Grinder Speed.

The simple way:

SFPM = .262 X (DIAMETER OF DRIVE WHEEL) X (RPM OF MOTOR)

Be aware that some vfd's are double sped so a 1750 rpm motor at 30% is running 1050 rpms, for example.

Belt slippage is another variable that is much more difficult to measure.
 
Contender Machine said:
The simple way:

SFPM = .262 X (DIAMETER OF DRIVE WHEEL) X (RPM OF MOTOR)

Be aware that some vfd's are double sped so a 1750 rpm motor at 30% is running 1050 rpms, for example.

Belt slippage is another variable that is much more difficult to measure.
Click to expand...
Belt slippage.... That's why I get my rubber drive wheels from you 😜😁 helps I'm sure
 
Contender Machine said:
The simple way:

SFPM = .262 X (DIAMETER OF DRIVE WHEEL) X (RPM OF MOTOR)

Be aware that some vfd's are double sped so a 1750 rpm motor at 30% is running 1050 rpms, for example.

Belt slippage is another variable that is much more difficult to measure.
Click to expand...
We must also calculate speed loss to friction in the system and pressure from grinding
 
Thescrawnylumberjack said:
We must also calculate speed loss to friction in the system and pressure from grinding
Click to expand...

Not sure if this is serious or not?

But this is over thinking it, and totally not necessarily.
We aren't building watches. We don't need posi driven belts, nor do we need servo motors. Not worried about trace belt slipage . How do you propose to measure it. I know all of us Should have encoders on all the output shafts..... Haha

Just don't over heat your blades, glaze your belts, or burn your wood.
 
I think most people would be surprised how much belts slip. With a fine tooth ratchet tensioner you can hear the belt speed up when you click to the next tooth (more tension equals less slippage). If you want to know true belt speed it is necessary to calculate slippage but if you just want to make knives then no it really doesn’t matter haha.

I suppose a timing light of some kind would be the best way to measure true belt speed.
 
Contender Machine said:
I think most people would be surprised how much belts slip. With a fine tooth ratchet tensioner you can hear the belt speed up when you click to the next tooth (more tension equals less slippage). If you want to know true belt speed it is necessary to calculate slippage but if you just want to make knives then no it really doesn’t matter haha.

I suppose a timing light of some kind would be the best way to measure true belt speed.
Click to expand...

I'm not saying belts don't slip.....

A belt with zero grinding, Just running will slip. Just running around it's spindles.
I've done comparison tests measuring against timing belts.

But (insert Hilary meme) what difference does it make?

Does 10-40 FPM difference, or whatever matter at all? For conversation sake maybe, but not for just making knives.
 
Crag the Brewer said:
I'm not saying belts don't slip.....

A belt with zero grinding, Just running will slip. Just running around it's spindles.
I've done comparison tests measuring against timing belts.

But (insert Hilary meme) what difference does it make?

Does 10-40 FPM difference, or whatever matter at all? For conversation sake maybe, but not for just making knives.
Click to expand...
Yup I agree it really doesn’t matter to get that detailed about it for most people. I build belt grinders so it is wise for me to study this in a little more depth.

The best thing to do is observe what is happening and react to it. Speed up, slow down, more pressure, less pressure….
 
"Speed up, slow down, more pressure, less pressure…."

It's definitely an Art, or a Science..... I just don't know which, Yet?

Abrasives are still a somewhat mystery to me.
Ive seen some going into crazy deep analysis over that. I could see myself wanting to do that someday.... I feel like I still don't get them right
 
Contender Machine said:
I think most people would be surprised how much belts slip. With a fine tooth ratchet tensioner you can hear the belt speed up when you click to the next tooth (more tension equals less slippage). If you want to know true belt speed it is necessary to calculate slippage but if you just want to make knives then no it really doesn’t matter haha.

I suppose a timing light of some kind would be the best way to measure true belt speed.
Click to expand...
How can you hear belt speed? All of my grinders are ratcheting tension and yes the sound changes when you tighten the belt, but that is due to the tension changing, not the speed. Just like tightening or loosening a guitar string will change its sound.
 
J. Hoffman said:
How can you hear belt speed? All of my grinders are ratcheting tension and yes the sound changes when you tighten the belt, but that is due to the tension changing, not the speed. Just like tightening or loosening a guitar string will change its sound.
Click to expand...
I believe it’s a bit of both. The tension changing and increased drag does change the pitch but I do believe the belt is also speeding up. The most noticeable thing is if you have a belt with a large seam that you can hear going across the platen or a pulley etc. making the clicking sound. This is less noticeable with rubber drive wheels so to me that seems like they are slipping less. It’s all pretty negligible though.
 
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