1/4 Baltic Birch Feeds and Speeds

(John Ellenberger) #1

I had been successfully cutting ornaments from 1/4" baltic birch and then I started experimenting with raising the speeds because it was taking almost a day to do a single piece. Now I am getting pretty bad splintering on the edges and I can’t seem to get back to a clean cut cranking things down to 50 ips.

Using a chinese 1.5 mm bit with a cross-hatch blade (i.e. looking at the side it is an X pattern) so not really a downcut. Swapped bits but it doesn’t seem to be an issue with worn cutters.

Anybody have a good F&S setting/bit recommendation for this?


(Adam X) #2

I was running a 1/16" 2 flute up-cut in BB last weekend, 55ipm .05doc and it went pretty well. Mild sanding after took the burs off. Those “burr” style bits are kinda nasty on edge finish, IME.

(John Ellenberger) #3

Looking back on past configurations it seems the biggest impact on the cut quality came when I dramatically increased the depth per pass. Still experimenting but my current theory (completely out of the blue) is that as the cut depth increases towards the width of the baltic birch layers bad things happen.

(William Adams) #4

When cutting plywood you want to avoid creating stresses which will overcome the glue holding the layers together or what’s left of the structure of the wood (remember, most plywood is formed by shaving a log into a veneer, flattening it out — that’s how you get a 4’ wide sheet w/o starting w/ a >4’ diameter tree) — that’s what causes splintering.

(Kenton) #5

I have cut a lot of Baltic Birch, mostly 0.375". I have found that I get the best results with a compression bit (both up and down cut sections), like the Onsrud 60-102. The “trick” with a compression bit is to make sure that you are always using the down cut section when cutting.


Bit LoC: 0.375"
Bit Upcut LoC: 0.205"

Router Speed: 18K RPM
Feed Rate: 50 IPM
Plunge Rate: 20 IPM

First Pass DOC: 0.225"
Final Pass DOC: 0.380"

No splinters and I almost don’t have to sand at all. Ramp into all plunges and never drill with a compression bit.

(Dan Nelson) #6

I haven’t tried a compression bit yet, but all I’ve read says they work well on ply. I have however been using these (my new favorite wood profiling bit):

They leave a fantastic cut on the 3/4" maple ply I’ve been cutting lately as well as regular hardwoods. I think I fed them at about 50ipm/25 plunge with the router around 23,000rpms. They can be pretty loud, but I wear earmuffs (neighbors probably hate me). Being straight flute they don’t pull the ply apart like an upcut tends to do. I tried a 2 flute down cut router bit on some ply and it was slow and left a ton of hairs everywhere. Haven’t tried any Baltic Birch though.