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Best Bits for Birch Plywood

Bit suggestions for 18mm Birch Plywood (furniture design)

Ill be cutting a lot of 18mm birch finger joints and would like the cleanest finish at a reasonable speed. Can you suggest the best bits for the job? Im currently considering purchasing a 1/8 Carbide Compression bit. Any additional 1/8 or 1/4 downcut or compression suggestions? How much faster will a 1/4 bit be vs an 1/8 on average?

Hardware: XL X-Carve, Quite Cut Spindle with 1/8 collet. (I will purchase 1/4 collet adaptor for 1/4 bits)

With the stock spindle, I’d think the gain would be fairly modest since you are pushing it to have enough power to drive a 1/8" bit at a proper feedrate anyway. One you upgrade to a DeWalt, you will definitely want the quarter-inch bit.

I’d suggest a downshear bit, a compression spiral won’t really help when your lower surfaces are pressed against the wasteboard. It only helps when you have them hanging free in air, for the most part. It’ll help a LITTLE, but not nearly as much as you’d see in a free-routing or a pattern tracing situation. A downshear spiral is likely just the ticket for you, they’re relatively inexpensive and work very, very well for making nice, clean cuts.

I got a 1/4" down router bit from my local Lowe’s
This was my first cut with it in 3/4" plywood


My Makita router powered through it with no issues
Feed: 4000mm/min [157 in/min]
RPM: 18,000
Depth of cut 3.175mm [1/8"]

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That looks very similar to the results with my two-flute Freud quarter-inch downspiral in the DeWalt. :slight_smile: I love the downshear bits, they cut SO darn nice!

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Thanks guys! Ill go with the downshear bits.

Can you please share the link of the bit? Or the full name?

The name is “Downcut” spiral bit. That is the threads are the reverse of traditional drill bit so as they turn they push the chips down into the cut (instead of pulling up. This is good for plywood or veneers as it won’t lift up and tear the thinner layers of material.

Here is a link to the one I use:
https://www.lowes.com/pd/Bosch-1-4-in-Solid-Carbide-Downcut-Spiral-Router-Bit/3743597