[Frederic Gagnon]

Hello CNC aficionados

I'm working on the completion of a 24 x 48" CNC router, based on the Solsylva plans. Early on, I have decided to use 2 steppers for the X-axis (the 48" direction) instead of 1 motor with a belt to drive 2 shafts. My feeling was that with a belt the torque was split in 2, so this axis would be weak....

I am using a Gecko G540 for controller, with a 24V power supply. I have 425ozin steppers on X and Y, and a 250ozin for the Z. All have a 10mAh impedance. I have found that this 10mAh impedance is not optimal for the G540 (2mAh would be better), but I am stuck with them...

Unfortunately, very often one of the X steppers loses steps when machine is routing and the whole thing jams. It forces and twist the rails and gantry, so it's very bad on the whole machine...

To fix that, I'm thinking of 1) upgrading to a 48V power supply, and 2)switch to a single X-direction stepper with the belt drive.

Do you think that will help my problem ??

[PaulRowntree]

I would go to 48V AND move to lower inductance motors, ~2 mH if possible. If your current motors are 10 mH (inductance), Gecko's std formula suggests a 32*sqrt(10)=101V supply to get the most of the existing motors. If you only boost the voltage you will still only be using a fraction of the motors' potential. If you want to save a bit, move one of your current X motors to replace the weaker Z motor.

[louieatienza]

Well there are pros and cons for both ways. I went with the belt driving tow screws. Although I used 8-start screws, and using a xylotex with only 24v psu, I can still do some relatively heavy cutting, and still have power to spare...

[JerryBurks]

I did both...used for the x-axis 2 stepper motors/lead screws AND a belt to keep them synchronized. Normally the belt does not see any load because the steppers turn in lock-step (so to say). But if one happens to lose power or is overpowered (or if not powered and I want to move by hand), the gantry will stay true/perpendicular. I know it is a bit unusual but it works very well.

It also means I don't need to slave the 2nd x-motor and re-sychronize/home it for startup. I just run both stepper drivers from the same pulse/dir output

[Frederic Gagnon]

Thanks for all the replies. The 48v power supply is already on the way! I suppose doubling the voltage will greatly improve the power of these babies.

If that doesn't cut it, I'll play with the belt drive and move the spare 425ozin to the Z-axis.

[crane550]

I run dual X motors on my solsylva. It was the best upgrade I ever did, bar none. I think your 48v power supply will do the trick. Some people say the 7ish A will work, and I'm sure it will, but I went with the 12.5A just to be on the safe side. Bad cuts cost me way too much.

[ger21]

If you're using 1/2-10 acme screws, then changing the screws to 5 start screws will make the biggest difference.

[Frederic Gagnon]

If you're using 1/2-10 acme screws, then changing the screws to 5 start screws will make the biggest difference.

I have 1/2-8 acme screws. Am I in trouble? I don't mind a bit slower speed, as long as it works..

[jckstrthmghty]

I have 1/2-8 acme screws. Am I in trouble? I don't mind a bit slower speed, as long as it works..

Trouble no. Many machines run a similar leadscrew with great success. Slower yes.

[Frederic Gagnon]

Holy cow!! That 48V PS was the best imprvement I ever made to the machine! I did a couple of test runs, and absolutely no lost steps, and my god, the speed!! 100 ipm travel easily... Me happy!

[PaulRowntree]

Bravo!