Thread: Fluffy mdf

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  1. #1
    I am new to the world of cnc but have been woodworking for years. I have been making models out of mdf for a few years now and have been routing these using a handheld or table top router. I have been using standard grade 18mm mdf from local B&Q stores etc with no issues. Using the same mdf on the cnc the finish cut is very poor. The core (centre part of the board) goes extremely fluffy and you can see a slight step where the cutter has moved to the next cut down. I have been reading that there are different grades of mdf and maybe the stuff I have been buying is not dense enough. The other observation I have made is following the feed speed calculator the router moves very quickly over the piece. I am wondering if anyone else has experienced this problem and can offer a solution

    Thanks Steven

  2. #2
    Make sure the mdf isn't damp.

    I have.the same problem

  3. #3
    Thanks jcb. Mdf is bone dry in my workshop. As mentioned above I don't have any issues routing the stuff manually only on the cnc

  4. #4
    If the same material machines well wiTh a hand router, the problem must be with the cnc. Never mind the calculated speeds ctc. try to replicate the hand router conditions, speed feed same cutter etc. If the problems persists it sounds to me that it may be a rigidity or vibration problem. G.

  5. #5
    Thanks Geoffrey. It's a brand new machine albeit from the cheaper end of the market. I have routed all sorts of other types of softwoods and hardwoods and they have been perfect. I think the speed of the router has a lot to do with it. Will try slowing down the feed rate. Steven

  6. #6
    You might find you have to slow the CNC down to a snails pace. The MDF from B&Q and the likes is the lowest grade. Go to Wickes or Jewson and get the moisture resistant type. This is about the best you can get easily. If you have a good wood merchant they should be able to get you deep router grade which makes B&Q MDF look like toilet paper. It will be double the price though, but the reduction in messing about with sorting the edges can make it good value.

  7. #7
    Cheers Ritchie. Just went and bought a sheet of Medite MR. It's a much denser board and not that much more expensive 26 per 8x4 sheet. Thinking about the speed I pass the piece with manual router it's an awful lot slower than the cnc. So with denser mdf and slower feed speed I will hopefully get the result I am looking for. Will let you know how I get on. Steven

  8. #8
    Quote Originally Posted by richie00boy View Post
    You might find you have to slow the CNC down to a snails pace.
    No quite the opposite.!! . . .Chances are your not cutting fast enough or deep enough.

    What speed & feeds are you using and what DOC.

    Also what machine is it.? If it's the 6030-40 type machine then chances are you'll never be able to cut MDF without flufff has it's not upto the job.?

  9. #9
    Jazz - just tried Medite MR mdf at a feed speed of 20mm/sec and this has stopped the fluffy core. Not sure what the spindle speed as its reading a frequency number (3000) not rpm. DOC was 3mm through an 18mm board. Its a beautiful finish even better than the manual router finish which I was pleased with. The issue now is it takes a nation to route so next trial will be to step the feed speed up a bit and maybe try and increase DOC. Not sure how much life I will get from the cutter
    Thanks for everyones input on this one as I was giving up hope. Hopefully this will be of use to anyone else with the same problem.
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  10. #10
    3000 won't be the frequency as it's far too high. It's probably the RPM!

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