I was looking for a way to use the Mach3 PWM spindle motor speed control feature for my Mill that is a build in progress. So With the Help of Bill Grumble from the TC robotics Group, I built this PWM Motor controller that I thought i would share with you.

***First and foremost**** This design is connected to the AC power line and has a large capacitor that can store a deadly charge for hours after it is unplugged. THIS IS NOT FOR THE INEXPERIENCED OR FIRST TIMER! You can and will be hurt if you are not careful! build at your own risk!


with that said....

 I plan on using a modified Dremel 395 as my spindle motor. I have removed the Dremels internal Triac based speed control as the internal motor is a universal motor that will run on AC or DC. I added a IR LED and a Phototransistor to the dremel motor to send a speed pulse back to Mach3. I removed the AC power cord and added a 5pin CB radio type connector on the rear for the 2 wires for the motor and 3 for the speed sensor system(details on that later...thats next).

 next I needed a way to take the PWM signal from the printer port and control a motor with it. I was talking with Bill Grumble at a TC Robotics group meeting and he pencil sketched this basic design. I took it a bit further and worked out the details to make it run.

 The PWM signal from the PC's printer port is Optically isolated from the Motor controller through a H11L2 Optocoupler. the output from the Opto then feeds the PWM signal to a IR2109 Mosfet driver. I am only using the low side of the driver. and I choose to use a IRG4BC30S IGBT instead of a mosfet for higher current handling should the Dremel lock up. this is the basics of it. For the power supplies, I basically took apart an old switching power supply and robbed all the AC line components. the AC line enters through a fuse to an In rush limiter, then to a MOV or Zener surge suppressor. to a cap and to the bridge rectifier. the bridge converts the AC to DC and a large filter cap cleans up the ripple a bit.

 I choose a 100uf 200V cap as it is what i had on hand. this is a very small amount of capacitance and a larger cap would be better...however. there is some debate on if any benefit would be had as it seems to run perfectly fine as is.

 there is also a 12V Zener regulated supply that feeds 12V to the IC's. The mosfet really needs 15V but I choose 12V to start with. mosfets tend to die if the voltage exceeds 18-20V or so. so i choose caution to start with. you can experiment with 15V if you like. less loss through the mosfet if the mosfet is turned on all the way.

 You will not a large inductor on my PCB...this was in the original supply so i added it but its a bit overkill and really doesn't do much as it was originally part of a Pi filter. it has since been removed.

This design works well! and could be revamped to handle as large of a motor as you like! a bigger heatsink is needed if you plan on running a motor larger then 1 amp. I found with the dremel tool that the heatsink isn't even needed! the Mosfet/Igbt never even gets warm running without a load. but its a good idea to have some form of heatsinking.

 The IR2109 has a saftey lockout should the IC's voltage drop below 10V. this threw me at first. Also the rectified and filtered AC line is about 170vdc, the dremel needs to be speed limited to about 70% pwm so as not to over run the motor. you could use a 80-90vac transformer to provide 120vdc instead. would be a degree safer too.


Enjoy

the photos seem to be what blows the post's up

I think the schematic was way too big in size causing some problems...sorry for the multiple postings

This controller works VERY well! I need to next build a Pulse feedback system to take advantage of the speed feedback function within Mach3

Excellent post Zero Cool, very detailed and informative - don't know how I missed this post before.

If you haven't already seen it, this thread gives some details of pulse feedback which may be of interest to you. http://www.machsupport.com/forum/index.php/topic,995.10.html

Tweakie.

For those that are less electronically inclined, take a look at the Super-PID at www.superpid.com

Gives 5,000rpm up to 30,000rpm from any universal (brushed) AC motor. Has optical feedback to maintain precise RPM control. The $4 optional PCB allow Mach3's PWM output to control rpm. This will be a built in function on V2, which will be available soon. It also gives you on/off control from Mach3, with no additional hardware required.

In testing on a Porter Cable 690, I've found the actual rpm to be within 50rpm of the commanded RPM in Mach3 over the entire usable range, 5,000-27,000 for the PC 690.

I've got it wired directly to a Xylotex drive. It's so nice to be able to use the Spindle Override slider in Mach3 with a regular handheld router.

Oh look at that! I couldn't find anything like that to buy so i had to build one LOL! that is a super nice unit! I like the RPM display and motor Load bar graph! those are really nice touches. wow! thanks for posting that link!


I wanted to be able to choose the speed from within Mach3. and mach3 has the uber cool PID function and PWM signal generation built right in it! from Mach3 i can set the spindle to an exact RPM, ie: 6550rpm and it will run at that rpm or even change speeds while machining. maybe for different operations etc. and mach3 does all the work! and with PWM you have more power at lower RPM.s vs a Triac based speed control type system.

BUT that superpid is an awesome stand alone unit with some really really nice features! I thought about building a completed version of my controller to sell but there didn't seem to be much interest.

There's a huge amount of interest in the Super-PID at CNC Zone. For a router, it gives you a lot of the features of an expensive spindle, without the VFD and the cost.

I sent an email to the SuperPID people asking about a PWM version. will see what they say.

You might want to ask Roman in this thread at CNC Zone. He's the designer.
http://www.cnczone.com/forums/diy-cnc_router_table_machines/112658-super-pid_new_low-cost_router_speed.html