D2 flat platens and water cooled aluminum chillers, KMG, TW-90

I just got my platen chiller and it is simply amazing! incredible fit and finish-Thanks Nathen!!!!:thumbup::thumbup:

even though I didn't get the platen....how can we get the harden steel platen dead flat again after they do become non-flat?
 
chknifemaker said:
I just got my platen chiller and it is simply amazing! incredible fit and finish-Thanks Nathen!!!!:thumbup::thumbup:

even though I didn't get the platen....how can we get the harden steel platen dead flat again after they do become non-flat?
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I lap mine out on a surface plate and 220 grit paper, but mine doesn't really get that wonky. After 50-100 blades on it I'll dress it out in a couple minutes. My good platen has hundreds of blades on it and is in good shape, but I only use it for flat grinding and the belts I use don't build up a lot of sticky abrasive gunk on the inside of the belt.

I sharpen wet, so I use an old platen for that because wet and damp grinding tend to get grit between the belt and platen which accelerates wear.

I don't profile on a platen, I use a wheel for that. Wheels cut better and belts last longer. Profiling on a rest wears a spot on the platen.

I got one back a couple days ago from someone with some deep grooves in it from some trouble with abrasive grit building up on the inside of the belt which cut the platen pretty bad. I'm not sure what type of belt he was using or the grinding conditions that created the problem, but I had to remove about .010" to get it to clean back up. I milled it flat with a big face mill, but wide cuts in hard steel requires a very stout mill and special tooling to do well. A surface grinder would work pretty well as would a flat disk grinder. I've also heard of folks using a big belt sander.
 
Got my chiller a couple of days ago. As always, AWESOME work, Nathan! Fit and finish is A+++.

Thanks!
Ted
 
PT Doc said:
Can you comment on the wear of the A2 platen in comparison to a D2 platen? Thanks
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Some folks have trouble with wear. Others don't. I attribute this to differences in grinding conditions.

A2 is working well for me, wear isn't a problem. But for folks who, for whatever reason, need more abrasion resistance there is D2.

There are plenty of charts comparing the abrasion resistance of D2 and A2 to each other and to other materials, but they tend to be over simplifications because they're not looking at a range of hardness and differences in HT, but they agree on D2 being a more abrasion resistant steel.

The heat treat on these D2 platens was tweaked to maximize abrasion resistance, so the abrasion resistance values would probably be a little different than the standard HT but I'm not able to specifically quantify it.

These D2 platens were austenitized at 2150, which is well above the normal range and quenched with cryo (HRC 65-66 before tempering) and taken to the secondary hardness hump (HRC62). This is not a standard HT, but I wasn't concerned with grain size, dimensional changes and impact resistance like one would with a stamping tool.
 
Hey Nathan!
I'd like to get a platen and a chiller for a KMG please, email headed your way.

Thanks,
Aaron
 
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