584,850 active members*
4,400 visitors online*
Register for free
Login

Thread: Backlash

Page 2 of 2 12
Results 21 to 29 of 29
  1. #21
    Join Date
    May 2010
    Posts
    0
    Would models such as the Grizzley iGaging with remote display be good options for the Taig. I'm a little torn because I love the idea of the rotary encoders, it seems like a wonderfully slick way of mounting, but the sliding should be more accurate in theory, although these have a .001 accuracy so my mileage may vary. Reports seem to be pretty favorable, will I just be furious with them, having been used to things like Bridgeports with glass scales and a Hurco with 10,000 count encoders and ballscrews, or will they be plenty accurate for a Taig?

    T21577 0-6" Digital Fractional Horizontal / Vertical Remote Scale

  2. #22
    Quote Originally Posted by efinkg View Post
    Would models such as the Grizzley iGaging with remote display be good options for the Taig. I'm a little torn because I love the idea of the rotary encoders, it seems like a wonderfully slick way of mounting, but the sliding should be more accurate in theory, although these have a .001 accuracy so my mileage may vary. Reports seem to be pretty favorable, will I just be furious with them, having been used to things like Bridgeports with glass scales and a Hurco with 10,000 count encoders and ballscrews, or will they be plenty accurate for a Taig?
    The iGaging style scales are a good improvement over the earlier versions, and remove a number of the problems. When Scott has it back in stock, the DRO550 will take up to 5 of them and display them on it's LED display.

    Re 'handcranks' - all the CR machines I've had came with handcranks ... must get around to making some sleeves up so they can fit the 1/4" shaft on the motors, and recycle them ... but the handles wit the drop down crank are a little safer when using CNC, and a few of my customers have fitted them.
    Lester Caine - G8HFL
    http://medw.co.uk - Home of electronics for the Model Engineer

  3. #23
    Join Date
    May 2005
    Posts
    1662
    Have an old computer (and monitor) kicking around and a bit of extra space in your work area ? This open source DOS software is worth a look:
    DRO SOFTWARE

    I've gotten as far as testing the system with rotary encoders, just the mechanical bits left to complete (waiting for the right salvage to come along lol). On my mill converting linear motion to rotary via timing belt won't be difficult, on a small mill mounting the extra pieces needed would take some planning. The software claims to do backlash comp, so reading directly off the lead screw should also work.
    Anyone who says "It only goes together one way" has no imagination.

  4. #24
    Join Date
    Nov 2007
    Posts
    980
    Maybe a little off topic, but still along the same lines, I've heard different stories about using a cnc mill manually with the motors installed (with dual shafts) with crank handles on the back.

    I haven't not used one like this, but is it correct that if you use it manually this way, with the motor cables still connected, that it can actually become a generator and burn out the drives? It makes complete sense so I would think just disconnecting the cables would be fine, yes?

    Thanks,
    Dave
    Dave->..

  5. #25
    Join Date
    Jul 2009
    Posts
    205
    They can't just become a generator - they are always a generator by definition. Cranking them creates current, and that current has to be absorbed by your unpowered driver chips if they are plugged in. Simply unplugging it does solve the problem, however.

    My only real objection to manually running a dual-shaft machine with hand cranks is just the feel - you have added some resistance of spinning the motors, so it isn't as smooth of a cranking as it could be. Some people don't mind it, but it annoyed me. My first machine was set up that way, Now I just have a separate manual machine.

  6. #26
    Join Date
    May 2010
    Posts
    0
    Isces, good to know, I may go with those and start with the remote displays, update to a proper DRO if it seems necessary. So it is only the handcrank dials that the CR doesn't come with?

    cyclestart, that looks like an interesting method, but I don't know that I would go with that kind of setup, particularly as you say due to the small size of these machines.

    frestman, True, and something I will take care to avoid if I do upgrade to a CNC.

    cameraguy, Good points, I don't know that this machine will ever become a CNC, but I may try and do some trickery to avoid the dual-setup, though at the same time, I do like the idea of some small Sherline handles on the motors like frestman seems to have, so that I can move things around to center and such. It's a bother on my big mill that I will probably have to fix with a handcrank mounted in an encoder for moving the axes around, since there is no good way to throw a full size set of handles on there short of milling out a set of timing belts and installing handles inside the frame of the mill.

  7. #27
    Join Date
    Nov 2007
    Posts
    980
    Quote Originally Posted by cameraguy View Post
    They can't just become a generator - they are always a generator by definition. Cranking them creates current, and that current has to be absorbed by your unpowered driver chips if they are plugged in. Simply unplugging it does solve the problem, however.

    My only real objection to manually running a dual-shaft machine with hand cranks is just the feel - you have added some resistance of spinning the motors, so it isn't as smooth of a cranking as it could be. Some people don't mind it, but it annoyed me. My first machine was set up that way, Now I just have a separate manual machine.
    Thanks for that, and yes, I thought of the extra "feel" that would have so it may take a bit to get used to. Of course, I've run a manual bridgeport for 25 years, so cranking the little Taig manually will take some getting used to, to begin with, lol!

    Dave
    Dave->..

  8. #28
    Join Date
    Sep 2010
    Posts
    717
    The resistance is a stepper only "problem", servos don't have any resistance when powered off (to be exact, the do have a tiny bit from bearings etc). That can be an advantage and disadvantage. Advantage if using it manual. I have a stepper on my Z axis, it keeps the spindle from falling down when unpowered. With a servo, it would crash down to the table by its weight. (I have no counter weight system).
    Current build: http://www.cnczone.com/forums/diy-cnc-router-table-machines/264838-new-machine-desing-quot-cnm13-quot.html

  9. #29
    Join Date
    May 2010
    Posts
    0
    The new toy has arrived, I finally understand why mass of machines is so important. Definitely going to have to get it bolted down properly.

    A little unsure how to do DRO so far, with the iGauging scales.

Page 2 of 2 12

Similar Threads

  1. Spiral anti-backlash couplers introducing backlash!
    By MArruda in forum DIY CNC Router Table Machines
    Replies: 22
    Last Post: 06-07-2011, 08:31 AM
  2. Backlash Compensation / Backlash
    By dwessels in forum Benchtop Machines
    Replies: 58
    Last Post: 02-23-2009, 05:27 PM
  3. Replies: 8
    Last Post: 03-10-2008, 09:35 PM
  4. Servo idea - elimated backlash - zero backlash !
    By synthetiklone in forum Linear and Rotary Motion
    Replies: 6
    Last Post: 12-06-2006, 08:35 PM
  5. backlash
    By fred klusmann in forum MetalWork Discussion
    Replies: 2
    Last Post: 10-04-2006, 05:19 PM

Posting Permissions

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