glass platens...are they worth the risk of shattering? Do they make a better knife

LARRYZ10

LARRYZ10

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Feb 6, 2010
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Are the fireplace glass platen liners worth using considering they can come apart in jagged pieces and probably will? Do they make a better knife? Is there a substitute for the stock platen on my KMG that is better? I would appreciate some opinions. Thank you, Larry Lehman, Bakersfield, CA
 
It's good to be aware that they can break, but they probably won't. I think most folks that use them have some sort of stop below the glass platen to prevent it from slipping down into the idler wheel if it should come loose. I don't think it'll make a better knife, but it can be a consistent, reliable, long wearing surface. I make use of a slightly shorter platen, so it works for me to just run a bit longer lower platen mounting bolt so it sticks through the platen and serves as a stop for the glass. Maybe just run your grinder as is until you start getting a feel for what you like. It'll work out fine, Craig
 
The thing is that your flat platen is only going to stay flat for so long. Then, the back of belts will wear low spots where you tend to use the platen most. So, you need a flat flat platen again. The ceramic liners are the quickest cheapest way I've found to do this. I guess other options are resurfacing the platen, or just replacing the metal platen with a new one.

I don't have a stop on mine. I've never had one de laminate from the metal platten.

I have shattered one while putting on the rest. You have to be careful not to slam the tool rest onto the front of the platen while adjusting it before tightening it down. I've never had one shatter during use.

I recently bought an air cooled hardened A2 flat platen. I haven't put it on yet. Mine is still flat, so I'm waiting till it is of no use again.
 
Yes, they're worth it. No, I haven't broken mine or had it come loose in nearly three years of steady use. Yes, mine needs to be lapped, everything wears eventually.
 
I broke one when sticking the arm in the tool rack. I hit another arm hard against the pyroceramic. It cracked across, but certainly didn't shatter. I used it with the break for several years before I replaced it. It never fell apart.

Put a nice even layer of slow set epoxy or JB-weld on the platen, and set the pyroceramic on it. Clamp with the lightest pressure clamps you have....all you want to do is hold it in place. You want a nice layer of resin between the glass and the metal platens.
 
Glass platens are great. I've gone through two so far.

I don't use a stop at he bottom of the platen, and have had no issues.

If you prepare the glass and platen properly, you should only need some JB Weld and some duct tape to hold the platen in place while it cures.

The last time I replaced my glass platen, I had to use a hammer and a MAAP torch to get it off.
 
usaknifemaker has them

I have also had pyroceramic cut locally a few times. It is used as the glass in fireplaces.
 
I put one on my grinder and it helped a lot. My mild steel platen wasn't flat, so this was a big improvement for me when I first started. I welded a small strip of metal across the bottom as a shelf to hold the glass. I used jbweld behind the glass and it's VERY stuck on there. I personally haven't had any static issues from it either. I intend to replace this one with another when it wears out. You can also radius the edges with sand paper to your liking.
 
In wood gluing it would be called a rubbed joint; same thing applies to attaching a ceramic glass platen to a steel one. Apply the JB weld to the steel platen in a sheet coat, top to bottom. Place the glass on the JB weld and "rub" the two pieces together; you will feel the two pieces grip each other. Place the steel platen in the horizontal position. Kitchen matches super glued around the edges will keep the glass in place while the adhesive sets.
They won't come loose if applied in this way; no shelf needed.
When one side wheres out; place in a 500 degree oven and the JB weld will release. Use the edge of a blade to clean the surfaces, turn the glass over and attach with a rubbed joint.
 
i scuff the back of the glass and then prep the steel and glass then JB weld them
i have cracked both that i have used but never fear them sliding off or falling apart
i have 2 cracks in mine and ware dip for profiling blades on it so i guess i ll replace with my spare one of these days
 
Man, I had terrible luck when I tried the pyroceram platen. I followed the instructions, but after heavy grinding my JB Weld turned to goo. I'm assuming it was an installation error on my part, but after losing so much time dealing with it I was soured on the whole idea of it.

My platen issues (both excessive heat and deformation) have been completely resolved with Nathan's A2 platen and platen chiller set-up. Can't recommend them enough!
 
Karl B. Andersen said:
I use exterior mounting tape. Forget all the mumbo jumbo and epoxy and JB weld, and "this works better than that", etc.
Set on a small ledge.
No muss - no fuss.
The only way to get your platen off is in itty-bitty pieces.\
And then it's so difficult you'll wonder why you ever did it any other way.
http://www.amazon.com/3M-Scotch-Exterior-Mounting-60-Inch/dp/B00004Z4BV
Click to expand...


Wow, great tip Karl. I wouldn't have trusted it unless you told me, of course I'm always amazed when I stick something non-ferrous to the surface grinder with double sided tape and it holds up to deep passes, hell half the time I think the hold is better than the mag chuck (which admittedly isn't fine pole or electric).

I'm going to try this.
 
Nathan the machinist's hardened platens are great. I'm not sure how they wear but after having my KMG platen milled flat twice in less than a year I haven't had any problems with the platen from Nathan.
 
Now, Karl... Sidestepping the mumbo-jumbo and ego-trips and super-duper-secret stuff takes all the "magic" out of knifemaking. Shame on you!

I'm only teasing, of course. :D

I've had no problems at all with the JB-weld that holds my pyro-glass platen in place. If it ever fails, I'll be happy to try the tape Karl describes.
 
I use one, It cracked but hasnt shattered or split any further. I put 2 horizontal bolts under the glass that act sort of like a shelf if it ever were to release..
 
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