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Thread: Favorite insert spoilboard / slab surfacer?

  1. #11
    Join Date
    Oct 2000
    Location
    Willis Wharf, VA
    Posts
    1,627

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    Amana makes a surfacing bit with replaceable inserts, their #2242, that uses inserts with 2 radiused corners and 2 with square corners that you can rotate depending on your use. It's pricey at $150.

  2. #12
    Join Date
    Nov 2008
    Location
    Knoxville Tennessee
    Posts
    34

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    Thanks Bill! That’s a very interesting option that would take some of the pressure off my DIY bit modding skillz. But wow, pricey for sure.

    So (just so I’m certain) does that mean there aren’t radiused inserts that are compatible with the 2250 I already own?

  3. #13
    Join Date
    Aug 2011
    Location
    Wilkesboro, NC
    Posts
    82

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    Brady, I’m trying to picture how a dial indicator can be used to true up the z-axis without something to offset it like the aforementioned shiny object.
    Would you mount it to the table and chuck a pin into the router? Then run the router up and down?
    Thanks

  4. #14
    Join Date
    Mar 2013
    Location
    Memphis TN
    Posts
    676

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    If you search Google for the term "tramming" and especially look at the image results, you'll get your answer.
    ShopBot Details:
    PRS Alpha 96x60x12
    4hp Spindle
    12" indexer
    Aspire
    Rhino

  5. #15
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,871

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    Quote Originally Posted by Red F View Post
    Brady, I’m trying to picture how a dial indicator can be used to true up the z-axis without something to offset it like the aforementioned shiny object.
    Would you mount it to the table and chuck a pin into the router? Then run the router up and down?
    Thanks
    Red,
    A dial indicator will report displacement - this means that if you move in a parallel direction to the fixed indicator, it will report any deviation from your set zero point, along the length of the stroke. This means that if your Z axis is out, say 1°, and you set the indicator to zero at either the bottom or top of your Z stroke length, the indicator needle will move one way or the other, reporting the displacement from your set zero point. The numbers on the indicator are irrelevant - because you are shooting for zero movement of the needle along the entire stroke of the Z axis.

    The attached drawing (I'm going to hang a copy on the fridge ) shows how an indicator may be used on a ShopBot (any model - but mounting options will vary) to check parallelism. You can think of parallelism as 'squareness' where a framing square against the spoilboard is impractical or just not accurate enough to get your Z dialed in. It is possible to get your Z axis well under 0.001" parallel in both directions using a cheap indicator. Some models are easier than others in terms of having a good place to magnetically stick the indicator base - however, you can also use a clamp or any other means to mount the indicator. In some cases, just a piece of steel bar/strap with some holes drilled in it to mount to the aluminum extrusions is very helpful.

    IndicatorUse.jpg

    Avoid using the router or spindle body as a reference - I have found them to not be true. Some of this is because of how it is mounted and some because of the body itself. When I was setting up new ShopBots, I always loosened the spindle bolts that held on the spindle mounting plate and then MADE SURE it was as parallel as I could get it to the spindle itself. I chose either the left or right side of the spindle and forgot about the other side - then I'd pop the 'tail' out of the back of my 6" digital caliper and checked between the plate and the top and bottom of the spindle, until both measurements were EXACTLY the same. This is a little bit of a pain sometimes because the countersunk screws that hold the spindle to the plate can influence the distance and walk the spindle over while tightening them down...so you have to do some back and forth - but only once. Just set it...and forget it! The aligned plate gave me a pretty decent edge to check side to side parallelism when adjusting the Z (on a PRS or DT) in the Y direction. Deviations in the X direction are more complicated on a PRS because (and this is NOT that uncommon) - the gantry beam is rotated from the vertical a small amount - which becomes large at the bottom range of the Z axis because of it. On a PRT, a rubber mallet will knock that Z the small amount needed before you king kong the bolts tight on it.


    I said the dial indicator was the king of measurement tools because it is so versatile. It can be used to check parallelism/squareness, runout of a shaft, to position things perfectly concentric in a lathe (although a test indicator is better for this), you can use it to check your tablesaw fence to blade parallelism to see if that is what's binding your cuts, and to check that your dual compound sliding chop saw is running true when it's set to the 0 mark. You can use it to check that your part or fixture (like a milling machine vice) is square/parallel to the spindle, and to also check for highs/lows in your table. You can also use it to test machine deflection and gantry sag (as you press down lightly on the YZ car), and to check for slop/backlash in your gearbox motors when the tool is powered on and at a rest. The list goes on...For times when you can't get a square in there...or you don't have a square/flat/true reference to anything - the dial indicator is the go to tool.

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

  6. #16
    Join Date
    Jun 2013
    Location
    Pasadena, CA
    Posts
    962

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    My poor man's version of that shiny tramming gadget. With almost 20" sweep diameter it will detect even very small spindle misalignment. It is just a 1" x 1/4" aluminum bar, twisted 90 degree in the vise with a large pipe wrench. There is a 1/4" or 1/2" decapitated bolt shank for the collet and a cheap dial indicator on the other side.

    I clamp that aluminum square tube on the table to get an average across the uneven crowned table extrusions. For a newly skimmed spoilboard table that would probably not be necessary. The indicator must sweep freely without pushing on that lever.

    DSC00365.JPG
    Last edited by Burkhardt; 08-19-2018 at 03:01 PM.
    Box Joint, Dovetail, Guilloche and MazeMaker Software Here

  7. #17
    Join Date
    Apr 2007
    Location
    Marquette, MI
    Posts
    3,372

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    Brady alludes to it, but I would like to emphasize this point. My method is to surface the table first. This must be done! (even is spindle is out of tram) Then I place a 12 by 16 piece of aluminum that has been surfaced on both sides. This gives a qualified surface to ensure that whatever method you use your reading actually means something. See pic below.

    Attached Images Attached Images
    Gary Campbell
    GCnC Control
    GCnC411(at)gmail(dot)com
    ShopBot Controller Upgrades
    http://www.youtube.com/user/Islaww1


    "We can not solve our problems with the same level of thinking that created them"
    Albert Einstein


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