How I modified a Makita GV5000 Disc Sander
to use a 4" zirconium flap disc

(Click on thumbnail photos for full-sized versions.)

This is a lighter, more compact grinder option to trim horses that's better for people with smaller hands.  It does need to be modified to use 4" (10.2 cm) zirconium flap discs, though.  You wouldn't want to just use a 5" (12.7 cm) diameter zirconium flap disc!  4" is as big as you can use on a hoof, practically speaking.  Anything bigger would be too clumsy.  It's hard enough to trim soles and bars, etc., with a 4" diameter flap disc.

There is a 5" diameter black plastic backing disc, washer, and a screw goes through the whole thing.  Note this black backing disc's side view in photo above, after I reduced its diameter using a bench grinder, to a little under 4".

Black plastic backing disc, after I reduced it in diameter with a bench grinder, but not yet attached to the grinder with its washer and bolt:

Here I attached the flap disc on top of the backing disk with the washer and bolt provided.  It attaches with a washer and bolt that you use an Allen wrench on: 

The 4" flap disc attaches just fine once you've reduced the diameter of the black plastic backing.  The bolt is long enough to go through the flap disc OK.  The flap disc centers pretty readily.

It tightens down with an Allen wrench.  You hold the black plastic disc in one hand and tighten the bolt with the wrench in your other hand:

The Allen wrench has a nice little caddy on the cord:

I reduced the diameter of the black plastic backing disc.  I reduced the backing plastic to a somewhat smaller diameter than the flap disc diameter.  This took longer than I thought it would, but I did get it reduced, perfectly centered, and in round. 

With both the bench grinder and sander spinning, here is how I positioned them to reduce the diameter of the black plastic backing disc:

It IS very light and compact.  My antique kitchen scale indicates 2 lbs. 10 oz. (1.2 kg), including the flap disc--but who knows how accurate this scale is?  That's more than 2.1 lbs. on the Home Depot display card, but it's still lighter and more compact than the Cummins angle grinder.   The same scale gave me a 3 lbs. 1 oz. (1.4 kg)  reading on the Cummins 6758 4" angle grinder, which is the lightest 4" angle grinder available, and popular among people who trim horses.  I can't vouch for how accurate this scale is, but it's an indication, anyway. 

Note the switch converter on the Cummins 6758 to overcome the awkward spot the paddle switch is on this model.  You can order this from Phil Morarre at: for $15.  If you were to hold this grinder where the handle is so you could use the switch conveniently, it would be too out of balance, and put a lot of strain on your wrist.  This makes it tempting to just lock the switch to "on," but he advises against this.  If you drop the grinder, you want it to turn off immediately and automatically, not go skittering all over the ground scaring the horse.  This is why he only recommends using a grinder with a paddle switch to trim horses.  He also offers a DVD on how he uses an angle grinder to trim horses, and he gives clinics.

I bought the Makita GV5000 at Home Depot for about $90.  If this model is not available in your area, the modifications I made to mine could probably be made on other compact disc sanders to enable using smaller zirconium flap discs.

I did see 4" angle grinders for compressors that were light and compact, but most people don't want to drag compressors around, and I'd be leery of how a horse would respond to a compressor kicking on and off without warning.  They even startle me, and I'm used to them...sort of!  Not that electric tools are silent, either, but they're not as bad.

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Copyright by Gretchen Fathauer, 2013.  All rights reserved.