Wood cutting bit question

Does anyone make a downcut bit that reverses to an upcutting bit after maybe 1/8" or so?

I’m working on a project where I’d like to use BB plywood, and get the best cut available. I’d be backing the bottom of the plywood up with scrap, so I wouldn’t expect to get much chipping on that side even if I do come through it with the downcut bit.

The problem with using a downcut bit all the way through, is the degree to which the downcut bit packs the kerf. But if the bit reversed after 1/16" or 1/8", I’d think it could still evacuate chips.

Or am I nuts?

I haven’t seen a compression bit that reverses that near the top.

This wouldn’t technically be a compression but, more rather an expansion bit (I’m coining that phrase). A downcut bit with optimized chip removal, as it were.

Hmm… so, what we really want is a bit with a somewhat downcut actual cutting flute coupled with a more emphatic upcut-like flute (continuous or segmented) that is slightly undersized so as not to actually cut into the stock. It’d work like a single-flute downcut bit as far as cutting, but like an upcut bit with respect to chip evacuation.

If only I hadn’t lost my carbide whittling spoon.


Probably impossible to do, is why it hasn’t been done.

Spoons or no spoons.

This is what a compression bit looks like (this one is single flute, it’s easier to see) - which is sort of the opposite of what you want as the others have pointed out.

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Order a compression bit from a country south of the equator, they are made to spin counter clockwise :crazy_face:

Joking, …



Couldn’t I just install a northern hemisphere bit upside down?


Only if you have a Southern Hemisphere reverse thingus

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I can get a couple here in Aus and post them to you? You’ll have to run your spindle in reverse though

Seriously though… There are people that make small batches of endmills, it may be worth hunting them down and getting a quote

Before you pay for a custom designed end mill, you might consider a tool change.


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