Belt grits, Speed and Heat

T

Taximanny

Joined
Jul 27, 2015
Messages
460
Ok just got the craftsman 2x42 and did all the mods.
It came with a 80 grit belt. I have placed an order from super grit for 80, 120, and 220.

I went ahead and ground a blade out last night to get the feel of the machine.
It is a fast machine and until I can get pulleys and another motor to gear it down, I've got a few questions.

As I got to the tip it heats up quick with 80 grit.
Will a less aggressive belt help, say 120 grit ?
I did order the ceramic belts.

I know I got to get the feel of the machine speeds but I'm pretty sure I was really going light with it.
So I'm thinking the 80 creates More heat...

Some one set me straight.
Thanks
 
Also the 80 grit belts they come with are crap,80 grit ceramics will run cooler.
 
Make a pass, dunk in water. Make a pass, dunk in water. Also use less pressure with higher grits to reduce heat.
 
Even with good belts you will get heat,pretty much one pass and dunk in water. Don't linger in one spot,good smooth passes on the belt.
 
As you get to the tip, the blade has been in contact with the belt longer so that is why it heats up. Use new belts and less pressure. You want the grit to do the work, once I start hearing the blade like that I usually toss the belt. Also, like other said dunk after every pass or have a coolant system. A mister works but will rust everything...
 
That grinder runs fast as heck. That's why you are getting so hot so quickly. Not because of the belt.
 
Watch your fingertips. I lost a few with that grinder. :)
 
I used that grinder to start as well. I had some luck spraying the belt with a hand mister. It actually kept the belt wet for several passes. Poor man's wet grinder!
 
The heat build up has more to do with the condition of the belt and the pressure used than it does anything else. New ceramics, such as the 80 grit, can be used with lighter pressure than one that has lost some of its cutting action due to use.
You will hear it said around the knife shop, use belts like they're free. It will make you a better knife maker.
 
Get a glass platen, and kool mist sprayer, best 2 mods for that machine. I have one. also replace the platen with 2x3x1/4 angle the stock one has to much flex I found.
 
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The glass platen was out of stock at the time so I'm using a 2"x6" ceramic tile.
I haven't had an issue yet of the platen flexing...
It's only my second grind so I know I'm not putting a lot of pressure on it. Maybe as I get quicker it will be s factor.

I'm in the process of getting another motor and pulleys to hook up to the disk side to slow it down.
 
That grinder runs FAST. Don't listen to any one who tells you speed isn't a factor in heat build-up; that's just plain ignorant. :rolleyes:

Having said that, better ceramic belts will cut better and run cooler. The AO ones sold at SEARs, Home Depot etc are nearly worse than useless for metal work.

The first thing to do is put a tempered ceramic face on the platen; that will help heat problems and make it easier to grind flats, because it's just gonna be slicker and smoother.

The second thing to do is cut the thing apart, and bolt or weld an extension between the drive wheel and the idler so you can run 2x72 belts on it. There's a far better variety, and they last a lot longer.

Regardless, it's still a FAST, but fairly weak (low torque) machine, and that makes for a steep learning curve. But if you're stubborn enough to learn to grind decent blades on a Craftsman , every other belt grinder you ever come across will be easy-peasy to work with.
 
Can you use one of those voltage controller plug in modules to slow down the sander instead of pulleys and such?
 
Only if the motor is designed for it. You would have to replace your motor with a DC motor and get a PWM or get a 4pole 3 phase motor with a VFD. Both are kind of expensive but you can scavenge a treadmill off craigslist or a garage sale for a the motor and control for variable speed. It does have to be a decent sized motor though.
 
Robert L Sr said:
Only if the motor is designed for it. You would have to replace your motor with a DC motor and get a PWM or get a 4pole 3 phase motor with a VFD. Both are kind of expensive but you can scavenge a treadmill off craigslist or a garage sale for a the motor and control for variable speed. It does have to be a decent sized motor though.
Click to expand...

Sounds very technical for me. I think I'll give the variable speed control a try anyway. They are around $25 and the sander is getting old and I had to use vacuum belts just to keep it in service. It might work and if it does then great, if it doesn't then it's time for that new knife making sander and some changes to the motor like suggested in other posts.
Thanks for the info, I copied it to my journal for reference. Craig
 
james terrio said:
Regardless, it's still a FAST, but fairly weak (low torque) machine, and that makes for a steep learning curve. But if you're stubborn enough to learn to grind decent blades on a Craftsman , every other belt grinder you ever come across will be easy-peasy to work with.
Click to expand...

I went from a Craftsman to an Esteem with VFD / tilt and you are right on that one!! I still have belts though for my Craftsman and still hog with it from time to time for fun.
 
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