Grinder Speed.

Yes, contact wheel can't run any faster than the belt speed. The drive wheel determines belt speed. The two variables are motor RPM and drive wheel diameter.
 
I had thought about that Burr King grinder but you previously stated all of your grinders had ratcheting tensioners so I ruled it out.

I am pretty sure that grinder uses stepped pulleys (at least from the factory) so the wheel isn't spinning as fast as the motor.
 
My other Burr Kings have the same size drive pulleys I assume the BBA 20 does also, but I've never had it apart.

All my Burr Kings do have ratchet tension. The original BBA20 had spring tension but it had tracking issues so I retrofitted the ratchet tensioner. The photo shows it before I upgraded.
 
Contender Machine said:
I had thought about that Burr King grinder but you previously stated all of your grinders had ratcheting tensioners so I ruled it out.

I am pretty sure that grinder uses stepped pulleys (at least from the factory) so the wheel isn't spinning as fast as the motor.
Click to expand...
Yep, it does look like the drive pulley is 1.62" and the driven is 2.5". So it's under driven a bit.
 
J. Hoffman said:
My other Burr Kings have the same size drive pulleys I assume the BBA 20 does also, but I've never had it apart.

All my Burr Kings do have ratchet tension. The original BBA20 had spring tension but it had tracking issues so I retrofitted the ratchet tensioner. The photo shows it before I upgraded.
Click to expand...
Ok that's sweet. Those big wheels sure look cool haha.
J. Hoffman said:
Yep, it does look like the drive pulley is 1.62" and the driven is 2.5". So it's under driven a bit.
Click to expand...
If my math is correct that would put you at around 5950 sfpm. That is a much more common speed.
 
I'm still a bit confused - is this a shaft setup like the old original KMG grinders with a motor pulley, a pulley on a shaft with the drive wheel on the other end? You mention the drive pulley is 1.62" - is that the pulley mounted on motor shaft? Usually a shaft setup has 2 pulleys and a drive wheel. All 3 are required to calculate belt speed.

Looking on the Burr King site they don't tell much, but do list this about the BBA20 so your cal about speed is correct. 6K is pretty fast for sure. My grinder maxes out at 5K
"
  • 1.5 HP Variable Speed Motor – Plenty of power for even the most demanding applications
  • 600-6000 SFPM Variable Speed
  • Runs standard 2″ x 72″ belts
"
 
Looks like for the most of my bevel grinding I use 1,509 SFPM. Probably the reason I get the best results using VSM 880s and Cubitron 947s, belts designed for low to medium pressure applications.
 
Ken,
The Burr King grinders have a motor with a small pulley that is belt connected to a larger pulley on the contact wheel shaft. The contact wheel is the drive wheel. The ratio of the pulleys is 1:.65, so the wheel is driven at 65% of the motor speed.
 
Ken H> said:
I'm still a bit confused - is this a shaft setup like the old original KMG grinders with a motor pulley, a pulley on a shaft with the drive wheel on the other end? You mention the drive pulley is 1.62" - is that the pulley mounted on motor shaft? Usually a shaft setup has 2 pulleys and a drive wheel. All 3 are required to calculate belt speed.

Looking on the Burr King site they don't tell much, but do list this about the BBA20 so your cal about speed is correct. 6K is pretty fast for sure. My grinder maxes out at 5K
"
  • 1.5 HP Variable Speed Motor – Plenty of power for even the most demanding applications
  • 600-6000 SFPM Variable Speed
  • Runs standard 2″ x 72″ belts
"
Click to expand...


You can see the micro-V belt in the housing on this view. The belt is enclosed in the housing.
 
Thank you for the exploded view - that explains a lot. Sure does look complicated to use the drive wheel as the contact wheel - a direct drive is much simpler with fewer moving parts.
 
Ken H> said:
Thank you for the exploded view - that explains a lot. Sure does look complicated to use the drive wheel as the contact wheel - a direct drive is much simpler with fewer moving parts.
Click to expand...
It's actually pretty simple, the exploded view shows every nut and washer so it just looks complicated. The front wheel drive is very smooth and seems to have more power.
 
Actually, a two-wheel setup with the contact wheel as the drive is pretty much as smooth as it can get. Just a contact wheel and a tracking wheel.
 
feeling a little grinder envy up in here
 
Yeah that grinder is a very simple set up with the advantage of added torque. The way they're designed I imagine they are very rigid. The downside is that it is a dedicated contact wheel grinder, you can't put a platen on it.
 
I make do with a radius platen, but ultimately having a dedicated machine with a rubber faced wheel would do a better job. Two grinders isn't excessive- I know guys with like 8 grinders, so like....
yeah....
 
Lorien said:
I make do with a radius platen, but ultimately having a dedicated machine with a rubber faced wheel would do a better job. Two grinders isn't excessive- I know guys with like 8 grinders, so like....
yeah....
Click to expand...

So.....by definition that would be grinder(s) envy.
 
Contender Machine said:
Yeah that grinder is a very simple set up with the advantage of added torque. The way they're designed I imagine they are very rigid. The downside is that it is a dedicated contact wheel grinder, you can't put a platen on it.
Click to expand...
Yes, it's a one-trick-pony. I only use it for bevels and sharpening.
 
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