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Thread: Downspirals for MDF

  1. #16
    Join Date
    Mar 2003
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    SE PA - Central Bucks County
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    Tooling type is the same. Whether or not you can do those materials with a single cut or not is going to be determined by how stiff your machine is combined with the capability of your router/spindle. For the thicker plywood, you can use a compression bit in two or more passes with good results as long as your first pass gets below the transition on the cutter so that the downcut shearing is engaged with the top surface of the material. You'll sometimes need to be thoughtful in your tool paths relative to ramping since that first bit of the bit, as it were, is going to be up-cut.
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    The most expensive tool is the one you buy "cheaply" and often...

  2. #17
    Join Date
    Mar 2014
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    Iowa USA
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    So when removing material like MDF if the bit is going downward spiral how do the chips get removed from the cut?

    And on the table I like your idea of 1 inch thick. But what I plan on is 1/2 inch multi ply plywood on the bottom and 1/2 inch MDF on top and glued. Track slots for the aluminum T slot material cut in the top. That way the plywood would hold the track screws better.

    BTW Happy 4th of July for our US members and I think Canada has something like it.
    Last edited by Bill George; 07-04-2018 at 12:49 PM.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  3. #18
    There are definitely issues with a downspiral in any material but there can be issues with slow feed speeds and down spirals causing burning in the bottom of the cut and you can read back in the archives of even a few mentions of smoldering. I can only imagine these were on jobs/machines that were running very slow feed speeds. The down spiral bits do auger out a lot of the chips but in MDF the chips are often just dust so the cuts many times unfortunately just remain packed with chips.

    The only issue I can see with your ply base option is how flat it will be or the ability to deck it off flat even if your going to apply an MDF top over it. Even with the T tracks you will want your top surface dead flat but Im sure many here have a lot better input on top surfaces that I do. We have an HDF plenum on our machine with the vac grid and then run 3/4" LDF or MDF spoil board over top and dont have any T track. We have made a few fixtures out of 1 1/8" MDF with T slots cut in them (just a T slot milled directly in the MDF no aluminum track) that we vac down when we need them. I do have rare occasion that we could run some work and not run the vac and for those we generally just clamp the spoil board down and screw/nail a fixture down.
    Last edited by Mark Bolton; 07-04-2018 at 1:40 PM.

  4. #19
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    Mar 2014
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    Iowa USA
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    4,441
    I would think it would not make a lot of difference on the multi layer ply on the bottom (and it will be a good flat piece) as long as you surface the MDF on top before you install the tracks.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  5. #20
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    Mar 2003
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    SE PA - Central Bucks County
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    Bill, for your spoilboard, I would just use an up-cut spiral to cut your slots for the tee tracks. You're not going to get a whole lot of problem with the edges that mean anything...your situation is different than Mark's in that he's producing a product that has to have a very refined edge. Your spoil board isn't in that category, IMHO. My original answer isn't necessary applicable because at that time, I didn't know you were talking about the whole CNC router setup thing rather than "making things" with your CNC. MDF doesn't really have a grain, so up-cuts work fine. There will be a tiny about of "fuzz" but that comes off with one or two swipes of 320 or 400 paper in your hand. This also solves the chip evacuation thing you mentioned and reduces risk of ignition if you don't have the right speeds and feeds.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #21
    Join Date
    Oct 2014
    Location
    Cleveland OH
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    195
    Mark what type of router do you have ?? Do you have a ATC ?
    3X Camfive 1200 48" x 24" 100watt Tube
    Zcorp 450 3d Printer
    Laguna Smartshop 2 - 4x8 ATC

  7. #22
    Quote Originally Posted by Robert Bonenfant View Post
    Mark what type of router do you have ?? Do you have a ATC ?
    Yep. 10HP HSD, 10 pos ATC.

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