Machining Carbon

[Pogo]

Hey All, Looking for someone with machining knowledge.
Quit my 3 Yr job as a machinist like 3 months ago, but still cool with shop owner.
Access to CNC and Manual lathes.

Got some bowl pushes from JoAnn Fellatio, and we were talkin about getting them machined for a perfect push.

Without further adieu,

Question #1:
Feeds and Speeds????? (recommendations)

Question #2:
Tooling Grade (Ceramic, Cemented Carbide, etc.)

Question #3:
Surface Finish Requirement (32 RMS?)
Bullshit it in on a manual lathe and throw some 240-grit on it?

Question #4:
How does it cut? Does it pepper you like cast-iron or brass? Does it put a bunch of shit on your ways?

Any assistance would be greatfully welcomed.

[Greymatter Glass]

it will cut with just about any tool made for cutting, at just about any speed. It can blow out at higher speeds.... slow feed, it's very brittle.

You can finish it however you like, 320 grit is usually enough, but newsprint (paper) will give you a nearly mirror finish.

If you have a good grade it cuts really smooth. The dust will get everywhere. It's non-corrosive, lubricating (and somehow slightly abrasive), and CONDUCTIVE. If your motors aren't totally enclosed / explosion proof you'll need some level of filtration on them. Dish soap is the best thing for clean up. Don't try to vacuum it up without a HEPA filter.

... mostly I say play with it. It's easy to work with, just _VERY VERY VERY_ messy.

Machining grades are usually non-porous and you can use water to flush it and keep dust down, but there will still be dust. Peppering is a very applicable term.

[Greymatter Glass]

to be more exact on speeds: somewhere between turning wood and turning brass....not sure what I've done it at... 800-1200rpm maybe?

[Pogo]

cool... so shallow DOC, high speed, low feed...
what about cutting and tapping????
(If i can turn my pushes into twice as many with handles that would rock!!)

[Greymatter Glass]

I cut on a diamond wet saw... but any HSS or carbide blade will work, the more teeth the better and so on. expect LOTS of dust if you cut it dry.

You can cut it on a lathe, there's no heat or binding issues like you'd have with metal - any angle, any depth is fine as long as you're not feeding too fast.

Tapping works fine, I have only done 1/4-20 and 3/8-16, anything smaller and the threads will just wear out too fast. I'd only hand tap them - you can hand turn the lathe I guess. Coarse threads work best.

[Pogo]

What a wonderful tome of knowledge your head is, Greymatter.

Hearing about it first makes doin' it easier.
(The bowl pushes i got were JoAnn Fellatio's first set. If i can turn them into two sets I can give her half of them back as a token of my gratitude!)

[Greymatter Glass]

sweet.

Seriously tho... shit will make a mess.

[somewhere]

Sounds like you have it under control but I'll add my 2 cents for what it's worth.

Bowl pushes sound a little rudimentary for a machine shop. I would forget tapping them graphite it so cheap forget the handles. If you really want handles I'd sleeve the outside with copper pipe (just another idea). I'd shape the ends by hand on a wet belt or just use sandpaper. Then cut them with a fine tooth hand saw.

I just finished making some fly cutters for some molds to make tops. That should let you know how easy graphite machines. I made the cutting blades from mild steel and shaped them on the grinder then the belt sander. I also made a variety of marble molds the same way. Run the machine slow so it doesn't throw graphite powder all over the shop.

Tapping when necessary works but I found if you drill it slightly under then cut your bolt to make it into a self tapping thread works great. This is an easy process just cut into the threads at the tip to make a cutting grove at the beginning of the threads.

Clean up. Graphite is a nuisance but it's not toxic. It will short out electric motors but it does lubricate. I stick an old sock over the end of the hose on the shop vac and it does reduce the amount of carbon that will coat the inside of the vac. I let the sock suck in about half way and put a rubber band around it. Throw the sock away when your done.

Here's a good tip for making handles for paddles. (I learned this in the scientific shop I worked at) Copper pipe about 1/2" and a copper T fitting. Cut the top of the T open and slide it over a piece of steel same thickness as the graphite. With the pipe inserted into the bottom of the T smash the fitting flat on the steel just like it was sandwiching the graphite then slide it over the graphite drill two holes and bolt it to the paddle. I can post a pic if you can't imagine it.

