Supporting > Additive Machining

Idea 3D printing cylinder sleeve

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AlexS:
Hi All.

After some practical expertenting at home with 3D printen M300 (18Ni‑300 maraging) this material even hardend is good machinable. Strong, 50–55 HRC, wear resistance. Great to machine to tolerance with good surface roughness.

An idea pop up couple months ago. Could you make use this material AM methode as cylinder sleeve?

For an two stroke engine with printed ports at freedom of shape and angles. Counter parr the cylinder housing could be printed from aluminium with swirl an angled ducts. Waterjackets included.

Maybe a test for an 4 stroke engine is interesting where lubrication is more better. But have idea of an concept 2 cyl 2 stroke opposite stepped piston engine which has splash or spray lubrication like an conventional 4 stroke. Uniflow/loop flow could be created for better scavenging on part load. No blue smoke on the two stroke.

Stepped piston create an 1.5x times volume flow to displacement cylinder for the counter cylinder (180 deg phasing angle).

M300 would be a hard and though cylinder material with freedom of shape of ports. For methanol or nitro engines could also select other tool steel CX (EOS stainlessteel) for corrosion resistance. The piston rings and piston skirt need a bit of lubrication, where the oil scraper is placed quit far below compression rings. Maybe a 200:1 mixture to feed oil to pump section.

Size only make it expensive, for selecting piston rings for commercial engines. picture showed idea setup with 3 different cylinders pressed together with Loctite 510 as seal. Combustion cylinder 39mm bore around 70 euro incl shipping as reference, machining would be better to do it at home.

What do you guys think?

petertha:
I've wondered the same thing myself. One might add integral water jackets to the list of normally difficult things that possibly 3DP metals could assist. I'm almost certain one could not count on bore circularity so would have to be printed with some allowance. From what I've read on this & other forums, it machines nicely. The question in my mind is would it lend itself to lapping like bar stock, or would the microporosity create issues if its open enough to capture abrasive, much like a lapping tool? Another wish list question is could it ultimately be coated with Nikasil? I've read there are refurb shops that can re-Nikasil liners, I think it can be brought to conformance with diamond paste lappingin home shop environment but have no direct experience.

Jasonb:
I can't see anything on either of those parts that would be particularly difficult to machine so what is the reason for 3D printing.

The pistons are all turning, grooving, boring and a cross drilled & reamed hole All would need to be finish machined even if starting with a print

The sleeve would need machining all over too as the printed surface is too rough so that just leaves the ports which look easy enough to mill and even if printed I have found holes come out undersize so again you would need to finish machine them.

In both cases you would have a good length of the original bar material to grip while you did the various machining ops from solid. Not so with a print unles syou had a sizable chucking piece included as part of the print or maybe double ended two and printed as one.

AlexS:
Petertha, I was looking on your inline 6 topic. I got idea for wetted water cylinder material H13 1.2344.

"H13 tool steel (DIN/W Nr. 1.2344) is a highly heat resistant steel that offers great thermal fatigue
properties. It comprises of primarily iron alloyed with Chromium, along with other minor elements.
It’s great toughness and resistance to wear and impact lend itself to be used in a wide variety of tooling
applications for industries such as automotive and construction"

Corrosion resistance also good for nitro/methanol engines.

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