1/8 shank bits snapping

I’ve had 2 of my 1/16 ball nose bits with a 1/8" shank snap recently. Would my feed rate or plunge rates be too high that would cause them to bind? The first one I watched as it was carving and it was carving across the plane of the wood and snapped, no real binding on it.

Each time I switch to a 1/8 ball nose with a 1/4 shank and have no issues, but I’m trying to get more detail than that bit provides.

How do I keep them from snapping?


What settings were used for the instance where they snapped? Can you post a photo of the carve where the bit broke, and the cut settings used (feedrate, plungerate, etc)

I didn’t get a pic, but it was about 5 minutes into a 3d carve of a butterfly. The first time I was working on a dragonfly. Each time one has snapped, it’s been in the initial stage as it’s starting to shape the edge of whatever I’m carving.

Settings were 90 in/min feed rate, 36 in/min plunge, 8% step over, spindle speed 16k rpm.

My guess is maybe the plunge rate is too aggressive?

You can get a 1/16 ball nose or smaller in 1/4" shank. That would be the best option.
I use this for fine detail it is less that 0.04" radius.


Oh, youre doing 3d finishing passes…
A tapered ball bit would be more appropriate for this and the taper geometry make them much stronger than straight sided ball bits.

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