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Topics - rcaffin

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1
G-Code, CAD, and CAM discussions / Swap A and B axes - how?
« on: January 14, 2023, 03:32:12 AM »
I have Mach3 on 2 PCs: one on my desk for design and one on my CNC for operations. I have added a rotary axis to the CNC, and this works very well.

However, because of physical machine constraints (ie space), the rotary axis is aligned with the Y-axis, not the X axis. Somehow I was able to get Mach3 to treat it as being the A axis, which fits in nicely with the standard screen set. This was done some time ago - pre-COVID.

I am SURE that I was able to get my desk machine to behave in the same way. However, just recently it seems to have forgotten this and the A axis on my desk is now aligned with the X axis. This is extremely inconvenient for design work!

I am sure that there is some way to swap the X and Y axes, but I cannot find it. I imagine that I used the same commands to swap the A and B axes - I think? But my brain seems to have gone fuzzy - Long COVID maybe.

Help? How does one do this?

Cheers
Roger

2
G-Code, CAD, and CAM discussions / Subroutine Library in Mach3
« on: May 29, 2022, 06:46:27 AM »
Has anyone tried to implement an external subroutine library with Mach3?

It would have to be invoked via something like m98 (-c:\dir\filename), and the actual subroutine in the library addressed by a passed variable along the lines of m98 p##1.

I believe it is theoretically possible, but I know the stack space in Mach3 is a shade limited.

Cheers
Roger

3
Mach4 General Discussion / Unlicensed Mach4 on desktop?
« on: December 19, 2019, 04:56:23 AM »
At present I am using Mach3. My fully-licensed version is on the PC running my CNC, with an ESS. But I also have a copy of Mach3 running on my office desk with no hardware attached. This is where I do all my programming and initial testing. I seem to remember that it is legal to run a copy like this for Mach3.

Question: can I do the same with Mach4?

Cheers
Roger

4
OK, a report on the latest ESS driver for Mach3 and threading.

The background is that with only one speed update per rev, threading anything difficult with Mach3/ESS was often just not possible. If the cutting forces were significant, the spindle would slow down and the thread would be ruined.  I had been nagging Andy at Warp9 about PID control for Mach3. When the latest driver was released I tried it but found that the full PID stuff still did not work - although the Proportional part does. This is now acknowledged.

Then I made a throw-way comment on the Warp9 Forum that I don't NEED real PID control; I just need the ESS to sync the Z axis movement with the real Spindle speed much faster than one index pulse per rev. To which Andy replied that this feature had been included in the latest driver. I had just not seen any mention of it.

So, today I went into the bowels of Mach3 and of the ESS driver and configured it all for the 512 line encoder which was already on the lathe spindle. Then I ran some tests.

#1: Soft plastic, M12x1.0 metric fine thread, HSS threading tip. I chose this because I have taps and a die for it for comparison. Result: success - but that was soft plastic which would not slow the spindle down.

#2: Using the general test program I had written for #1, I then cut a thread on 5000-series aluminium. This is harder than plastic, but still not all that much of a load on the spindle. This let me fine tune the tip-correction factor for the tool in use (HSS, 60 degrees, sharp tip). The result was successful when tested against the M12x1 die.

#3: A real test: an M14x1 thread on forged steel. (It was some scrap I had rescued ...) This is where all previous efforts had failed: the steel is very tough and the spindle does slow down at times. The thread used to get trashed. Away we went, and the spindle did slow down in places. Quite apart from the fluctuating RPM on the Mach3 screen, I could SEE the spindle slowing. I swear it must have come close to dropping to 50% of speed at least once. OK, it was not a very conservative cut - but that was the whole idea.

Result: a quite satisfactory thread! No sign of wobbles in the pitch. This was checked against a Moore&Wright thread gauge and an M14x1 die I have. Just lovely, despite the variations in RPM.

Conclusion: the dynamic syncing between spindle RPM and Z-axis movement in the latest ESS driver works fine with a good-enough encoder (512 lines is the top end of what is available cheaply). I would imagine that a 256 line encoder would also work OK, or even a 128 line one. I don't care if the actual RPM is different from what was programmed, as long as the threading works on steel! Which it now does.
:) :P  ;D

Thank you Andy.

Cheers
Roger

5
General Mach Discussion / Step/Dir control of spindle?
« on: March 17, 2018, 06:38:23 AM »
Mach3 gives three relay control options: Relay, PWM or Step/Dir.
However, I have yet to read of anyone actually using the Step/Dir option to control a spindle. Anyone?

The problem, as I see it, comes when you compare what Mach3 does when running an axis motor vs a spindle.
For an axis drive Mach3 will issue a number of step pules to move the axis from A to B. Fine.
But for a spindle, Mach3 would have to be sending out a fast and continuous stream of step pulses with no further limits. And if you are asking for S24000, then Mach3 would have to be issuing 24000 Step pulses per minute. That's 400 Hz. I am not sure it can do this. Or can it?

