Line Boring Metal 3D Print

[Mtndew]

$30 plus $30 shipping from CHINA. Quotes from the US and Canada are 10x plus that number. Is the quality the same, I have no idea.

Is it worth the extra cost when you find out this one is a hunk of shit or you scrapped this one by using a tapered reamer?

 

[Novaguy]

If China can make good metal prints on machines in the $50K range and make a profit on sales like the OP's (and it's a solid, homogeneous part), then we've got some issues to worry about...

It boggles my mind the price they can make things and still turn a profit. I read this book while trying to figure it out.

The part in my hand cost $45 to make from a type of maraging tool steel and is shot peened. It's the head for a breaker bar and I have taken it up to 276 ft-lbs without failure, so I guess it's homogenous lol.



Quote from the same company, the parts were initially printed in Aluminum and Ti.

 

[Novaguy]

Is it worth the extra cost when you find out this one is a hunk of shit or you scrapped this one by using a tapered reamer?

Absolutely not. Because I'll have saved hundreds on a prototype. If it needs "certs" or is a production part, maybe it needs to be made outside of Asia.

 

[Milland]

With the cost of that part I'd have ordered at least two, so I could have a fallback if I messed up the machining.

The point about it being soft and gummy during machining is a good one, be careful of it pulling out of fixtures due to that if you're doing something sketchy. But with DLS it may be a little harder from the process itself (don't know for sure).

 

[AlfaGTA]

You are going to machine the piston OD ????
This is a prototype,so what is it to verify?
Pistons have “cam” and taper.
Running a straight/round slug will require excessive clearance offsetting or at the least call into question any running results.
Cheers Ross

 

[DDoug]

Best I can tell, that is about the same as A360 aluminum.

Without heat treat, machining it will be like machining bubble gum.

,,,on a HF mini lathe by "I'm not a machinist"....

 

[Novaguy]

This is a prototype,so what is it to verify?

Whether a generative designed, 3D printed piston will work right off the bat.

Pistons have “cam” and taper.

Yes, I mentioned this in post #20 to avoid comments on it.

Running a straight/round slug will require excessive clearance offsetting or at the least call into question any running results.

Like the OEM piston, the ring groove area will be ~0.5mm smaller than the OD and ROUND. Seeing as the skirt is much shorter and narrower than stock, I will test out how it goes without making it oval shaped and tapered.

 

[Novaguy]

,,,on a HF mini lathe by "I'm not a machinist"....

I can probably guess what "D" stands for in @DDoug

So only machinists can turn aluminum? I might as well start taking bets on this now.

If it's gummy, I'll heat treat it

 

[jccaclimber]

What the community in this thread is doing is similar to what I’ve seen happen in a few of my last jobs. It’s well accepted that only processes X, Y, Z can make an acceptable part. Usually that’s true, every now and then someone comes up with a quick 90% correct hack. It isn’t “right” but it’s right enough to answer the question they want to answer. It lets you answer an engineering question without all the burdensome overhead of a part that lasts forever and works 101% of the time. It also lets you answer that question faster AND cheaper.
Innovation sometimes takes a mysterious path.

 

[Milland]

In fairness, I.C. engine pistons have been designed and developed for over a century now, and their requirements are well understood. I think the OP should at least have his piece hardened, which will help it machine better and be less at risk of material transfer in use, but that's likely much more than what he spent for the blank.

Cutting the ring grooves will be the trickiest bit if the metal is gummy. No good way to DIY the barrel, but a shallow taper for the crown could be approximated.

 

[jccaclimber]

Thinking about oil squirters under pistons and some of the other recent developments for piston cooling and such, I think you’ll find there’s still a decent amount of development going on there.

I’m assuming if the OP is working on bike pistons it’s to try to put some of these recent development concepts into an existing engine, vs. just a same-as.

