Page 1 of 3 123 LastLast
  1. #1
    Having just got my first CNC table up and running, has anyone got any practical advice on axis tuning in mach3?

    i have no idea of what speed or Acceleration G's to Aim for in motor tuning.

    its only a small table, I have a work envelope of 650x680mm to play with.

    any tips or tricks?

  2. #2
    Quote Originally Posted by Davek0974 View Post
    Having just got my first CNC table up and running, has anyone got any practical advice on axis tuning in mach3?

    i have no idea of what speed or Acceleration G's to Aim for in motor tuning.

    its only a small table, I have a work envelope of 650x680mm to play with.

    any tips or tricks?
    Unfortunatly Dave motor tuning is quite specific to each machine with many factors playing apart to what can be achieved.
    Best advice is start low and work up and only raise one thing at a time, ie Velocity and test the affect.

    The way I do it to get a ball park quickly is to double then half.? So say start at 2000mm/min on Velocity and 300s/s Accel.
    Test and if ok double Velocity to 4000, test again. if too much then drop to 3000, test again. If ok raise to 3500 and so on.
    Do the same with Accel but just be aware you can't have high velocity and high Accel so start with Velocity and find the limit where motors stall then back off 25%. Now do the Accel in same way and you should be in a nice balance. Just tweak from here to get the best performance.

    The figures I've quoted are just guide lines and the volts you are running the machine motors/drives and the pitch of the ballscrews etc will determine the starting speed. For instance with only 24-36V and cheap drives on 5mm pitch screw then you may well be near the limits at those starting speeds I quoted.?

    Give some info on your setup and will be able to give a better idea of a good starting point.

  3. #3
    Sounds good,

    my machine is all aluminium build, carriage runs on steel rails with bearings.
    im using nema 23 motors, 3.1Nm, 4.1A, and a 36v 11A psu.

    The drives are all T5 belt, 3:1 reductions on both axes and I'm using 1/8 micro-stepping.

  4. #4
    Well you should have high rapid speeds due to high pitch but this obviously depends on pulley sizes thou with 3:1 ratio I can guess at around 25-35mm pitch.
    With only 36V then you'll have lower speed and there fore torque from the motors than they are capable of so for this reason I suggest you keep the motor tuning down so the motors are in the lower Rpm range where more torque is available.

    Like I mentioned before your problem could come from lack of resolution and motors running too slow causing rough movement.?

  5. #5
    There is no problem JAZZCNC, I'm just looking for facts and figures at the moment.

    I now have it set for 15,000mm/min and 1300 mm/sec/sec and it's been running a pen over various files repeatedly and has not missed a step yet.

    Seems pretty good so far, I think that speed is more than enough for a small machine???

  6. #6
    Quote Originally Posted by Davek0974 View Post
    There is no problem JAZZCNC, I'm just looking for facts and figures at the moment.

    I now have it set for 15,000mm/min and 1300 mm/sec/sec and it's been running a pen over various files repeatedly and has not missed a step yet.

    Seems pretty good so far, I think that speed is more than enough for a small machine???
    To be honest I forgot this was for a plasma machine so very little forces involved and at those speeds your running about half the motors speed which is about right where I'd have predicted would be ok without missing steps etc. You may find you'll need to tune slower if ever cutting forces are involved.?

  7. #7
    If plasma is limited to say 4500-5000 mm/min, is there any point at all tuning a small machine to 15000-20000mm/min???

  8. #8
    Quote Originally Posted by Davek0974 View Post
    If plasma is limited to say 4500-5000 mm/min, is there any point at all tuning a small machine to 15000-20000mm/min???
    Now there's a question that gets people butting heads. . .Lol. . . . Why do you ask.?

    My answer is NO absolutley not. High rapid speeds are only any use for A-2-B positional moves like drilling lots of holes or with very large machines. Small machines then IMO it's pointless and can easily get folks into trouble with crashing machine into hard stops etc.
    With a small machine your much better off sacrificing Velocity in favor of accelleration and often it brings cycle times down anyway.
    Last edited by JAZZCNC; 22-02-2014 at 08:06 PM.

  9. #9
    Brilliant, that's exactly what I was thinking too.

    the reason I asked is that many threads go on about tuning for high speed, must go this speed etc. but then I realised that plasma itself is limited (at least in home size machines) to speeds of around 750 to 4500mm/min so what the heck is the point of mega speed.

    as you said, acceleration seems to be important and on a machine with an envelope of 600x600mm, 20,000mm/min is pretty scary and damaging.

    i think I'll limit mine to 5000 max.

  10. #10
    Quote Originally Posted by Davek0974 View Post
    the reason I asked is that many threads go on about tuning for high speed, must go this speed etc. but then I realised that plasma itself is limited (at least in home size machines) to speeds of around 750 to 4500mm/min so what the heck is the point of mega speed.
    Bragging rights and showing off that's all there is to why they chase Rapid speeds.!!

    If your working with small machine for cutting woods then I'd aim for between 8000 to 10,000mm/min Max Rapids. If cutting mostly Aluminium or hard materials then you won't need much above 3000mm/min and 5000mm/min is a good Rapid speed.

    Also Resolution is important so think about that when building a machine.

Page 1 of 3 123 LastLast

Similar Threads

  1. Setting the zero point on a CNC lathe
    By Robin2 in forum Lathes, Lathe Rebuilding & Conversions
    Replies: 7
    Last Post: 20-10-2013, 10:37 PM
  2. setting up a business
    By dstivens in forum Opportunities Available & Sought
    Replies: 5
    Last Post: 16-05-2013, 10:28 PM
  3. setting the origin
    By Fivetide in forum Computer Software
    Replies: 9
    Last Post: 04-02-2013, 12:18 AM
  4. hi i nead help please with setting up dsp control
    By cockneyrebel in forum Machine Control Software
    Replies: 1
    Last Post: 19-01-2013, 01:18 AM
  5. Setting up work on the rotary table
    By irving2008 in forum Machine Discussion
    Replies: 6
    Last Post: 09-01-2010, 10:27 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •