# spiral bit



## drainman (Mar 25, 2006)

there are 2 types of bit 1 an up spiral and the other is a down spiral bit.If i want to do a groove which one do i get and if i want to face edge my wood do i use a down spiral bit.


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## jschaben (Jun 21, 2009)

drainman said:


> there are 2 types of bit 1 an up spiral and the other is a down spiral bit.If i want to do a groove which one do i get and if i want to face edge my wood do i use a down spiral bit.


Actually, with spiral bits you have 3, see picture. The one on the left is the down spiral, on the right is upspiral and the middle one is a compression (up/down) spiral. When cutting grooves or dados the down spiral will give less surface tear out but will tend to pack the chips into the bottom of the groove where the upspiral will pull the chips out but have a tendancy to tear the top surface. The compression bit uses a down spiral for the first 1/4" or so of the depth and then uses an upspiral to pull the chips out


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## bobj3 (Jan 17, 2006)

Just to add to John's post

2 flute flat bottom cutters. Top quality micrograin solid carbide. 

Will cut faster, smoother and stays sharper longer. 

Produces a very clean, fast and accurate cut with minimal chatter. 

*Upcut *spiral helps remove material. 

Ideal for making mortise and tenon joints. 

*Downcut* spirals help hold the material in place while using *handheld* routers. 

Will plunge cut and plane edges. 

Eliminates chipping at the top of the cut. 

Ideal for soft & hard woods, plywoods & composites, laminates, plastics and some non-ferrous metals.


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## LMan (Nov 23, 2010)

Cool I did not know that I learn something again today it is nice hanging around here so much to learn..


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## drainman (Mar 25, 2006)

many thanks for the info and your time


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## istracpsboss (Sep 14, 2008)

Incidentally, Cripe Distributing seem to have some cheap Bosch ones. On the other hand, I suspect these are CNC specials. When I subtracted the cutter length from the overall length, it only left a maximum of 1/2" of plain shank for the collet to grip on. Probably not a good idea, after all.

Cheers

Peter


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## jschaben (Jun 21, 2009)

istracpsboss said:


> Incidentally, Cripe Distributing seem to have some cheap Bosch ones. On the other hand, I suspect these are CNC specials. When I subtracted the cutter length from the overall length, it only left a maximum of 1/2" of plain shank for the collet to grip on. Probably not a good idea, after all.
> 
> Cheers
> 
> Peter


Hi Peter, That's where the one pictured came from. Hard to beat the price but mine has 2" of shank.
cripedistributing.com : Bosch 86024M Sc 1/2 X 1-1/2 Compression Spiral Router Bit 2F 1/2 [86024M] - $20.00


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## S.E.W. (Jan 5, 2011)

down cut is very good for a groove they will not chip face of the material.and if you have two sided material you would use a compression spiral.


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