Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: corymacgill on September 10, 2021, 11:47:29 PM
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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?
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Some code and pictures will help and also your XML file.
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Attached is a copy of the XML, gcode and pics of the problem.
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Just for reference also These are the parts i am running
Warp9 smooth stepper
Control Board https://www.automationtechnologiesinc.com/products-page/featured-cnc-products/6-axis-ethernet-smoothstepper-motion-control-board-mach3-mach4-relay-spindle-control
Stepper Driver https://www.automationtechnologiesinc.com/products-page/kl-stepper-drivers/kl5056
Stepper https://www.automationtechnologiesinc.com/products-page/nema-34/nema-34-high-torque-stepper-motor-640-oz-in-55
I also have 4 48v 10A power supplies. One for each Driver/Motor
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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.
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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.
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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.
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will do. Thank you for the ideas. I will let you know some time tomorrow. Thank you again!
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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
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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.
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ill go back through all the set screws on all the drives. After that I think ill try replacing all the bearings on the Z axis. If you come up with any other ideas please let me know. I really appreciate the help and if I find anything ill let you know. Again thank you for the help.
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I would run your program at 50% feed and then at 25% feed rate and see if you get a nice corner, if you do then it must be flex in the machine. If it was overrun then the next move would be a straight line from the bottom of the gouge point.
Are you using solid carbide tools or carbide tipped tools, solid carbide are better less flex in the shank. Also keep the tools as short as possible.
It may be worth checking your CAM software some have an option to slow down in the corners to stop this type of problem also filleting the sharp corners with a small radius can also stop this.
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I am in the middle of tearing down the machine as far as i am willing to go. I don't want to get so far into it that I mess something else up. So far I have found nothing loose or appearing to be worn out but dirty for sure.
I have some 1/2" shank bits that I plan on doing some test runs with. they are all carbide tooling as far as I know. They range in size from 1/4" to 1/2". I will modify the test program a little to accommodate the bigger tooling.