Belt Sander/Grinder ???

[ACHiPo]

From videos I've watched a belt grinder seams to be something I'd use for shaping parts and rough grinding lathe cutters. Most use a 4 wheel system which would use up a lot of valuable space in my shop. I see a few that use 2 wheels that would fit better on an already full bench, not taking up much more space than a conventional wheel grinder.
View attachment 253786

I don't plan on getting into knife making where I'd want the contact wheel to grind concave surfaces. Would one of this design limit me in any way?

Thanks
Greg

Greg,
That's a good question. I'd never paid any attention to 2" belt sanders until recently. They have a big following, but I struggle to understand how they are that much more usable than a decent bench grinder with a good rest (yes, I understand you can avoid the curve of the grinding wheel). I've been toying with "souping up" my grinder by adding Harold Hall's rest, etc., but now I'm contemplating a belt grinder instead--sure takes up a lot of real estate, though.

Evan

 

[mikey]

From videos I've watched a belt grinder seams to be something I'd use for shaping parts and rough grinding lathe cutters. Most use a 4 wheel system which would use up a lot of valuable space in my shop. I see a few that use 2 wheels that would fit better on an already full bench, not taking up much more space than a conventional wheel grinder.
View attachment 253786

I don't plan on getting into knife making where I'd want the contact wheel to grind concave surfaces. Would one of this design limit me in any way?

Thanks
Greg

There have been some negative reviews on the Kalamazoo grinder, mainly because the entire upper mechanism is supported by a somewhat flexible tube. Under high grinding pressure, it moves. If the upper wheel was supported by a solid plate then that would be better.

Another grinder the knife guys seem to like is the Coote grinder but it is very expensive for what it is. I think the current KMG-type design is a much better design, although it does chew up some real estate.

 

[Alan H.]

A belt travelling at 5 to 6k feet per minute is a dangerous thing when it comes off. I have a friend who's brother received a very serious laceration on his forearm.

I am bringing this up to support Mikey's warning about rigidity and plus the benefit to tracking. These are both top considerations of a good belt grinder. The belt joint should also be inspected on regular intervals. Any signs of wear, trash the belt and put on a new one.

BTW, age damages the joints so if you have an old belt you should be cautious. I have had some 4 x 36 belts that were 7 or 8 years old fail almost instantly but they weren't 3M, Norton, Hermes, or the like. So when I put on any belt (old or new), I stand to the side, adjust the tracking if needed, and then give it a high speed test.

 

[Z2V]

In it’s current configuration ( drive wheel and motor pulley size ) my grinder tops out at 4K FPM. The belt is singing along pretty good at that speed. As was mentioned I bet that belt would slap the snot out of you if it were to break. I think I’m content with 4K for now.

 

[f350ca]

Just looked at the Cootes one Mike, Thanks, neither look very substantial. I really don't have the time right now to build one, BUT, was making some brackets today that sure would be nice to do on one. Thats one problem with these forums, they create work for me.
What would an all around belt speed to shoot for, can't see spending the money on a VFD right now.

Greg

 

[mikey]

Just looked at the Cootes one Mike, Thanks, neither look very substantial. I really don't have the time right now to build one, BUT, was making some brackets today that sure would be nice to do on one. Thats one problem with these forums, they create work for me.
What would an all around belt speed to shoot for, can't see spending the money on a VFD right now.

Greg

According to Burr King, the thing that determines if a machine is a "sander" or a metal "grinder" is speed. Below 3500 rpm, you have a sander that is not well suited for metal work, whereas a metal grinder runs somewhere around 8,000 sfm. The higher end belt makers like 3M and Norton develop belts that work at these speeds so if you intend to have a single speed motor (instead of VS) then I suggest you go for at least 3450 rpm. You will find that at that speed, a coarse belt will remove metal with very fine control. For fine finishing, it is better to run at lower speeds so a VS motor is ideal.

Burr King also recommends adequate HP and solid construction. Furthermore, they suggest using a contact wheel for optimum metal removal instead of a platen.

Given these considerations, I think the KMG-type design is the best I've seen. You can change tool rests, platens, contact wheels and a VS motor will allow you to use multiple belt grits to suit your needs.

I've been meaning to make one for myself for years now and I have a pretty clear idea of what I need. Like you, something else always seems to come up but it is pretty high on the list. Besides, we cannot let @Alan H , @Z2V and @ddickey and the other guys have all the fun!

 

[ttabbal]

Join us mikey! You know you want to! And then we can have another reason to try to talk you into grinding lathe bits for everyone...

 

[mikey]

Join us mikey! You know you want to! And then we can have another reason to try to talk you into grinding lathe bits for everyone...

Yeah, I forgot to add your name to the list of guys who are making me soooo jealous! I WANT a 2X72 but I NEED a DRO for my lathe and mill first, and that has to come after I recover from a $200K home project. In the meantime, I have a really good ass-kicking 2X42!

 

[ttabbal]

I know how that can go. NEED a DRO for a lathe? I keep hearing people say they don't see why I would want one and you say that... Interesting... I'm planning to get one anyway, just because I like the idea, but interesting.

Besides, I blame you for my grinder building. You went and educated us on HSS lathe tools, making me want to grind them. And my wood sander and bench grinder just weren't up to it. Your 2x42 is probably a good machine for this stuff though.

 

[ddickey]

I ran a Bridgeport-Romi lathe last summer for a day. It had a DRO, what a treat that was.
Really liking my grinder Mikey.