UP or Down Cut Sprial Bits

[Tom H]

I have never used a spiral bit but hear they are great to work with.

I'm looking to purchase a spiral bit set from Infinity & can't afford both the Up & Down cut set. . Any suggestions on whether one should purchase UP or DOWN cut bits

I'm going to use them for multi-purpose cutting of various woods & man made panels.

[Morris Dovey]

| I have never used a spiral bit but hear they are great to work with. | | I'm looking to purchase a spiral bit set from Infinity & can't | afford both the Up & Down cut set. | . | Any suggestions on whether one should purchase UP or DOWN cut bits | | I'm going to use them for multi-purpose cutting of various woods & | man made panels. | |

spirals are good for chip removal and smooth bottom edges on through cuts.

Down spirals are good for pushing the stock down, smooth cut bottoms, and smooth top edges.

I use 'em both (in solid carbide) in a CNC router; but only when I need one or more of their particular strengths - otherwise I prefer straight (HSS with carbide edge) bits because they're less expensive both to buy and to have re-sharpened.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Steve Peterson]

Good answer, Morris. What it comes down to is this: one spiral bit, up or down cut, can't be optimal for all applications. You need to decide what you want to do, and get the best one for that use. If what you really want is some experience with one, either will do, but keep in mind that it will do some things better than others.

[SonomaProducts.com]

I know we use one for in the table and one for handheld but I can never remember which is which. The reason for the difference is which way we want the chips to fly. I think its up cut in the table to pull the chips down into the table so the dust box can get them and down on the handheld to push them away from the face and toward the floor.

[Morris Dovey]

| I know we use one for in the table and one for handheld but I can | never remember which is which

"Up" and "down" only make sense in the context of a router above the work (as with a hand-held router).

Up spirals pull the bits toward the shank end. Down spirals push the bits away from the shank.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Never Enough Money]

The infinity web page

says "Upcut spirals clear chips from the kerf and allow faster feed rates than downcut spirals. Downcut spirals push wood fibers down for a cleaner top surface."

Tom H wrote:

[Jay Pique]

And then there are the up & downcut spirals....

JP

[dadiOH]

I prefer down because they leave a clean edge. With some woods, up cut will leave you with lots of fuzz.

Downside to them is that if you take too big a bite (and/or collet is worn) they can actually come creeping out of the collet giving you a deeper - sometimes LOTS deeper - cut than you planned.

If I were you I wouldn't buy a set...I'd buy 2-3 each of upcut/downcut. Buy the smallest you will likely need plus another wider. In my case, that is 1/4 and 1/2. Others might prefer 1/8 and 3/8. Depends on what you want to use them for.

-- dadiOH ____________________________

dadiOH's dandies v3.06... ...a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at

[Morris Dovey]

| "Up" and "down" only make sense in the context of a router above the | work (as with a hand-held router). | | Up spirals pull the bits toward the shank end. | Down spirals push the bits away from the shank.

Obviously not enough coffee. "bits" should have been "chips".

8-P

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[George]

Bits are pulled in the opposite direction, aren't they?

I like the shear for clean cuts when edging or pattern routing with router up or down, and the cooler and smoother results from the up spiral chip ejection when mortising.

Doesn't chatter a thin piece as much as a two-flute, either.

[bridger]

that's true for blind, non-through cuts. if the bit is clearing the back of the work it's not true.