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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > G0704 CNC Conversion - I'm almost there!
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  1. #1
    Join Date
    Jan 2005
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    136

    G0704 CNC Conversion - I'm almost there!

    I've had a G0704 setting in my garage for close to 2 years, and I've had the CNC conversion on it for about 6 months or so. It's been moving, but I havn't gotten around to dialing it in. Naturally, I've got a project that I could really use a CNC mill for, and of course I'm having trouble.

    This is the 2nd CNC mill conversion I've done, and it was much easier this time around. I had an RF-45 clone last time, but sold it when I moved because I didn't want to move it. Anyway...

    This G0704 has the ArizonaVideo ball-screw conversion kit on it. The install was pretty easy, but the grizzly castings were poor so I had to make a few small mods. I don't remember what though. I highly recommend his kit, it was a pretty painless install.

    X & Y: 570 oz.in. Nema 23 steppers, KL-8056d Drivers
    Z: 1200 oz.in. Nema 34 stepper, KL-8070d Driver
    Power Supply: KL-600-48, 48VDC @ 12.5A

    Running Mach3 on a Windows XP machine.

    Now on to my problem.


    I can run the machine at 200 IPM pretty easily and it will run fine for what seems to be random amounts of time. Then it will bind up and skip a ton of steps. It does this at several different feedrates. The weird thing is it seems to be following one of the drivers. I've switched the X&Y drivers and the problem seems to follow the driver. The stepper will also occasionally just stop moving at all, not even making noises like it's trying to move. This seems to happen after a bind.

    Also, I'll be the first to admit, I don't know much about adjusting the gibs. However, I've followed several videos and I think I've got them dialed in. I pushed them in while wiggling the table until I didn't feel it wiggle any more. I then put the screws back with some locktite to hold the gib in place. I havn't tried to manually slide the table around, but that's my next move.

    Is it possible I have a bad driver? I havn't noticed the fault light come on. Any other ideas?

  2. #2
    Join Date
    Nov 2009
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    4415

    Re: G0704 CNC Conversion - I'm almost there!

    A few things to try first.

    Are you lubing the Gibs during or before use. There is a proper way of adjusting them using an indicator to check for movement. Tight isnt necessarily good, especially at extents of travel. I would back off of all 3 a little and rerun the code above the table and see if it repeats. Or even take the steppers off of the machine but still connected to the drivers and see if the issue appears (in fact this would be first test as it would be easy and quick. It would also tell me if it were electronic or mechanical.

    What service pack are you running? If lucky enough to be SP2, turn off the automatic updates for windows!
    Have you tried using the Mach 3 optimization steps for XP? See here Shut down Windows services, which ones?

    You say you can run 200 ipm pretty easily. Are you referring to jogging a singular axis? Speeds are divided by how many axis are in play at that particular moment. So if all 3 axis are in motion, really only around 70 ipm is occurring. Though I have video of my machine running 200+ ipm I would never leave those settings in place for actual machining. I run about 60-80 ipm max on most axis settings during machining.
    A lazy man does it twice.

  3. #3
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    Jan 2005
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    136

    Re: G0704 CNC Conversion - I'm almost there!

    Gibs are lubed when installed. I do have mor trouble towards the ends of travel.

    I'll try the windows optimization to ight. Not sure which xp version.

    I was referring to 200 IPM on a single axis. I don't plan on running it that fast either, but I was just trying to see what it could do and if the problem got worse.

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  4. #4
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    Jan 2005
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    136

    Re: G0704 CNC Conversion - I'm almost there!

    Thanks for the help

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  5. #5
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    Nov 2009
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    4415

    Re: G0704 CNC Conversion - I'm almost there!

    I dont have an automatic oiler on my G0704 so due to the possible long codes I keep an acid brush in a small can of way lube. Before starting the machine, I basically paint all of the sliding surfaces and squirt oil on the ballscrews. I then run a small wizard in Mach3 that moves each axis thru the full extents of their travel for 25 or so repetitions. During long projects, while vacuuming chips or whatever I will apply some more occasionally. Cheap insurance to say the least.

    Regarding tightness of the gibs at the full extents, this is normal for these machines. It would be nice it it wasnt that way but that is what you will have to set up the machine around. This will also be an issue on a machine that has run for a while. Mostly due to the work being fixed within a central place on the table. This itself makes the gib adjustment difficult and critical.

    Are you using this machine computer for the net or anything else? Interrupts cause the stalling issue. Does the computer have McAfee or other security software running?
    A lazy man does it twice.

  6. #6
    Join Date
    Jan 2005
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    1943

    Re: G0704 CNC Conversion - I'm almost there!

    When you say that you switched the x and y motor driver, did you totally switch them, meaning both the inputs and outputs to the drive? If so and the problem followed the drive, then it sounds like a driver problem. If you only switched the output to the stepper motor, then it could be a problem with the step/dir input stream to the driver from the computer or breakout board or either or both.

  7. #7
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    Jan 2005
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    136

    Re: G0704 CNC Conversion - I'm almost there!

    I'm not running anything but mach 3 on this pc, but it is second hand from a coworker and probably has a bunch of stuff I don't need. I'll check that tonight too.

    I switched the motor output plug, then switched the pin assignments in mach3.

    Sounds like I could be having problems with the step/dir inputs too. I'll try completely swapping the driver.

    Thanks guys

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  8. #8
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    Re: G0704 CNC Conversion - I'm almost there!

    Before swapping the driver completely, switch the inputs to the driver. If you didn't actually switch the input wiring to the driver, you could be having an issue with the parallel port, or the breakout board rather than a motor driver problem. Switching the input wiring to that driver will tell you. I just would hate to see you buy a new driver if nothing is wrong with the one you have. It may still be the driver itself, but I would eliminated the other possibilities first before replacing it.

