I am looking to reduce the rpm on my rt angle grinder fixed at 11,000rpm. Spoke with a nice rep at Highland Woodworking. He said that the voltage type regulators used for reducing the rpm on routers will not work on angle grinders. The motors are different. Am I relegated to buying a new variable speed grinder starting at $150? The grinders are not continuously variable but have a step system of 4 or 5 speeds.
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Voltage-rpm reduction
- Thread starter Wayne Spence
- Start date
If it is a series motor (with brushes) it is really a DC motor and these can be run at lower speeds with a reduced voltage. (reduced cooling also). Some newer designs using permanent magnets in the stator (smaller diameter motors) would need some type of rectifier to make DC from AC. As this may require a power supply check with the grinder manufacturer as to the type of motor used.
Stu
Stu
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If it is a simple universal motor then you probably could use a thyristor speed control, but not all small hand tool motors are the same. Since it has the five fixed speeds, it in all likelihood already has built-in electronics. Piling one electronic device over another is asking for trouble. The other thing that creates an issue with using an add-on speed control is that most hand tools these days are soft-start which is basically a simple electronic speed control device.
Have a CHEAP HF grinder running on a router speed control from Woodcraft. Bill Nedow Woodturner from Canada talk about this at a demo at the Cincinnati symposium around 2007 and it was on his site which has been removed because of his passing. He did High speed sanding around 4 to 5000 rpm with the grinder. Mine's been running for about 8 years when I do any big work over 18". He also had how to make his adapter for the grinder to use 2"3"4"5"6" sanding disc 1/4" stems. Now this thing was a OK I'll try, he said he burnt up a couple grinder tell he bought a CHEAP Chinese grinder so I got mine from HF for like $12.99 on sale now I think there $19.99 on sale.It works and actually the High speed sanding works very well also.
Well, there are a number of trigger type angle drills. Personally I prefer the angle drill to a right angle drill, mostly because they are easier to get down inside a bowl. The Milwaukee angle drill is in the $150 range. The cheapo ones from Harbor Freight are in the $30 range. I had one similar one, and the casing wore out in less than a month. Vince, at Vince's WoodNWonders had one in the $80 range. I have been using the Milwaukee/Sioux angle drills for years. They have all been rebuilt many times (brushes, bearings, and cases). They do come in slow and high speed models, or they used to, haven't checked out the new ones in a long time.
For longevity, two main things. Blow them out regularly. Some have double sealed bearings which are the best. Also, I found out I get way better mileage with slow speeds. I used to get 300 plus bowls with the trigger all the way down. When I slowed down to 600 rpm max, I would get around 500 bowls. Another advantage of the slow speed sanding is the abrasives cut WAY better at slower speeds. My guess is that at high speeds, the grit doesn't really have a chance to dig in, where at slow speeds it really digs in. Vince started me doing this, and every once in a while, I try higher speeds, but there really is a big difference.
robo hippy
For longevity, two main things. Blow them out regularly. Some have double sealed bearings which are the best. Also, I found out I get way better mileage with slow speeds. I used to get 300 plus bowls with the trigger all the way down. When I slowed down to 600 rpm max, I would get around 500 bowls. Another advantage of the slow speed sanding is the abrasives cut WAY better at slower speeds. My guess is that at high speeds, the grit doesn't really have a chance to dig in, where at slow speeds it really digs in. Vince started me doing this, and every once in a while, I try higher speeds, but there really is a big difference.
robo hippy
I recently bought the Metabo electronic disk sander SX E 400 built specifically for inner and outer curves. I've used not much so cannot say anything on longevity but for sanding inside bowls is fantastic. Has a double movement, rotation and swing and is dust proof. $119 at Amazon and it is made in Germany. I love it.
Metabo sander
Got mine a week ago (from the Sanding Glove) and I love it. Thanks to Odie a couple of years ago mentioning about random orbital sanders. Then it was recently revived. With my arthritic fingers, my other drills were making a "strain" if used over several hours of turning. Using Metebo, I don't have near the scratches from the other sanders as well.It is thicker than regular drills and I use 2 hands. Don't have to grip a trigger, part of which saves my fingers!!!!. I still use drills too.:cool2:Gretch
Got mine a week ago (from the Sanding Glove) and I love it. Thanks to Odie a couple of years ago mentioning about random orbital sanders. Then it was recently revived. With my arthritic fingers, my other drills were making a "strain" if used over several hours of turning. Using Metebo, I don't have near the scratches from the other sanders as well.It is thicker than regular drills and I use 2 hands. Don't have to grip a trigger, part of which saves my fingers!!!!. I still use drills too.:cool2:Gretch
Metabo
Thanks Gretch. Arthritis is really changing the way I do things. Weight is a problem whether drills, sanders, angle drills or saws. A year ago I thought there would be no problem working until 80, I am 77, but now I have some doubts.
Thanks Gretch. Arthritis is really changing the way I do things. Weight is a problem whether drills, sanders, angle drills or saws. A year ago I thought there would be no problem working until 80, I am 77, but now I have some doubts.
Wayne-Where there is a will, there is a way!!!!!!!!! Don't lose the fight!!!!!😀Gretch