re:Re: How to mount rails on surface plate?

workaholic_ro writes:

>Subject: Re: How to mount rails on surface plate?

>An alternative solution to attach rails to a granite surface:
>wall expansion anchors. Chose metallic not plastic ones, better with
>knurled surface . They are available in lots of shapes and dimensions
>are safe and much easyer to use than resins. Take care and make deep
>holes otherwise you risk to brake the plate. The expansion force is
>enormous. Try first in a concrete wall. Use a hammer drill and a
>carbide tipped tool.
>Not much but I hope it helps.

Stressing the granite in this way will warp it to a convex surface.
If you want to keep it flat, introduce as little stress as possible.

For example, when gluing in inserts, minimize the bond thickness of the
epoxy.
Use a filled epoxy, these have much lower (<1%) shrinkage than the unfilled
epoxies (>1%).
A steel threaded insert will be better than a aluminum one, the thermal
expansion of steel is a better match to that of granite than aluminum is,
and stronger too.

Making the inserts diameter small will also scale down the distorting
forces.

I made inserts from 1/4" steel rod, threaded 10-32. The 1/4" drill made a
hole a bit oversize, so it worked fine.



Elliot