1/16" Downcut - MDF

Evening All,
I’m going to be cutting 8 760 x 760mm sheets of 6mm (1/4") MDF in the next few days which has many components for a small hobby drawer system that will interlock and only require a small amount of glue to build. I am looking to cut this with a 1/16" bit that has a 12mm cutting length.

I have been advised to start with 1mm DPP and 1500mm feed and up this to around 1.5mm DPP and 2500mm feed. I am a bit sceptical of these figures and just looking for some reassurance from anyone that’s worked with 1/16" bits in the past. There is no pockets, it is all just contouring out components.

Thanks

Why such a small diameter bit? For contouring, a larger diameter would seem to be more efficient, and if you wanted to sharpen the interior corners, I would use two operations.

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The small diameter was so that I can do the whole thing in 1 operation, im only using Carbide Create so I dont think i can make an operation to just tidy the inside corners only.

So the work around would be to create two different files, I would do all of the small detail first, then load the larger bit last to be able to plow through the material. And then there’s also copy and paste to put multiple files into one.

So its not so much small detail, its to get the tight corners to make it easier to get it all in 1 toolpath.

I’ve used bits down to 1.5mm in MDF and Aluminium, I find it most disturbing when I read the manufacturers feed rates on such tiny bits but they are oddly strong, for their size.

In the Aluminium my worrying toolpath did 1mm plunge followed by horizontal full engagement slotting, I accidentally left feed override up and the 1.5mm cutter happily sailed through 6083 T6 at 800mm / min 1mm depth, full width, that was still well below the feed rate the vendor listed, but I was just having trouble believing that tiny toothpick could feed that fast.

In MDF particularly with a downcut the enemies of that small cutter will be clogging and burning. If you’re worried about the strength of the bit, do cuts with less depth, not less speed, keeping the bit moving fast and shallow will allow it to clear the chips instead of clogging up. Push the DoC as you get more confident with the cutter and you’re sure you’re getting good chip evacuation, especially in the deeper parts of your cut. Use dust extraction and check that the slot is clearing between passes.

HTH

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I have found downcut endmills to be problematic in MDF, and upcut endmills to be better for MDF, making it less likely that the chips will get packed into the cut.

It may also help to add offset geometry (say 10% greater than the endmill diameter) and cut as a pocket down to tab depth.

Thanks for all the responses guys, I think in this instance I’m going to adjust my files to include a small dogbone on corners in which the curve of it is in line with the internal corners and run it with a 1/8" up cut for efficiency.
The 1/16 would have been nice to use but I get the sense im pushing the boundary using it first time on such a large job. I’ve got 3 parts that dont fit onto the 8 boards so I’ll run tests with the 1/16" on those with 3 different settings, including 1 Tab on each as I’m told due to how small the flutes are that it has very low chance of moving the piece after cutting. This might be worth it for my own research :slight_smile:
Thanks again all!

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