# Upcut Downcut



## patlaw (Jan 4, 2010)

Can someone give me a beginner's explanation of when to use an upcut and when to use a downcut bit? For starters, am I correct that upcut moves the sawdust towards the router?


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## vindaloo (May 30, 2009)

Upcut pulls the chips towards the router so use if it's a blind hole/slot

Downcut pushes chips away so use for through slot or trimming.


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## RainMan 2.0 (May 6, 2014)

Mike I want to see if I remembered . An uncut bit forces the wood out evacuating the hole better out of the material , but for laminate you want a down cut as it would have less of a chance of chipping the melamine etc. 
let's see how close I am lol

Ok I posted a few seconds to late and got beat :|


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## Stick486 (Jan 4, 2013)

tes on the saw dust removal...

see if this helps...


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## patlaw (Jan 4, 2010)

And here goes the confusion. Angie says, "Upcut pulls the chips towards the router so use if it's a blind hole/slot". The PDF that Stick posted says, "DOWNCUT Bits (naturally) cut downward (away from the router base). This motion gives grooves, dadoes, rabbets, shallow mortises and plunge cuts a smooth clean edge. REMEMBER: Downcut bits push sawdust into the cut. Making multiple passes reduces the buildup of sawdust in the groove."

Wouldn't a dado be a slot? It seems that these two recommendations are at odds with each other, and Angie's recommendation makes more sense to me.


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## vindaloo (May 30, 2009)

If you use a downcut to cut a dado (non-through slot) the corners are not raised by an upcut, so are smootherwith less to no whiskers. The problem that can occur is sawdust buildup in the slot.


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## vindaloo (May 30, 2009)

@patlaw

Mike you could always get an *upcut-downcut bit (called a compression bit)*, best of both worlds. They do seem to be a little on the expensive side for a hobbyist like me though


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## Mike (Nov 22, 2004)

It was so nice and easy when everyone could see all the sticky threads on the main menu.

Hope this helps people.

http://www.routerforums.com/router-bits-types-usage/55801-router-bits-stickies.html#post505441


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## Nickp (Dec 4, 2012)

An upcut makes a cut towards the router, the downcut away...

Upcut clears sawdust in a blind slot, downcut makes a clean edge on the face closest to the router, upcut makes a clean edge on the face away from the router.

...so which way do you want the sawdust to go and which face do you want cleanest...both are allowed...

Compression bits clean both ways and leave a clean cut on both faces (if aligned properly and through-cut)...they come in different lengths...

Downcut in a mortise will give you a clean cut but will not clear sawdust very well...bit will heat up faster...Upcut will clear the sawdust, leave a bit of fuzz but can be sanded and hidden by the shoulder of the tenon... (eeeuwww)...everybody hides bellybutton fuzz... 

...it's up to the imagination...

...did ya learn me right, roomies...?


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## Nickp (Dec 4, 2012)

Mike said:


> It was so nice and easy when everyone could see all the sticky threads on the main menu.
> 
> Hope this helps people.
> 
> http://www.routerforums.com/router-bits-types-usage/55801-router-bits-stickies.html#post505441


...change is inevitable..."resistance is futile"...

It used to be "ars gratia artis"...nowadays it's (tech gratia techis)


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## timbertailor (Oct 4, 2009)

RainMan1 said:


> Mike I want to see if I remembered . An _*uncut*_ bit forces the wood out evacuating the hole better out of the material , but for laminate you want a down cut as it would have less of a chance of chipping the melamine etc.
> let's see how close I am lol
> 
> Ok I posted a few seconds to late and got beat :|


I do not think I would every buy an uncut bit.:no:

But, yeah, you are right on. And if you have a really nice dust collection system on your router, (nudge nudge wink wink) down cuts are really not that big of an issue to use and you can still see what you are doing.

And remember, these are usually made from carbide. They are BRITTLE. Do not drop or use excessive force when using them. Only make passes about half the depth of the bit diameter max. at one time. Expect to break one or two if you use them at all.


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## DaninVan (Jan 1, 2012)

...at $30+ a pop!


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## DesertRatTom (Jul 3, 2012)

Amen to brittle. Downcuts make very clean box joints.


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## Garyk (Dec 29, 2011)

Had a project full of blind holes (game board for Fast track) and on the advice of Whiteside's customer service ordered down cut bits. Their advice was the down cut would not damage the surface of the board whereas the up cut would pull against the wood and splinter the surface. Haven't used the compression bit but it sounds like it would be a good compromise. My experiments proved Whitesides advice to be correct.


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## patlaw (Jan 4, 2010)

It sounds like the one to use is a matter of choice and that either will work in either situation.


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## timbertailor (Oct 4, 2009)

patlaw said:


> It sounds like the one to use is a matter of choice and that either will work in either situation.


No. They do have their specific purposes.

Use the downcut to protect the top surface, especially when using a laminate of some sort on top and the finish makes a difference.

Use the upcut if you need to see better, while cutting or just have a need to clear the shavings more efficiently. I do not use this bit much. My router has excellent dust collection.


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## Cherryville Chuck (Sep 28, 2010)

The Stickies had become a mess Mike. Some were outdated and others didn't really make a significant point. They needed to be cleaned up.


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## JFPNCM (Dec 13, 2009)

And to confound the situation, does it make a difference if the cut is being made on a router table so that the work is facing down vs. a pass across the face of he board say with plunge router?


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## Stick486 (Jan 4, 2013)

JFPNCM said:


> And to confound the situation, does it make a difference if the cut is being made on a router table so that the work is facing down vs. a pass across the face of he board say with plunge router?


just remember that you are inverted...


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## Garyk (Dec 29, 2011)

Guess you could use a spiral upcut/downcut bit in a table but they are designed for plunge routing.


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