# Machining graphite pistons



## David Morrow (Dec 29, 2013)

This may already be obvious to some of you, but when I made my last graphite piston, I came up with a somewhat different approach to boring out the center. I used a Forstner bit which is normally used for woodworking. Graphite is so soft that the Forstner bit cuts through it like butter and gives a nice flat bottomed hole. They come in many sizes so, with the right sized bit, there may be no need for a boring bar to arrive at your final size. Just keep your vacuum running near by to suck up all that nasty black dust.


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## lennardhme (Dec 29, 2013)

Beauty,
thats one of my jobs for today, so a very opportune post for me.
Dont think I would have thought of that.
thanks,
Leonard


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## robcas631 (Jan 4, 2014)

I have gotten some good results with Forstner Bits. Where do you find the graphite?


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## AussieJimG (Jan 4, 2014)

I love that "nasty black dust". It makes my lathe sooooo smooooth.
It also makes my hands and everything around it dirty of course.

Jim


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## David Morrow (Jan 4, 2014)

robcas631 said:


> I have gotten some good results with Forstner Bits. Where do you find the graphite?



Why... The Graphite Store... of course 

http://www.graphitestore.com/


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## barnesrickw (Jan 4, 2014)

Wait a very long time for diamonds to degrade.


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## mrspoom (Nov 11, 2014)

I used a 2 flute end mill, it worked great and gave a square bottom.


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## RonGinger (Nov 12, 2014)

> Why... The Graphite Store... of course



So how do you select the type to use for Stirling engine pistons? They seem to have lots of types and sizes- the first  one I pulled up was $2,999 !


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## Nerdz (Nov 12, 2014)

RonGinger said:


> So how do you select the type to use for Stirling engine pistons? They seem to have lots of types and sizes- the first  one I pulled up was $2,999 !




Try this link

http://graphitestore.com/items_list.asp/action/prod/prd_id/25/cat_id/22

1/2'' and 5/8'' are reasonable prices. Ive ordered 1/2'' there and Im happy as one can get about graphite.


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## portlandron (Nov 12, 2014)

Another source for graphite is ebay, that's were I got my last two pieces.


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## David Morrow (Nov 17, 2014)

I just checked my last Graphite Store purchases.

Nov / 2012 : GT001593 - 2.00" x 7.75" long, Isomolded Graphite Rod, $25.56

Aug / 2009 : NC001360 Fine Extruded Graphite Rod, 1.25" x 24" long, GR008G, $45.43

Not sure why I ordered a different product on the second purchase unless it was an availability issue. But they both worked just fine.


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