Drive wheel size comparisons

[hugeo]

Hello All,

I'm in the process of building my second 2x72 grinder. First one is about 7 years old and is a old pulley set up with a 4 inch drive wheel. Looking to upgrade to a VFD direct drive type primarily for small wheel and other low speed applications.

Short version:
I'm thinking 6 inch drive wheel which gets me above 5000 SFPM (3600 rpm) and down to about 282 SFPM (180 rpm)

Long version:
6 inch drive wheels don't seem very common. Here are drive wheel sizes that a few of the the big makers use.

Reeder 5 inch
Northridge 5 inch
Pheer 5 inch
KMG TX 6 inch
AmeriBrade 4 or 7 inch
OMB 5 or 7 inch
TW90 ??? couldn't find info will edit if someone can provide #s

Assuming 180, 1800 and 3600 rpm SFPM for the various sizes should be as follows

4 inch
188
1885
3770

5 inch
236
2356
4712

6 inch
283
2827
5655

7 inch
330
3299
6597

Based on what I've read a 5 inch drive (which a lot of makers use) does not get you above 5000 SFPM which you want if you are using ceramic belts.

I have no experience with a VFD and being able to slow down. What SFPM do you guys/gals run on the low end for sharpening (as slow as possible)? Is there a noticeable difference between 283 or 330 SFPM?

Beaumont is the only place I found that offers a 6 inch drive wheel hows their QC these days?

Thanks for the input and hopefully having some numbers down will help someone else in the future.

 

[Hubert S.]

You can set the top end speed on the VFD within a range. On the KBAC-27D, for instance, you can adjust from 70-110% with a trimpot. I have a 7" Ameribrade wheel and I like it. I don't sharpen on the grinder, so I can't really say whether the bottom end speed is suitable for that. That said, the slowest speed seems really slow to me and I never use the lowest speed I can dial it down to for anything.

 

[tkroenlein]

There's a whole lot more valuable stuff to use it for at very low speeds than sharpening. I use a 2 HP 1740 motor and a KBAC 27D set at 2X, with a 7" Ameribrade wheel. It has the power and speed you could conceivably need.