Galloway Castings

[PatJ]

I started making a bar-stock Galloway, not to any particular scale, but with flywheels about 10" dia.
As I recall, the 1/4 scale was smaller than I wanted, and the 1/3 scale was too big, so I think I was between those sizes.

This was a few years back, and just learning 3D.

I have since got into backyard castings, and so I will revisit this engine and try to cast a one-piece frame and cylinder from cast iron.
I don't really care for the bolted frame/cylinder kit designs since that is not how the originals were made.

I think I have enough photos to go by, and my dad had two that were 7.5 hp, one being a round rod.
I remember the simplicity of this engine, and how well it ran.

Here is a piston I made from gray iron bar stock, but I need to cast this to make it lighter.
And my first attempt at a 3D flywheel, which is only partially correct.

[PatJ]

My dad's forged-rod Galloway.

[Jasonb]

Pat the 10" flywheel is about right for a 1/3scale 5HP engine but if you are going for your Dads engine then as you say something like 3/10 scale. You will have some fun with the cores if you do a single casting to get the water jacket around the cylinder.

Here is a challenge for you, cast wheels for a Hand portable cart Those 5/32" dia spokes won't be easy to get the iron to flow down. Should be able to post my finished wheels next week.

J

[PatJ]

I am not really trying to match a particular engine, just trying to find a convenient size that will fit the lathe and not have fiddly sized parts.

I noticed that the galloway has a bolt-on water hopper, and I would make mine that way.

Many of the hit-and-miss engines did have the water hopper cast as an integral part of the cylinder and frame, but I would have to think about that core.  Obvioiusly if they use to make them that way, then they can once again be made that way.

For those wheels, I would use steel rods, and cast the hub and rim around the rods, as was done on some of the old John Deere tractor wheels.

[PatJ]

Hey Jason, I found your Galloway thread:
http://www.modelenginemaker.com/index.php/topic,2160.0.html

Great work as usual.

[PatJ]

It looks like the horsepower ratings were 2.5, 5, 7.5, 10 and 15.

My dad's was a 7.5 hp if I recall correctly.

And the flywheels for that engine were about 36" dia.
Bore was perhaps 6.5" with a 12' stroke, to give a compression ration of about 5.25:1.

So while I don't like the flywheels to get too big, I also don't like trying to handle and machine small parts, so my leaning is a 1/3 scale of the 7.5 hp engine, which would give a 2.17" bore, a 4" stroke, and a 12" dia. flywheel.

A bit on the big side, but probably castable/machinable with the equipment I have.

[PatJ]

Here is where I got with the cylinder/frame model tonight.

More work to do on this, but getting it roughed out enough to be able to make patterns.

Water drain hole is on the bottom of the cylinder jacket.
The compression release is on the side of the cylinder, down the stroke a bit.

Still need some bearing flanges, and miscellaneous bosses.

I will probaby have to make the curved parts of the frame using sheet metal, and then glue some foam or thin plywood layers to the inside to get the correct wall thickness.
The shape of the interior of the frame will be defined by the frame walls.

This is a 3D PDF, so you can click on it, and pan/tilt/zoom it.

Now I need to determine cores and parting line.
I guess parting line vertically down the long axis.

The bottom of the frame will be open, and there will be a core print extending down from that opening.
Another core print will go upwards out the top of the water hopper opening.
A core print out the bore where the cylinder head goes, and one more print at the ignitor hole.

The water holes in the end of the cylinder would probably be best machined after casting to simplify the water jacket core.

[Jasonb]

Looking good Pat, the base is open at the bottom which should make it a lot easier to put a core in.

PM sent

[PatJ]

Here is today's progress on the 7.5 hp Galloway.

This frame and cylinder are very tricky to model.

I don't have a way to add the compound curves at the back of the cylinder and at the back of the base yet, but don't really need those to make the pattern, since those can be manually added.

[PatJ]

And the 3D PDF file.

You can pan/tilt/zoom with this file.

[PatJ]

The large parts of the engine have been modeled, including the gears, and the engine operates well in simulation so far.

Now on to the small parts, then it will be 2D drawings, and then the pattern making can begin.

This engine is about 20% larger than a 1/3 scale 5 hp Galloway, with flywheels just under 12" dia.

[PatJ]

And a video of the first simulation run.

[PatJ]

And we got gears !!!!     

[PatJ]

I drew the gears for this engine with the correct number of teeth, and the correct approximate tooth shape, but the small gear got a bit thin at the keyway.

I need to draw the gears accurately so I can cut them, and I remember that in the past there has been a great deal of discussion about gear cutting.

Seems like you start with a chart for number of teeth, and then get the blank dimensions, and then select a cutter type, and go from there.

Anybody got a quick synopsis on making gears?

I have the standard cutters and an indexing head, I just need to dial in the correct geometry for the blanks and cutting setup.

[Jasonb]

Whats the centre distance between the two gears? then its easy enough to work out but if you have just plotted it without a specific PCD it may need tweaking to suit standard gear pitch