Speed control for 120V drill

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Shaneyj

Shaneyj

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Location
Katy, Texas
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Project Engineer
I have a Milwaukee 3/4" super hole shooter 350. We would like to be able to vary the speed without compromising rpm. I spoke with a tech from Milwaukee that said they don't make a product but he did not recommend against.
Will a simple voltage control achieve this without loss in torque?
Is there a vfd capable of this?
Thanks for any input!


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Frank DuVal said:
You meant vary rpm w/o compromising torque?

Back in the small universal motor single speed drill (1/4", 3/8") days, we just used a lamp dimmer.

Frank DuVal
Click to expand...
Yes, I mistyped. Vary speed without compromising torque.


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Shaneyj said:
Yes, I mistyped. Vary speed without compromising torque.
Click to expand...

What do you mean by "compromise"? In a Universal Motor, torque decreases as speed increases. So if you are talking about LOWERING the base speed you are using it at now, you will actually get MORE torque at the lower speed.

real-time-monitoring-control-of-electric-drive-a-custom-software-based-networked-control-of-220v.jpg
 
K8MHZ said:
If your drill is DC rated, which is very likely, no VFD is needed.
Click to expand...
If your drill is DC rated, varying the frequency won't vary the speed.

A Milwaukee 3/4" Super Hole Shooter 350 has a 120-volt, 10-amp AC/DC brushed motor. Any variable-voltage controller with a 10-amp capacity will suffice, and this type of motor (unlike many other types) will not be harmed by undervoltage.
https://www.milwaukeetool.com/power-tools/corded/1854-1
 
I installed a 15A voltage control. On first test when I slowed the drill using the controller I was able to stop it by grabbing it with my hand.
The guys used the drill and after 2 days and about 10 holes the controller no longer functions.
Any ideas?
 
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retirede said:
10A at rated full load/speed? Look at Jraef's curves. Current and available torque will increase as you lower speed.
Click to expand...

That's what has me confused. Torque dropped when speed was reduced. I was able to stop the drill with my hand. When on the lowest speed setting; I was expecting more torque.
retirede said:
10A at rated full load/speed? Look at Jraef's curves. Current and available torque will increase as you lower speed.
Click to expand...


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Look at the curves again. As speed drops, torque increases, but so does current. If you bought a controller rated for 10A, you burned it out and before it burned, it was likely current limiting to try to save itself. You persisted in using it and it eventually fried anyway.

The reason your drill is not variable speed at that size is because the trigger, the device to vary the voltage, would need to be rated for 50-60A. It would be huge.
 
try 400hz PWM control signal to a Omron SSR. hence, control the current, not the voltage. finding this as COTS may be difficult though.
 
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