 

[Novaguy]

What the community in this thread is doing is similar to what I’ve seen happen in a few of my last jobs. It’s well accepted that only processes X, Y, Z can make an acceptable part. Usually that’s true, every now and then someone comes up with a quick 90% correct hack. It isn’t “right” but it’s right enough to answer the question they want to answer. It lets you answer an engineering question without all the burdensome overhead of a part that lasts forever and works 101% of the time. It also lets you answer that question faster AND cheaper.
Innovation sometimes takes a mysterious path.

Well said!

I worked with a guy at my last job; absolute mechanical savage - he had no engineering degree but he could design like nobodies business. He made a cycloidal gearbox, hobbed the worm gears and everything in his garage! It was about 90% correct but as a prototype it showed the idea had promise. Then we had real gear cutters cut it for production

Had he come to PM to see if it was feasible, he would've gotten a million excuses for why he couldn't and shouldn't do it.

 

[Novaguy]

In fairness, I.C. engine pistons have been designed and developed for over a century now, and their requirements are well understood. I think the OP should at least have his piece hardened, which will help it machine better and be less at risk of material transfer in use, but that's likely much more than what he spent for the blank.

Cutting the ring grooves will be the trickiest bit if the metal is gummy. No good way to DIY the barrel, but a shallow taper for the crown could be approximated.

I'm sure there were a few round pistons early-on that worked just fine. Might've slapped like crazy and didn't go for 200k mi, but didn't need diamond tooling and special cam profile cutting machinery.

I actually wonder if the original Benz in 1886 had straight, round pistons?

 

[Garwood]

Thinking about oil squirters under pistons and some of the other recent developments for piston cooling and such, I think you’ll find there’s still a decent amount of development going on there.

I’m assuming if the OP is working on bike pistons it’s to try to put some of these recent development concepts into an existing engine, vs. just a same-as.

Piston oil squirters have been commonplace for atleast 75 years.

 

[Milland]

Piston oil squirters have been commonplace for atleast 75 years.

Ya, they call them Diesels...

 

[empower]

Hi again Novaguy:
Last time I checked, an EOS DMLS machine was 3/4 of a million dollars and it had to go in a special room equipped for handling the hazardous powdered metals safely.
The metal feedstock was breathtakingly priced too.

You gotta make an awful lot of 30 dollar pistons every month to make the payments on the machine.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

this, i have a few friends that do DMLS work, and its everything but easy. one shop has spent a few million dollars in R&D developing methods, techniques and procedures to get reliable prints. there is no free cake.

 

[Nmbmxer]

Novaguy, some guys are giving you a hard time but I think it’s a mess project and the break bar head looks like the output from an iterative FEA optimization — neat stuff. We’ve done similar things, taken a popular bracket or component and let ANSYS churn on it over a weekend and see if there are opportunities for weight / cost reductions.

I do think it would be helpful to get a few more tools to make your life easier, if you have a unexpected manufacturing error that results in a prototype failure during testing it can lead to confusion and setbacks. For a home project that’s one thing, for a business it’s different.

 

[memphisjed]

what is the concept to prove with this? a tuna fish can will work as a piston. Not long, not efficiently, but will work.
Will this concept deliver more power to wheels with less btu? Will it last longer?

 

[jccaclimber]

Piston oil squirters have been commonplace for atleast 75 years.

Fair point, allow me to rephrase. There is an awful lot of knowledge about pistons which is not being utilized in every engine. Improvements in manufacturing over the past decades combined with some new methods along with more effort being dedicated to emissions and whatever else mean there are things we can now easily do that may not have been done yet.

I’m guessing cylinder head and piston geometry is different in a direct injection engine than one with an external fuel source. I’m also guessing geometries are different in spark ignition vs diesel engines.

I know there are some interesting things you can do with cooler temperature components that are 3D printed due to variable density and hollow sections, so I wouldn’t be surprised to find out the same is true of pistons with metal 3D printing.

 

[crossthread82]

Best I can tell, that is about the same as A360 aluminum.

Without heat treat, machining it will be like machining bubble gum.

Can confirm, even heat treated those DMLS Aluminum prints machine like shit. It's almost mind blowing how soft they are while not being made of actual butter. God forbid you have to put threads in it, you have to use a form tap, cut tap will just yank the threads out as it goes.