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Question on Facing MDF Spoiler

Discussion in 'CNC Mills/Routers' started by Scotty Orr, Jan 25, 2018.

  1. Scotty Orr

    Scotty Orr Master
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    I picked up this 1" surface planing bit on Amazon to face my spoil board.

    SurfaceBit.jpg

    From a couple of calculators, I have come up with around 10000 rpm at about 4500 mm/min for speeds/feeds (with 40% stepover and 0.5mm DOC). This feed rate seems kinda high to me. My router will go down to 9000 rpm, so I'm thinking of slowing down the feeds a bit as well.

    Anyone milling MDF with a similar bit? If so what are you doing? Thanks!
     
  2. Giarc

    Giarc Master
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    I used a similar bit and it worked great. I can't remember what speed I used, but I believe I went with well over 6000 mm/min at 0.5mm DOC with 50% step over. I believe I had the rpms up over 20000, though. I can't remember the exact speed, but I just watched an old video I took surfacing my bed and it took about 12-13 seconds to go the length of the 1276mm cutting surface length. But my acceleration was reeeeeeeaaaaaaal sllllooooooowwwww. If I remember right, I think the feed rate was actually 8000mm/min just to see if it would. I suck at math, but here is how I got my estimate:

    1276m/12 seconds = 106.333333333333mm/second
    106.33333*60 = 6379.999800000001 mm/min

    If I have totally messed this calculation up, please feel free to make fun of me.
     
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  3. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    You might also verify if this bit has a max recommended speed. The larger bits usually do especially on the 1/4" shanks.
     
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  4. Scotty Orr

    Scotty Orr Master
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    Thanks guys! This was helpful information. I got the bit on Amazon (EnPoint brand), but no speed info there. The bit itself only has Chinese language documentation, but I think I found it elsewhere and it gave a recommended max speed of 22000 rpm. So maybe I'll bump up the feeds/speeds a bit and not worry about it. I will report back...
     
  5. Michael Gunn

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    Well?
     
  6. Scotty Orr

    Scotty Orr Master
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    I guess I forgot that I said "I will report back", sorry.

    I ended up using 9000rpm at 3500mm/min. I used a 95% step-over (24.13mm), and 2 passes at 0.5mm DOC (removing 1mm material). It worked great!

    I'm sure I could have gone faster (both feeds and speeds), but it was quick enough for me for my 260mm x 406mm spoil board.

    BTW, I designed my cut file using F360 and created oversized stock, then used a "pocket" cut that covered the complete face of my spoil board. This allowed my mill to cut by spiraling out from the center (I saw that recommended somewhere). Another CAM program might allow for a spiral cut using a "facing" operation, but I couldn't find it in F360.
     
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  7. Giarc

    Giarc Master
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    This is a great idea.
     
  8. Scotty Orr

    Scotty Orr Master
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    Thanks, but it wasn't my idea. I wanted to do it to help plumb my mill. It makes it easy to tell, by dragging a fingernail across the surface (in all four directions) what adjustments need to be made, and in which direction. Even a tiny bit off will leave small ridges that are easy to feel.
     
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