Wheel questions: 1 vs 2 crowned wheels, idler width, etc.

Fitzhugh

Fitzhugh

Joined
Feb 5, 2013
Messages
194
TLDR;
Do you want one or two wheels crowned on a standard 4 wheel grinder?

Should idler wheels to be a bit wider than the belt?

....
From reading threads about tracking issues I thought the consensus was your should only have one crowned wheel, that two crowned wheels can end up competing. It sounded like most sets only have one. Seemed logical as I read it.

Now that I'm looking for wheels to make a grinder I'm only finding both wheels crowned:

Ameribrade
Diktator
Kadrmask
knifegrinderparts.com / vwjackstraw
nylon-pulley
OBM
US Knifemaker
(who did I miss?)

Is it important?
If so, anyone know a source for an uncrowned 4" drive wheel for a 7/8 shaft?

[Please correct me if 4" is a poor choice for a 2 pole 1hp motor w/ VFD].


Ameribrade has good prices, offers 7/8 shaft, has bearing spacer. The idlers are only 2" wide. Is this a drawback, like when tracking the belt off the edge of the platten for plunge lines?

Thanks - It's hard to know what details matters without having used a proper grinder.
 
I currently have two crowned wheels, as that is what my set came with. They don’t track very well. I will switch one (or turn one flat on the lathe next week.) I was unaware until the thread a few weeks ago.
 
Fitzhugh said:
TLDR;
Do you want one or two wheels crowned on a standard 4 wheel grinder?

Should idler wheels to be a bit wider than the belt?

....
From reading threads about tracking issues I thought the consensus was your should only have one crowned wheel, that two crowned wheels can end up competing. It sounded like most sets only have one. Seemed logical as I read it.

Now that I'm looking for wheels to make a grinder I'm only finding both wheels crowned:

Ameribrade
Diktator
Kadrmask
knifegrinderparts.com / vwjackstraw
nylon-pulley
OBM
US Knifemaker
(who did I miss?)

Is it important?
If so, anyone know a source for an uncrowned 4" drive wheel for a 7/8 shaft?

[Please correct me if 4" is a poor choice for a 2 pole 1hp motor w/ VFD].


Ameribrade has good prices, offers 7/8 shaft, has bearing spacer. The idlers are only 2" wide. Is this a drawback, like when tracking the belt off the edge of the platten for plunge lines?

Thanks - It's hard to know what details matters without having used a proper grinder.
Click to expand...
I have four grinder and they have not crowned ANY wheel and tracking is perfect .I think that crown on tracking wheel don t improve tracking that much but make it more sensitive /responsive .
What is important for good tracking is perfect alignment of wheels ......and good belts of course :)
 
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I charged my tracking wheels to all 5 inch contract wheels. Tracks 10 times better with them yellow j flex belts. Get the poly ones from USA knifemaker. With the 2 crown wheelsit was a pain to get them j flex belts to track.
 
Fitzhugh said:
[Please correct me if 4" is a poor choice for a 2 pole 1hp motor w/ VFD].
Click to expand...
That is a 3 ph 2 pole motor which is 3600 rpm range? With a 4" wheel that would give you around 3700 SFPM belt speed. With VFD set the max freq at 70 hz (or 80 hz) for a faster belt speed. 4,000 SFPM belt speed is pretty good for profiling, unless you're really experienced, then like Natlek you'll want 6,000 SFPM as a minimum. A 36 grit ceramic at 4,000 SFPM will thru sparks like you won't imagine.

Wait, with only 1hp 3600 rpm motor a 4" is as big as you'd want - not enough power for really high speed grinding. Anything smaller than 4" you might have problems with belt slippage.
 
Ha, no... I am not experienced.

For now I'll be using the 1hp motor since it was free, though I'll upgrade eventually and let other tools fight over which gets the grinder's hand-me-down motor.

I'll probably have to replace the drive wheel when I do since this has a 7/8 shaft, so no big deal if I have to change diameter.
 
That free motor is a 3ph? It'll have to be 3ph for VFD use, well, the cheap VFDs anyway. Once you do upgrade the 1hp motor, be sure to save it for a disk grinder. Is there anyway you could get 220vac to grinder? Even with long extension cord?
 
Ah, I should have stated that it is 3 phase.
I'll definitely have a use for the motor: probably safest to step back and watch the lathe, drill press and unborn disk sander fight over it. Seeing the possibilities made me pick the KBAC 27D even if it means taking an extra couple months to have enough money to complete the grinder.

I don't have any 220 outlets, and I rent so I have to assume it won't happen.
I'm still going to see how hard it would be. I mean, the panel is just on the other side of the shop wall. I've got to do some reading on the topic.

It's odd about crowned wheels. Nobody has argued here for 2 with crowns.
 
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