The MPJA stepper will work with the hobbycnc card but will have a reduced holding torque. Look at the data link on the page of the stepper. The spec will tell you the torque in unipolar and how to wire it.

 

I started out with the easycnc set up. I am an idiot when it comes to computers. My Y and Z axis were moving a little more in one direction. IE the bit would go deeper and deeper into the foam during a cut, until it would be cutting during the rapid moves between parts. After about a 5 minute cut the Y axis would be about 1/2'' off as well. I tried every suggestion from the Phlat bros, and the guys on the Mach3 support forum as well. I finally decided to try a different board. Hobbycnc had thier 3axis stepper combo on sale for $159 so I got that. I was a little intimidated by the soldering at first, so I read up on soldering pc boards and watched a few tutorials, and went ahead with the soldering myself.

The hobbycnc board works perfectly. It comes with some nice stepper motors, and a parallel port cable(no power supply). You will need a power supply that can deliver 12-36v and at least 6.5 amps, I am using a 24v 6.5 amp. 4 wire bipolar motors are not usable.

The easycnc board is a beautiful piece of work. My cpu or my cpu skills just aren't up to running it ( probably the skills ).

I will be a return customer with hobbycnc.

Jeff

 

Both the easycnc and the MPJA vextra stepper have 6 wires, so they are wired up just the same for uni or bipolar. The 2 extra wires from the easycnc steppers have just been cut back and heat shrunk, so not noticeable. The two extra wires are the center taps of the two coils. Don't quote me on this but my understanding is, as the name implies, bipolar can switch the current in both directions. But this takes more components. For example you would need 1 transistor to turn on a brushed motor, but I think a bridge of 4 transistors to get reverse. My guess is you need half as many for uni ,which just switch the ends of the coils on/off. The center in the unipolar coil is always connected, so basically it can only power half the coil at any given time. That's why you get less torqued using unipolar.

-Kwok

 

Oh! that would be really cool if you start stocking them Mark.... I'm assuming you've got a supplier where you can get close to the price on them. To be honest, I'll probably hang fire until you have them in. I can't really afford them right now and they're one of those things it would be nice to have, but not urgently.

Best Regards,
Julian (Fozzy The Bear)

 

From what I've read, the story is this. A unipolar board uses one coil to go CW and one coil to go CCW. Less complicated electronic, like Kwok said. A bipolar board uses both coils to go CW or CCW, it just changes the polarity (like you do with dc motors). Obviously, one coil has less torque than two coils together.

 

I have 4 of the Vexta steppers now, and I will tell ya. They work very very well with the easycnc board.

At the end of the day though, I find blucor needs to cut at a much lower feedrate in order to get good bite for the bit. I can run at 200-300 feedrate all day long, but the blucor has alot of mess left over that needs to be sanded off the edges of the cuts. I typically do a full sheet at 3.07 minutes per gcode @ 200 feedrate. I slowed down to 100 feedrate and I have laser cut edges now, no mess at all. Take an additional 3 minutes per sheet but well worth the wait to get the smooth consistent edges. Depron I can cut smooth all day long at 200 feedrate and even higher, but the blucor seems more brittle.

 

That is a very interesting situation you highlight Toxic. Mark I wonder is this possibly the case on some of the cuts I do. I do get a similar situation. Some scripts I run cut perfect everytime, others seem to leave rough edges. Even with a feed adjust I still get this. Its not as bad now that I have all 3 on Vexta motors. But It still happens once in awhile. Is it possible that the phlatscript is running paths against the bit counter-clockwise on some G-code creations ?

-Peter