Graphite

[J. Tranter]

Where can someone get graphite for pistons from?

 

[Philjoe5]

McMaster-Carr (mcmaster.com) sells graphite rods in various diameters. As an example:

Part Number 9121K74
1" Diameter, 12" Length, Graphite Rod
In stock at $37.83 Each

Cheers,
Phil

 

[Powder keg]

There is usually a bunch on Ebay for pretty cheep.

Ebay

Wes

 

[J. Tranter]

Thanks for the reply guys.
John

 

[shred]

Very small pieces (0.3"x0.2"x2" or so) can be found at art supply stores in with the drawing tools.

 

[rwells]

I got some Stirling Engine plans from Jerry Howell. He also some precision bearings and graphite for pistons in the engines.
The following address should get you to his site. I am building the Victorian Stirling Cycle Engine and will use graphite for the piston.
http://www.jerry-howell.com/Vintage.html

Rick Wells

 

[mklotz]

ENCO sells EDM rods in sizes from 0.125 to 2.0 in 12" lengths.

http://www.use-enco.com/CGI/INLMK3?PMK0NO=882312

Use the free shipping code, PFSHS7, on your orders of >=$50.

 

[BobWarfield]

Aha, the Enco stuff says its for EDM. I wonder if it will be especially easier to machine?

I'm seriously tempted to add a rod the next time I order from Enco (gotta save up for that $50 minimum!) just so I can play with it a little bit.

Cheers,

BW

 

[mklotz]

I have some but I haven't gotten around to machining it yet. Aren't EDM electrodes routinely shaped (i.e., machined) to cut special shapes?

 

[BobWarfield]

I have some but I haven't gotten around to machining it yet. Aren't EDM electrodes routinely shaped (i.e., machined) to cut special shapes?

Exactly!

What I don't know is what (if any) the "tricks" are. Speeds and feeds, best tooling, different graphite compounds, etc.. I bet it makes a difference on how well things go though!

Should be easy enough to research on the web. The EDM guys use it to make sinker dies, which can be quite intricate.

Best,

BW

 

[Davyboy]

Yes I have machined graphite for sinker EDM's. Worst part of it is the mess. And you thought cast iron was black! Keep the SHOP vac handy and use it when cutting to suck up the black cloud. DON'T use Mama's good vac!

No special tricks for machining, just when milling, the small fins at the edge will want to break out, taking some of the corner with it. Climb mill as needs arise. The fins can also break off in the middle of a flat, leaving a divot in the face, best to allow for a light ( .010-.015 ) cleanup cut. Drill and tap as any steel or plastic. The graphite can be filed, sanded and polished with scotchbrite type stuff. Use latex gloves when sanding or polishing, keep your hands a bit cleaner. Wipe it with a rag after cutting, too.

I see alot about this "self-lubricating" material. You should see a carbide ball endmill after about 2 hours at 3000RPM, contouring a mold form. Wears the flutes right gone. Probly not anything we got to worry about on a scale as we'll see in our shops. The use of graphite as a piston I think is quite interesting, I'm trying to get some for myself at a budget price...

Hope this helps. Dave

 

[shred]

FWIW, I found a couple graphite rods ~0.75" x 3" in a big artist supply store the other day, filed under "chunk graphite" in the pencils-and-charcoal aisle for about $2 each. They had some larger randomly-shaped chunks of graphite and the 12mm pencils as well.

 

[PTsideshow]

Here is a site for graphite used to turn nozzles for rocket motors, for the home body. they also have some infor on it with some pictures of it being worked.http://www.aeroconsystems.com/graphite/index.htm

It also makes a good hot plate for holding or soldering or brazing stuff, or working Glass.
;D

 

[Bogstandard]

If you have any local machine shops that use EDM for profiling, the electrodes can only be re-machined so many times, after that they are usually discarded.
This is my lifetimes supply that I grovelled for and got for nothing. These were used for profiling turbine blades in jet engines.

If you don't ask, you don't get.

John