CNC Sherline Pt. 2

Previous Next

Home CNC Machining Radio Control My Projects Links About Me Contact Me

Driver Setup

Next: Enclosure Setup

Sadly, Dan has stopped selling these boards and they are no longer available .

I bought Drivers from Camtronics, 3 Axis 2 Amp bipolar choppers and they work great. These are step/direction drivers made for bipolar motors. You can connect a 4, 6, or 8 wire motor to these drivers. Odd number wires motors are unipolar (you can connect a 6 or 8 wire motor to unipolar too-I think?). Camtronics

Dan suggests you check out the Xylotex boards.

For other ways to run a stepper or servo also check out Gecko 201

Sadly, these boards are no longer available

Later I bought a single axis 2 amp driver for my 4th axis. You will need to make larger heat sinks and add a cooling fan if you plan to run the boards on 24v as I am.

Note: I would buy a 4th axis driver after you find a reason for its use and know how to use it.

Making the Rotary table CNC ready is an excellent idea still! You can plug it into the Y axis and get a lot accomplished (everything I have done to now). Again, Dan suggests you check out the Xylotex boards but my suggestion is just to buy some Geckodrives ; you won’t go wrong.

-MAIN POWER TO MOTORS-
I made my own power supply for the drivers per Dan's recommendation. The schematic for it and how to step 24V down to 5V is in the next cell.

    • 10 amp 12-0-12 transformer (wired as 24V)
    • 15,000 uF, 50 volt capacitor
    • 400 volt 25 amp bridge
    • Inline 1 amp Fast blowing fuse
    • Stepper motors use 2 amp Slow blow fuses

Most parts bought from: MPJA Supply
Cheap, but nice 12v 13 amp Supply

-POWER TO BOARD-

Here is the schematic for powering your boards and stepper motors. The parts here are listed in the previous window.

How to step 24Vs to 5Vs. Same transformer
using the 12v section. I stepped the voltage down using power transistors, 7812 stepping to a 7805 bought from Radio Shack. Thanks
Ballendo for pointing this out to me.
ADD HEAT SINKS!

I used 12 volt computer fans for cooling but they kept burning out as the transformer put out approximately 13.7v on that section. Finally I bought a 110 volt fan from radio shack ($20) and have not looked back. Lots of air out of this thing.

I made LARGER heat sinks for my drivers since I am running them on 24 volts. I used 1/8" aluminum and 1/8" 90° angle putting many cuts and holes to increase the cooling surface area.

YOU WILL NEED LARGER HEAT SINKS IF YOU PLAN TO RUN ON 24 VOLTS.

-BUILT IN SHUTOFF-

A spot on the Sherline speed control, made by
KB Electronics, controls spindle on/off. When l1 and l2 are connected the spindle will shut off.
Click Here to go right to the PDF manual.

NOTE: This is SMALL l1 and l2
NOT Big L1 and L2 !

-CONTROLLING SHUTOFF VIA M03/M05 G-CODE-
Build your own

I told my brother, Zaig about this and wanting spindle control via CNC. He was on it! He made a 100% custom board which uses the computer's output to turn on an LED. A sensor detects it, clicks a relay and turns on/off whatever is connected. It's safer since there is no direct connection to the computers' parallel port. The board also has a safety light incorporated so you will know when the "application" is on/off.

I blew out all of my L298 chips!
I was connecting an "all windings off" switch to the jumper on the Camtronics board. I figured I would connect the single axis and the 3 axis ones (in series) with one switch. ZAP! You can see how one of the L298 actually cracked! Ouch. Don't do this in series. I ordered them from Mouser electronics. Thanks Dan for the help

Click photo to make larger

Click photo to open in new window

After the board has been carefully soldered, checked and rechecked, I hooked up all of the required elements and hit the switch!

No Smoke!!! Yippie!!!!

It works and is SO FREAKING COOL!!!

The motors make some really cool noises as they go through their motions. Much quieter than the unipolar setup I first tried.