Glass platen repair questions?

weo

weo

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Sep 21, 2014
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Hello all. I JB welded a piece of pyroceramic glass on my flat platen about 2 years ago and yesterday, while feeling the edges to see how bad the cracks were getting, it popped off like it was just resting there. It's now in 3 pieces. It took an hour or so of scraping to get the JBWeld off the steel platen so I could have something to finish my handle.
I thought JB Weld was the go to product, did I do something wrong or is this just normal wear and tear with use?
 
i think 2 years is a good life for a glass platen. even if i am careful i end up chipping some of the edge eventually. i think to get great adhesion you would need to rough up the back of the glass before gluing it. but that might cause a stress riser and cause the glass to crack when it gets hot ? i am not sure. next time if you heat the metal platen with a propane torch, the jb weld comes off easier.
 
i keep a back up glass in the shop for when i crack it. funny thing is that last one i have got so much life out of that its dished out. im going to keep it and have built another platen to put the back up glass on (grinder tools never seem to stop being added ) i have 5 arms for the KMG and need to make 2 more for now
 
I replace the glass bout every 6 months or so. Agree with John ya can have the old JB Weld off of there in a couple of minutes using a torch and a scraper.
 
If your glass isn't cracked you can heat the back of the platen with a torch remove the glass flip it over and glue it back on.
 
For proper adhesion, sandblast and degrease prior to putting the jb weld on.
 
I use double sided tape and its been good so far (about 6 months). I would imagine that would be easier to remove than jb weld but i have not tried yet.
 
How do you guys feel about your glass platens?
I've been using one. It stays remarkably cool. but that heat has to go somewhere. I feel like it's going into my work piece instead. Help with thermodynamics, please!
 
daizee said:
How do you guys feel about your glass platens?
I've been using one. It stays remarkably cool. but that heat has to go somewhere. I feel like it's going into my work piece instead. Help with thermodynamics, please!
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I think that generated heat from grinding/contact of blade with belt/ is less then belt-plate friction / and part of that heat stay in blade because ceramic grain cool down wile belt running fast ..
First I have HSS plate , last very short time .Then I put ceramic tile one , last much longer .Then I put ceramic glass......................after one year it is like new .Most heat I have with HSS , then ceramic tile and less heat with glass....I think that it generate less heat from friction belt/glass then steel one and tile one . Most temp come from that friction.
 
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I have a glass platen held on with jbweld. I left a bit of jbweld at the face edge of the glass and it managed to melt and get transfered to the center of the platen. It only took a few minutes to scrape it off....but I learned to keep the glue away from the face.

A related question. How far in front of my wheels should my platen be? Just a hair? or 1/8"?
 
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Randydb said:
I have a glass platen held on with jbweld. I left a bit of jbweld at the face edge of the glass and it managed to melt and get transfered to the center of the platen. It only took a few minutes to scrape it off....but I learned to keep the glue away from the face.

A related question. How far in front of my wheels should my platen be? Just a hair? or 18"?
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The platen should be as flat with the wheels as possible. At first I mounted mine (on a grizzly 2x72) pushing the belt out about 1/2-3/4 in. I moved it back after someone mentioned it and I immediately notice a difference.
 
I like exterior grade double sided carpet tape. I get the 2" wide "Duck" brand IIRC (it's more like 1-7/8"). Make the steel backer as flat as possible with a 1/8" thick ledge on the bottom. I clean the glass and steel really well (denatured alcohol works), then I put a piece of tape on the back of the glass (full length, trim flush) and one on the front of the steel backer. I do a full length piece of tape on the glass AND the steel just so I can make sure I get full adhesion across both. Then it's just a matter of sticking the two taped sides together. In all the years I've been using the tape, I've never had one fail or move at all, and I've had the steel backer hot enough that I couldn't hold my hand on it for more than a couple seconds.

As for removal, a torch and a putty knife pops it off relatively easily, and acetone or denatured alcohol cleans it back up again. Just a note: if you use acetone, make sure you clean the film/residue that it leaves behind. I normally just hit the parts with a torch to burn it off before I put my tape on.
 
Ian Fifelski said:
The platen should be as flat with the wheels as possible. At first I mounted mine (on a grizzly 2x72) pushing the belt out about 1/2-3/4 in. I moved it back after someone mentioned it and I immediately notice a difference.
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You most definitely do not want your platen and wheels even. You want your platen extending past the wheels just a fraction. If you had a blade longer than the 8" platen. When it extends above or below platen. You do not want the wheels to come in contact with your work and dish it.

Get a perfectly flat area. Loosen the platen wheels. Stand on end (platen face down). Put a nickel under each of the platen wheels then tighten them down. Now your platen extends a nickel thickness past the wheels. All set.
 
jll346 said:
You most definitely do not want your platen and wheels even. You want your platen extending past the wheels just a fraction. If you had a blade longer than the 8" platen. When it extends above or below platen. You do not want the wheels to come in contact with your work and dish it.

Get a perfectly flat area. Loosen the platen wheels. Stand on end (platen face down). Put a nickel under each of the platen wheels then tighten them down. Now your platen extends a nickel thickness past the wheels. All set.
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You are right. I didn't finish that sentence. You want the platen as flat with the wheels as possible without the wheels coming into contact with the piece when laid on the platen.
 
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