Glass Platen questions

[Randydb]

I finished getting my tracking all lined up on the 2x72 grinder that I am making. Onto the platen now.
I have a piece of angle iron to get the platen surface and have a piece of flat iron to use as a platen. I bought some hardened glass too (purchased it from a company that was mentioned in a thread here about a year ago...can't remember the name of the company or find the thread). So my question is attaching the steel platen and glass platen to my angle iron.

1) Do I attach the glass platen to the flat steel platen or straight to my angle iron?
2) If I need the flat steel platen. Basically drill and tap it, then drill through angle iron and attach with bolts short enough to not come through the front of the platen? Or do I drill and countersink steel platen and put machine screws from the front?
3) Glue glass platen on? Using?
4) Should I be putting a small shelf at the bottom to "support" the glass platen? Weld a narrow bead there?
5) I remember people talking about static shocks with glass platens. Stacey had a comment about using a chain and a weight or something to ground himself. How bad is the shocks...and is the chain idea the best way to deal with them?

Thanks all. This is getting exciting.

 

[Lieblad]

As far a glue, we use urethane sealant. I think it was intended for gluing car windshields, but maybe not. I use alot of Masterseal urethane products, so it could be something else. Its black anyway, all I know nowdays... Just be sure whatever you use will withstand operating temperature.
Static electric shock ? Dunno...Its never been a problem in my shop.

 

[Drew Riley]

I'm not sure how your flat platen is set up, so I can't make a specific recommendation on whether to attach directly to your angle or to a flat bar attached to your angle.

What I can recommend: You want whatever you set your glass on to support the full length of the glass. You also want a small "ledge" or "lip" at the bottom of your platen to keep the glass from sliding down, should the adhesive holding the glass fail. Some guys just use a couple of screws at the bottom, or screw or weld a ledge on. I've milled them in before as well. However you do it, just make sure it's square and matches up the glass well.
Here's an example I found in google images:

You also want the material your adhering your glass to, to be as flat and clean as you can get it. Personally I use an exterior grade double sided tape (duck brand, I believe), and use this to stick my glass to a steel platen backer that's bolted to my angle brackets (similar to the pic shown above).
Others have success with JB weld. If you use an epoxy like JB weld, DON'T CLAMP the platen while the adhesive is curing. Just let it "rest" in the epoxy. Obviously you want to make sure it doesn't move or slide while it's curing, but if you clamp it, it will break after the epoxy cures.

Here's a vid that has some good tips. I've also got a couple on my channel if you care to listen to me droning on.

As for static shock, I almost never have an issue with it, but a lot of that depends on humidity levels in your shop and such. If it becomes an issue, just spray some anti-static spray from the grocery store on your belt every once in a long while.

 

[Randydb]

Hey Andrew, that droning video was very helpful. Pretty well answered all my questions. Don't need to mess around with the piece of flat steel as a platen. Just glue the glass onto my angle iron.

Thanks....off to the garage.

 

[butcher_block]

no lip under my glass sept for over flow of JB weld i like the fact i can take the platten off and put a crappy steel one on if need be (or my fancy 48" platten from nate) i have i think 3 platens right now and only 2 arms set up for them

 

[Natlek]

I have a piece of angle iron to get the platen surface and have a piece of flat iron to use as a platen.

I don t like angle iron there , find some T profil for platen .Extra room from both side can be useful sometimes ..............

 

[Ian Fifelski]

I used jb weld and it holds up amazingly and I don't have any pin underneath.

+1 on T profile platen steel like Natlek said.

 

[Drew Riley]

Hey Andrew, that droning video was very helpful. Pretty well answered all my questions. Don't need to mess around with the piece of flat steel as a platen. Just glue the glass onto my angle iron.

Thanks....off to the garage.

The video above isn't mine, but another maker I follow. My videos are in the channel linked in my signature.

 

[Stacy E. Apelt - Bladesmith]

JB weld.
No lip, just the epoxy.
I stopped using the ground strap except in very cold and dry weather. I spray the back of the belt with Static Guard and it dissapates the static pretty well.

The amount of static can be pretty huge. I have had the grinder make 1" sparks to my hand. It stings, but is basically harmless.