Granite or steel surface plate for machine base?

[will gilmore]

Has anyone tried or succeeded in using a used granite or steel surface plate as the base for a machine tool? I saw this on ebay:

http://cgi.ebay.com/Starrett-B-Cryst...QQcmdZViewItem

It has fixtures on it so its obviously possible to put fasteners in to it. Heavy, good vibration damping, flat. Anything I'm not thinking of?

[ironDigit]

I guess steel would be easier to custom drill for mountings and stuff but great base if you got one lying around.

i even saw one of them fancy diam measuringstations transformed into a minilathe.

good luck.

[will gilmore]

I don't have one laying around but a few hundred dollars for a nice flat base seems like a deal. You couldn't buy accurately ground steel or aluminum for that price.

[JMcDonald]

I wouldnt use granite to actually build a mill off just for the difficulty of machining mounting surfaces. If I found one that had rows of mounting points (maybe drilled / tapped holes), Id consider it. Then again, that would probably be really expensive, so maybe not, heh. Were I to build a new base, it would probably be made of bolted-together steel plates or bars, and possibly filled with concrete and / or some other filler.

[will gilmore]

I was thinking of drilling the granite with some kind of masonry drill (not sure how easy that would be) and then epoxying in some threaded inserts.

now that i said that it sounds like more trouble than its worth

[JMcDonald]

The only way you could really do it would be if you had a mill big enough to do the machining on the entire base.

[will gilmore]

well the advantage of the surface plate would be that you wouldnt need to flycut or surface the whole thing in one pass. you would just need to accurately drill which i could probably do in my bport

[JMcDonald]

Yeah you should be able to do a decent sized surface plate on a mill like that. Were I to build a mill, Id probably use maybe an 8x24 plate, mounted longitudinally to support the y-axis. That should be easily machinable with a big vertical mill.

So, since you do have a machine like that, I say go for it if you can find the right sized granite plate!

[will gilmore]

anyone have links to drilling, epoxy, inserts for granite? someone must have already figured this out for fixtures on surface plates

[ironDigit]

If your going to buy a surface go for a cast-ironplate and drill&tap on the Bport ,that sounds wonderfull from over here.

I once contemplated : a large*ss 3x3foot surface plate and have some1 with a "portable" gantry-style router do the layout engravings for all the mountingholes whilst having it set-up as the 3x3foot surfaceplate was the actual table and the gantry cutting into itself to afterwards de the drilling with a magneticbaseDrill.It still sounds good to me but then the surfaceplate was snatched( i was overbidden) and i never looked back.

with some luck you'll come acoss a closeby angleplate on e-boy or alikes to make you up a real nice'n easy Z-column.

i'ld say lead the way and i might very well follow as i'm starting to get close to the stage of composing meself a base for the screws-n-slides i've collected sofar.

BTW i'm kinda itchy bout the granite after all i heard about cracking plates and molten drills and trying to accurately epoxy treads into the created holes seems asking for it.

Good luck.

[lgalla]

http://www.granitecitytool.com/showi...=88&mcatnum=92
http://cgi.ebay.com/18-X-24-BLACK-GR...ViewItem<br />
Larry

[ironDigit]

made me wonder if the ironsurfaceplates won't warp after drilling lots of mountingholes.

Hope someone can chime in on this.

I'm quite confident that this won't be of any concern when granite is used.