Re: [CAD_CAM_EDM_DRO] How to mount rails on surface plate?

Hi Jay:
I've been following this thread, and I like your solution the best, but
I'd put in steel plugs instead of aluminum.
Straining the granite by putting in expansion anchors is a poor choice in my
opinion.
I'd always be worried that the plate would crack from the strain.
Natural stones are full of irregularities in microstructure; they're just
waiting for an invitation to propagate a crack.
The reason I'd avoid aluminum is that it's coefficient of thermal expansion
is very high, and I'd want the plugs to sit in the plate as passively as
possible.
Just my two cent's worth.
Cheers

Marcus

----- Original Message -----
From: "J.Critchfield" <js3mc@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, April 19, 2002 10:06 PM
Subject: Re: [CAD_CAM_EDM_DRO] How to mount rails on surface plate?


> Not so difficult.
>
> I'm assuming the rails will need to be mounted with some precision?
Drilling
> stone with a carbide bit is not a precision process. I would drill the
holes
> for an aluminum plug large enough to handle some misalignment (there will
be
> some) The holes should be at least 1/16" larger than the plug to allow the
> adhesive to flow completely around the plug. Make sure to put some small
> groves around the plug to help the adhesive grab it. I would not use oil
as
> a coolant. Most masonry type drill bits are meant to be used dry or with
> water. Why contaminate the stone. A hammer drill will make the drilling
> process much quicker.Some granites are very hard and may destroy the
typical
> hardware store masonry bit rather quickly. Bosch and Milwaukee make some
> very good quality bits that will drill most any natural stone. For
adhesive
> I would use the structural epoxy made by Simpson. You can get small tubes
> that self mix when applied from most lumber yards or DIY stores. Drill
your
> holes, epoxy the plugs in place and once cured drill and tap. If you find
> the granite very difficult to drill start with the smallest bit you can
get
> and work up to the size you need. If all else fails diamond coated bits
can
> be had from natural stone suppliers.
>
> Jay
>
>