Straight bits vs. Spiral upcut bits

[njorgens]

I was wondering what's the real advantage of using a spiral upcut bit to make grooves rather than using a regular straight bit? Any takers?

[PaulMarcel]

Straight:

Chopping action to cut the wood; this can cause nastier chip-out if you are using the bit for a rabbet

Doesn't clear chips much

Cheaper; can sharpen easily yourself

Up-Spiral:

Slicing action; much better for wild grain, "chippy" wood, splintery stuff

Lifts chips from the groove

More expensive

Faster for plunging if demarcing a mortise

When I first switched, I seem to remember less burning

Available in considerably longer lengths than straight bits

More awkward to add a bearing without collars whereas a straight can take a bearing more easily (you can skip the collar usually)

With a top-bearing (up-spiral), makes a fantastic pattern bit

Often need a collet adaptor (like a 3/8" adaptor for certain size spirals)

I only use spirals now. I have some straights left and I guess I do pull them out when the spiral demarced a groove/mortise and I need to 'hog out' the remains. Rather use the straights for that than dull my spirals.

I'll add that if you are making grooves that need a clean top surface, plunge a hair under the surface and make basically a scoring pass then do your groove. The downfall of an up-spiral in this situation is that the shearing action is towards the top surface so there can be some tearout there.

[PaulMarcel]

Brain not working... I meant to add my favorite spiral: compression spiral. No chip-out on the top surface and it clears chips pretty well (not as well as the up-spiral). Since I read on the other thread that you have an OF-2200, the vacuum on that is more than enough to clear the chips very well. They are expensive. One quality compression will last a long long time. Basically the tip of the bit is up-spiral while the rest is down-spiral. The down-spiral makes perfect cuts on the top surface (uses the board to back the cut) while the upspiral makes the initial plunge faster and clear chips better.

[dinkjs]

I have a 1/4" spiral up cut that I have only used on the router.....but I have used a straight bit on the router table....before I go and do it....are spirals effective on router tables? Or could I end up with clogging since they are working up side down

[Bobby Slack]

Spiral is the way to go, if you thing about it the better planers come with spiral cutter heads as well. 95% of my usage is spiral up. The other day I had to fit a veneer panel inside a groove and used the straight cutter and worked perfect.

[PaulMarcel]

I have a 1/4" spiral up cut that I have only used on the router.....but I have used a straight bit on the router table....before I go and do it....are spirals effective on router tables? Or could I end up with clogging since they are working up side down

Yeah, the name of the bit is only valid when the router is hand-held The up being "toward router" and down being "away from router".

Everything mentioned will still be valid, but upside down. Trenching a groove with an up-spiral on the table will pull chips toward the router, which is under the table. That's exactly where you want them to go.