Upcut or downcut spiral bits for router table?

[jjowen]

Have you also consider Spiral Compression Bits? More expensive but they are worth the price.

I am still relatively new to routing. While I have been forming my own conclusions about which bits are good for what, I found the video really helpful, even if only to confirm my own conclusions.

Re the compression bits; I bought one a while ago and recently got around to trying it out.  I mainly work with high quality birch ply. The compression bit gave a fantastic cut when cutting 'through' with the compression point somewhere in the middle of the material.

 

[ElectricFeet]

This is also a very useful article that explains how to choose the correct depth of cut to get the advantages of both the upcut and downcut spirals of a compression bit:
https://www.popularwoodworking.com/woodworking-blogs/cnc-tooling-basics-for-woodworkers-part-three

It also explains why you really shouldn’t use downcut spirals in MDF (tl;dr: dust forced downwards + heat = fire).

 

[Neal W]

Thanks for all of the very useful responses.  I purchased two whiteside compression bits for my projcect.  A half inch and a 1/4 inch bit.  I was able to use the 1/2 bit this past weekend on plywood and it was terrific.  I never felt like the router was going to push away from the material, and the dust collection from the cuts were very good/exceptional.  They were certainly an upgrade from the two flute straight cutters I had been using.