MDF "rough cut" speeds

CNC Machines
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5 PRO with VFD Spindle. I am not doing fine detail work. I am cutting larger parts out of 3/4 MDF, with dado’s and rabbets.

I am currently using a 201 quarter inch endmill, quarter inch depth. When i need to “pocket” I am going with a 50% stepover. I am setting the RPM to 24,000. I want to drive this machine as fast as I possibly can. Projects look like they are going to take 2 hours to run with these settings. I think the machine can feed up to 200 IPM, currently at the default 60.

What is the fastest feed rate I should do with a quarter inch cutting depth?

Would I be better off to reduce the depth of cut to 1/8" and then crank up the feed speed?

I am thinking about purchasing a “hog” roughing endmill from IDC. Any experience with these types of endmills?

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It’s been a few since I cut MDF, but you should be able to easily double the feed rate at 1/4". Maybe triple.

I’m a huge proponent of messing around on scrap. Carbide Motion has the feed +/- buttons and I used them a lot. :slight_smile: Program a test piece at 100IPM and you can possibly increase to 200% to 200IPM in 10% increments.

Also note that MDF is abrasive and dulls endmills pretty fast.

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Well a couple things.

If your carbide motion is up to date you should have a max machine speed of 275 ipm.

Bits like the hog which are chip breacher won’t have any real benefit in mdf.

I don’t use 3 flute bits like the 201. I only use two flute bits.

I use an 80 mm spindle and cut mdf at 275 ipm at 1/4 depths conservatively. 1/2” doc is no problem for me but you need ramp in.

Most of my rough cutting in mdf is done with a 2 flute 1” diameter 1/4” shank mortising but from Amana. 1/2” doc and 250 ipm.

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MDF is saw dust with glue. I think it is the glue but I have never analyzed the structure of MDF.

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Thanks for the info! I will probably run 1/4" depth and 120ipm for now. The 201 came with the machine I will expand my bits as budget allows.

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Awesome, good to know!

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Yep, some type of resin. Good stuff for some projects, horrible for others.

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I have several 201 bits and one is reserved for MDF and is marked accordingly on its box.

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As said above MDF will dull bits very quickly, it’s very abrasive, I tend to focus more on the feed per tooth / chip size in MDF, making dust is a really fast way to blunt a cutter in MDF. Ryan’s feeds and speeds look like they’re taking a good bite with each rotation.

Also, you want to avoid re-cutting the dust so if you’re slotting or similar it really helps to have aggressive dust extraction getting the fluffed MDF out of the slot and away from the cutter. Of course your lungs also benefit from trapping that nasty stuff.

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I amusing a harbor freight dust collector with a cyclone in front of it. Seems to do a good job of getting the dust off of the work surface.

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Virtually all of my projects will be made out of MDF.

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275ipm at 24k rpm is only .006” Chipload. Which is Amana’s recommendation. My feeds are not anything crazy.

People are just used to the machine being a much bigger limitation than the bits. With the 5 pro the machine is still the limitation. Just much less of one.

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What is this chip load you speak of?

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Chip load is the size of the slice each flute of a bit takes every rotation.

It calculated using feed speed and rpm. I don’t know the math. I use a calculator. Ill post a link

Every bit msnifscutr posts recommended Chipload. It’s the best way to calculate feeds and speeds.

20k rpm’s and 200 ipm is the same Chipload as 10k rpm’s and 100ipm.

You can increase Chipload by increasing feed rate. But you can also change it by lowering rom.

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Excellent, thank you

:fire: :fire: :fire: :fire:

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I would go 18k RPM, .25 DoC, 150-200 IPM. I would likely go at the higher end of that and push it even further. But I use carbide 2 flute bits. You may have different speeds if you aren’t using carbide bits (the material not the brand).

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I cut 3/4 MDF all of the time using the HOG & BEAST from IDC. Neither bit has a problem chewing through the MDF & I Spiral Ramp in @.75. F/S 100 & 100 with DoC @.25 on my baby machine. IMO, the Pro 5 won’t even break a sweet.

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