Platen Deformation?

S

stubbornforge

Joined
Jan 1, 2022
Messages
26
Is it by design or usage that a grinder Platen will bow in the middle, just enough that edges of the abrasive belt are doing more work than the center? I have found that the center of my platen is ever so slightly recessed causing it to bite less from the center of any material and the sides of the belt will wear out faster. Should I look at replacing the platen? It has about a year and half of medium duty use. Now I am using contact wheel for some tasks. Am I wrong to think that there would be an advantage to having a perfectly flat platen?
 
It is pretty common knowledge that platens will wear down unevenly during use, resulting in a not-flat platen.

This is the reason many people end up using a piece of pyro ceramic glass over the platen. The glass is flatter at the start, does not wear nearly as fast, and can pretty easily be replaced for a new piece when it wears out.
 
You can also get belt wear if you grind in the middle of the belt and then try to use it for a full flat grind, but platen wear is a problem. If you’re able, make a heavy/heavier platen out of heat treated steel like D2.

Hoss
 
If you grind wet many ceramic belts will cup outwards at the edges (just an fyi)... But regarding platen wear yeah it happens for sure, either surface grind it down or get a new one and jb weld ceramic glass to it, then when it wears you can pop it off and replace just the glass.
 
Also depending on what grinder you got, it might be that your platen was not flat to begin with. I put two m5 threads in the original platen and screwed a piece of untempered d2 on it. I can flaten it enoough on my disk grinder when it starts to wear down.
 
I used double sided carpet tape (Gorilla brand) on a piece of pyro glass sized properly for my steel platen from Little Bear Knives in Montana. That makes a very flat, wear resistant surface that can handle the heat and also be replaced much easier with a bit of acetone and a little careful work with a scraper. Haven't had to change one out yet, but I like the idea of being able to without destroying anything if needed.
 
I have 3 hard D2 platens. When they wear I reverse them and use the back side. When both sides are worn I put on a new one. I have three of these. When all three are worn I re-grind them flat again and start over. I've been using the same three platens in daily production for years.

Hard D2 wears very well but it does wear. But they're easy to dress flat again if you have the right surface grinder or know somebody who does. I feel this is better than soft platens or glass platens.
 
Yes, the surface of your platen and contact wheels are like the cutting surfaces of a drill bit - they will wear, and you need to replace, regrind, machine, or otherwise true them up.

I also use a D2 platen.
 
That's funny, I always seem to have a slight bow outwards in the center of my belts on my flat platen. I'm assuming it's from the crown on my tracking and/or drive wheels. I did recently cut the crown out of my tracking wheel with my lathe, which did seem to flatten the belt out a little. It also helps if I adjust my platen about a 1/16" forward of my idler wheels. I'm using a ceramic glass liner, FYI, and wear is pretty minimal.
 
Drew Riley said:
That's funny, I always seem to have a slight bow outwards in the center of my belts on my flat platen. I'm assuming it's from the crown on my tracking and/or drive wheels. I did recently cut the crown out of my tracking wheel with my lathe, which did seem to flatten the belt out a little. It also helps if I adjust my platen about a 1/16" forward of my idler wheels. I'm using a ceramic glass liner, FYI, and wear is pretty minimal.
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I am curious, what was the motivation behind flattening the crown on the tracking wheel? How did the tracking of the grinder change after you did that?
 
Hubert S. said:
I am curious, what was the motivation behind flattening the crown on the tracking wheel? How did the tracking of the grinder change after you did that?
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I was having some trouble getting belts to lay flat against my flat platen face. It always seemed like they wanted to pucker a bit in the middle, so that if I was taking a light pass while grinding, it was difficult to get a straight, flat grind. The tracking wheel I have had a somewhat pronounced "peak", so I figured maybe the hump in my belt was just following that. I figured maybe a flat crown on a tracking wheel might give it a better chance of laying a little flatter as it came over the idlers and platen face.
It did seem to flatten the belt a bit better, though some belts still have a very slight hump, but that's probably due to the remaining crown on my drive wheel.

As for affecting tracking, it didn't seem to in any appreciable way.
 
Drew Riley said:
I was having some trouble getting belts to lay flat against my flat platen face. It always seemed like they wanted to pucker a bit in the middle, so that if I was taking a light pass while grinding, it was difficult to get a straight, flat grind. The tracking wheel I have had a somewhat pronounced "peak", so I figured maybe the hump in my belt was just following that. I figured maybe a flat crown on a tracking wheel might give it a better chance of laying a little flatter as it came over the idlers and platen face.
It did seem to flatten the belt a bit better, though some belts still have a very slight hump, but that's probably due to the remaining crown on my drive wheel.

As for affecting tracking, it didn't seem to in any appreciable way.
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Interesting that it does not really impact tracking. I have not noticed any belts puckering, still find it really difficult to get a straight, flat grind though...

I have a spare 5" tracking wheel that I'm thinking about removing the crown from to test in my new SGA to see if it makes a difference compared to the rubber wheel I'm using. If the crown is not really needed for tracking, I might as well go ahead and try it out.
 
Hubert S. said:
Interesting that it does not really impact tracking. I have not noticed any belts puckering, still find it really difficult to get a straight, flat grind though...

I have a spare 5" tracking wheel that I'm thinking about removing the crown from to test in my new SGA to see if it makes a difference compared to the rubber wheel I'm using. If the crown is not really needed for tracking, I might as well go ahead and try it out.
Click to expand...
I have no wheel with crown on any of mu grinders and they track perfect .What crown do / I think/ is that it allowed MORE adjustment ...probably to compensate for not perfectly aligned wheels
 
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