Hi
I have been researching home made cnc routers and would like to build a small unit based around a Dremel tool. Can I, in addition to x,y,z axes, control the speed of the Dremel tool through software and hardware mods?

Thanks
Patrick

 

The short answer is yes!
Then come the details. Hopefully someone will come along that knows how a Dremel works. It would probably help them to know which model we're talking about.

 

The Dremel is a universal motor and generally uses a built in Triac style controller, you could build an external one that has a programmable rate, and jumper/bypass the internal one.
The problem with Universal motors is the rpm varies quite a bit with load without some kind of feedback based controller.
Max.

 

Max is the someone I was referring to.

 

If you are going to the trouble of building your own CNC router, a Dremel tool is a crappy choice for a spindle drive.
The Dremel has crappy bearings and is not capable of dealing with the cutting forces, it will burn out quickly, and before it does, it will make ratty cuts and break lots of bits.

 

a dremel has uses in cnc, but using a real router is the way to go. with full horsepower units and the right tool bit you can even cut brass and aluminium.
www.aquickcnc.com/machines
if you missed this website it might be good to browse.

 

If you want PID control of the average router, there is a product designed by a member that has since left after the new Forum layout. (THE_RB).
It is sold as SuperPID universal motor controller for CNC etc.
Max.

 

Hi,

I agree with Max, a triac can be used to 'adjust' the speed of the motor but if you want speed 'control' then you need feedback.

Feedback can come in several different forms, as pulses from a light sensor or voltage from a very small generator, but the simplest is to use the back EMF of the motor to control the speed. Using the back EMF you dont need any sensor other than maybe a small value resistor to measure the current in the motor.

I have actually built a couple speed 'adjusters' and 'controllers' in the past, three different types for motors with brushes and two of them were Dremels.
The first used a triac and op amp to control the firing of the triac, for the Dremel.
The second was the same except it had to adjust the speed for a much bigger motor for a big router.
The third type was an actual controller based on back emf used to control the motor in a tape player.

There was a fourth type that had to control an AC motor, that needed to change frequency as well as applied voltage in order to change the speed. That was much more complicated because it had to be a DC to AC converter to start with and then the frequency had to be adjusted as well as the output voltage when the user turned the pot.

They also make routers that are not as big as a regular router but twice the diameter of the usual Dremel tool. These things have quite a bit of power when used with small cutting bits. We used one once to cut a rectangular hole in a door jam for a new lock and it took like 2 minutes to do. The regular Dremel (1 to 1.5 amp motor) would have taken 15 minutes to do that.
These larger routers usually are advertised for cutting sheetrock and often come with a couple cutting bits that look almost like drill bits but with longer flutes.

One caution though is that if you intend to control a Dremel that already has a speed control built in, you should open it up and disable the speed control or remove it entirely before you attempt to use your own triac speed controller. The Dremel with a speed controller already on it requires an AC input not a triac pulsed AC.

 

...a member that has since left after the new Forum layout. (THE_RB).

I haven't kept up. Was RB's departure merely coincidental with the format change? Surely he didn't leave because of the change?

 

Surely he didn't leave because of the change?

That was essentially in his last post, he said he was taking his ball and going home.
He evidently could not use the new format or some such.
Max.