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Author Topic: AXYZ Retro Fit - CNC stop/start at 90 degree increments  (Read 245 times)

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AXYZ Retro Fit - CNC stop/start at 90 degree increments
« on: September 10, 2021, 11:47:29 PM »
I have been messing around with this upgrade for a few years now.  I Have AXYZ 4008 that I updated to a Mach3 control system.  All the axis work and move smoothly and I can start and stop the spindle.  So the basics seem to be good.  My problem is when I actually cut a job the machine does not run as smooth as it should.   For example it I do a profile cut of a circle it come out correct however when I do a pocket cut it will leave a "dent" at the start and stop point.  the remainder of the circle is ok.  While cutting the circle the machine will stop at ever 90 degree point.  Also if I do a pocket of a square the machine will leave "dent" at every direction change (at each corner).  I have changed CV settings and tried exact stop settings and nothing seems to make a difference.  I have looked at lots of videos of other Mach3 controlled machines and they don't seems to stop at the 90 degree mark on any movement.

I use VCarve Pro for the cad/cam and use the Mach2/3 arcs inch post processor. I am using a smooth stepper network adaptor to a break out board.

Should I upgrade to another more robust Mach3 controller?

Offline Graham Waterworth

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Re: AXYZ Retro Fit - CNC stop/start at 90 degree increments
« Reply #1 on: September 11, 2021, 08:27:40 PM »
Some code and pictures will help and also your XML file.

Without engineers the world stops
Re: AXYZ Retro Fit - CNC stop/start at 90 degree increments
« Reply #2 on: September 11, 2021, 09:42:29 PM »
Attached is a copy of the XML, gcode and pics of the problem.

Offline Tweakie.CNC

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Re: AXYZ Retro Fit - CNC stop/start at 90 degree increments
« Reply #4 on: September 11, 2021, 11:11:10 PM »
I think that the controller and associated electronics that you are using are just perfect.
Sorry to say this but from the images that you have posted the 'dent' is typical of tool flex or other lack of rigidity in the mechanics of your machine. Lowering the feed-rate and/or reducing the depth of cut may improve the situation by reducing the cutting tool loading. Beefing-up the mechanics of your machine so that the cutting tool is more rigid in relation to the workpiece would be my best suggestion for a way forward.

Hope this helps,

Tweakie.
KEEP SAFE !
Re: AXYZ Retro Fit - CNC stop/start at 90 degree increments
« Reply #5 on: September 11, 2021, 11:29:17 PM »
Thank you for the reply.  Attached is a pic of the machine.  Any idea of where I can start looking for flex in the machine?  The tooling am using are Freud cutters.  That test was run at 125ipm.  I am pretty sure that the bearings are pretty old.  I bought the machine from a local snowboard making company and they bought it used.

Offline Tweakie.CNC

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Re: AXYZ Retro Fit - CNC stop/start at 90 degree increments
« Reply #6 on: September 12, 2021, 01:19:27 AM »
Wow, that’s certainly a good solid looking machine.
With the machine switched off…
Check for any backlash (slack) in each axis in turn – if there is any small amount of slack investigate the cause and eliminate.
Using a gloved hand grip the tool bit – can it be flexed or moved in any direction ?
For these tests you may need to somehow temporarily lock the axis drive motors (G clamp or something similar perhaps ?).
Please report back on your findings.

Tweakie.
KEEP SAFE !
Re: AXYZ Retro Fit - CNC stop/start at 90 degree increments
« Reply #7 on: September 12, 2021, 01:27:11 AM »
will do.  Thank you for the ideas.  I will let you know some time tomorrow.  Thank you again!
Re: AXYZ Retro Fit - CNC stop/start at 90 degree increments
« Reply #8 on: September 12, 2021, 09:05:59 PM »
OK so I spent some time with claps and blocks of wood to keep things in place. I tried to get movement in any direction that I could.  No luck that machine doesn't move at all.  I took the drive covers off and looked at the belts and pullies and they all move in tandem, no slop anywhere.  I looked at the bolts that are holding the gantry to the bearings and they don't look like they move either.

Is it possible that there is some sort of electrical interference/grounding issue?

What do you think 2000lbs of aluminum scrap is worth.  lol

Offline Tweakie.CNC

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Re: AXYZ Retro Fit - CNC stop/start at 90 degree increments
« Reply #9 on: September 12, 2021, 10:02:54 PM »
Quote
Is it possible that there is some sort of electrical interference/grounding issue?

Anything is possible but if it was electrical intererence that would cause a loss of position and that is not apparent in your pictures.

In my opinion, everything points to flex in your cutting tool / machine and if all the mechanics are really rigid then I would look for a loose grub screw on an axis drive, pulley, coupling, thrust bearing, etc. After that I would replace the spindle bearings.

Sorry but I am just about out of ideas now. You have an excellent machine there which is well worth fixing and when you do find the problem I am certain it will be something very simple to fix.

Tweakie.
KEEP SAFE !