SFPM for belt sander

[The Fixer]

Contemplating building a belt/disc sander combo, what kind of SFPM should I be using?

thanks al

[platypus2020]

I have a Jancy RAM 1000 RadiusMaster, 2" x 48" belt sander/grinder and it runs at 3600 sfpm. A couple of the Burr Kings are over 5000 sfpm and one unit is 8000 sfpm. I find the 3600 sfpm, is plenty fast enough for what I'm using it for.

[Tait]

I was just reading up on this question over at bladeforums. (Here's one google search).

It looks like Platypus's 3600 isn't far off. My experience with coarse ceramic belts for hogging steel is that they last longer when going even faster - like 6K SFPM.

I would guess you'd need tighter tolerances and better bearings for faster speeds.

[lakeside53]

Mine has a vfd and 3hp - variable up to 6000sfm.

Be careful with sfm and wheel diameters. 6000 sfm and 1 inch diameter is 23000 rpm. 2 inch is 11.5k. etc...

Sealed bearings often have a 7k limit, and at that they run hot. Choose the largest wheels you can live with.

[RWO]

It depends. Just this morning I was finishing some acetal with a nonwoven abrasive belt and it worked well at 900fpm without risk of melting. Hogging off steel needs at least 4000fpm, faster is better. I usually run aluminum at about 2500-3000fpm. A VFD is a big advantage for a general purpose grinder.

RWO

[jkilroy]

Top speed? At least 5000 sfm with serious power as well, say 3hp min for serious work like tube notching.

[metalmagpie]

If you ever want to run a fine grit belt, you'd better be able to slow that beast down. I run up to 2000 grit micron belts but my grinder will easily slow to about 700 fpm (also goes up to nearly 6000 fpm 'cuz some belts like to run fast when really trying to light your shoes on fire). If you run really fine belts fast you will simply strip off all the abrasive.

But if you're not making an all-purpose knife grinder then sure, something like 3.5k should work fine. Consider the ubiquitous 6x48" belt sanders. Their wheels are what, 4" diameter? They come with either 1760 or 3450 rpm motors. That translates to somewhere in the 1800 to 3500 sfm range, quite a big range.

[noah katz]

If you run really fine belts fast you will simply strip off all the abrasive.

Is that from heat?

For the same material removal rate, higher surface speed should require less application force, reducing the shear force on the abrasive grains.

[metalmagpie]

Is that from heat?

For the same material removal rate, higher surface speed should require less application force, reducing the shear force on the abrasive grains.

I cannot explain the physics. That comes straight from the school of hard knocks. I invite you to go invest in a high-grit micron belt and run it fast. I would love to be proven wrong.