HobbyCNC 3 axis controller board review

[CNCadmin]

I did my test on the board to verify that the components that I installed were done so correctly. The test failed, I did not get 5volts on the test point, so after close inspection, (using a magnifying glass) I found a bridge in one of the from soldering. Once that was cleaned up, a re-test gave me the green light to install the rest of the parts. Now on to testing the out put to the steppers. So far I have spent 1/2 hour on building the board, I waiting on my case and transformer to arrive. Stay tunned...

[pminmo]

JayC
There is nothing wrong with unipolar steppers. Yes a bipolar of the same arrangement is stronger, but if you don't need it, it's not an issue. Unipolar electronics are almost aways going to be less expensive. I think the biggest thing that should concern you is what can you get for what price. If brand X bipolar driver costs $50 more than brand H's unipolar, and you can get a unipolar motor(s) that have the strength you need, it probably is the way to go. Stepper performance is really a combination of the driver, motor (and type) and power supply. By that I mean if you have a 6V rated stepper, and you run it bipolar with a chopped biploar driver and a 12V power supply, you may (probably) not be as happy with the result as the same motor being run with a chopped unipolar driver and a 44V power supply.

Phil

BTW, I would add brand H driver is a pretty good bang for the buck if you can solder. Plus I imagine if at a later date you wanted to drive your motor bipolar, you could sell your brand H board without any difficulty.

[HobbyCNC]

Originally Posted by Jay C Ok, I've done some research on Unipolar versus Bipolar motors: Step motor reference From ST Micro Now, if the torque is reduced, and it says it's better for "relatively low step rates" can anyone tell me how slow is slow for the Unipolar case? Guys I come from the RC airplane world and most recently building my own brushless motor from CDROM parts. The biggest obstacle in "jumping in" to CNC in is knowing what is good enough. I want to start with adding CNC to my Taig lathe to get a feel for things, but I don't wnt a "lot" investment in equipment. The one video of the application of HobbyCNC's drive was not as impressive as I would have liked, though I don't know what ipm the guy used. Any other videos of this system in service with reasonable speeds to showcase the possibilities? CNCadmin, can you explain why you picked this kit ... ie the decision process. Jay

We get 2,000RPM no load on our 127 or 200oz-in steppers at 40VDC with our 4AUPC driver board. FASTER than the Xylotec board we tested against.

Dave Rigotti
HobbyCNC

[pminmo]

Jay C,
You can't make a determination on somebody elses video, to many variables. Start by picking your motor.

Dave,
"We get 2,000RPM no load on our 127 or 200oz-in steppers at 40VDC with our 4AUPC driver board. FASTER than the Xylotec board we tested against."

Now that's misleading!

Phil

[Jay C]

Originally Posted by pminmo Jay C, You can't make a determination on somebody elses video, to many variables. Start by picking your motor.

Well, for the lead screw since I'm adding one, I am eyeing the 127 oz-in one from Hobbycnc for the carriage. For rhe cross slide I need to think more about what will fit Also, when I said I didn't want to invest too much I meant I didn't want to buy twice ... I don't mind buying the best solution for me once

The videos were so I could see the potential.

[Jay C]

Just an update. I ordered a driver board and a 80 oz-in stepper from Dave for my lathe project. After reading the allegromicro datasheet on the driver chip, looking at the photos on Dave's site, and reading some feedback on this site I concluded that this was the system for my needs. I expect the kit to arrive today or tomorrow and I have volunteered to write a tutorial (with lots of pictures, tips and tricks, a description of how the circuit works and what section does what, and a troublshooting section/FAQ to ease any electronics learning curve.

Thanks, and Paul would you prefer that I start my own review thread or tack on here to yours?

Jay

[CNCadmin]

The more reviews the the better, I be comparing this board to the Xylotec board as well. I just have not had any time to devote to this right now hopefully next week I will get back to this. But please be my guest, start a new thread.

[Dan Mauch]

I was really impressed with the Hobby cnc three axis board. When I ran a variety of tests using a 28VDC power supply it ran quite nicely with no lost steps and there was no stepper motor resonance. However, when I installed the unit in one of my nice cases with 36VDC power supply and ran the same tests I was surprised to run into stepper motor resonace using the G03x0y0i.4f3 G code command with turbocnc and also with desknc for dos.

I suspect that the 8 volt difference is the problem even though I have a 10000 UF 63 v cap in the power supply. I have a feeling that the problem is caused by the common ground plane and the higher voltage.

Is anyone else running their hobbycnc boards at 36VDC and set for 3A and experiencing what appears as stepper motor resonance even though it is set for 8 microsteps?
Dan

[HobbyCNC]

Originally Posted by Dan Mauch I was really impressed with the Hobby cnc three axis board. When I ran a variety of tests using a 28VDC power supply it ran quite nicely with no lost steps and there was no stepper motor resonance. However, when I installed the unit in one of my nice cases with 36VDC power supply and ran the same tests I was surprised to run into stepper motor resonace using the G03x0y0i.4f3 G code command with turbocnc and also with desknc for dos. I suspect that the 8 volt difference is the problem even though I have a 10000 UF 63 v cap in the power supply. I have a feeling that the problem is caused by the common ground plane and the higher voltage. Is anyone else running their hobbycnc boards at 36VDC and set for 3A and experiencing what appears as stepper motor resonance even though it is set for 8 microsteps? Dan

Dan,
We ran many test cycles at 42VDC with 3 and 4 3A steppers hooked up. No problems detected on this end. Try turning down the Vref to 70% of the actual value. We find the steppers stay MUCH cooler and the loss of power (RPM) is hardly noticeable.

Dave Rigotti