I don’t recall how I ended up with a handful of 4 flute bits, but I have yet to figure out when you would bother using this type of bit?
I recently tried it and it was a terrible idea because it caused such fine waste that it clogged the bit area and ruined the product when it lost steps.
To use a four flute bit effectively you need to be able to use a much slower rpm than the Deealt 611 will allow.
Since I can push the feed rate faster with them, I use 4 flute upcut bits all the time for pockets. I will also use them to cut out items when they are large enough that I can use a pick to pull dust out behind the bit.
That’s what I would have had to do to prevent the failure because even when I used a two flute to repeat the project I needed to keep clearing out behind the bit.
The wood I was using was awfully sticky/sappy so that made it even worse!
How much faster do you usually run with 4 flutes? I don’t recall if these are upcuts or not though.
The final speed depends on the material, but in general you can go 2 times faster than a 2 flute bit and 4 times faster than a 1 flute bit. It also depends on your machine, since stiffness modifications can make a huge difference in the machine’s ability to haul butt without flexing.
Right now, Amazon has the set of 5 I bought on sale for $13: https://smile.amazon.com/gp/product/B00SKFWOLU/ref=oh_aui_search_detailpage?ie=UTF8&psc=1. At less than $3 per bit, I’ve got no problem overheating them a bit since I’m more interested in cutting fast. As long as the bit isn’t torched or doll, and your speeds/feeds are appropriate, the finish they leave is good.