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Iopo234

2 stroke engine

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Hello,

I'm new to this so sorry if this is be wrong placw to ask this, but has anyone created a working 3d printed combustion engine? (one that actually runs off of gas or some sort of combusting liquid)

I would think that the plastic model wouldnt explode as long as the size was kept quite small (like 4ccs).

Also, I was thinking that one could print out the parts, make a mold around them, melt the plastic part out of the mold, and then cast a real engine with metal. What would be some flaws with this idea?

Just wondering if someone has done this.

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If you actually want to incinerate gas, regular thermo-plastic will not survive this heat so I don't think this can be 3D printed. A prototype can, but not with actual combustion.

I know of Eventuri who does some fit testing and actual prototyping with his models, but only very briefly. He uses some special kind of rubber (I believe he mentioned some reference to a scuba diver suit) to wrap around the printed parts and protect them from the heat. But I imagine this only a potential work-around for easy accessible parts. Not an entire engine.

Making a mold to make metal parts could work.

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Any combustion goes way over 1500°C. You could make an educated guess of the temperature, based on the color of the flame: compare it with color temperature charts like those used in photography or interior lighting. Plastics can only handle about 100°C maximum, and PLA even only 50°C. And plastics do burn very well. Further, they don't provide the required cooling. So there is no way you could make a functional combustion engine in plastic. You will have to go for the casting method.

You might be able to make an engine running on cold compressed air, provided that it has very good lubrication, low friction, and low RPM. But I guess it won't be easy and won't last long. Might be good for a demo-model, not for real use.

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Any combustion goes way over 1500°C. You could make an educated guess of the temperature, based on the color of the flame: compare it with color temperature charts like those used in photography or interior lighting. Plastics can only handle about 100°C maximum, and PLA even only 50°C. And plastics do burn very well. Further, they don't provide the required cooling. So there is no way you could make a functional combustion engine in plastic. You will have to go for the casting method.

You might be able to make an engine running on cold compressed air, provided that it has very good lubrication, low friction, and low RPM. But I guess it won't be easy and won't last long. Might be good for a demo-model, not for real use.

There are some cool YouTube videos of people doing this with bought models (styrene type) such as the Revell 1/8 scale 8 cylinder and others. Some are great because they have see through parts that show the actions of the engines and timings.

May be a good place to start if you want to play with that philosophy.

Or, metal cast as suggested above. Not only is the heat a big problem, but the expanding force of each firing.

I think the closest you could get is with a printer that can print in Kevlar, Carbon Nanotube or Fiberglass. And, even then, I doubt it is a good idea. Dem tings be metal fer a reason.......

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Yes, model engines are fascinating. Sometimes non-functional demo-models, but sometimes also really working models in metal, or metal with glass cylinders. Some of these Youtubers have made fantastic things.

Also, I just thought about it: there do exist companies that can 3D-print in metal. Some only for decorative items (thus low dimensional tolerances) such as Shapeways, but some also for industrial applications with higher accuracy. They often use this for injection mould making.

So what you could do is design the model, print it in plastic first to test if everything works as desired (no valves or cylinders hitting each other etc...). This will save you a lot of time and money. And then have it printed in metal. Don't expect it to be cheap.

But I still doubt if it can be done without a lot of post processing. Industrial iron or aluminum cast engine blocks also require a lot of machining to get them within tolerances.

The best known industrial 3D-printing companies in Belgium are, as far as I know:

Melotte: https://www.melotte.be (specialised in metals)

Materialise: http://www.materialise.com (specialised in really big prints, mostly plastics, for car manufacturers)

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Yes, model engines are fascinating. Sometimes non-functional demo-models, but sometimes also really working models in metal, or metal with glass cylinders. Some of these Youtubers have made fantastic things.

Also, I just thought about it: there do exist companies that can 3D-print in metal. Some only for decorative items (thus low dimensional tolerances) such as Shapeways, but some also for industrial applications with higher accuracy. They often use this for injection mould making.

So what you could do is design the model, print it in plastic first to test if everything works as desired (no valves or cylinders hitting each other etc...). This will save you a lot of time and money. And then have it printed in metal. Don't expect it to be cheap.

But I still doubt if it can be done without a lot of post processing. Industrial iron or aluminum cast engine blocks also require a lot of machining to get them within tolerances.

The best known industrial 3D-printing companies in Belgium are, as far as I know:

Melotte: https://www.melotte.be (specialised in metals)

Materialise: http://www.materialise.com (specialised in really big prints, mostly plastics, for car manufacturers)

Did not even think of the metal printers.....duhhhhhh

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https://ultimaker.com/en/stories/18361-using-ultimaker-3d-printers-for-manufacturing-at-siemens

"To do so they found a specialized foundry based in Sydney, who take the component 3D printed in PLA and place it in a wax form. This form is dipped in a ceramic slurry and left to harden. The PLA is perfect for the next step, as during the firing stage the PLA is completely burnt off. The result is a cavity mold that they can directly cast steel into."

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