Tip: Don’t Use Wire Brushes on Your Angle Grinder
By Chuck CageWhile I was doing some quick research on Ryobi’s angle grinder (below), I saw this disturbing bit in the “specs” section of their site:
Included 4-1/2″ grinding wheel interchanges with industry-standard accessories such as wire brushes, chain-saw wheels, cut-off wheels, etc.
They don’t list any specs for the grinder in question, so maybe I’m out of line. But I’d assume that for it to be effective as a grinder, it’s probably turning at least 8k RPM or better, in which case you definitely wouldn’t want to use a wire brush on it.
A grinder spinning that fast (or even 10k-12k RPM on a wired unit) can throw wire at amazing speeds — enough to shoot the wire right into your body.
If you want to use wire to clean off rust or paint, that’s a great idea; use a knot cut brush — I’ll find one and write it up for you shortly — and use a polisher designed to spin at less than 3k RPM. It’s just as effective and much safer.
Oh yeah, and while I’m in annoying soap-box mode: don’t remove the guard on your angle grinder. Sure, it makes it easier to get into tight spots and make it much easier to cut with, but it only takes once for a disc to come apart — and your life is forever changed.
December 9th, 2006 at 1:31 pm
What about the wire brushes sold for use with Dremels?
December 9th, 2006 at 1:36 pm
The force pulling the wires from their mounting is a function of RPM and diameter — a bigger brush will experience more force than a smaller one at the same speed.
December 9th, 2006 at 3:56 pm
There are wire wheels designed for angle grinder speeds.
One example is here:
http://www.jwalter.ca/walter_ca/servlet/ProdSearch?item=13L454
December 9th, 2006 at 5:49 pm
I recently bought my first angle grinder, but I haven’t had a chance to break it in yet. I’ve never used one before so I really appreciate the tips.
I would love to see more articles like this.
December 9th, 2006 at 11:11 pm
The Dremel brushes aren’t meant to be used at full speed, either - they’re for the variable speed models, and maybe also the little battery powered multi-tools that don’t turn that fast anyway.
The edge speed of a little Dremel brush turning at X RPM is much lower than the edge speed of a big brush for a power drill, so the little wires hold in place better despite the higher speed of even a Dremel at a low setting. The smaller wires are also less dangerous, though they’d still punch into you pretty well at close range.
December 10th, 2006 at 7:30 am
I’ve used wire brushed on all sorts of angle grinders and I have NEVER had a problem.
December 10th, 2006 at 10:34 am
eschoendorff: The guys on American Chopper have used angle grinders without the guard for years without injury, too. Give it time.
December 11th, 2006 at 6:27 am
I highly recommend a full-face-shield instead of just glasses when you’re using a cut-off wheel on a grinder. It doesn’t take much to shatter a wheel, and you’ll be glad for the extra protection if one ever flys apart on you.