[legomeister]

I am new to this forum and not a native English speaker. I am sorry if I do something incorrect :)

I started studying at a university last fall and discovered that we had a CNC router in the student workshop. Because I don't have access to other machines during the weekend and the afternoon a CNC would come in handy. Because nobody really knew how to operate the machine I started to learn Fusion CAM and Mach3 and basic CNC machining with the help of youtube and forum posts. After solving many in retrospect trivial problems I am now stuck a point where only help from an expert can help.

The major Problem is that the machine is only moving at max 1000m/min and the steppers are still stalling.I tried to change the mach3 motor tuning settings but the only thing that helped was reducing the feedrate. Is 500mm per minute really the maximum feedrate achievable with this hardware? If so this machine is pretty useless for anything else than starting a fire. Because this is exactly what happened when I tried to cut with a 2 flute 6mm bit into pine at the spindle min speed(10 000rpm). My questions are now: Is this machine any good without major investment?

The specs of my machine:
YAKO 2 phase Nema23
Model:YK57XN78-03A
(Single shaft)
Step Angle:1.8
Voltage:3.6V
Holding torque:1.57N.m
Current:3.0A/Phase
Resistance:1.2Ω
Inductance:2.2mH

4 Axis CNC Router 3.5A TB6560 stepper motor driver

12.5 A 24V Power supply

leadscrew(?) with approx. 3 teeth per Centimeter

[awerby]

Those drivers are what's limiting the performance of that machine. You can look them up here and find out what people think of them (not much). You could get a little boost in performance by giving them more voltage - according to this datasheet https://www.allelectronics.com/mas_a...spec/SMC-5.pdf they can take up to 32v - but replacing them with something else would be better. With drivers that could handle 48v, the motors would be running at their full potential speed.

[ShallowPass]

So I think this is your controller board. https://www.google.com/amp/s/m.aliex...519326624.html.

It's very true that the 6560s have a bad reputation, but more because they blew up easily. Since you seem to not be on fire. Have you reviewed the dip switch settings on that panel?

[CitizenOfDreams]

What is the voltage of the power supply feeding the TB6560 board? If it's 12V, replace it with 24V. I would not go higher than 24 with those boards.

Check the motor current settings (the DIP switches on the board).

Also, what kind of drive screws does the router have? What is the lead, how many mm per turn?

[cgallery]

My early experiences with my K2 prototype made me think I had a stepper stalling issue, when in fact I had a crappy parallel port on my computer issue.

[wizard]

Those drives are terrble but there may be other issues at play! Look into these areas:

1, Are the current settings correct on the drives? This is rather critical as you can lose considerable torque with low current settings on your stepper drivers. It is where a lot of people screw up fearing damage to the steppers.
2, Is it one axis or all that stall?
3, Have you disconnected the steppers and manually checked for binding of each axis saddle.
4, Determine the lead of the leadscrew to the best of your ability. You need to know this to get close to proper setup of the CNC software but the other thing is you need to know if too high of an RPM is expected out of the steppers.
5, Is there a mechanical ratio between the stepper and leadscrews?

Given the above pictures would help.

[legomeister]

Thank you for your replies!
About the leadscrew: I think it has 3 windings per cm.
The settings of the controller board should be: working current/ pause current: 100/50 (doesn't go higher than that), no decay and 1/8 microstepping. The board is running at 24V. Of course, I could buy a 32V power supply and try it out but in the board manual, it says max. 30V.


The y-axis seems to stall the most but the other steppers speed max. is also not very high. The axis seem to run smoothly. I think the issue is not mechanical because I can't stop the gantry with my whole weight pushing on it at 500 mm a minute. At 1000 I did a 2h carve but lost steps in the finishing pass with no high cutting forces and the same speed as in the roughing passes. Of course, there might be two different problems, one that is causing the step loss combined with a general lack of power at high rpm due to the low driver voltage of 24V.

A gecko drive or something similar would, of course, be way better but I am not sure if it is really worth the effort because the machines base structure is okay but far from ideal. The Z-axis tends to flex a little and ball screws would be nice too.

[steryd]

it would be lot easier to change a screw drive to bigger pitch or even a belt drive. then You wouldn't need bigger motors rpm.