Fun and games. Trying to make mill factional

[terry1956]

Hi, so today I tried to set the motor tuning in mach3. First setting the motors to as high a speed that they could take, then backing off. All good so far. Motors turn at a good rate, and sound ok. Then I try to set the steps and all hell starts to happen. First I set Mach3 up to run in mm. then I try to set the steps. First I input 10mm movement and the machine bed moves near the end stop and I need to stop the machine. I reduce the number of steps in the motor tuning page of Mach3 to 2000 steps from the 15600 it had input before. Then go back to set up the movement of the x axis. Input 20mm, the machine moves 37mm. Input 37mm set axis. Now the x axis moves at a crawl. What is going on. Thanks.

[JAZZCNC]

Hi Terry,

First, you can't set motor tuning until you have the correct Steps per setting , your just wasting your time if you do.

The steps Per MM setting isn't something you can guess at. It's a fixed calculation based on several other parts of the machine. Luckily it's simple enough to work out.
I'm working this out on a typical stepper with a 1,8deg step angle or 200 steps per revolution.

First, you need to know the pitch of the lead screw, or simply put how far that axis travels for one revolution of the lead or ball screw.
Next, you need to know the micro-step setting the drive is set to.
lastly, if you have any ratio between the motor and lead screw you need to know this.

So let us say you have a 5mm pitch with 1600 micro steps set on the drives and you are directly driving the lead screw. The calculation for steps Per is this:
1600 / 5 = 320 Steps per mm

If you had let us say a 2:1 ratio between the motor and screw then it would be.
(1600 / 5) / 2 = 160 Steps per

When you have set the steps per correctly and it moves the correct distance then you can start adjusting the motor tuning.

[terry1956]

Thanks, sorted that bit. Now a new problem. Mach 3 is set for mm. The job is set for mm and so is the gcode. But on starting the program, the cutter moves not 50mm as the program states it should but only moves a few mm. It’s the same on all axis. I have never come across this before so at a loss.

[terry1956]

Thanks, sorted that bit. Now a new problem. Mach 3 is set for mm. The job is set for mm and so is the gcode. But on starting the program, the cutter moves not 50mm as the program states it should but only moves a few mm. It’s the same on all axis. I have never come across this before so at a loss.

[JAZZCNC]

Thanks, sorted that bit. Now a new problem. Mach 3 is set for mm. The job is set for mm and so is the gcode. But on starting the program, the cutter moves not 50mm as the program states it should but only moves a few mm. It’s the same on all axis. I have never come across this before so at a loss.

If you give it a MDI command to move say 10mm does it move 10mm.?

If so would need to see the G-code.

Do you have any scaling set.?

[terry1956]

Hi. When I set the axis to 20mm it moved 20mm. Last test. Checked x and y axis moved correctly to measurements input which they did. However had to stop test as a red led came on for the z axis. This is the 6th time this led as lid up and I have checked all the wiring so think it maybe a fault in the unit. So before I go ahead wasting more time, what’s the best place to buy good Quality stepper drivers in the uk. I did use zapp automation but that’s gone now. Thanks.

[routercnc]

I have only ever seen UK sellers reselling drivers made in China, at least for the hobby market. So you are paying a premium for after sales support and easy return if you buy from here.
ArcEuro used to sell them but I think they don’t anymore. CNC4YOU (?) I think still do.

For the red LED have a read here

http://www.mycncuk.com/threads/3899-Driver-Lights-Red

Switch off the drive and they should spin freely. If not the coils are shorted out due to incorrect wiring. Check which coils you have joined together depending on if you intend them to be parallel or series wired.
Usually if the wires are shorted the driver will pop. At least the older analogue ones did.

If it is intermittent then the coils are wired ok and as you say the drive could be faulty, or in theory the stepper itself could be faulty. You could try swapping drivers over and see if the fault stays with the driver or with the motor.

Another option is to power it up without the motor and step dir connected and let it warm up and sit there. Maybe something is not right and is getting hot because it is faulty.

[terry1956]

Yes, that’s what I have found out, it,s amazing the price difference between sellers for the same item. I think that the z axis motor is failing, so have ordered a new one along with the drivers. I would of liked to go closed loop, but the cs-labs controller can play up at times using a closed loop system. The new parts should turn up this week, so will play around over the weekend. With luck it should work out ok.

[JAZZCNC]

I would of liked to go closed loop, but the cs-labs controller can play up at times using a closed loop system.

Who's told you that load of rubbish.?

The Cslabs controller knows nothing about what drives it controls, that goes for closed-loop stepper drives or Servo drives. All it does is send out pulses to the drives after that it knows nothing about the position or even whether the pulses were received.
The closed-loop portion of the stepper system is solely kept between the drive and the motor and nothing gets fed back to the CSlabs controller, the only part it plays is producing the pulses and to that end, it doesn't know or care what receives them.

I have built dozens of machines with Cslab controllers and closed-loop steppers and I can tell you with 100% certainty that it works perfectly fine with them.

[terry1956]

Hi jazz, I fitted a closed loop motor and driver to my last machine, and it did not like it. It may of been that I only used it on one axis. But it could of been me. However I have read on a few forums that people have had a few problems. I think if ever I get this mill working as it should I will fit closed loop on all axis.

[JAZZCNC]

Hi jazz, I fitted a closed loop motor and driver to my last machine, and it did not like it. It may of been that I only used it on one axis. But it could of been me. However I have read on a few forums that people have had a few problems. I think if ever I get this mill working as it should I will fit closed loop on all axis.

Hi Terry, I can assure you 100% that the Cslabs or any other open-loop Step/Dir controller for that matter knows nothing about the drive which is attached, they just send out pulses and trust the drive receives them. Now, you can get drives that handle pulses timings differently but I've yet to see a Closed-loop drive or any drive for that matter that doesn't work with the Cslabs controller. However, pulse timing issues can usually be dealt with in the control software motor tuning.

[terry1956]

All sorted now. It was a bad stepper driver coursing the problems.