  9. #9
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    136

    Re: G0704 CNC Conversion - I'm almost there!

    I'll give that a shot. Thanks for your help. I think this driver is still under warranty, but I would rather just have a machine that works...

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  10. #10
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    Re: G0704 CNC Conversion - I'm almost there!

    So I just switched the input plugs into the drivers for x and y, and then changed the pins in mach 3. I ran it around manually for quite a while and didn't notice any lost steps. I'm running a program now to see if it loses any over time.

  11. #11
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    Re: G0704 CNC Conversion - I'm almost there!

    Ran a program that has missed steps before (above the part) twice and no missed steps I can see.

    It might have been as simple as a loose connection at the stepdir inputs of the driver. We'll see if it misses any while cutting.

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  12. #12
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    Re: G0704 CNC Conversion - I'm almost there!

    It is something simple most of the time. Finding it is another story ;-)
    A lazy man does it twice.

  13. #13
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    Re: G0704 CNC Conversion - I'm almost there!

    Quote Originally Posted by Fastest1 View Post
    It is something simple most of the time. Finding it is another story ;-)
    You mentioned you machine around 60-80 IPM, I assume that is rapids? Does 28IPM 2000RPM .075" DOC full WOC with a 4 flute 3/8" HSS endmill sound like a good recipe for 6061 aluminum? It's what gwizard recommends, but my motors can't seem to handle it.

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  14. #14
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    Re: G0704 CNC Conversion - I'm almost there!

    I set my max velocity in those ranges. The cut speeds are much lower but I have a tendency to use the feedrate override and increase it all. Once successful I will use the updated speeds. They vary for me. But I am usually tinkering and doing a single part. Too many factors come into play for 1 specific set up. I am a hobbyist, not a machinist. I do know a lot of things seem very counterintuitive as I learn more.

    Regarding the example of cut you mention. Is this a slot? 100% woc requires many things, slower feed, excellent chip evacuation, sharp tooling and proper entry technique. Many of those factors will depend on the width of the slot/pocket etc. Chips dont have anywhere to go in a slot the same width as the tool.
    When you say cant handle it. What is occurring?
    A lazy man does it twice.

  15. #15
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    Re: G0704 CNC Conversion - I'm almost there!

    I havnt got to the slot portion yet, but I will eventually be cutting one. I'm having troubles pocket milling at that feedrate where i lose steps and my circle pocket becomes an oval. I predrilled the pocket too, which helps the entry.
    I set FRO to 30% and it seems to do just fine. I'll probably run at that speed until these parts are done an I can tweak things and experiment.

    Sent from my SAMSUNG-SM-G870A using Tapatalk

  16. #16
    Join Date
    May 2008
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    1185

    Re: G0704 CNC Conversion - I'm almost there!

    With the 570 steppers at anything over 4A you will never loose steps unless something is really too tight or a defective driver.
    Can you turn the screws by hand using the couplers? With tight ball nuts its easy to get binding on the screws.

    A hand check of each axes will let you know.

    You should be able to move the X and Y by hand if the ball screw mounts are removed. It may be stiff and even really hard to move an axes by hand but if you cant then its most likely too tight and will cause stick slip and perhaps loosing steps.
    youtube videos of the G0704 under the name arizonavideo99

  17. #17
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    Re: G0704 CNC Conversion - I'm almost there!

    Well I'm going to chalk it up to a loose connection and maybe just moving too fast. I got the part done in aluminum, now I've got one more in 1018 and once that's done I'll be able to experiment.

    Here't the first part off this machine. Those bearings are press fit with an interpolated hole. I must say I'm rather impressed with myself...



    - - - Updated - - -

    Thanks for your help everyone, it's greatly appreciated.

  18. #18
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    Re: G0704 CNC Conversion - I'm almost there!

    The part looks very good to me. In the angle you presented I am not seeing any directional changes in the pockets or outside radius. This indicates to me you have low backlash and or proper backlash compensation settings. There is a little chatter but I am sure the part will do its job well. Just out of curiosity, which direction do you pocket? Which for profile? Conventional or climb. How much do you leave for the finish pass? I always left too little for finish. Just sharing.

    IMO there are gremlins in CNC, whether they be Mach, Windows or security software something inevitably rears its head to screw it up. The stalling is 1 of those issues. There is no solid consensus of what the culprit is.

    I have had old resurrected from the dead computers run flawlessly at high speeds via the parallel port and I have had newer more powerful computers stall at crawling speeds. Recently I have tried to understand LinuxCNC and find that it too has plenty of issues in regards to the computer to use.
    A lazy man does it twice.

  19. #19
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    Jan 2005
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    136

    Re: G0704 CNC Conversion - I'm almost there!

    I believe I climb milled this entire part, but I can't be sure. I'll check the code when I get home. I've got .012X and .004Y backlash compensation on, and I can see direction changes on the profile but not the pockets.

    I didn't use a finish pass on this part, but I've used .015 in the past and it worked well for me. The 1018 part coming up will have one, mostly as a test for another part that's coming eventually.

  20. #20
    Join Date
    May 2008
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    1185

    Re: G0704 CNC Conversion - I'm almost there!

    Always do a finish pass if your not in a hurry.

    If you have the re packed ball screws you should have much lower backlash. Did you get re packed screws? I quit selling the stock ball nut screws because I want people to be happy. All have been repacked for this year and you should get .002" or so with gibs set not too tight.

    Nice looking part for the first time out.
    youtube videos of the G0704 under the name arizonavideo99

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