Results 1 to 9 of 9

Thread: Bit is trying to step over while cutting, help

  1. #1
    Join Date
    Feb 2015
    Location
    NC, USA
    Posts
    80

    Default Bit is trying to step over while cutting, help

    I have been cutting acrylic letters for a while now but yesterday while trying to cut the machine started acting weird. While cutting different passes on a profile tool path in V-Carve pro v8 the bit is trying to cut like a slope, but it's not consistent in where or how it does it. I have attached some pictures. I have tried using different bits and different shanks. I did put in a 1/2 x 1/2 bit and cut it just to see what it would do and it worked. Of course this is too big of a bit to use. I have tried 1/4, 1/8 and 1/16 bits all with the same results.
    I have changed feed rates, number of passes and RPM's and nothing works. It seemed like it did get a little better with a feed rate of 3 and rpm of 19,000 but the number of passes didn't really matter. The material is .375 acrylic.
    Any help would be appreciated.
    Attached Images Attached Images

  2. #2
    Join Date
    Apr 2013
    Location
    Kennebunkport, Maine
    Posts
    4,419

    Default

    Will,
    Might help the guys to know what year and model of machine and what maintenance it's had if bought used. Also Version of SB3.
    Good luck.
    scott P.
    2013 Desktop/spindle/VCP 11.5**
    Maine

  3. #3
    Join Date
    Feb 2015
    Location
    NC, USA
    Posts
    80

    Default

    Hey Scott,
    Thanks for the suggestion.

    It's a 2006 PRT 4x5 with a router. I just put the newest controller on it and new motors with the latest download for SB. It has cut the same letters fine up to yesterday. I have also cleaned out the collette.

    Could it be a collette issue?

  4. #4
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,986

    Default

    With the control box on and the machine at rest, grab the gantry and wiggle it front and back (X). Then proceed to the Y and wiggle it front and back. Grab the router and wiggle it up and down, front and back. You should not feel any appreciable movement in any of them. If you do, some adjustment is in order. You want to make sure that each axis is able to hold its position without moving under light hand resistance.

    One of the pinion grub screws could be loose. One of the X motor drivers could be flaking out or wiring pinched not allowing full motor power.

    -B
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

  5. #5
    Join Date
    Feb 2015
    Location
    NC, USA
    Posts
    80

    Default

    Thanks Brady,
    I will try this today.

  6. #6
    Join Date
    Apr 2011
    Location
    New Jersey
    Posts
    120

    Default

    Machines jump like that under two scenarios.

    1. Mechanical issues like Brady mentioned.
    2. Pushing the router too hard.

  7. #7
    Join Date
    Oct 2010
    Location
    TX
    Posts
    803

    Default

    Could be a bit that is inappropriate for acrylic getting loaded up with semi-molten acrylic, and pushing away from your cut. It looks like you did level cuts at about .1" depth each pass. I have never used 19K RPM on acrylic. I use bits specifically for acrylic, and try to watch my cut to see if the material is fusing back to itself or if it is cutting and sending off loose chips. Brady is starting you off at the first thing you should check. Then I would look into the type acrylic you are cutting ( cast and extruded DO cut differently). Look at bit type. Look at rotational speed (and chip size) and recommended feed rates. ( I will go to my machine and look at what I do when I am cutting some acrylic and what exact bit I am using... but you may solve your trouble with the checks that you have already received!)

    OH: AND you need to look at the drawing file and see if you have smooth arcs or what.... That cut is jagged. Should not be like that at all. If Brady's suggestion on loose pinions in the gear track is not the issue- then I would be checking my file from which I set up my cut. Blow it up and see how smooth your curves are.

  8. #8
    Join Date
    Sep 2006
    Location
    Garland Tx
    Posts
    2,334

    Default

    What I’m seeing…
    In your first photo, all the issues seem to be in one axis… (all the paths seem to line up on the left ok) This would seem to point to something mechanical, such as grub screws or other adjustments already mentioned…
    SG

  9. #9
    Join Date
    Feb 2015
    Location
    NC, USA
    Posts
    80

    Default

    I changed the router motor, didn't help. I changed the stepper motor and that seemed to fix the issue. Thanks for all of the help, you guys are great!

Similar Threads

  1. Another step forward!
    By kurt_rose in forum Sign Making
    Replies: 7
    Last Post: 09-09-2015, 10:47 AM
  2. This a step by step (somewhat ) on making a quiet vacuum box.
    By knight_toolworks in forum ShopBotter Message Board
    Replies: 13
    Last Post: 02-14-2014, 02:25 PM
  3. Step n Start
    By myxpykalix in forum ShopBotter Message Board
    Replies: 1
    Last Post: 07-26-2012, 10:24 PM
  4. lost step
    By David White in forum Troubleshooting
    Replies: 17
    Last Post: 07-12-2011, 11:24 PM
  5. Does anyone have a step-by-step
    By phil in forum ArchivesSchools
    Replies: 12
    Last Post: 11-18-2006, 10:43 AM

Posting Permissions

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