Dremel Slowdown

[onlyonmonday]

I have the one speed (Multi-Pro 275) and wonder if I will do damage if I put a (Volume switch) Dimmer switch in line to slow down and vary the rotation ??

So many attachments to be used but believe some would work better if twirling is diminished..

[CNC Molds N Stuff]

I have the one speed (Multi-Pro 275) and wonder if I will do damage if I put a (Volume switch) Dimmer switch in line to slow down and vary the rotation ??

So many attachments to be used but believe some would work better if twirling is diminished..

Get a router speed control like this...

http://www.harborfre...trol-43060.html

This will work on any router or rotary brush motor that does not have internal soft start or RPM / LOAD compensation circuitry. Your dremel should work fine with it. I personally like the Harbor Freight rotary tool over and above any of the Dremel tools I have played with. More power, higher RPM, less end play, less runout, and comes with a variable speed foot control, and the router speed control in the link above will work in place of the foot control if you want to hold a constant RPM. Its even a decent price.

I have two of these:

http://www.harborfre...rver-40432.html

I even used it for a while as the spindle on one of my mini CNC mills for cutting aluminum injection molds. The one headache I had was that the chuck key on one of them had an alignment pint hat was too long. Took me about 2 seconds on the bench grinder to fix that.

As a side note: You might expect to be able to step up to a Foredom tool and get better performance. Their motors are a little better, and their durability is good, but their more affordable handpieces actually have more runout and side play than the one that comes with HF tool. Their low end handpiece costs as much as the entire HF tool. For more durability AND low runout and play Foredom does have a heavy duty handpiece available, but the price jumps to about $150.

Yes, I do have some of the Foredom handpieces also including one of the expensive ones.

Anyway... IMO the HF unit is a much better value than the dremel.

Edited January 15, 2011 by Bob La Londe

[not a bear]

As long as you get one that can handle the wattage I think this will work. A better approach than a volume switch would be a wall dimmer I'd think. Let us know how it goes!

I have the one speed (Multi-Pro 275) and wonder if I will do damage if I put a (Volume switch) Dimmer switch in line to slow down and vary the rotation ??

So many attachments to be used but believe some would work better if twirling is diminished..

[Vodkaman]

I have the one speed (Multi-Pro 275) and wonder if I will do damage if I put a (Volume switch) Dimmer switch in line to slow down and vary the rotation ??

So many attachments to be used but believe some would work better if twirling is diminished.

This question comes up once or twice a year, so I decided to have a read. Modern dimmers work by switching the power on part way through the a/c cycle and off again when the voltage crosses zero. The knob adjusts where in the cycle the power is applied. So the voltage (110VAC) remains full, but the length of time the power is on, is reduced.

Essentially, you are switching the drill on and off 120 times per second. For techy reasons that I won’t go into, this causes an increase in current flow in the motor windings. Your motor may or may not be able to take this extra current. If not, the coil wire will burn through and the motor dies. If the motor manufacturer was generous and spent more money than he needed to, then it will work, but it will get hot.

Secondly, the dimmer circuit does not like the inductive load, again techy. The dimmer will work, but sooner or later the triac will fail. From here on it is a crap shoot. If the triac fails close to zero crossing, the motor will survive, but if it fails further away from zero, a massive current surge will destroy your motor.

To try to save your motor from the surge, you could fit a fuse in the power line, rated just high enough for the motor. If the voltage is 110VAC and the motor wattage is 135W, the fuse will be 135/110 = 1.22 amps, so 1.25A to 1.5A fuse would work to save your motor from the current surge.

Motor dimmers have more electronics to counter the inductive load problems. Why risk your expensive motor for the sake of a few extra $$.

Dave

[onlyonmonday]

Si I see that this is the answer, TRUE..

http://www.harborfreight.com/router-speed-control-43060.html

[CNC Molds N Stuff]

Si I see that this is the answer, TRUE..

http://www.harborfre...trol-43060.html

Yes, that control is specifically made to work with AC brush motors. Your dremel tool is an AC brush motor. I still think the rotary tool from HF is far superior to the dremel.

Edited January 20, 2011 by Bob La Londe

[rixon529]

Bob -

Thanks for the link to the flex shaft carver / grinder.

After reading all the reviews (including yours), I think this is what I've been looking for.

For only $50, if it don't perform to my liking, it's not a huge loss. If it does what I want it to do, then I may get another.

Thanks again for sharing the info.

Rick H.

[CNC Molds N Stuff]

Bob -

Thanks for the link to the flex shaft carver / grinder.

After reading all the reviews (including yours), I think this is what I've been looking for.

For only $50, if it don't perform to my liking, it's not a huge loss. If it does what I want it to do, then I may get another.

Thanks again for sharing the info.

Rick H.

I have two of them. Both work fine. At max speed continuous they go thru brushes rpetty fast, but take the speed down just a tiny notch and they run pretty good for a long time between brush changes. You should also read the pages on Foredom's site on taking care of the flex shaft. It does need to be lubed every once in a while.

[onlyonmonday]

The items will work I believe on the prototypes but will not know for sure until I can get back at it anf the cold goes away some..

My chair does not run well in snow and still am NOT done building the shop..

Thanks for any and all info to all that post..