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Uneven depth of profile cut from one side to another with OOZnest 1500x1500

Discussion in 'CNC Mills/Routers' started by MplsArtist, Feb 3, 2018.

  1. MplsArtist

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    I'm cutting out shapes from 3/4" Baltic Birch (with a black laminate on the face) for my sculptures, and getting uneven depth of profile cuts from one side of each piece to the other. The strange thing is that the right side of each piece being cut, is cut too shallow, requiring me to manually finish the cuts with a hand held Dremel Tool. The spoil board has been leveled. The gantry is level to the spoil board. The collet of the router is also level to the spoil board.This behavior is pretty consistent from one side of a 4'x4" piece of board to the other side.



    I'm using the OOZnest 1500x1500 with a Dewalt 611 router, Whiteside 1/4" spiral up cut bit. I'm using Vectric Cut2D Pro with the following settings:
    Board thickness: 0.714
    Start depth: 0.025
    Total thickness entered: 0.739
    Total cut depth entered: 0.739
    Individual pass depth: 0.0616
    Total passes: 12
    Conventional cut
    Feed rate: 80 ipm
    Allowance offset: 0.04
    Separate last pass
    No reverse direction
    No allowance
    3D tab thickness: 0.125
    3D tab length: 0.35

    I've attached a photo so that you can get a better idea of the problem. I can't determine if this is a mechanical problem or a software problem where the last pass is not cutting to full depth. Any ideas?
    Shallow Right Side cuts.jpg
     
  2. jeffmorris

    jeffmorris Well-Known
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    The feed rate is too fast. The cut depth should be increased.
     
  3. Giarc

    Giarc OpenBuilds Team
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    Are you starting your z-zero on top of the material you are cutting, or the spoil board? You could try zeroing on the spoil board and cut it again if you are not. This is what I do. What I like about it is that I never cut into the spoil board. It amazes me how accurate these machines are that I can fully cut through the material without leaving a mark below it.
     
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  4. MplsArtist

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    Craig:
    After posting this same thread on the Vectric forum, someone on that site suggested the same solution. I also used a 4' spirit level to discover that my whole table was racked. After readjusting the table level in both the x & y axis, I readjusted the router mount to assure level in x & y as well to assure that my router bit was plumb. This morning, I will be re-doing my spoil board to assure it is also level in x & y as well. After that, I will do a test cut using the spoil board as my zero instead of the top of the material. I'll let you know the results.
     
  5. Giarc

    Giarc OpenBuilds Team
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    My first instinct was the bed wasn't level, but you mentioned it was. I actually wrote a big long thing about zeroing on top the work and how it may not cut through in some areas if the bed is not level and you zeroed on the high spot. I edited it when I reread your post. :) I am glad you got it sorted out.
     
  6. Coleman Martin

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    I'm having the same problem. I have a LEAD 1515 (60x60") and the middle of my spoiler is nearly 2mm lower than the edges. The table upon which the machine rests is home made. I wonder if the middle of my table sags if that could be causing my problem. Or, are the beams on the LEAD stiff enough that I should be looking at a problem on my spoiler side?
     
  7. Giarc

    Giarc OpenBuilds Team
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    Was your table flat to begin with? The best way I know of to ensure you have a good rigid and flat surface to mount your machine to is to build a torsion box table top. When you build it, it needs to be built on as flat of a surface as you can find and a best practice would be using glue with your fasteners. Use MDF or particle board as your material. Particle board is the cheapest. Both are dimensionally stable. I went so far as to laminate plywood to make my own 2x4s for the bench it is mounted on to avoid the expansion and contraction of regular 2 x 4s and because a straight 2 x 4 is next to impossible to find.
     
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  8. Coleman Martin

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    I welded my table of 1 1/4" steel tube covered with 3/4 plywood. If the table is not perfectly flat is the C beam and 2x4cm extruded AL enough to keep the bed flat?
     
  9. Giarc

    Giarc OpenBuilds Team
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    Is there any support for the 1500x1500 plywood other than the perimeter?
     
