Variable Speed for Right Angle Electric Grinders

[Wamsutta]

Why have variable speed? I can see having it on a drill, but why a grinder?

 

[The Cobbler]

I don't own one, but I suspect for more control of the grind

 

[larry_g]

I tend to slow things down when sanding or using a wire wheel. It also helps when putting an edge on a blade so as not to burn the metal.

 

[B_Bimmer]

I thought it was silly. Then I picked up a really nice makita that had it at a pawn shop for $20, which was way too cheap to pass up. It's now my most used grinder and I have a lot of Metabo. The slower speed in a powerful grinder just makes everything more controlled feeling. I would love to find more.

 

[dnschmidt]

The correct speed at which is use a flap disk is about 7,000 RPM. This provides the longest service life according to the man that owns Lehigh Valley Abrasives. That's considerably slower than the typical one speed angle grinder.

 

[Joemctag]

Why have variable speed? I can see having it on a drill, but why a grinder?

They bought one at work for polishing brass. There are, traditionally, other, and probably better, tools for that.

 

[toolenthusiast]

Because… different abrasives, different substrates, and different scenarios… require… different… speeds?

 

[OccupantRJ]

If you want variable speed and the application is a brush type universal motor under 8 amps, this should work. I have a speed control for my router that I may try on a grinder today to see.

 

[Steve_P]

3 threads to debate this? Buy a single speed grinder if your goal is removing crappy welds ASAP. VS grinders exist the same reason VS belt sanders, drills..... do. Once you use them you'll understand.

 

[engineer2]

My Makita 18V was my first variable speed grinder. I love it. It even senses kickback and slows down.
My other grinder is a 30 year old 120V Craftsman 12,000rpm. It could be scary to use at times.
Variable speed improves battery life and is quite useful for delicate work. It is essential for polishing stone.

 

[Chilliwack Murray]

I'd never considered the need for variable speed (some kind of movie reference there I think) but I'm repairing the walls and ceiling on a bigfoot fiberglass trailer and needed a way to remove the old, hardened and partially delaminated contact cement from the fiberglass and found a 5" and a 3" wire cup wheel on the lowest speed work very well without removing any significant fiberglass. Both my 18V and corded grinders are not only too fast for the cup wheel ratings but are impossible to finely control at the 10000 and 11000 RPM they run at. In addition to the lack of control, there's also too much heat generated at that speed.

There are definitely uses, just not what I've traditionally used a grinder for. It's like heated steering wheels or the little work lights all the corded tools have now, I figured it was just another gimmick until I tried it.

 

[RedRambler]

I find variable speed useful when grinding welds down on thin Sheetmetal. I use my metabo variable speed die grinder on full speed when knocking most of the weld proud down, but as you get closer to the base metal you want to slow down the speed so you can blend the weld into the base metal. At full speed that is tough to do, so slowing down the speed gives a much more controlled approach.