Best CNC Router bit for 3/4" MDF?

Router bit? Are you wanting to cut it or do an edge profile?

Carbide is the way to go as MDF has some hard resin bonding all that sawdust together 8^)

@splintergroup I updated the title - I'm specifically looking for a CNC router bit.

I'm not sure about the best but a Vortex 840 (3/8" 1-flute upcut) is pretty good. That will handle full depth cuts in 3/4" MDF at 300+ ipm feedrates assuming your machine is up to the task.

18-24k RPM is too fast for 300ipm if using a 2-flute bit. That's why I recommend the 1-flute. 300ipm is close to the recommended feed rate for that bit.

@jaaune what RPM would you run a 2 flute but at?

That's a complicated subject since it depends upon the spindle, machine rigidity, material type, hold down strength and various other factors.

Start by looking at the Vortex chipload chart to see what the bit manufacturer recommends. They recommend around 720ipm for a 2-flute, 3/8" diameter bit.

Vortex Chipload Chart

That's the ideal for bit life but not always achievable depending upon the factors mentioned earlier. With our router, we'd probably run about 17,500RPM at 250ipm because the spindle and steppers can't do much better than that which means our machine can't get much benefit from larger diameter, 2-flute bits.

wilschroter said:

@jaaune what RPM would you run a 2 flute but at?

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We run a 2 flute 1/2” compression cutter in 3/4” at 750ipm to 800ipm with 20,000 rpm
Chip load is everything.
300ipm is slower than anything we cut with two flute tooling.
1 flute seems more suited to those speeds.

The math isn’t too crazy for figuring chiploads, but some experimenting on your machine and your setup will be the final factor in figuring out the best feed rate and rpm for any particular material with any particular bit.

If the tool runs hot, speedup the feed rate or lower the rpm, or reduce the flute count, or a combination of these.

I experimented with high speed tooling to 1200 IPM some years ago, just because it was theoretically possible. I bought three bits, knowing that one would get burnt up, one would snap off and one would run perfect right in between those two limits.

Just FYI 1200 IPM makes some eerie scary sounds, but is cool as heck to watch it go.

JAAune said:

That's a complicated subject since it depends upon the spindle, machine rigidity, material type, hold down strength and various other factors.

Start by looking at the Vortex chipload chart to see what the bit manufacturer recommends. They recommend around 720ipm for a 2-flute, 3/8" diameter bit.
Vortex Chipload Chart

That's the ideal for bit life but not always achievable depending upon the factors mentioned earlier. With our router, we'd probably run about 17,500RPM at 250ipm because the spindle and steppers can't do much better than that which means our machine can't get much benefit from larger diameter, 2-flute bits.

Click to expand...

Thanks for posting this information!!! This is the kind of stuff I like to see on here!!