Four Axis Unipolar Stepper Motor Driver


After receiving lots of emails about my 4 axis unipolar driver, I've decided to offer the artwork for $25. Keep in mind that you can get a pre-etched board from John Kleinbauer's site for $38, but if you are adventuresome, like etching boards, live outside the U.S., or just cant wait to get started, then this board is for you.

See the ordering page for details: ordering page

Well, as usual I learned a lot building this circuit board. I initially tried using the PnP Blue toner transfer sheets, but after about 5 ruined attempts, I decided that there has got to be an easier way. So I read all over the net and found out about clay faced paper. I then went to the local paper supply place and they had about 5 different kinds for me to try. Let me say that if you are using PnP Blue, throw it in the trash and go get some clay faced paper. It works 100% better. The resolution is perfect when printed from a laser printer and the iron on process is very easy. It is also very cheap compared to the blue transfer sheets.

The first step is to iron the image onto the board. To do this, you need to clean the board with very fine sandpaper and then scrub it with acetone to get all of the oils off. Don't touch the board after this or the toner won't stick. Next you crank your iron up full blast and iron the image onto the board. This step is so much easier than the PnP blue because the paper doesn't shrink when the heat hits it causing distortion. Press very hard and make sure the board gets super hot. This board took about 2-3 minutes to iron the image on. Next, run the board under cool water to stabilize the toner and then soak the board in cool water to soften the clay layer. I waited about ten minutes and then peeled the paper from the board. Some of the paper stuck to the board, but it was easily removed with a cleaning pad. Clean all the clay from the traces and holes and make sure there are no flaws. The whole process took me about 20 minutes before I was ready to put the board in the etchant. You will be amazed at the resolution and clarity as well as the results of the finished product that you can achieve with this method. I highly recommend it! I'll get the name of the paper and post it here in the next few days.

Here is a list of the types of paper that can be used. I haven't tried all of them, so the results will vary, but you should be able to get something going with one of these: JetPrint Graphic Image Paper, JetPrint Multi Project Paper, Fortune No.3 70# gloss, 80lb clay coated paper, Centura 70# gloss, Productoligh No.2 60# gloss, and Frostbright 60# matte.

This first shot shows the board right after I cleaned the clay faced paper from the transferred toner.


A close-up of the resolution that is possible with the toner transfer method.


Completed board, ready to be drilled and stuffed. If you are interested in purchasing a similar board that is professionally etched, you can get one from John Kleinbauer. Go to his site and look under plans for the Piker4x.


Another shot of the sharp lines and clean look. I leave the toner on the traces because it protects them from oxidation. When you solder the components onto the board, the toner melts away and the solder sticks, leaving a very professional finish. You can still see some of the white clay on a few of the traces. The toner is so sticky when hot that it really adheres to the clay.


My bench is a total disaster right now! Just the way I like it when I'm in the middle of a project. I am looking forward to having it cleaned up and ready for the next phase of the project. Initial tests are showing about 18ipm with my 18V power supply and 10 ohm resistors. This is more than satisfactory for my purposes.


A shot of the completed board. I learned a valuable lesson about the db 25 connector: The pins are reversed for male and female versions of the connector. Design your board around one or the other and stick to it! It took me about an hour to figure out that I had soldered a db 25 male connector onto the board when I should have used a female. Since all of the pins were reversed, nothing worked.


Final shot showing everything hooked up and being tested. It looks like I'm almost ready to button up the cabinet and get ready to do some milling!