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Thread: ripple marks along the x axis

  1. #1
    Join Date
    Jul 2011
    Location
    Scarsdale, NY
    Posts
    13

    Default ripple marks along the x axis

    Surfaced my spoilboard yesterday, the y axis was smooth while the x axis had ripples every half inch. How do I solve this problem?
    Thanks
    Michael

  2. #2
    Join Date
    Mar 2008
    Location
    Tulsa Oklahoma
    Posts
    1,229

    Default

    Michael.. sounds like your z axis is not square to the table.

    Simple check: use a precision square and check it.

    Better check: mount a dial indicator in the collett, offset several inches from center and turn it around so you can see the changes in the spoilboard surface. You may need to put down a temporary material because your spoilboard is un-even now. The temporary material will give you a relatively good reference if you push it down with some sand or shot bags.

    When things are square and the bit is running perfectly true you will still get a little difference side to side in the direction of the cut. The material on one side gets cut at a higher speed due to the combined speed of the XY motion and the bit rotation, the other way has the difference between the speeds. How the material reacts to that difference will leave a slight effect.

    If you can feel an edge at the cut boundaries, then the z is definitely out of plumb.

    D
    "The best thing about building something new is either you succeed or learn something. Its a win-win situation."

    --Greg Westbrook

  3. #3
    Join Date
    Jul 2011
    Location
    Scarsdale, NY
    Posts
    13

    Default

    Hey thanks Dana...I will give it a try with my dial indicator and see if I can true it up some. This forum rocks...one of the reasons I went with a shopbot! CNC is awesome too!
    Best,
    Michael

  4. #4
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
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    7,013

    Default

    By ripples - I assume you mean ridges that you can catch your fingernail on? If so, Dana is pointing in the right direction. If you are running a spindle a decent square from the spoilboard to flat side of the spindle will tell you which way it is leaning. The only real way to get this right is to pull off the spindle. Pull off the spindle plate from the back of the spindle, square the plate to the spindle - then re-install spindle & plate & square side of spindle to table before tightening the bolts.

    To make life infinitely easier on yourself, remove the 3/16" stop bolt near the top of the Z axis gear rack. Lower the Z down until the pinion is disengaged from the rack (over travel) so you can access the top spindle plate to Z extrusion bolts. You might have to move the nose of the spindle off the table to get it down low enough. Then wedge a 1/2" thick piece of wood or something between the pinion and rack so that it stays put until you are done.

    Sounds convoluted...but once you get the machine dialed in, you should never have to do it again.

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

  5. #5
    Join Date
    Nov 2009
    Posts
    727

    Default

    Its not too bad but its worth the time even if your not really sure if it needs to be done. They should really supply a trammel jig, and an inexpensive dial indicator with the machine. Most squares that are large enough are not terribly accurate. Especially framing squares. Even with a square your not actually measuring the true plane of a bit. I think the manual needs to be updated, to suggest this method.

    I put my own together using parts from the magnetic base for my dial indicator and a 1/2" dowel Not perfect but it worked just good enough. I might make a better, trammel, or buy something for future use.

    I used my vacuum table to pull the reference surface down tight as can be.

    With the trammel you have to keep in mind your working with what would be an effective cutter diameter of perhaps 8-12" Simply put You don't need to get it to within .001 or so at this distance. You might drive yourself crazy trying. Get it as close as you can, depending on what you feel comfortable with. A 2.5" spoil board cutter might show an error that would not appear with a 1.25" diameter bit.
    Michael Schwartz - Waitsfield VT
    Shopbot prs standard 48x96. Aspire. SB Link.

  6. #6
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,013

    Default

    A standard adjustable 16" square works perfectly from the table top to the side of the spindle body. When I setup new machines, this is how I do it...and when I flatten the table there are no ridges. Much easier on a PRS than a PRT.


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

  7. #7
    Join Date
    Dec 2008
    Location
    , Friday Harbor, San Juan Islands Washington
    Posts
    500

    Default

    To make my spindle 90 degrees to the table all I did was stick a Wixy Gauge to a long arbor installed in the spindle. Since it is magnetic it would stay where I put it. I then turned the spindle 90 degrees to the table. If need be I would install a piece of paper between the spindle and the mount. This got me dead nuts and have had no problems surfacing. It really is quite simple!

  8. #8
    Join Date
    Sep 2006
    Location
    Garland Tx
    Posts
    1,802

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    from Amazon Re Wixy Gague
    "The 0.1 degree accuracy and repeatability"
    just curious... this works out to about .0035" rise (or fall) per inch. To those in the know... is this accurate enough?

    Sounds easier than my 16" trammel.

    Steve

  9. #9
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
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    7,013

    Default

    It depends how complicated you want it to be or how much money you want to throw at it. I've used 2 different types of trammels over the years, and always came back to the adj square as the most efficient tool. A trammel will certainly work, but it is more complicated than you need. Plus, if you put a fresh table together and use the trammel, then there will be a lot of variations in the table that the trammel will pick up, that the square won't.

    There's no wrong way...but why make it complicated? A PRS is super easy to dial in. There will only be adjustment in the Y to swing the nose of the spindle one way or the other. In the X direction, if you get lines, then you need to look at the lower v-roller bearings and make sure they are tight. On a PRS, you have to square to the body of the spindle - not the spindle adapter plate, which may have to be removed if it was not properly adjusted at the factory.

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

  10. #10
    Join Date
    May 2012
    Location
    Maine
    Posts
    3

    Default

    There is no adjustment for the plate that attaches the spindle to the z slide, the spindle is bolted on with counter sunk self centering flat head screws leaving no room for adjustment.

    I am having the same issue with ridges due to the router/spindle not being perpendicular to my table top, it is true fwd and back but moving left to right you can see the spindle is out a degree or two creating ridges parallel to the x axis.

    Called the tech group and they told me my best and only solution is to over size the mounting holes in the z axis slide. Before I go drill and oversize the slide I wanted to see if anyone had any input on somthing I am missing?

    Everything on my machine is level and true except for the spindle, the y gantry and the splindle mounting plate are level and square to my surfaced table. The spindle itself is crocked, meaning the plates mounting holes for the spindle attachment where machined wrong. Unfortunate
    Last edited by MaineShopbotter; 05-24-2012 at 11:26 AM.

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