On Dec 4, 11:34*am, (Doug Miller) wrote:
In article , Ignoramus4371 wrote:

I want to glue a piece of steel to my truck's windshield, with some
threaded holes so I can attach anything to it (such as radar detector,
parking permits etc).

My question is, what sort of steel glues best

Clean, smooth, flat, and small (large pieces won't mate to the curvature of
the windshield -- you want something the size of a rearview mirror mounting
button).

and what is the right
surface prep. Should I sandpaper it? Should I sandpaper the glass?

No to both.

What is that rearview glue exactly?

Cyanoacrylate aka "superglue".



Also what is the minimum ambient temp at which I can do the gluing.

Consult the manufacturer of the glue. Typically 60F and up, I believe.

NO-NOT SUPERGLUE! The proper stuff can be had at the auto parts
places, it's a two-part glue, vinyl-based, same as OEM. Has enough
flexibility to take up the difference in temperature coefficients
between glass and metal. FOLLOW DIRECTIONS! Failure to do so will
result in the part ending up in your lap at the worst possible time.
The stuff I've used was under the Loctite label, has lasted about 10
years so far.

If you're designing something, grab a rearview mirror and mounting
button off a wreck and you'll be miles ahead. Usually a couple of
bucks for the non-powered kind from a U-Pullit. Put your holes in the
shoe that mounts to the button, not the button itself. Another thing
to check is local and state laws about stuff around the rearview
mirror, some states are picky about having absolutely nothing except
the mirror on the windshield. Tickets for same can be costly.

Stan