I have been searching the web for several hours, looking at many web sites, postings here and Youtube videos and I have not found exctly what I am looking for.
Presently, I am controlling the motor speed of my Bosch colt with a simple Harbor freight motor speed control. Router Speed Control
I got rid of the soft start circuit in the Bosch and wired the motor direct to the power cord so that the motor control above could work properly. It works just fine, but you loose torque at low speeds.
For $175 all your homework is done for you, debugged and tested. When considering the total cost of your CNC it is a reasonable price to pay.
I also have looked into building my own PID controller, but not to save $175. It would for the design challenge since electronics was my trade - retired now.
Your hardware is basically your "brains" (arduino, micro, whatever...) via an optocoupler to a 15A triac phase control circuit. Another opto sensor for detecting the painted router shaft. From there it is mostly software of your favourite PID algorithm.
No, I don't have a detailed parts list for you. Just the concepts. This project can be educational to explore....
yeah, I came to that realization yesterday after about 4+ hours of scanning the web
I bit the bullet and ordered the Super-PID for $175
I really didn't need anything that fancy. I was thinking I could find a simple circuit that could read a hall effect sensor and adjust the triac output to the motor.
It wouldn't have a display, but it would self govern the motor speed.
Oh well, I got the mac daddy Super-PID coming which is way better than what I was looking to do.
I don't have any pics of how I removed the colt speed control but, it is simple.
Remove the top cap with the single screw and have a look.
You can pull the speed control out of it's mounting slots.
A wire comes in from the power cord and a wire leaves and goes to the motor windings.
All you do is remove the speed control and join those two wires together.
As to the Super PID, it is really nice.
Noise level is greatly reduced because I can now use 15k and lower motor speeds which makes a huge noise difference.
I don't really need ear protection with the lower speeds.
Torque is great because the speed control feeds the motor when under a heavy load.
To mount the sensor, I drilled an off center hole in the end cap.
I painted the end of the spindle half black and half white
You can see in my pic below that I soldered together a small brass tube and a brass mounting plate
I slide the sensor down the tube and used some RTV silicon to seal the tube and hold the sensor in place.
I machined the PID box out of black HDPE and made a lexan face plate
(CNCZONE posters take note: EL34 stands thoughtfully by the keyboard, poised--I say POISED--to answer my questions INSTANTLY!)
Seriously, EL, thanks very much for the pictures and the explanation. Your top-mount bracket idea takes all the guesswork out of "where to put the tiny hole" because I can just drill a HUGE hole and slosh the sensor around until I find the shaft! +CREDS!!
Archaeologists stumbling on my Bosch Colt and the Super-PID nearby, still pristine in its shipping box from Down Under, will have their Clue, thanks to you.
My speed control (pic attchd) has three wires coming from it, so I have to leave one disconnected: I'm'a guess the white. (blue is power in from the switch; THICK yellow out of the board is series wired to THIN black, which I take to be a coil; THIN white out I take to be the other side of the same coil but waddoIknow?)
The schematic (attchd) which Al-the-Man posted elsewise for a Bosch 1617 I also believe holds a crucial hint, even though the power switch is in the line heading to a motor coil instead of to the speed control board, as it is in the Colt. I'm going to puzzle over both and come up with an idea.
Maybe my memory is bad on how I removed my speed controller
I tried to find the removed part but no good so I took the end cap off to see exactly what I had done.
See the diagram for how I have mine wired
Note that I also unhooked the Switch and Soldered/heat shrinked my connections to get the best connections possible.
The switch is a weak point and I don't need it with the Super PID.
I left the disconnected switch in the case to block dust from entering the switch hole
Also note that I removed the stock power cord and used some very flexible 18 Gauge cord from the Super PID to the Bosch Colt. My power cord is Red and Black in the photo below.
I painted the shat black first with some high temp spray paint and then used some white model paint to paint half the shaft white
I also had to enlarge the blue plastic housing with a dremel tool to be able to see the end of the shaft.
You have to remove the brushes first and then pull the router apart to be able to enlarge the rear shaft hole properly
There area a couple wiggle washers on the end of the shaft, so make sure you reach up there with a pick and get them out before you enlarge the hole.
Replacing the power cord (and I recognize instantly why you did it! to reduce any tendency to bind up as you go back-and-forth). Nice.
Even as I asked the question, I suspected you might reach for the screwdriver to take the cap off. (I was rooting for your memory...)
I'll stare at it again this evening, but my own memory is that there are two wires to the brush. No. That has to be wrong because the current goes THROUGH the brush to the Commutator. I mean if it were true that two wires carried current to and from the brush, it would be useless as a brush.
Anyhowway, there should be enough pix in this thread alone for Mother to figure it out for me.
Thanks for all your services to mankind. (Hey. I'm mankind.)
Last edited by cnczane; 11-27-2012 at 04:11 PM.
Reason: clarify--if twere even possible
Yes, my black and white diagrm is absolutely correct.
I was staring at my router wires when I sketched it out.
If you want to keep your switch, just interrupt the black wire as it goes from the power cord inlet to the coil.
That's on the right side of my diagram.
But, the switch is a weak spot cause it has the wimpy little screw terminals and I doubt the contact points are as beefy as they should be for the large current that the motor can draw under full load.
I replaced the power cord cause it's 12 feet long and way too bulky.
All I needed was about 3ft of 2 conductor wire that was flexible and di not get in the way.
Also, the PID has screw terminal blocks for the Ac to the motor.
It just makes sense to ditch the big bulky power cord and run a nice clean and short dual conductor wire to the motor.
I have had the original Bosch power cord trip limit switches on my Y axis several times in the past and that sucks
Okay, I didn't see that one coming: the floppy power cord banging a limit switch...
OTOH, I coiled up the power cord into a bundle, and I just have Super-PID control the outlet it's plugged into, which rides along on top of my Z axis.
I had the idea that someday I might need to quick yank it off and I'd at least get the full-speed. I have to admit that I have not thought about, until just now, the fact that I will need to coil up the long sensor cord if I ever do it (it terminates in a Conxall fitting so I wouldn't have to lug the Super-PID box along at least).