Drilling holes with 1/4" bit

I’m having trouble drilling holes – the bit gets very hot quickly and and starts to burn the wood.
I’m using the “drill” operation in Estlcam, so it makes multiple passes. I’ve tried different speeds on the router (Makita running at full speed, then 6 then 5 on the dial). The Z speed is 3mm/second and I’m drilling 3/4" pine to full depth.

It strikes me that the bit I’m using might not be appropriate - its a 1/4" 2 flute downcut. Would the downcut be packing the chips in and causing the heating?

Downcut is the worst choice for drill operations.

When I’m planning a lot of drill operations, I’ll turn the Makita down to its lowest speed, and use an upcut bit.

I have actually used a drill bit in the collet with the router at its lowest speed. At the lowest speed, it’s slightly faster than my drill at its highest speed, but a high speed drill bit was OK. Of course you end up with that 135° bottom angle with the drill bit, too.


I’ve had this issue with a downcut and I never found settings that worked, really. If I refuse to put in an upcut bit, I will just mark the holes at 2mm depth and the. Take the work to the drill press to do them the rest of the way. Upcut should not have the same problem.

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Yeah, I was leaning in that direction too. Sometimes I get in the mindset that my CNC should be a one stop thing - to do everything…

Drilling a hole with a downcut endmill is like drilling a hole with a drill bit running backwards.

Yeah but it’s possible… Speaking from experience :joy:


If you’re looking for 1/4" holes but the straight drilling is problematic, then could you use a smaller 1/8" bit and the ‘Hole → Peel’ option in Estlcam? With like a 30 degree z slope the bit would ease into the cut instead of straight drilling.

I’ve been getting nice results from that approach because most of the cutting is being done by the side of the bit instead of the tip; only difference is I’m cutting 1/2" holes with a 1/4" upcut bit.


I’ll try this. Thanks!