Deciding on which board to get

[AssassinXCV]

Okay, I have 3Amp 6 wire Nema23 steppers, I want 4 axis driver board.

The hobby cnc pro driver board has up to 3Amps per axis, while the Mechatronics's Easy cnc 4 axis only goes up to 2.5Amps per axis. I have 3Amp steppers so will that be a problem if i only supply 2.5Amps to the motors?

Also, the hobbycnc pro driver board has 6-wire connections, the Easycnc Mechatronics board only has 4 connections. I know that you can wire Unipolar steppers (6wire) to a Bipolar board, but i'm wondering if I will lose accuracy or anything such as torque.

One advantage of the EasyCNC by Mechatronics is that it's pre-build, while the HobbyCNCPro driver requires assembly.

The Easycnc Mechatronics is$170 + $34 shipping (total is $204) to Canada while the HobbyCNC Pro is $104 + $26.80 (total is $130.80). Since i have a P.O box in the states since i live 20min away, i could get the HCNCPro shipped there and the total cost would be $111.XX. <--seems like a better deal since i can pick up some gas while i'm down there. (gas is getting expensive in canada).

For the price difference, I'd get the HobbyCNCPro driver since I dont count assembly as a price (i think it'd actually be kinda fun to build the driver).

There was some Chinese 4 axis board, T6560 for $60 + $20 shipping on ebay, but the length that you have to take, to modify it to actually work, isn't satisfying the quality I'd prefer.

I'm not about to go and get a Gecko for $300 yet, maybe when i build a bigger machine.

Any thoughts on which one would be better would be appreciated. Thanks.

Machine info: 6" x 6" x 6" travel Using 1/4" - 20 all~thread, (using springs and two nuts for anti-backlash).

[dertsap]

this would probably be a better deal , 3 drivers and a breakout board 3 Axis Stepper motor driver peak 4.2A 128 micsteps CNC | eBay

for my mill I've got the same drivers as in the ebay ad (different seller) , and I'm happy with them so far , I haven't used them much because I'm still piecing the mill together but I've tested the x and y for a good while and was happy with the way that they performed , and its a great price
I've got gecko 201 drivers for my router setup and they are great drivers , a bit more pricey but the support and performance is good , If your budget allows for a higher price then gecko s the way to go , if not then the other drivers are a great value for the price

[rgammage]

Hello

You say

Also, the hobbycnc pro driver board has 6-wire connections, the Easycnc Mechatronics board only has 4 connections. I know that you can wire Unipolar steppers (6wire) to a Bipolar board,

.

My understanding is that the last part of this statement is incorrect. The Bipolar motor has either 4 or 8 wires and it is possible to wire an 8 wire version (by joining 2 pairs of wires) to match a unipolar board, but no other combination will work.

You have Unipolar motors and should look for a unipolar driver board capable of at least the current of the motor, power is calculated as current squared times the resistance of the coils (I know there is an AC effect), so 3*3 = 9 and 2.5*2.5=6.25 c.40% down in power.

Richard

[doorknob]

Originally Posted by rgammage Hello You say . My understanding is that the last part of this statement is incorrect. The Bipolar motor has either 4 or 8 wires and it is possible to wire an 8 wire version (by joining 2 pairs of wires) to match a unipolar board, but no other combination will work. You have Unipolar motors and should look for a unipolar driver board capable of at least the current of the motor, power is calculated as current squared times the resistance of the coils (I know there is an AC effect), so 3*3 = 9 and 2.5*2.5=6.25 c.40% down in power. Richard

You can connect a 6-wire stepper motor to a bipolar drive by simply ignoring (leaving unconnected) the two "center-tap" wires, which leaves you with 4 wires to connect to the drive.

[rgammage]

Hello

Unipolar motors were made first and to ease manufacturing the windings were bifilar wound, that is to two wires were wound together and the start of one winding and the end of the other were joined. Making the three wires .... now if you, as you suggest place a voltage on the out sidewires the coil will try to make a magnet with both north and south at each end the result being no magnetic field.

An easy check is this, spin the motor by hand ... should be quite stiff, join the middle to one of the outers .... it should be harder to spin ..... no join the outer two .... if you are right it will be harder still ..... if as stiff as it was with no wires connected then perhaps I am right .... (try both windings if you have a soft motor).

Richard

[doorknob]

It was my understanding that 8-wire bipolar motors are also bifilar wound. Is that not the case? Wouldn't a bipolar serial connection using bifilar windings be similar? I guess that it would depend on the phase with which the two windings are connected.

[doorknob]

According to Jones (Jones on Stepping Motor Types):

It should be noted that essentially all 6-wire motors sold for bipolar use are actually wound using bifilar windings, so that the external connection that serves as a center tap is actually connected as shown for winding 1 in Figure 1.4. Naturally, therefore, any unipolar motor may be used as a bipolar motor at twice the rated voltage and half the rated current as is given on the nameplate.


If you look at the referenced figure 1.4, winding 1 shows the use of the "cross-over" wiring connection between the two coils in a "6-wire motor sold for bipolar use", instead of the simple center-tapped arrangement.

So, my interpretation is that it depends on the motor, with some 6-wire motors being suitable for connection to a bipolar drive as I stated above, but with the potential that some other 6-wire motors could be wired differently internally.

It's an interesting point that you have brought up, inasmuch as the internal wiring details of the 6-wire motors that are commonly used are rarely disclosed in depth (at least, when buying motors on eBay, that is). It is entirely possible that you have highlighted a cause of weak torque in some 6-wire motor bipolar drive installations, whereas others work perfectly well with bipolar drives.

[RobosaurusRex]

Getting back to the original poster's question, does anyone else have any suggestions or input about inexpensive drivers? I'm also interested in that topic.

[RChadwick]

Just my two cents... I've played around with my own designs in the past, and various kits. Mostly, I bought myself problems and wasted time. Then, I got what I thought was a nice 4 axis board from SOC Robotics. It was absolute junk. After setting the current, it would randomly vary 50% (You could even hear it in the motors when it happened). Despite after being run well below it's ratings, and fixing a bad solder joint I noticed when it arrived, it died after about 15 minutes of use. Meanwhile, I was looking for an optocoupler board to save my PC in case of a catastrophic failure, or just for ground loop issues. I decided to not waste any time, and just get a Gecko G540. A cute little module, with built-in everything, for $250. The motors run with more power, a bit cooler, and no weird issues. Everything just works. No constant tweaks, planning on spare parts, or add-on optoisoator board and it's issues. If I just got the Gecko in the first place, I would have SAVED money. Then again, I wouldn't appreciate the gecko.

[dertsap]

Originally Posted by RChadwick 4 axis board from SOC Robotics. It was absolute junk.o.

a few years i made the mistake of buying a couple single axis boards from those clowns , never did get them running , I had a thread called " burned by modularcnc " (his ebay name) , a guy from soc came onto the thread and was making promises of firmware etc , eventually the thread got closed on us for some stupid reason , a lot of unresolved crap came of it
unfortunately threads like that sometimes get closed and buried and then people continue to get ripped off

[AssassinXCV]

Well, i've decided to get the HCNCPro. When i build a bigger and more demanding machine, i'll get a Gecko because the HCNCPro has quality for the price that you can't beat. For the price of that Easy-cnc Mechatronics, i might as well upgrade to the Gecko for $60 more. I might contact the people at HCNCPro and see if they're about to have another 15% off sale in the next while.

thanks for your input

[melw8111]

I don't know if it helps or not but I have purchased everything from Hubbard CNC inc on Ebay. They have fantastic stuff, and they help with all the setups etc. I've found them to be of great value when setting up my machine.