Platen overheating and a solution

JoeBusic

JoeBusic

Joined
Jan 21, 2020
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466
My platen overheated significantly to a point where belts break at the joint. Reason for it is that I pulled the platen cca 2" in front of the idlers to grind lengthwise and get nice plunges. The platen has rounded bottom and upper edge. But the friction was to high so I got only 10-15min before belts snap. To little work and too long of a wait to cool. Started thinking of building a new thick platen out of aluminum and fix rollers up and down but a simple solution caught a thought. Graphite strip. It rocks. Nothing new. Ignored it as I thought it's not important. I changed my mind. Simple solution. Roller thing is going to happen, just no hurry now. Work is good.
Maybe this helps someone.
 
DevinT said:
A heavy, hardened steel platen will help. At least 3/4 of an inch thick.

Hoss
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I have a 10mm D3@66HRC platen. Thicker would give me a little more time but not enough. Friction was just to high. Belts transferred heat to wheels and soon everything was smelling hot. Position of the platen is the source of friction. All works now efficiently. Belts don't heat up. Small things...
For the future plan is to make a thick Al platen with a carbide sheet on it. For now graphite works well.
 
Aluminum makes the best platens if they have a pyro glass, graphite, or other cover over them. Take a 3/4" X 2" aluminum plate put a nice large radius on both top 'n bottom and cover with graphite - bet that would work good for you.
 
I like graphite cloth. PITA to get off when it wears out, but definitely an improvement over plain steel. I eventually went to the glass platens. With patience and a lot of effort, you can manage some shaping with a AISI 60 or 80 grit ceramic. Tediously. I have a diamond sharpener for engraving. Diamond does it much quicker. If you have a glaser friend, they certainly have diamond abrasives.
I eventually purchased a circulating water, magnetic platen cooler from Contender Machine Contender Machine . That thing kicks butt. Cold platen. Put a couple bottles of water in the freezer and add them to a 20L bucket of tap water and it is surprising.
One other thought about this: consider a shortened platen for a bit. Thought experiment...
 
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Ken H> said:
Aluminum makes the best platens if they have a pyro glass, graphite, or other cover over them. Take a 3/4" X 2" aluminum plate put a nice large radius on both top 'n bottom and cover with graphite - bet that would work good for you.
Click to expand...
That sounds like the simplest solution. I have some 30mm Al plates from my plate quench setup (I'm quenching in oil all stainless now) and will try this. Way easier than hardened steel. :) Test will be to see how much the graphite deforms with use (uneven squishing).
 
fitzo said:
I like graphite cloth. PITA to get off when it wears out, but definitely an improvement over plain steel. I eventually went to the glass platens. With patience and a lot of effort, you can manage some shaping with a AISI 60 or 80 grit ceramic. Tediously. I have a diamond sharpener for engraving. Diamond does it much quicker. If you have a glaser friend, they certainly have diamond abrasives.
I eventually purchased a circulating water, magnetic platen cooler from Contender Machine Contender Machine . That thing kicks butt. Cold platen. Put a couple bottles of water in the freezer and add them to a 20L bucket of tap water and it is surprising.
One other thought about this: consider a shortened platen for a bit. Thought experiment...
Click to expand...
High chance I'll make more of them and figure out a quick release system for fast exchange.
 
Graphite strip busted. Friction was to high and the belt bit thru. Roller thingy is next. :)
 
JoeBusic said:
Graphite strip busted. Friction was to high and the belt bit thru. Roller thingy is next. :)
Click to expand...
Would likely be a good idea to not go too small with the rollers, or the bearings may not live long if you want to be able to run the grinder at full speed.
 
ak650 said:
Would likely be a good idea to not go too small with the rollers, or the bearings may not live long if you want to be able to run the grinder at full speed.
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Going for 20mm. When the bearings go dead I'll exchange with high speed bearings. 10mm radius plunges look very nice. We'll see how it works. Tricky stuff.
 
Use the Contact wheel.. grind with the tip down (just like you are with the platen) then when most of the material is removed
Switch to the platen for finishing... like many both of my machines have Pyro glass on the platens..
Hard steel could also work .... friction and belt pressure are likely not your friends here...(maybe reduce the belt tension a little)
 
I have not observed this problem. Some solutions/preventions:

1) Make a specialized hardened steel platen - Radius (round) the leading and trailing edge of the platen. I would also radius the sides. I would make the radius .125".
The top of the platen should be just slightly less below the top 2" wheel. This way the belt comes off the top wheel and forms around the platen lip.
2) Angle the bottom of the platen back a until the belt comes off it as normal and goes to the wheel. There is no need for the bottom of the platen to be proud of the wheel alignment. This will reduce some friction.
3) Use a glass platen like above with rounded/radiused edges. You can easily grind pyroceramic glass with a 120-grit belt running slow to medium speed.
4) Use a water-cooled platen backing. The platen screws directly to the cooler.
5) Use a Kool-Mist system or clone. Use ice water in the water tank. See below.


I regularly recommend using an old Breg Polar Cube for the water tank/pump/hoses on a cooled platen or mist spray system. Beast place to find one is a thrift store or flea market. Sometimes you can find one cheap or free in Offer-UP and similar sites. Ebay has them too, but the price varied wildly.
 
Stacy E. Apelt - Bladesmith said:
I have not observed this problem. Some solutions/preventions:

1) Make a specialized hardened steel platen - Radius (round) the leading and trailing edge of the platen. I would also radius the sides. I would make the radius .125".
The top of the platen should be just slightly less below the top 2" wheel. This way the belt comes off the top wheel and forms around the platen lip.
2) Angle the bottom of the platen back a until the belt comes off it as normal and goes to the wheel. There is no need for the bottom of the platen to be proud of the wheel alignment. This will reduce some friction.
3) Use a glass platen like above with rounded/radiused edges. You can easily grind pyroceramic glass with a 120-grit belt running slow to medium speed.
4) Use a water-cooled platen backing. The platen screws directly to the cooler.
5) Use a Kool-Mist system or clone. Use ice water in the water tank. See below.


I regularly recommend using an old Breg Polar Cube for the water tank/pump/hoses on a cooled platen or mist spray system. Beast place to find one is a thrift store or flea market. Sometimes you can find one cheap or free in Offer-UP and similar sites. Ebay has them too, but the price varied wildly.
Click to expand...
I'm using the bottom edge as it is more secure. Tried with looser belt but it jams and the drive wheel slides and heats up. More pressure works good so the belt has to be tense. Graphite worked for a day but it wasn't precise as naked steel. Softness here was not a benefit. Mist system sounds good. I'll try that on the bottom rear of the platen to cool the platen at it's hot spot and the belt as it exits. We'll see. Ordered the wheels from China. Now I'm back to hand sanding to fix things up from the softness of the graphite and because of the slight irregularities from non consistent thickness of it as it was ground of the edge of the platen.
And to answer why I'm doing this. Lines are straight and there is no need for hand sanding. Going down the line with Trizacts makes a nice finish (except for S90V). Just to manage the heat...
I tried ceramic glas for the platen and it got ground of in the middle due to force when shaping. So I doubt the continuance of it in this matter. The platen I have now is D3@66HRC. After a year, there are some scratches but no irregularities in straightness. So, misting is next to check. :) For platen cooling systems, for now, it's out of my financial reach. My grinder is totally a fix-up. Bought for cheeps in bad shape but got it working. One day I'll grow up and buy all the necessary goodies to make work more efficient. :)
 
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