# What is the difference between these two?



## zm15 (Dec 16, 2013)

I have came across these type of bits with a diamond like fishtail:










And then these regular spiral bits: 










Both are downcut, but what's the difference between the two?

I'm looking to do lettering with a smooth bottom of the channel and a smooth edge, so compression bit would be best, but out of my price range right now. Curious the difference between those two.


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## Mike (Nov 22, 2004)

The regular spiral bits are designed for woodworking and will evacuate the chips as they should.


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## Quillman (Aug 16, 2010)

Ignore the cutters in the colored holders. They're for fiberglass and other mean substrates. They have serious traction in wood.
A real control problem.


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## OPG3 (Jan 9, 2011)

The top section of bits are what we use ONLY as a deburring tool - and being VERY CAREFUL. Some of my guys refer to them as "Rotary Rasps" - which is pretty accurate IMHO.

Otis Guillebeau from Auburn, Georgia


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## zm15 (Dec 16, 2013)

Thanks Otis, so would you say those top bits aren't capable of being plunged into wood then? Basswood in my case...

I've never used them before.


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## bobj3 (Jan 17, 2006)

Hi Zach

I use my set in wood all the time they will drop right in but the smaller ones will break if you look at them the wrong way for VERY fine work only and they are not a deburring tool !
I will say they are great for Basswood just don't push them sideways they will break if you are to deep in the wood..

Just a note they use the same pattern ( diamond ) for router bits for plastic, I have some that are 1/4" diam.

http://www.precisebits.com/products/carbidebits/fdrouter.asp

http://www.precisebits.com/?gclid=CNzDiOuhursCFclcMgodQAIAoQ

http://www.precisebits.com/Reference/chipbreakerfeedspeed.asp
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zm15 said:


> Thanks Otis, so would you say those top bits aren't capable of being plunged into wood then? Basswood in my case...
> 
> I've never used them before.


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## zm15 (Dec 16, 2013)

Hi Bob, thanks for the info. In your opinion, when you say Very fine work, take a look at what I'm currently looking to do with a small dremel with router base and possibly these bits, carving out the letters about 1/8" deep or so:









Is that too 'fine'?

For this size and detail, would you consider the diamond pattern bits alright for this use? Do they have the smooth top finish like a downcut spiral bit would?


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## bobj3 (Jan 17, 2006)

Hi Zach

They should be just fine,be sure you turn speed down all the way down on your "Dremel",
" Do they have the smooth top finish" yes they come in both ways the norm is a flat bottom cut ( fish tail tip) 
I will say if I do that type I use the scroll saw in that way if I make a error the part will just go right into the pocket hole and I'm the only that knows about the error  easy to take it out with a router bit but very hard to put it back in...

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zm15 said:


> Hi Bob, thanks for the info. In your opinion, when you say Very fine work, take a look at what I'm currently looking to do with a small dremel with router base and possibly these bits, carving out the letters about 1/8" deep or so:
> 
> 
> 
> ...


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