Upcut or downcut spiral bits for router table?

Neal W

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My experience with router bits (straight bits in particular) is with the typical two flute or one flute straight bits.  Since I've worn out my 1/2" and 1/4" bits, I'm looking at spiral bits from whiteside as replacements.  I will use them both in handheld applications, and in a router table.  Mostly they will be for Dadoes.

Should I be looking at up cutting or down cutting bits?
 
You likely want an upcut bit. It will pull the chips up towards the router, which gives you better control in both handheld and table routing situations. Downcuts, especially on router tables, have a tendency to want to push the wood/router away from each other, though they may give you a slightly better finish on the edges of a dado.
 
I agree with the above unless I am routing plywood. The upcut bits can lift the top layer up.... delaminate.
 
I only ever use upcut or straight.

Upcut clear the dust out of a cut quicker, so I prefer them when routing solid wood.  But like the other post says, they can delaminate ply, so then I use straight cutters or go very gently.

Andrew
 
It depends on what you're doing.  The case for downcuts is to preserve the integrity of the face when dealing with material prone to tear out or chip out.  Also, when using a bearing guided bit and template on the router table I'll use a downcut with the bearing on the bottom of the bit (which is probably the most frequent application I find for these bits).  The template serves as a support to eliminate tearout on that side of the work piece.   
 
Remember also that the directions “up” and “down” change their meaning when you turn a freehand router upside down to mount it under a table.

So while for freehand an upcut will send dust upwards towards your dust collection, it will send the dust under the table when mounted on a table.

You might also want to look at compression bits, which have both upward and downward spirals. You have to be careful about getting the heights right so that both spirals can engage on the edges. In theory (I have no experience on this) both edges come out clean.

(Those “The router bits” videos from Timbecon are really good. I watched them all the other day — very useful before buying.)
 
Here's an example of a dado in maple ply using a Whiteside downcut spiral bit. This dado was made in a single pass.
 

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Cheese said:
Here's an example of a dado in maple ply using a Whiteside downcut spiral bit. This dado was made in a single pass.

That sure is one clean cut.  How was the dust extraction with the down cut bit?
 
Dick Mahany said:
That sure is one clean cut.  How was the dust extraction with the down cut bit?

The dust extraction was fine, used the 1010, my favorite. The dado is 1/4” deep.
 
Have you also consider Spiral Compression Bits? More expensive but they are worth the price.

5638.jpg


"Excellent for creating grooves and dado cuts in plywood and composite materials. Solid carbide compression spiral bits designed for CNC applications requiring high feed rates and a clean finish. Special unique carbide for longer lifetime in abrasive material. Designed for CNC applications requiring high feed rates and a clean finish. Particularly suitable for double sided melamine or laminated material."

Works very well on soft and hardwood. To me this is the best type of bit when it comes to do hand free pockets. Since I use those on my CNC I never looked back.
 
Mario Turcot said:
Have you also consider Spiral Compression Bits? More expensive but they are worth the price.

Works very well on soft and hardwood. To me this is the best type of bit when it comes to do hand free pockets. Since I use those on my CNC I never looked back.

I have been thinking about the compression bits and they get good reviews albeit expensive, hence my reluctance to buy one yet.  Have you used them in a router table or hand held router as I don't have a CNC and would be using them primarily on plywood edges and hardwoods ?
 
[member=66597]Mario Turcot[/member] thanks for mentioning that hit it reminded me that had one to put in the rotation and hadn’t gotten around to it.

[member=59951]Dick Mahany[/member] just put it in my handheld router this morning and it does a great job. Smoother cutting and a great finish on the cut.

Here's the one I'm using.
https://www.amazon.com/Whiteside-Ro...id=1534358812&sr=8-3-fkmr0&keywords=whiteside+ud2105

Ron
 
[member=59951]Dick Mahany[/member]
Dick Mahany said:
Have you used them in a router table or hand held router as I don't have a CNC and would be using them primarily on plywood edges and hardwoods ?

Unfortunately I only used them on the CNC, cutting 9mm to 18mm BB and some Bubinga, Purplehearth and Shedua. Three pretty hard wood. On the hard wood it was for contour only using a 1/4" bit. I am looking to get some 1/8" and 1/16".
 
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