Mach3 - Engraver - Axis won't stay calibrated

[Burf86]

Hey there all you cool cats and kittens.

Let's start this off by saying I have had no CNC experience until lockdown. I have had a 2030 engraver in the workshop for years and never touched it. I acquired it in a job lot on eBay, with a PC tower, but it has just been sat there collecting dust. Until now.
As I said I have had no experience and the learning curve has been steep. Figured out how to get the machine running/use Mach3 (after laying out £150 for the updated software), learnt CAM in Fusion, output some Gcode and cut my logo in a piece of ply. Proper well stoked so I was.
My problem now is all of the axis' won't stay calibrated and I have no idea what to do in order to try and fix it. I have been on the Mach support forum but things move at a snail's pace over there so thought I would try my luck here.

So my setup. I have a PC tower running Windows XP. I think it's 32bit and it has a parallel port (I don't know if its 5v but I would assume so as the engraver is covered in wood-dust so must have been running at some point). I have a T-D 3 axis controller with a JP-3163B board set to 1/8 step. The motors on the engraver are 57HD0401-15S.

Please let me know if you need any more information, or pictures, whatever.

Thanks,
Paul

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[joeavaerage]

Hi,
I've followed your thread on the Mach forum and suggested you get some real data on you steppers and drivers that we might asses whether
one or more are faulty or whether you are demanding more than they are capable of.

You have not responded. If you can't be bothered to answer the questions then I can't be bothered to formulate solutions for you.

Craig

[Burf86]

It's not a case of not being bothered. I have looked pretty hard but cannot find any info on the motors. Not really knowing what I'm on about doesn't make it easy trying to find stuff, I don't expect anything to be handed to me on a plate, but maybe a few clues on where and what to look for? I don't know what you mean by drivers, is that the board inside the "T-D 3 Axis Controller"? It's a JP-3163B set to 1/8th step. What other info do you need on that?
I did ask you about the other motors I have and the other boards.
I don't really see how I can be asking too much of the motors, all I want them to do is stay calibrated at the moment. The setup had been running before it came into my possession so I highly doubt I am.

The part number on the motors is 57HD0401-15S and I have just found this spec list on RepRap.org
Brand: ???? Taizhou Yasukawa
Model: 57HD0401 15SB*
NEMA: 23/57mm
Step: Angle 1.8 º
Rated Voltage: 6 V
Rated Current: 2.0 A
Phase Resistance: 3 Ohms
Phase Inductance: 5 mH
Max Static Torque: 4.5 Kg*cm
Number Lead Wires: 4
Motor Weight: 0.45 Kg
Detent Torque: 0.21 Kg*cm
Motor Lenght: 41 mm
* Others 57HD0401 could match as well

[routalot]

I can't help with most of the problem,but the voltage for the motors looks absolutely tiny.My Nema 23's run on 36 volts.It occurs to me that the problem might not be calibration but rather losing steps because the steppers lack the power to implement the Gcode.The detent torque converts to 2.91 oz.inch or 0.02059 N.m.
Seems more like a 3D printer level to my eyes.

[joeavaerage]

Hi,
well you found some of the information I asked for. The steppers have moderately high inductance and resistance and as a result
I would expect them to have little torque over 200rpm.

I need you to pull the cover off the control box and measure the voltage to the stepper drivers, my guess is it will be 24V.

If I am correct then I suspect that the reason that your steppers are losing steps is because they are being asked to perform beyond
their capacity. As I have posted earlier all steppers lose torque the faster they go. It may well be if you commanded the axes move very much more
slowly then they would not lose steps.

This stepper has 4.5kg.cm which is only 0.45Nm....its scarcely enough power to pull the skin off a rice pudding.

I suggest you test that theory by MDIing a set of moves, starting slowly and gradually increasing speed until you start to lose steps.
This will inform you of the capabilities of your machine.

Craig

[joeavaerage]

Hi,

The detent torque converts to 2.91 oz.inch or 0.02059 N.m

That's 'detent torque, not holding torque.

Holding Torque = 4.5kg.cm (per spec supplied)
= 45N.cm
=0.45 Nm
=62 oz.in......which is pretty damn gutless.

Craig

[Burf86]

I'm not so worried about the torque. I have run a Gcode, and due to the calibration, towards the end, it was cutting 5mm deep with a 1mm cutter, with no problems.
A quick google search of MDling doesn't give me any clues as to what that means...

[routalot]

That doesn't tell us very much really.What was the feed speed and what was the material?I remain convinced you are losing steps due to inadequate torque.None of the small engravers has too much power-either for the spindle or the steppers.

[joeavaerage]

Hi,

I'm not so worried about the torque

Do you remember Netwons Laws?....in particular:

Force(F) = Mass (M) x Acceleration (A)

And the rotational equivalent:

Torque (T)= First Momement of Inertia (I) x Angular Acceleration (dW²/dt²)

If you want your machine to have any thrust to cut then your steppers need torque to produce that thrust.
If you want your machine to be able to follow a varying tool path then your steppers need the torque to accelerate the axis.
If you want your machine to run at speed then the steppers need the torque to accelerate the axis and overcome the frictional forces.

In short without torque your steppers cannot follow the toolpath that you provide it nor will it have the thrust necessary to cause the tool engage
the material with sufficient force to cut, nor will it be able to oppose the reaction forces of cutting.

Craig

[joeavaerage]

Hi,

A quick google search of MDling doesn't give me any clues as to what that means...

MDI= Manual Data Input

On the MDI tab there is a panel where you can type in Gcode commands. MDIing a command like G1 X4 F50 followed by (Enter)
will cause the X axis to drive to work coordinate X=4 at 50 inch/min.

MDI is the prime means of testing your machine. For example try:

G1 X4 F50 followed by:
G1 X0

This should cause the axis to move to X=4 and then back to X=0.....unless it misses steps.

Craig

[Burf86]

Thanks, guys, I really appreciate you taking the time to help me this.
That 5mm cut was in plywood, I can't tell you what the feeds where. They have long since been changed and I cannot remember what they were.
If the torque is not high enough, will it just loose steps, or will the cutter have trouble moving through the work?
I am unsure which points I need to stick the voltmeter on to measure the voltage on the stepper driver. I've attached a picture of it.

Those MDI numbers you gave me, I don't understand what that all means. Is there a good place for me to get educated?
I typed in G1 X4 F50, moved 101.5mm and stopped.

The attached picture is my latest attempt at engraving my logo, it's looking much better but could still do with some fine adjustment.

[routalot]

If you typed in X4 and it went 101.5mm it could be a clue that you were using imperial units since 101.5 is very close indeed to 4 inches.Which wouldn't be bad calibration really.A quick google will find lots of sites with information about all aspects of programming.For basic stuff you don't need to understand a great deal and a couple of youtube videos should take you a long way.I won't recommend any in particular because I don't use your software.