Cheers
Roger

6
General Mach Discussion / Mach3 Sin() cos() tan() problem
« on: January 19, 2018, 05:15:42 AM »
Hi all

Just sometimes I want to machine around a curve which is not a circle, so I calculate the points using trigonometry. That is fine until I get to 360 degrees. In the real world
sin(360) = sin(0) = 0
tan(360) = tan(0) = 0
cos(90) = sin(0) = 0

On my Mach3 V0.062 I get something a little different.
sin(360+0.01) = 0.0001745  (correct)
sin(360) = -2.4492
cos(90 - 0.01) = 0.0001745  (correct)
cos(90) = 6.1230317

Of course, neither sin() nor cos() can ever be >1.000.

Has anyone else met this problem?

Cheers
Roger

7
General Mach Discussion / G16 and G83 interaction (again)
« on: December 02, 2017, 01:20:26 AM »
Hi all.

The Mach3Mill manuals states (10-19) that you can put Mach3 into polar mode, but that this only works for G0 and G1 instructions (Note 1, 10-20). I have no problems so far.

But the same part of the manual goes on to provide an example which drills holes on a circle using a G83 instruction, ignoring the restriction in Note 1. At least on my system, programming a ring of holes this way produces a screenful of rubbish. Trying to run the code does likewise. Changing the G83 instruction (or G81) to a simple G1 results in the program working perfectly.

My interpretation is that the command sets a flag saying 'polar', but that only G0 and G1 check this flag. Executing G0 x10 y20 works fine, and saves 10 and 20 in the 'current X&Y registers'. But note that these are POLAR values. If you then issue a G83 z-5 instruction, the interpreter first sends the spindle to X=10 Y=20 and then does the peck drill. But these are CARTESIAN coordinates!

This is as expected if you believe the restriction in Note 1 that polar coords only work for G0 and G1 instructions. It is a pity that the example in the manual violates that restriction.

Or do others get different results?

Cheers
Roger
PS: Brian Barker's hole drilling wizard uses the G83 instruction - but does NOT use polar coords. Of course it works fine.


8
General Mach Discussion / Questions re "PWM bumped to minimum" on lathe
« on: September 18, 2017, 03:57:10 AM »
I spent the last couple of days playing with spindle control on my CNC lathe with some interesting results. I am wondering whether anyone else has explored this area.

System:
W7, Mach3 .062, ESS, BoBs, KBWT-26 motor DC power supply, Baldor DC motor 180 VDC max, 1/2 kW. PWM control used. (NOT a VFD.)
There is a home-brew optical isolater between the BoB and the KBWT because the input is floating at ~-100 VDC. Artifact of the KBWT design apparently.

First of all, I checked out the max pulley rpm when the motor was getting 'full scale volts'. It was 3860 rpm, but 4000 rpm was a better match over the range. That was set in.
Then I set pulley min rpm to 1.
Question: has anyone used 0 for the pulley min? Does it make any difference?

Then I went to ports&pins, spindle control, to look at PWM Minimum. Now for many VFDs you have to set this to something like 30% to avoid burning out the VFD, but with a DC motor you can go down to 0% in theory. However, while 1% worked fine, 0% seemed to freeze the whole spindle output. It was as though the M3 command was being ignored.
Question: has anyone managed to get 0% to work?

Then I tried 0.5%, but Mach seemed to round this off to 0% and the system didn't work.
Question: has anyone managed to get a decimal place working here?

I then ran a lathe program to step through the speed range (eg 5% steps) with M1 used to pause the loop at each setting so I could record the results: m98 p10 L20 for 20 steps. However, a few times Mach seemed to ignore the M1 and it whipped through the program 'real fast' and finished. I checked the M1 setting was correct, and tried again - whereupon it worked.
Question: has anyone found that the M1 setting and command was being ignored, even though the Config said it should be obeyed?

None of this would be relevant to a mill of course, but it does matter on a lathe when you want to do some threading.
Yes, the system is running just fine. I was fine-tuning.

Cheers
Roger


9
General Mach Discussion / Turn Manual Spindle Incr.
« on: September 15, 2017, 08:27:33 PM »
In Mach3 Turn, under General Logic Config halfway down the right hand side of the tab, there is a box labeled "Turn Manual Spindle Incr." On my system the box contains 50.
Does anyone have any idea what this is for?

Neither it, nor the box under it labeled "Spindle 0V increment" with 10 in the box, appear anywhere in the Mach3Turn_1.84.pdf manual (or in the Mill manual).
But then the pics of various tabs in the manuals do seem to date back to Mach2 in some cases, so ...

Cheers
Roger

10
General Mach Discussion / Coordinate Spaces - a Guide
« on: October 26, 2016, 05:14:15 AM »
Hi all

I was playing around with some routines for touch probes and got myself into a tangle over the different coordinate spaces in Mach3. Now, I know the Mach3Mill manual says you should understand how the coordinate spaces work before just using the screen DROS to zero things - but how many do? Searching on this web site I was unable to find a simple and explicit guide to the coordinate spaces.

So in order to understand what I was doing, I sat down and wrote a full Guide to Machine Coords, User Coords, Workspaces, Offsets and everything. I learnt a lot! (Best way to learn something is to try to teach it.)

I have attached V1 of this Guide as a PDF.  Please read and send feedback. In due course, if it seems to be of use, it may end up in the Members Docs folder.

Cheers
Roger

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