[modric]

I have TB6560 driver and DIP switches configured to 1/8 microsteping (power supply is 12V, and for axis a I have used M8 screws; 130x50 cm table)
If I configure switches to full step will I acive better speed?
Thank you in advance.

P.S.
Now it is very slow. 40 mm per minute.

[MooseCat]

Full step can speed you up a small amount, ~40% in theory. You will still be very very slow though at 56mm per/minute.

The real problem here is M8 screws, which travel ~1mm per revolution.
Also I assume you are using high impedance motors and hence this is the reason you can only produce 40 revolution per minute. This is slow.

Options for increasing speed include:
Increase voltage to 24v
Replace motors with low inductance motors.
Keep slow, high torque motors and replace screws with direct drive belts.
Use screws with larger travel per revolution.

For example, direct drive belts typically travel around 75mm per revolution (15tooth drive pulley, 5mm per tooth). So you would do 40x75 = 3000mm per minute.

[modric]

Dear MooseCat thank you for your reply.

I am using nema 23 motors (23LM-C355-P7V). I think they are good enogh for this purpose. Main weeknes is 12V power supply. But I have read that lots of people had problems with chinese drivers and 24 V power supply (missed steps, burned chips etc.).

I had dip swithes set to on,on - on,on - off,off (100% current, decay mode fast,1/8 microsteping). Now I have configured for x and y all to on. That means I will use 100% current, decay fast and full step. Z is like before 1/8 microsteping because it is fast enough.

Now I achive 900 mm per minute using M8 screws. M8 is moving 1,2 mm per revolution. My motors have ability to use 200 steps per revolution (360°/1,8°=200 steps). So 200 steps/1,2 mm and I get 167 steps per 1 mm. Am I right? So I get precision of 1/167 = 0,0059 mm.

It is more than enough for me because construction is hand made. Only thing that I notice is more vibrations on this higher speed from M8 screw because it is ~160 cm long.

So for x and y I have 0,0059 mm precision and 900 m per minute speed, and for z 0,00078 mm precision and 400 mm per minute speed.

For x and y mach3 parameters are Steps per 167, velocity 900, acceleration 200.
Is that ok?

[MooseCat]

Glad it is working out for you. That is good precision.

I'm surprised at the large jump in speed. Perhaps the bottle neck is the number of pulses per second that you can get to the driver.

[jhovel]

Not that it changes much, but M8 thread is 1.25mm pitch...

Cheers,
Joe

[modric]

Glad it is working out for you. That is good precision.

I'm surprised at the large jump in speed. Perhaps the bottle neck is the number of pulses per second that you can get to the driver.

First of all sorry for my first post it was 400 mm/minute not 40.
Maybe.
But this speed I got on a way that I have increasing velocity until construction start to get stuck. Higher speed - less torque.
I even have achive to drive it on 1000 mm per minute but then on some part of the table motors get stucked.

I think I will drive it on 800 mm per minute which is more then enough for me.
I have Makita rt0700c 700w so I think higher speed will be over kill for it while cutting.

P.S.
Can you maybe recommend some good ebay link for good bits? I need approx. 8 cm long, milling cutter mouth are 8 mm and milling diameter 12 mm and 8 mm ball nose.
So ball nose 80 mm x 8 mm.

[modric]

Not that it changes much, but M8 thread is 1.25mm pitch...

Cheers,
Joe

Main problem for me was torque. With 1/8 microsteping I have similar speed when try to drive motors without axis. But with axis connected my motors are more then a double faster using full step (they don't get stuck on higher speed).

Thank you for this M8 pitch. So I will have 200/1,25=160. So 160 steps per revolution and I will have 1mm/160steps = 0,00625 precision.