3d Printing in scale engine building

[rapidlaser]

I have posted this to show a con rod I had 3d printed as a test to see if it is viable and what forum members and engineers think of using these processes in scale engine building and also to see if I can get any advice on the next steps to produce the finished con rod and discuss other materials, there are a range of metals it can be printed in including cobalt chrome, nickel alloy, stainless steel and titanium, this one is printed in maraging steel I have never built a scale engine and am not an engineer as I understand it, it would need to be hardened and then the meeting faces and the big and small ends would need to be ground. The con rod is a copy of a 1/4 scale after market Subaru Imprezza WRX flat 4.

 

[lohring]

You must work for a company with commercial 3D printing capability. Hobby grade machines are limited to wax 3D printing for investment casting of a metal prototype. Limited production might involve printing the mold for the wax patterns. Can your 3D printing costs match investment casting? I've been quotes around $200 for a small two stroke cylinder in aluminum or $80 for a chrome cobalt model propeller. In both cases I supply the was pattern. Take a look at the 1/4 scale Merlin for what you can do with investment castings.

Lohring Miller

 

[Cogsy]

Do you mean you are just scaling everything down exactly from the original engine? If so, you will run into all sorts of issues of material strengths/thicknesses. Inverse square and inverse cube laws mean you will need to make many design changes and compromises from original scale to achieve a running engine. For your conrod alone I would expect it to be better suited in aluminium than steel for mass reduction, meaning comparatively smaller diameter crankshaft journals and gudgeon can be used, allowing a 'beefier' conrod than scale, more suited to handling the stresses of the engine.

 

[Nick Hulme]

It looks nice, will the cost frighten off MEs though?

 

[rapidlaser]

It looks nice, will the cost frighten off MEs though?

Costings I have so far are as high as £165 for a one off and as low as £35 for 150 off.

 

[rapidlaser]

You must work for a company with commercial 3D printing capability. Hobby grade machines are limited to wax 3D printing for investment casting of a metal prototype. Limited production might involve printing the mold for the wax patterns. Can your 3D printing costs match investment casting? I've been quotes around $200 for a small two stroke cylinder in aluminum or $80 for a chrome cobalt model propeller. In both cases I supply the was pattern. Take a look at the 1/4 scale Merlin for what you can do with investment castings.

Lohring Miller

No I don't work for a company that has one of these, I had it printed at a 3d printing bureau.

 

[lohring]

Could you tell us what company, and most important, the cost?

Lohring Miller

 

[stevehuckss396]

Could you tell us what company, and most important, the cost?

Lohring Miller

Cost was already posted: "Costings I have so far are as high as £165 for a one off and as low as £35 for 150 off."

 

[rapidlaser]

I have done more research and think the conrods could be titanium as it's much lighter 4.75 grams in titanium and 8.5 in maraging steel, The maraging steel can achieve 50 on Rockwell hardness most cranks are 40-50 so could be good for crankshafts and it might even be hard enough for camshafts and think it can do rockers too.
I like the 3D printing route as it allows you to be more creative with the design and 3d printers can print such intricate shapes. The cost is obviously much higher but if I can get a deal with a bureau to give me a quantity discount on all the parts I can print then it might be cost effective.

 

[rapidlaser]

Could you tell us what company, and most important, the cost?

Lohring Miller

Just do a search for DMLS Bureau and there are many dotted around the country.

 

[Wizard69]

A while back in one of the model railroad building sites a guy had a few parts manufactured via a 3D printing service. They where locomotive parts and actually had what i thought was a very reasonable cost. In this case it was a matter of complexity and form that made the 3D parts cheap compared to trying to have them machined. In this case the designer and builder didn't gave a well equipped machine shop either.

If you ask is it a good idea to 3D print parts id have to say that only the builder can answer that. Some are after the challenge of machining everything themselves. Some want to build a unique model and place a higher importance on that than machining everything themselves. Also investing in a full machine shop is not in everyones budget but at the same time 3D printed parts allow model builds that aren't otherwise possible.

In the end this isn't much different that buying castings as opposed to casting your own iron. To each his own.