Why a glass platen

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lonepine

Joined
May 7, 2010
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I am using a Sears Craftsman 2X42 grinder. I am thinking of getting a glass platen for it but would like to know what I can expect after installing it. What does it improve, or make better, or easier to do?

Do the “big” 2X72 grinders come with glass platens? Does anyone CHOOSE to use a metal platen for some reason?

LonePine
AKA Paul Meske, Sun Prairie, Wisconsin
 
lonepine said:
I am using a Sears Craftsman 2X42 grinder. I am thinking of getting a glass platen for it but would like to know what I can expect after installing it. What does it improve, or make better, or easier to do?

Do the “big” 2X72 grinders come with glass platens? Does anyone CHOOSE to use a metal platen for some reason?

LonePine
AKA Paul Meske, Sun Prairie, Wisconsin
Click to expand...

That sounds interesting. Do you have a source for someone who sells them?

I had one of those stick on graphite deals on my metal platen, but after a while, it developed an uneven surface, so I just went back to plain metal.
 
Flatter surface,less heat build up,crisper plunge lines.
My KMG did not come with one but I had one on my craftsman 2x 42 so it was the first thing put on.
Stan
 
They also let you have plunge lines rather than shallow curves on the grinders that use bent sheet metal platens. The platen on the Craftsman machine and many like it would bend and twist too easily without it.
 
I don't know if anyone else has tried this but I happened to have some nice left over flat porcelain tile (18") and a diamond blade tile saw. I cut it to size and it has worked great since I put it on over a year ago.
 
When I got my Bader BIII, the flat platen that came with it was neither very flat nor did it have edges that were consistant. It was, instead, a simple piece of angle iron, with one edge squared off from being cut and the other edge round. Not only couldn't I get flat grinds that I was happy with, the plunges looked totally different on each side(one 90 degree square and one side round). The glass platen took care of all the complaints, instantly.

Now, is this a perfect fix? No; there are some negatives to deal with. One, static build up. In cold weather, I get the crap shocked out of me sometimes. The platen also will crack; especially if your existing platen that you glue the glass onto, has a dip in it. Eventually, the glass will need replacing.

Having said all this, I won't ever be without a glass platen on my flat platen. It makes that much difference.
 
I just go to the local glass shop and have 1/4" standard plate cut for my platen . Best thing I ever have done . The steel platen was collecting crap behind the belt and causing worms in the steel ( magnetic , don' know ) but the glass has fixed that problem .
 
Summarizing what I've read so far about glass platens:

Flat (not mostly sorta flat)

Less friction = less heat (heat where?)

crisp and consistent plunge lines

Can cause static build up and shocks

Eventually glass platens will break, especially if there is a dip behind it.

Alternatives may include smooth flat porcelain tile and/or 1/4" regular plate glass.

Questions
How does one attach it to the platen? Since it is GOING to break eventually epoxy is probably out of the question, huh? Double sided tape? Rubber cement? Gorilla glue?

Is there any way to reasonably get rid of dips or uneven surface on the metal platen prior to gluing on the glass?

Jack - How do you handle the sharp corners on the cut glass?

Should a glass platen be exactly the width of the belt, slightly smaller, or slightly larger?

I'm assuming it would be the same length as the existing steel platen, right?

LonePine
AKA Paul Meske
 
I used JB weld spread evenly across the back of the glass. My piece is not quite as big as tall as the original platen but tall enough. Width is 2" but in practice you don't use it for the plunge lines on both sides without adjustment for a little overhang where you need it.

When it breaks I'll have to chip off the rest and sand the platen smooth enough to put a new one on.
 
lonepine said:
Questions
How does one attach it to the platen? Since it is GOING to break eventually epoxy is probably out of the question, huh? Double sided tape? Rubber cement? Gorilla glue?
Is there any way to reasonably get rid of dips or uneven surface on the metal platen prior to gluing on the glass?
Jack - How do you handle the sharp corners on the cut glass?
Should a glass platen be exactly the width of the belt, slightly smaller, or slightly larger?
I'm assuming it would be the same length as the existing steel platen, right?
Click to expand...

Most of those questions are answered by this link from above.
Tracy Mickley gives a little tutorial.

http://www.usaknifemaker.com/ceramic-glass-platen-liner-flat-platen-2x6x-0192-p-2030.html

It is known as "Pyroceram"
I bought some locally
Most good glass replacement businesses handle it as replacement for fireplace glass doors


If you have junkyard access
the window in a barbecue or oven door is the same stuff.
 
Last edited:
Yes, but a two or three second spray of the anti static spray for clothes, on the moving belt will stop this. The belt will remain static free if its put aside and then used again. Frank
 
Frank Niro said:
Yes, but a two or three second spray of the anti static spray for clothes, on the moving belt will stop this. The belt will remain static free if its put aside and then used again. Frank
Click to expand...


Thanks for that tip. I get shocked all the time.
 
I use 3M spray adhesive to attach my glass . Downside - if it gets too hot the adhesive will weaken and the glass will slide off . Some folks will use pins at the bottom of the glass to prevent this . Upside on the spray , if the glass cracks and needs to be replaced , once you chip the glass off ( I just beat it with a hammer ) then some carburator cleaner will clean the rest off . There are no idler wheels on my platen so I then turn a 60 grit belt inside out and angle the platen to round out the top and bottom edges of the glass .
 
I have the craftsman 2x42 as well. Just wondering, on that machine, the platen is significantly wider than the belt. I have been looking for an easy way to modify it.

If i went with the glass platen, would i have to grind down the original platen to the belt width, or will the height of the glass be enough that it will let me get my plunge lines even with the extra metal behind it?

I read the linked piece and he talks about the extra on the bottom not mattering, but the extra on the sides is a bit different because that's where you grind from.

Thanks,
Adam
 
Frank Niro said:
Yes, but a two or three second spray of the anti static spray for clothes, on the moving belt will stop this. The belt will remain static free if its put aside and then used again. Frank
Click to expand...


Also for anyone who happens to use Fred's Bubble jig (I've never sprayed my belts). But she shock seems to jump from the clamp of the jig to the metal platen behind the glass when you use it. I've occasionally caught the arc out of the corner of my eye when I grind. Either way it saves me the need to spray my belts.
 
I haven't had any issues using the glass's height for grinding, but I guess it would depend on the edge your glass had, how thick a piece you were trying to work with....

The only area I've run into problems is when using Fred Rowe's clamp with the bubble jig. It hits the edge of the base platen so I can't grind right to the clamp. It's still better than 100% freehand, but motivates me to figure out a better setup there. I'll probably just wait till I can afford a better grinder though.
 
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