Problem JGRO First Cut - Advice Needed...


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Thread: JGRO First Cut - Advice Needed...

  1. #1
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    Default JGRO First Cut - Advice Needed...

    So - after a very long delay, I've finally finished my JGRO router, and have made some wood chips with some very good results.

    I'm using:
    * HobbyCnc Pro board with their 305 oz-in steppers
    * 1/2" 10 TPI ACME screws/nuts - I'm using a little "liquid graphite" for lubrication.
    * DumpsterCNC anti-backlash leadnuts
    * HDPE – I used ¾” HDPE cutting board pieces for the adjustment blocks
    * 1" Gas pipe for X & Y axis & 1/2 Gas pipe for Z. The plans called for 1” only on the Y axis
    * 3 piece LoveJoy Couplers
    * Barrel nuts etc. - NO tapping or screwing into any MDF parts.
    * LinuxCNC Controller Software (was EMC2 when I started building...)
    * VcarvePro - trial version
    * Ryobi 1/4" laminate trimmer

    After I finally got my head wrapped around the various stepper configs, coordinate systems and offsets, I was able to cut the "Bulls Head" demo from the VcarvePro SW.
    Besides reminding me that I have to "surface" my bed surface, the V-carving showed some "chatter" - where it looked like the bit was bouncing a little as it went along.
    I didn't loose any steps, and the areas that had a "final" pass performed (because they were deeper ?), came out very good.

    I'm thinking that this might be one of the following potential problems:
    * Even though I'm using the DumpsterCNC anti-backlash leadnuts - There still may be some in the system.
    * The machine is not rigid enough, and really is bouncing...
    * The laminate trimmer is underpowered, and the bit is being pushed through the material (3/4" MDF) faster than it is being cut.
    * I'm trying to take off too much with each pass
    * The router bit I'm using is not carbide - it is new, but I've used it in the CNC while I was adjusting it.

    My first question is "what are your thoughts" on the cause of the chatter?
    It seems from the build threads that regular (heavy) routers are being used by others - so I'd also like to know if the JGRO with the 305 oz-in steppers is capable of lifting a router.
    Or - should I not even be having this problem... beacause the laminate trimmer should be adequate?

    Thanks for any input...

    Similar Threads:
    Last edited by dbprojects; 02-06-2014 at 02:35 PM. Reason: spelling


  2. #2
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    Default

    Here are a few pictures of the cut...

    JGRO First Cut - Advice Needed...-imag0208-jpgJGRO First Cut - Advice Needed...-imag0202-jpg



  3. #3
    Community Moderator ger21's Avatar
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    You need to make sure that everything is as tight as possible. If you grab the collet (with the machine turned off!), and push and pull (hard), any movement you see is bad. You need to eliminate it or minimize it as much as possible. Movement can some from a lot of places.

    Also, use a sharp bit, and take multiple, lighter passes.

    Gerry

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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Thanks Gerry,

    I'm going to look for any slop in the system like you described first, then try to reduce how much is cut for each pass [I think that I saw this in the VcarvePro "Tool" configuration...].

    If I'm still having an issue, I'll probably try a carbide cutter. As my Ryobi laminate trimmer only has a 1/4" collet (max), I might try to swap in a larger router that can take a 1/2" shank - that way I only have to buy a single new bit to possibly solve the problem.

    I guess that the question that I should have asked, is if anyone successfully uses a 1/4" laminate trimmer on a JGRO...

    Thanks again -



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JGRO First Cut - Advice Needed...

JGRO First Cut - Advice Needed...