on the internet.
I am not really adhering exactly to one particular variant, but leaning more towards Reliance's design on the Type "R" (to some extent).

I am using the Reliance-designed muffler, which reminds me of a canteen I had at summer camp.

This is a bit like carving a block of marble.
One cut at a time.

I am pleased with the progress I have made in such a short time.
I figured this engine was simple enough that I could probably knock out a design pretty quickly, but then again, I still have the valve train to add.






pat, you could always treat yourself to some wax filament and print your waxes, saves having to make moulds.
Great work! Looking forward to seeing it all in the flesh ... err, in the metal!
Thanks !
This has been a fun little break from work projects, which I really needed.
I like the looks of this engine, and the simplicity of it, and I hope this design will allow this engine to be built once again, either with castings or bar stock construction.
pat, you could always treat yourself to some wax filament and print your waxes, saves having to make moulds.
There was a big to-do about wax 3D printer filament about a year or so ago, and then the person who was mentioning it said something to the effect that it is not ready for prime time.
If they do get the wax filament thing worked out, that will be another game changer, and at that point I will probably start doing some investment casting.
Here is the start of the carburetor body.
I am not sure if Olds made their own carb, or whether they used one of the standard brand names of the time.

I found a damaged Lunkenheimer for sale a few years ago, and luckily there were enough parts remaining so that I could see exactly how it was made.

I still have to add the fuel inlet, and will have to figure out which side to put it on.

This may be a good item to look for to purchase as a complete unit, if one could find an assembled unit for sale in a scaled size.

From a casting standpoint, this would be a bit tricky, mainly due to its small size, but certainly it could be done.
I have not thought through the cores yet.

There is a cap that screws on the top of the body, and I have not started that piece yet.

I see a few spots I will need to touch up, but its a good start.






I think I am going to recycle the Galloway piston 3D model, and use it on the Olds.
The old hit-and-miss pistons all look very similar, as far as the ones I have seen; typically three rings.

No sense reinventing the wheel for something that won't really be seen anyway.



It looks like the original Olds Type "R" full sized gears were 32/64 teeth, judging from photos and brochures.

I don't see any standard 32/64 teeth gears, but I did find a set of 30/60 that may work, and are about the right diameter.

I think I can cast them, perhaps with the lost-PLA method, so I don't have to worry about scaled down cutter sizes.




Latest posts