New Rebuild on Sherline Chucker Lathe & New build on 5400 mill

[martyscncgarage]

When it comes to actual lathe operation I have to defer to those with more experience than I.

cncsnw, Uwe and Tom have given you some ideas.
You do have to learn to program the part correctly.

The machine likely did exactly as you programmed it to.
Marty

[BillB]

When it comes to actual lathe operation I have to defer to those with more experience than I.

cncsnw, Uwe and Tom have given you some ideas.
You do have to learn to program the part correctly.

The machine likely did exactly as you programmed it to.
Marty

Yes it did my feeds and speeds were to fast.

[BillB]

Guys, Ive confirmed with Marty that my drive ALM fault wiring is correct. Im looking for any input on WHY IF im missing steps the fault alarm is not being triggered? I know see the value in this circuit and I want it work.

To test it again, with the goal of trying to fault out the drive by running the motor really fast as I discovered before. I took the (working) program I made today from which I made my 1st round of parts and changed my feed rate from 10 FPM to 20 & 30 FPR to see if I could get the drive to fault out. Ran the program and again the machine looked like it was running backwards and when the 2nd tool changed it was trying to cut in the wrong location. also hit my M55 (GO to Z0, X0) and tool location was off. SO its defiantly missing steps but NO DRIVE FAULT, it just kept running till I stopped it?

Anyone have any ideas on this?

[suntravel]

You must connect the drivers to the PC using the driversoftware to change the settings in the driver in which case ALM is triggert.

Uwe

[BillB]

You must connect the drivers to the PC using the driversoftware to change the settings in the driver in which case ALM is triggert.

Uwe

Really? So what your thinking is there are settings that are not available by default, correct? From what I remember about my drives is that there was no programming or changes needed???? But this does make sense. I will ask john At Automation technologies. I did not order the PC connection cable he said I would not need it.

[BillB]

Insert manufacturers have tables for feed per rev and surface speed for various materials. There are also on-line resources such as FSWizard https://app.fswizard.com/, as well as mobile apps and PC apps for calculating speeds and feeds.

Your machine is moving backwards because you are loosing steps by attempting a 10" per rev feedrate. The control thinks it has machined toward the chuck by the length of your part. It then backs up to the length of the part at a slower feedrate where it's not loosing steps so that move is correct. It then proceeds to try and make the next pass at 10"/rev and stalls again, while again successfully retracting the length of the part for the next cut. That is why it is appearing to feed backward!

This is also why it will move past your soft limits becsuse there is no longer any relation to the coordinates you have set. The physical switch is a home switch, not a limit switch the way you have chosen to set your machine up, so it will be ignored once home has been set.

Since Acorn is open loop, once you loose steps for any reason, any settings related to machine position, such as home position, work offsets (X and Y zero positions), soft limits WILL BE WRONG. You have to re-home the machine snd reset your part zeros (unless you are using ZRI) ANYTIME you loose steps.

I contacted John From Automation Technologies he says the drives/motors should not miss steps. I agree with you that it IS missing steps, BIG question is WHY it is loosing its location in the 1st place from the very first cutting pass. This situation of me not knowing what I was doing with the feeds will never happen again and IF it does I know what to look for now BUT It would be nice to know the machine is doing what is supposed to. Becouse based on what John is saying the machine "should" correct it self in the event of losing location?? This is one of the main reasons I decided to upgrade to a closed loop system from the standard steppers with no encoder.

Any input on what he has to say?

This is exactly what John said.
Its a closed loop stepper system driver with auto correction.
If it loose step it will slow down or increase the current to try to overcome
or stop it
I do not know what your problem in your set up
it should not miss step

[martyscncgarage]

It is possible you maybe missing steps between your Acorn and the drives.
Can be EMI noise, poor wiring practices.

Set up an indicator zero it out and create a program to go a distance and return to zero. Loop it See if it's repeatable.

[BillB]

It is possible you maybe missing steps between your Acorn and the drives.
Can be EMI noise, poor wiring practices.

Set up an indicator zero it out and create a program to go a distance and return to zero. Loop it See if it's repeatable.

To clarify The machine is not missing steps when programmed correctly.
As per my video posting, the ONLY reason it was missing steps is that my programming was wrong "lathe newbie". Way too fast on the feed rates so the drive and motor could not keep up. After I adjusted it to a useable feed rate it has not missed steps at all.

My wiring is crap but it was not the cause.

My concern is in the future if there is an issue the drive will just keep running, be assuring to know the drive will fault when and if it does have an issue.

[martyscncgarage]

It is possible you maybe missing steps between your Acorn and the drives.
Can be EMI noise, poor wiring practices.

Set up an indicator zero it out and create a program to go a distance and return to zero. Loop it See if it's repeatable.

To clarify The machine is not missing steps when programmed correctly.
As per my video posting, the ONLY reason it was missing steps is that my programming was wrong "lathe newbie". Way too fast on the feed rates so the drive and motor could not keep up. After I adjusted it to a useable feed rate it has not missed steps at all.

My wiring is crap but it was not the cause.

My concern is in the future if there is an issue the drive will just keep running, be assuring to know the drive will fault when and if it does have an issue.

Understand.
The loop is closed between the drive and the motor.
If the motor is not where the drive commanded it, it "hits or lets off on the gas" to get it there. If it can't it faults
The drive receives the step and direction pulses from the controller (Acorn) via the wiring you provided.
The step pulse frequency is on the order of 100k per second on the minimum and HIGHER if you set the step rate higher.
You can imagine if there is any electrical noise, it can disturb that pulse stream.
As a general rule, I use shielded cable between Acorn and the drives to carry the step and direction signals.

I only suggested you test your machine for repeatability.
Likely not your issue is mechanical connection between the motor and the ballscrew or the ballnut mounts.
Have you tested your machine for backlash? I like (and use) Marc Leonard's (cncsnw) method for testing backlash. http://www.cncsnw.com/Lashhowto.htm

Don't take it personal. I am just sharing further thoughts and ideas. After all, its why we are here. We are making suggestions, might be right, might be wrong, but better than nothing at all.

You have come a long way with your projects. Be proud of that, continue to learn, keep an open mind.

Marty

[suntravel]

pls make sure that connection from motor to z-axis is not slipping.

after going three times 0.495 in +Z with G0 your Z is 3*0,495=1.485 off....

Not recommended way to see if ALM is working ist to disconnect the encoder cable from the Z axis driver and command a Z move

Uwe