Choosing an epoxy?

[mliptack]

Spill some beer on it and then let it dry, that shit holds like a VISE.

Haha, it does! Not like I'd want to admit that my college days taught me that.

I've used a variety of glues, depending upon the mirror, size of laser and other heat related variables, I like to use aquarium silicone. If you buy stuff that is specifically rated for aquarium use (either fresh or salt water) gassing will not be a problem. They are made not to contaminate the water.

Regarding the JB Weld stuff, last time I used that I vaguely remember it being able to spread fairly thin.

Steve, that glue/epoxy sounds pretty awesome, I'd just be terrified of attaching something that might change with that glue... it sounds like I'd have a hard time taking it off without ruining either optics or mounts

[Laser Ben]

Well, my goal is that I will be able to align the laser with the new optics, clean it in a clean-room, and then never open it again. So in all honesty, I need to have it permanent. I need to remount a mirror to this:
Oh yeah, that black stuff on the mount where the optic was, that is the coating getting ripped off of the metal when the optic came loose!

I am mainly worried about the cost! Looking at the stuff on that website Steve, 50mL of some stuff was like $500!

[Mr.Coffee]

well then, first thing you need to do is re-sputter the copper onto your mount.

[buffo]

In that application, JB Quick will be ideal. It's not putty when you mix it, but more like a thin paste. (Think runny toothpaste or thick gravy and you've got the idea.) Mix a little bit up, use a toothpick to smear a thin film on the mount and another thin film on the bottom edge of the optic, then set the optic in place and make sure it's vertical in the mount. Wait 5 min for the glue to set, then perform your alignment. You'll never have to mess with it again.

If you need to mount multiple optics, only mix up enough for one or two mounts at a time. Remember, this stuff sets in 5 minutes! Do one, then move to the next, making up new glue as you go. But yeah, it's very easy stuff to work with.

In this application, a non-viscous (watery or liquid) glue would be a real problem, since it would tend to flow off the mount, making a mess. But a thick epoxy like JB Quick will be ideal. You don't need a huge glob of it either. A thin film is enough. (If you use too much it will tend to run and drip just like a liquid glue will.)

And in the far future, if you ever take it apart again, you *can* break the joint loose without destroying the optic. (But you'll need a very sharp exacto-knife and some patience to do it.)

Adam

[Laser Ben]

When it dries, is it a really hard material? How is it with thermal expansion? Sounds like it will work well, I am just worried about it expanding or contracting.

[DMills]

Here are the numbers for Varian Torr Seal (Hysol 1C by any other name (And much cheaper by this name)):

Linear expansion: 30.3 * 10E-6 per degree C (30 to 90 degrees C).
Flexural strength: 11,000 PSI +-20%
Linear shrinkage: 1.25 mm/m
Compressive strength: 10,000PSI +-20% @ 25 degrees C
Thermal conductivity: 10.4E-4 cal/sec/cm^2/degree C/cm

Sorry about the funny units, cribbing from a technical report.

Regards, Dan.

[mixedgas]

Here are the numbers for Varian Torr Seal (Hysol 1C by any other name (And much cheaper by this name)):

Linear expansion: 30.3 * 10E-6 per degree C (30 to 90 degrees C).
Flexural strength: 11,000 PSI +-20%
Linear shrinkage: 1.25 mm/m
Compressive strength: 10,000PSI +-20% @ 25 degrees C
Thermal conductivity: 10.4E-4 cal/sec/cm^2/degree C/cm

And the 30 COE puts it close enough to the expansion rate of hard glasses.

Sorry about the funny units, cribbing from a technical report.

Regards, Dan.

I was paying 80$ a unit for a Torr Seal clone. One day the vendor got sloppy and did not ship the box with the sticker they used to repackage it on.... Then we went from 80$ a tube to 60$ a case. :-)

There is a 1 ingredient difference from Torr Seal to H1C white, and its minor according to the sales guy. I could not see the difference with a pressure gauge... So ./.

A box of H1C is 4.65 a box, usually 12 to a case for 65$ or so.

It is really, really good stuff. Used for bonding the leading edges of jet aircraft wings, too.

steve