Bottom line it's easier to machine cut drill graphite then it is wood. Like Doug said it is messy.

[Greymatter Glass]

dude +1 for the sock on the vacuum idea... awesome.

[kilgroth]

If you do tap your graphite for handles or whatever, add some thread locking stuff. The threads will wear out over time and become useless. Be very cautious of the dust. It will short out motors, computers, ect...

[Pogo]

you guys rock... will be a couple days (maybe weeks?) till i get the time to go to the machine shop and play. Will go with much confidence, however. : )

softer than wood and messy as hell. got it.

[RaindropRising]

I made myself a graphite reamer, I snapped the handle off of an old campfire sandwich cooker that was broken, got a drill, mounted a small rock grinding stone in the drill with the drill mounted to my bench, and I slowly but surely over an hour made a preeetty symmetrical reamer with a thick rod of graphite. Not perfect, but it only needs to be perfect on one side for flaring, which is all that I do with it. And for the handle I simply used a dremel drill to drill the hole in the bottom, and used gorilla glue to glue the sandwich-cooker handle to it. The thing works beautifully!

[Jennifer Menzies]

Oops, I guess I had a sex change over night, as my log in says I am Jennifer Quaid. Oh well, worse things have happened...

Few of points from my perspective...

1. Graphite is toxic and unhealthy. The graphite block is an amalgamate of carbon, binders and inhibitors(usually anti-oxidizing). Graphite might not be toxic(unless it was reclaimed from a TN reactor in Russia or China), but the other ingredients very well can be. You can get a MSDS from Poco.

2. Graphite causes the same effects as bakers lungs. It collects in the alveoli but the body has a hard time with the removal, so there is accumulation.

3. I advise against threadlock. Even Loctite 266 or 513 high heat will give in our working conditions. I suggest a metal epoxy such as jb weld or lab metal. This is only if you don't want to replace the graphite later.

4. Always calculate a little schwag into your taps and recessed fittings. The expansion between the graphite and metal attachment will cause the graphite to stress and crack if the tolerances are to tight.

5. Do not machine graphite even close to your glass shop. Ventilation pulls in the dust and makes your torch look like the world's biggest sparkler. Most messy shit I have ever worked with, period(5-30 micron grain size on the good shit). It will leak from everywhere, it gets in everything and your wife will get damn tired of black smudges on her switchplate covers, doorknobs, cabinets, bottom of tub, carpet, etc.
(thanks Jennifer)



Hooray black boogers(those who know, know)

Peace,

boxfan

[Icarus]

Hooray black boogers(those who know, know)

Hell yeah hooray, those are the tastiest ones after all.

All kidding aside, thanks Greymatter, Somewhere and Boxfan (with or without boobs). This is one of the most informative thread on working with graphite that I've seen on here. Rep points for all of you.

[Boxcutter]

I've been getting graphite residue on my pendants/marbles when i use my marble mold. What is the best way to clean your graphite molds/paddles?
It seems when I just wipe them down with a paper towel, it just makes more dust. Wet-cleaning doesn't seem much better....
What is the best method to remove getting little bits of scum on the surface of my glass?

[loydb]

I use a paper towel and ISO alcohol to clean my molds.

I've done a little bit of graphite machining -- I move my lathe/saw/sander into the yard and work outside on sawhorses. That way I can hose myself down before re-entering the shop/house.

loyd

[Boxcutter]

thanks i'll try the isoprop

[Illbilly]

My buddy runs a machine shop across the street and he has a graphite specific vmc... I have talked to him about it because I wanted to cut graphite on my old cnc mill. He kinda discouraged me, he runs all his graphite parts with a spindle speed upwards of 20,000 rpm and uses diamond tooling. He says that the graphite is so abrasive that it will eat right through hss or even carbide tooling.
Let me know if anyone has any luck with lower speeds and softer tooling. I think these requirements are more nessessary if you are running production jobs 20 hours a day?

[faded]

can you run milk on it?


all these machinists and no one owns the book? i can go look it all up if you'd like? http://new.industrialpress.com/node/970


edit: - http://www.crystallume.com/html/technical.html

[RamblezMarblez]

I was thinking of making a stickstack tool with my 1" graphite rod with a dremel tool. Any tips/ideas?