  10. Coleman Martin

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    First of all I want to thank people for helping me figure out how to fix my inconsistencies in cutting depth. Here is some more data and a picture. My machine is actually a rectangular hybrid of the Lead 1500 and the Lead 1000 (ideal for cutting pinball machines). The supporting table is square tubular steel measuring 1M x 1.5M, 4 legs on the corners. The top of the table is 1/2" (12mm) plywood. Under the plywood are two long axis tubes at the edges and 4 short axis tubes, evenly distributed. It's all welded. My spoil board is 1/2 MDF cut to the space between my V-slot. The MDF does not overlap the V-slot rail, rather sits on the supplied L brackets. I used my trim router and a piece of paper to find Z=0 at the front left of my cutting area. I thought the distances would be way off given the problems I'm having with depth consistency. But they all measure within 1mm. See photograph of inconsistency. I have not milled the MDF level (just received that bit today). I'm hesitant to do this milling because the cut area of my machine is smaller than spoil boards (see orange square on graphic for approximated cutting area). What is the best solution here for even Z's? A) mill the top of my boards, B) cut my MDF larger to overlap my V slot members, C) adjust my L brackets holding my spoil boards, D) try to level my table better.
     

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  11. Darce

    Darce New
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    I've just finished building my own 1515 as well. In the build instruction the 20x40 for the spoilboard are shown aligned horizontally, floating above the table, and sag terribly. There's a build video on Youtube which also has the same orientation (and it's so much easier building the frame before, instead of after assembling the router)
    I redid them so they are now vertical and the middle of my board is now flat and the sides sag about 2mm. I've ordered two more lengths of 2040 to sort that out.
     
  12. Coleman Martin

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    If I follow what you are saying, you oriented the spoil boards 90 degrees to the V-slot 20x80 and are picking up two more 20x80 to support the ends of your spoil boards?
     
  13. Darce

    Darce New
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    From your photo above, which showed up after I made my post, it looks like you have already got the 2040 upright. I'm getting two more lengths of 20 x 40 to match the middle pieces.

    I'll then place a spoil board no larger than the work area and run a pocketing path to level it all off - rather than messing about trying to get the machine flat.
     
  14. Coleman Martin

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    The way my 20x40 V slots extrusions are spaced from my C rails, there is about 3 cm I can't level with a my router. I can level the front but there is about 20 cm I can't level at the back. For a level bed, should I move my 20x40's away from the C rails shrinking my bed and cut the far end of my Y axis short limiting it to the size of my tool area? Also, do people cover the V slot with the MPF spanning across the 20x40's to prevent sagging? I suppose I could pocket over slots to give myself some attachment points for my clamps.
     

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    • Z.jpg
      Z.jpg
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    #14 Coleman Martin, Jan 30, 2021
    Last edited: Jan 30, 2021
  15. JustinTime

    JustinTime Journeyman
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    Martin, did you have a reason to build the spoil board this way? Are you going to use the V-slots for hold down clamps? I would have not done it this way. I would have left the MDF in one piece and it would have never really sagged.

    I drive drywall screws into my MDF to hold down the material I cut, be it with clamps or strait through the material at places outside the but parts.
     
  16. Coleman Martin

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    Justin, I agree with you that a single MDF is a simple and workable solution. The reason I departed from this tried and true method was because that's what the openbuilds lead machine instructions specify. But, I'm thinking it was not the best idea as I'm putting it into use. I think I may take elements from both ideas. It occurs to me that don't have to move my outside 20x40's if I don't want to. I just have to mill the area my tool can't reach down about 3 mm before I install on the frame. At the same time I can pocket holes over the V-slot members allowing me to fix clamps into the slots if I don't want to use dry wall screws.
     
  17. Coleman Martin

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    This is what I came up with for leveling my spoil board without changing the rail spacing. I cut my MDF to just overlap the 20x40 extrusions. because the spoil board is larger than my cutting area, before mounting the spoil board, I milled down the areas I wouldn't be able to reach with the tool. To allow clamping, I cut groves in the spoil board over the V-slot (again before mounting). To help line up my pieces I used a laser to mark the wood.
     

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