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  1. #111
    Quote Originally Posted by CNCRY View Post
    The stepper drivers were set by default at 1000 according to switches so have changed the switches to 1600 in the table as recommended.
    I was thinking the "units" referred to cm - as UCCNC defaulted to 200 steps per unit, I took this as meaning 200 steps @ 1.8 degrees to make 1 revolution which would equate to 10mm of motion, so a unit being 10mm. I guess I was calculating the wrong way round!
    Does jogging use the same velocity settings - as jogging seemed to be about 10m/min which seems about right , even with microstepping on drivers set to 1000 and steps /unit at 200?
    With the hybrid steppers I mean that many build logs on here and other forums use "standard" steppers without an encoder, and wasn't sure if mine having encoders that had any bearing on the tuning. Assuming it being a closed loop the controller never knows any different anyway.
    Once I get the replacement ballscrew and right size drag chain I'll do some more testing and tuning.
    Regards 1000Ms and 200units in uccnc then even thou it's traveling at 10mtr/min doesn't mean it's moving the correct distance. The test would be to tell it to move 10mm, which in your case with settings above and 10mm pitch it would move 20mm.
    The closed -loop won't make a jot of difference because it's been told to move 2000 pulses which dutifully does, it knows nothing about the 10mm and only does as it's told moving a set amount of pulses based on the Steps per unit setting.

    With that setting of 1000ms then you should enter 100 in steps per and it will move at 10mtr/min(or more) but only half the distance.

    The velocity is the Max velocity of the machine and is used by everything, however you will see it slow down at times when 2 or more axis are traveling together because the controller will control the speed of the faster axis so all axis arrive at same time.
    Jogging individually each axis will move at full velocity set in motor tuning if set at 100% jog rate.
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  2. #112
    So my replacement ballscrew arrived and it's 15mm O.D. it came with a ballnut but the screw is a different weight now . The existing one on dual axis is 16mm .
    Seller is saying it's nominal diameter as it's a ballscrew . is it usable or will the weight difference and inertia etc compared to the other axis side make it not worth it...

  3. #113
    Not ideal, but my gut feeling is if the pitch is okay, it should be workable.

    It will make one motor work marginally harder than the other, but probably not even noticeable?

  4. #114
    Thanks Andy , just trying to decide whether to try and straighten bent screw , use a diff weight screw or get an exact replacement from Fred ! Bit of a pain really but with the effort gone in so far I do want it to be right . Not sure I have the setup to straighten it but not much to lose on that !

  5. #115
    Quote Originally Posted by CNCRY View Post
    Thanks Andy , just trying to decide whether to try and straighten bent screw , use a diff weight screw or get an exact replacement from Fred ! Bit of a pain really but with the effort gone in so far I do want it to be right . Not sure I have the setup to straighten it but not much to lose on that !
    Have you tried to run the machine with the bent screw yet.? If not you may be surprised how much of a bend can be tolerated. Esp on a machine that isn't massively long.!!

    Did the 15mm screw come from Fred.? . . . I've never seen a 15mm screw that's sold as a 16mm.!
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  6. #116
    I did run it slow and seemed ok but worried it would wear the ballnut fast .
    Nope that ballscrew was the only one not from Fred , I ordered it in the EU to save time but wishing I hadn't now!
    The seller is saying "For a ballscrew the external outer diameter is a totally unimportant dimension, because it connects to the ballnut with balls" which kind of makes sense but why call it a 16mm screw then. And Fred's are 16mm within 0.01mm ...

  7. #117
    Quote Originally Posted by CNCRY View Post
    The seller is saying "For a ballscrew the external outer diameter is a totally unimportant dimension, because it connects to the ballnut with balls" which kind of makes sense but why call it a 16mm screw then. And Fred's are 16mm within 0.01mm ...
    If you're still within 14 days very easy to turn around and tell them you don't want it if you've changed your mind. They've advertised as 16mm, so it isn't what you ordered... Doesn't matter if they think that is important or not.

  8. #118
    Quote Originally Posted by CNCRY View Post
    I did run it slow and seemed ok but worried it would wear the ballnut fast .
    Nope that ballscrew was the only one not from Fred , I ordered it in the EU to save time but wishing I hadn't now!
    The seller is saying "For a ballscrew the external outer diameter is a totally unimportant dimension, because it connects to the ballnut with balls" which kind of makes sense but why call it a 16mm screw then. And Fred's are 16mm within 0.01mm ...
    Yes didn't think it would have been as Fred's screws are also ways within 0.01 of specified like they should be. Send it back would be my suggestion and fit the old one if it's only slightly bent. Then buy a new one from Fred if it gives you any grief.
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  9. #119
    Will post some progress photos soon, but have now pretty much completed the wiring and physical build.
    Cable chain finally arrived from China so the (crazy) amount of wiring is now running back into the control box and 4 separate limits wired in.
    I setup the limit and tested jogging into them and all good there. Machine is running at 4m/min currently as Jazz suggested, until I tune it further.
    I ended up straightening the ballscrew mostly, using the advanced method of compressing between some hardwood and rotating it. But now it's back in the mount it seems to be running pretty well at 100% jog speed. I think my drill test made it seem a lot worse plus there was some slight misalignment of the motor coupler. I do notice the X axis is very smooth even compared to the dual Y.
    My next test after jogging was homing.

    So X and Z - moved along, hit the limit stopped and backed off - great.
    Dual Y - both axis moved towards limit, one side hit limit switch fractionally before the other, then the one which hit the limit seems to keep going and the other side never hits the limit, so the gantry starts to go off square and hit the ESTOP before it breaks the gantry!

    I have both axis set to have homing to the negative limit and 2 separate limit pins set so not sure what is going on here.
    When I jog the axis slowly into limit it hit both pins and stopped, both flag up in UCCNC as hit.

    Before I post on UCCNC forum am I missing something obvious here in the homing sequence for dual axis?

    Click image for larger version. 

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  10. #120
    Sorted - the limit switches for each side of the Y axis did not match the drivers, so when one switch triggered it stopped the opposing side motor. Fine while I was testing limits, not so much for homing operations!
    Homing all working now. Just waiting on some ER20 collets now and hoping to make first cuts very soon.
    So far I just have a ply bed as I figure I'll probably have a few accidents, then thinking to use an MDF bed with threaded inserts fitted from underneath every X cm to allow fixing from above without using screws.
    Need some practice before going for a more expensive material for the bed!
    Still overwhelmed by the amount of settings in CAM around ramp speeds, lead in speed, plunge speeds, feed's etc and how much is OK to leave at default and how much to change.

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