Upcut? Downcut? Comperession??

[maginter]

I know that bits have different purposes, but what is the opinion of the collective of the best universal cutter. I was thinking that the Compression sprial would be best, but would like some opinions.

TIA and Merry Christmas!

[ryan_slaback]

Mark,
How deep of a cut are you planning on making?

If it is less than full depth you are pretty much wasting your money if you by a compression bit as you will only use the upcut section.

I personally use either straight (not often) or downcut spirals. In theory I think I get less tear of veneer but in reality an upcut might be just as good.

[mzettl]

I agree with Ryan that a compression is pretty much a one task bit. You want to use that if you are looking for clean cuts on both the up and down surfaces of 3/4 - 1 inch stock. If you do a lot of this type of work, then perhaps the significant additional cost is worth it.

Brady Watson suggested a "poor man's compression bit" a while back. With this technique, you use a downcut for the initial cutting, and then switch to an upcut when you have only 1/8 in. or so of stock remaining. You get the same result, but at the expense of the time for a bit change.

Generally, a downcut will tend to not lift the stock, whereas an upcut will. This can be a factor if your hold down is less than ideal.

I use a downcut for most of my work. The main downside of this that I've found is that it packs the sawdust into the cut, whereas the upcut ejects it.

To sum up, there is no one perfect bit. It all depends on the desired result, material, hold down, etc.

There, aren't you glad that I cleared that all up for you?

-Matt

[knight_toolworks]

I don't think there is such a bit. it really depends on what material your cutting and how deep.
for solid wood I find straight bits work about the best. they seem to leave very little if any fuzz on the cut. mdf does not matter a whole lot what you you use. plywood can be fine with most bits depending on the veneer. straight or upcut for universal I would say. but straight bits in smaller sizes are not as strong So I don't use them in 1/4" sizes.

[myxpykalix]

first of all my memory isn't that great anymore so i don't recall what fred at centuriontools.com
called this bit, but i think i do recall that it was supposed to be able to cut thru the top of your material and the center and thru the bottom without trashing either edge. I've used it on wood and mdf and it seems to work good for me. He gave me a good explaination but i just can't recall the details. Call him, he's the expert not me for sure. I hope i took the pic of the right bit!

26439.jpg

[Brady Watson]

This has been covered here:

"A Tale of Three Bits…and The Poor Man’s Compression Spiral Trick - March 2007"

Goto ShopBot's Main Site and then click on Brady's Tricks on the left side of the page.

-B