Pattern for a Steam Engine

I recently got a Prusa 3D printer (about a week ago), and have been having good luck with it (so far) printing patterns for a steam engine.

The filament is PLA.
I am using stock settings for PLA, with no adjustments to anything.

I like this printer.
I wish it had a larger bed.

It has been cold and/or wet/rainy every day for about the last two months, and so a good time to make patterns indoors, in anticipation of the good weather.

 

More pattern prints.

 

More pattern prints.

 

The largest piece has a bit of trouble pulling up off the heated bed, but I was able to complete most of that print (the large square one), and will be able to use that pattern.

The larger pieces had to be cut up into printable sized sections, and those will be glued together.

Each piece had to have machining allowances, draft angle, parting lines, alignment pin holes (when I remember to add those), and shrinkage added.

So far, it has been a fun project.

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Thanks, its a great little machine, and opens up a lot of possibilities.
The accuracy is great for small parts and details.

Its also very smart, and when it runs out of filament, it waits and asks you to load a new reel, and then picks up where it left off as is nothing happened.

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I have had several people mention that process, but I am not sure if it is perfected enough for me to try it.
I hear about spotty results sometimes, so I am biding my time.
What we need is a good wax printer filament, now that would be cool.
Perhaps they do have a good wax filament now?

I do use a binder and fine-grained sand, and so it picks up some very fine detail, such as a human hair, and it does it without any mold distortion, so the parts come out very close to the size they will be after machining.

I can make castings that are better than most that you can buy in kits.
There are a few very high quality kit castings out there, but high quality iron castings tend to be somewhat rare from what I see on the market.

And the castings I make are not available in kit form anywhere, so that is kind of cool.

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I finally learned how to make patterns in wood and steel, and can basically make any pattern by hand with good quality, but I have about 6 engines in 3D that I want to make, and hand-made pattern making is time consuming, and not quite as accurate as a 3D printed part.
This is my way to speed up the process, and perhaps get a few engines cast this year.

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Why not download meshmixer and then cut the pattern up into pieces. That way you can print out a much larger copy than your bed and then glue the parts together. I did that with my extruder screw and it worked very well. The screw is over 2 feet long and the bed is maybe 12 inches across?

Very cool project. I can't wait for the casting.

 

I know some people who print out the parts and just assemble them to make a functional plastic engine.
These parts do not mate with the respective adjacent parts because of the draft angles and machining allowances added, but it will all fit once the castings get machined.
My thoughts are to cast permanent patterns in aluminum, and possibly match plate arrangements.

I actually cut them in solidworks, using one or more parting planes, and then show/hide the appropriate section to generate an STL file, which then gets converted to a gcode file in the slicer program.
I am excited about making some iron castings.
I will have some challenges with cores, but I hope to get everything made.

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This is an engraving of one of the original engines, without the reversing valve on top.

 

Very cool!

Is that image posted a turbine?

 

It is a two-piston steam engine, with both pistons in a common crankcase.
The pistons are flat, like slices of bread, and the crankcase is also flat like a toaster.

There is an inner piston that rides inside of an outer piston.
The inner piston moves up and down only, and the outer piston moves side to side only.
The inner piston has a hole in it, and the crankshaft pin rides in that hole.
The inner piston rides up against the outer piston.

With a reversing valve, the engine can be reversed very quickly, and with a remote reversing valve, the engine can be mounted down in a mine, and the valve mounted at the surface.

The concept for this engine was created by Roots, and Dake made some changes too it, and mass produced the engine for a number of years.

Here is a video of a motion study (I will try to make a better motion study, this one is old), an some screen captures of the internal parts, here:



And here is a video of a small model engine that my dad built:

 

I wonder how much machining the cast parts will need to be usable. Could you get away with no machining on some parts?

 

Pat that is a nice printer. It is the same model my neighbor used to print the gear I sent you.

I bought a printer over the winter (more of a kit) with a 330x330x400 print area. Great print area, but this thing needs nothing but upgrades and more $$$.

 

I had a 3D printer a few years ago, but it was an absolute dog from both a hardware and software standpoint.
I vowed to never buy one again, but the price came down, and the quality and reliability appear to have gone up, so here I am with one again.

I hope to get around to molding/casting the windmill gears and also the bearing cap soon.
The weather is starting to get warmer, and we have had two days of sunshine, after perhaps 30 days or rain.
Maybe I can actually get some flasks built this weekend, and make some molds.
I am ready to make some iron castings this year. The bad weather really puts a damper on foundry activities.

The mating surfaces of the parts need a light skimming to get them perfectly square and flat, and also to bring them down to the exact size, since a little material is added to the model to the mating surfaces to allow any casting irregularities to be machined off, usually between 0.05" and 0.10" added.
The bound molds are very accurate, and if I used regular green sand molds, I may have to add more machining allowance.

The flywheel rim could be used as-cast if it comes out of the mold clean (sometimes it does), but skimming the surfaces makes it look much better.
There is also draft angle on the parts, and any surface that is bolted in place must be machined flat, else the bolt will shear off when tightened.

The draft angle on the outside of the rim also needs to be machined off.
It is probably difficult to see in the photos, but every surface that is in line with the direction of pulling the pattern has at least a 5 degree draft angle, and sometimes a bit more if such as the deep crankcase cavity.

 

I was trying to see the draft on the parts, and couldn't see much. Good to know you have 5 degrees.