Too much tension on belt?

R

running bird

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Sep 29, 2015
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I recently set up a marble plate as a platen for my belt grinder, but I’m concerned if there is too much tension on the belt. The marble is heating up rather fast, along with the belt being worn down from the back side.

Here as some pictures of how the belt sits: https://imgur.com/a/NxvCgRl

Does it look like there is way too much pressure on the belt, or is this normal?

It’s concerning to me but I wanted to check with what other think first. I’d rather not have a belt wear down and snap while I’m grinding. I can easily back up the platen a bit to reduce tension, I just need to file some slots for the platen (pic of the slots: https://imgur.com/a/Ay711Ps ). Shouldn’t be to big of a deal to back up the platen but I don’t want to do it if it’s not nesecary. What do you think?

Thanks,
Kevin
 
Tension is not your problem, the angle over the edge of the rock is. Personally I would ditch the marble and use the industry standard pyroceram. Its much thinner and designed to handle heat. Flat plattens do get hot and even hotter when used. I set mine up so its just a hair past the belt. The drastic angle change over the edge is whats causing your heat. I have ran belts like that but at slow speeds, I would not hog at high speeds with that steep of an angle.
 
Your marble is too far forward and rubbing off your belt
Move it back so it's flush or even a touch away from it
 
John mc c said:
Your marble is too far forward and rubbing off your belt
Move it back so it's flush or even a touch away from it
Click to expand...

Don’t do this if you want flat grinds. You platten should be putting some pressure on your belt but not as much as you have right now.
 
JT is right - take a straight edge and lay on platen, move it so the straight edge clears the contact wheels 1/8" or slightly less. You want a small amount of pressure to hold belt flat again platen, but not so much as to cause a big angle at top leading to wheel.
 
Remember to radius the leading edge of the platen, whatever you chose. If the edge is left square it's easy for the belt joint/lap to come apart as it hits the sharp edge of the platen. The ceramic glass will give you longer life than the marble. All platen materials will erode over time.
 
I do all my heavy grinding with my platten a hair back from the belt and when I'm getting near my dimensions I move it flush
I can grind all day with a cool platten and I haven't had an overused belt snap on me since I started doing it
And my flats are flat
Works for me
I should have been more specific in my earlier post
 
Thank you all for helping out. I’ll be sure to back up the platen a bit, but I’ll make sure it’s at least putting some pressure on the belt so I get good flat grinds. I’m also going to work on radiusing the top portion of the marble to reduce the wear on my belts.

As for the choice of marble, its what I have available to me at the moment and was able to get it cut to size, smoothed, and squared up for free. I’ve heard lots of great things about the ceramic glass platens that JT mentioned. I’m planning on ordering one when I do my next big knife supply order. But for now I needed something to get me by until then, the stock platen that came with my grinder make plunge grinds impossible. So for the time being I’m going to get what I can done with the marble slab.

Glad I checked in before messing up my belts, or worse. thanks again!

Kevin
 
Just wanted to update this thread real quick, I got around to backing the plates up on my grinder and it’s working perfectly now. Not much heat build up at all now. I made a machete blank yesterday and after about an hour the stone platen was just barely getting warm.

I haven’t had much time to work on knives this summer with work and other projects. Recently picked up an old 24” pedal powered grind stone that I’m working on repairing. But hopefully the next few weeks I’ll have a few days to practice on some short camp machetes.

Thanks again for helping out,
Kevin
 
Besides the position of the marble platen the other issue is that it is marble. Marble is a fairly coarse grained material. Wen polished, the surface looks shiny, but the stone itself is abrasive. The old timers had a marble stone for their razors.

Use pyroceramic glass and you will never have an issue.

Some folks will advise you to use glazed ceramic tile, but under the glaze is an abrasive material worse than your marble.

A cold water chilled platen with a pyroceramic platen or a hardened D-2 platen is superb, but pricey.
 
Thanks for the reply Stacy,

What do you recommend for a water cooled platen? Or is that the same as a spray system for the belts themselves?

I’d consider making a D-2 platen, is there anywhere I can buy a piece of D-2 ground to the demensions I need? I have an event heat kiln and I’m pretty comfortable with using it now. would I need to do any special heat treatment steps for the D-2 like cryo?

I’m really only using the marble as something temporary, because I know I’m not going to be able to work on knives much this summer. I’d like to look into a more proper option, and drilling and tapping a steel platen does sound like a good secure option. I’m just unsure of how to go about doing it correctly or what cooling set up to use.
 
Nathan The machinist makes chiller platens with ice water cooling. He also makes a variety of flat and radiused platens. They go fast, so you have to watch for when he has them available. Contact him about prices and availability.

A Kool-Mist system is very good for grinding blades post-HT. I highly recommend it for those who profile the blade and harden, then grind the bevels afterwards. Besides saving grinder time, this helps eliminate warping. It is by far the best way for thin blades and kitchen knives.
 
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