Making new flat platen - Harden?

Signalprick

Signalprick

Jason Ritchie
Gold Member
Joined
Apr 3, 2009
Messages
3,253
Hello,
I decided to replace the hot rolled steel flat platen on my grinder because it's not flat. I bought a bar of 1/4" thick precision ground A2 to replace with. Would hardening it be necessary? If so why or what would be the benefit? Thanks for any insight.
 
FWIW ... ameribrade tried (is still trying) to supply hardened steel plates ... and Ian told by them that they have aLOT of trouble getting consistently hardened product. Too thick maybe? So ... maybe not worth the effort?
 
Good to know. My grinder is Ameribrade. I can't imagine a 1/4" thick piece of A2 would get hot enough to warp or bend doing slip joint knives? Maybe in wrong?
 
Why not high temp sillicone some glass to that platen? I go to a local glass shop with dimensions. 5 minutes and 5 dollars later. Boom glass platen
 
jsut make sure its fire glass not plain type. since you already have the A2 it really should not be too hard to harden and if make the platen go over tempering tems grinding i think you must be doing something way wrong
 
Signalprick said:
Good to know. My grinder is Ameribrade. I can't imagine a 1/4" thick piece of A2 would get hot enough to warp or bend doing slip joint knives? Maybe in wrong?
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IIRC, the issue they had was consistently getting the thick metal piece to consistently harden in the first place, not softening in use. Not my area of expertise. Not my area of expertise though ... just passing on what they told me.

agreed though that the solution appears to be to put a ceramic piece on the front of the platen (something I will likely do fairly soon)...
 
Well I got it made and mounted up. Its def. a 100% more flat than my original. I havent heard an argument for hardening it so we'll see how it goes. If I feel I need the glass I'll upgrade to that but I have a feeling I should be fine. I can always harden later if I need to. It shouldn't be too difficult. It's just a 2x8 bar of 1/4" A2.
 
I would harden the platen myself, push the A2 to high hardness. A friend of mine used D2 for a new platten as the soft one that came with his grinder dished out pretty fast, he hardened the D2 to 64rc and it has lasted for many years of 6 knives per week production.
 
Yeah, I think you want to harden it. I am using a hardened platen on my 2x42 and even without much using it shows wear signs. I think Nick Wheeler mentions in his videos that he doesn't bother with ceramic glass plates and just uses a hardened steel platen and flattens it as needed on a disc grinder. Surface grinder or surface grinder attachment would even do a quicker job.

That said I found a cheap supplier for ceramic glass (also called fireplace glass?) in germany and plan to use that in the future.
 
Kali4nia said:
Why not high temp sillicone some glass to that platen? I go to a local glass shop with dimensions. 5 minutes and 5 dollars later. Boom glass platen
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Static electricity BOOM, no thanks

I have a couple of Nathans flat platens and they have held up well.
https://www.bladeforums.com/threads...cooled-platen-chillers.1086057/#post-12387820
This is from the post selling them - These are all machined of A2 steel and hardened to HRC 61-64

I dont think they would stay flat long if not hard.
 
Signalprick said:
Well I got it made and mounted up. Its def. a 100% more flat than my original. I havent heard an argument for hardening it so we'll see how it goes. If I feel I need the glass I'll upgrade to that but I have a feeling I should be fine. I can always harden later if I need to. It shouldn't be too difficult. It's just a 2x8 bar of 1/4" A2.
Click to expand...
It sounds to me like maybe you have a mill? If so, then I guess there might be an argument that goes, don’t harden, use it until not sufficiently flat, then just run it under the mill to reflatten it? The only counter argument I believe might be that glass platen liners run cooler (I think)?
 
I would harden it and use it and use it and use it alot longer than an unhardened one and when it does finally need flattening surface grind it flat again.
The platen that I first used came from KMG and was not hardened and it didnt take that many knives to dish it out. Nathans hardened plattens put that platen to shame , I have ground 10 times what I did on the non hardened platen and they are still in good shape.
 
Signalprick said:
Hello,
I decided to replace the hot rolled steel flat platen on my grinder because it's not flat. I bought a bar of 1/4" thick precision ground A2 to replace with. Would hardening it be necessary? If so why or what would be the benefit? Thanks for any insight.
Click to expand...
No reason to harden, flat is what you want to put glass over. Make this piece so it is easily removable. You will want to be able to heat it up so you can remove the old glass platens. Fred
 
Three questions for those with experience...

How much longer should a ceramic glass platen last versus the typical steel one?

And where might be the best seller to get a 2" x 8" ceramic glass platen from?

What is the typical thickness of the ceramic glass?
 
It's cheap and lasts a long time. Get a couple and you'll be set.
https://www.ebay.com/itm/2-X-8-High...-/372048391204?_trksid=p2349624.m46890.l49292
The default is 2x8 but they will cut whatever length you need.
What you DO NEED is a shelf on your platen for the glass to sit on, in case your adhesion fails the shelf will prevent the glass from being sucked into the wheels and exploding.
I did not take this advice and yes it happened to me yes the glass exploded.
 
My plan is to just drill and tap the bottom of the platen and a small piece of steel, thinner than the glass. I haven't done it yet, but I've seen others on here do it that way.
I'd get that done before ordering glass, so you know the exact length you'll need them to cut the glass
 
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