Routers and End Mills

[Chris Pyle]

I don't know if this necessary belongs under "heavy metal" as it's pretty light indeed but.... does anyone use end mills for routing?

I followed in Chris' footsteps and purchased a collet set from Precise Bits and it came with collets for 1/8, 3/16, 1/4 and 1/2" bits. I often receive industrial catalogs with a large swath of mill tooling. Many are carbide cutters and the smaller sizes would be cost effective if they work as well.

Would 3 flute mills be appropriate in a router? 2 Flute? 4 flute? And what helix angle? 30 degrees? 37? 40? 45?

Many questions for which I have not found answers.

[durbien]

Some cutters designed to work in metal won't do well at router RPM, but there are carbide cutters made specifically for CNC routing in wood. I'm not at work right now but I could look into the angles, feeds, and speeds, etc. if you want.

[Chris Pyle]

Some cutters designed to work in metal won't do well at router RPM, but there are carbide cutters made specifically for CNC routing in wood. I'm not at work right now but I could look into the angles, feeds, and speeds, etc. if you want.

I'd be interested in what you find but it's not time-sensitive. As a reference, here are some things I dug up on the webz:

http://www.finewoodworking.com/item/207 ... -mortising

http://www.sawmillcreek.org/showthread. ... outer-Bits

[Chris Hall]

I use end mills a lot, and have so far been purchasing them from companies who make them expressly for router use in wood, like Amana and Whiteside.

Now that I have a mill, a new and vast world of end mills has opened up. Instead of the three typical sizes we might use in a router or router table, 0.25", 8mm, and 0.5", in the metalworking field there are sizes from 0.125" up to 2.0". I've been strongly considering getting a 0.75" end mill - the extra length and rigidity is certainly a plus for certain situations. With a 0.5" router bit, a 2.75" cut length is about the max which is safely possible.

And a wide variety of helixes and number of flutes are available, along with various coatings. It seems the end mills with more flutes are intended for use in heat-treated or otherwise difficult to work alloys. Even a single flute router bit will work well in wood of course, though in the past, when I could obtain more flutes or cutters in a tool I have generally found the results to be good. I'm wondering if the end mills designed for aluminum work might be a good choice for wood. A shear cut is almost always going to leave a better finish than otherwise, however shear cutting also introduces loading in a vertical direction, which can have repercussions in terms of tear-out and part fixturing.

[Chris Hall]

It seems there is a direct relationship between the number of flutes on a tool and the feed speed. Higher feed speeds generally associate to tooling with more flutes. It boils down to the rate at which chips are taken from the material.

[Evans]

It boils down to the rate at which chips are taken from the material.

I have only limited experience with routers/mills. It was explained to me once that when a chip exits, it also takes heat with it. Faster chip ejection equals more cooling of the tool, and less scorching of the work. Have you found this to be the case?

[Chris Hall]

It boils down to the rate at which chips are taken from the material.

I have only limited experience with routers/mills. It was explained to me once that when a chip exits, it also takes heat with it. Faster chip ejection equals more cooling of the tool, and less scorching of the work. Have you found this to be the case?

That sounds about right. Looking at a brochure for Onsrud End mills I came across, it is noted:

"The most effective way to reduce the heat is to have it removed with the chip. This can be accomplished by cutting the correct size of chips which will both dissipate heat as well as yield a high quality part edge finish due to minimization of re-cut chips. This is only possible when a tool possesses the proper geometry allowing for optimization of both speed and finish characteristics."

A cutter should always produce chips. If it is producing dust, it is dull, and getting duller at an increasing rate.

It did occur to me that those high helix mills, like this...

s-l1600-1-small.jpg (184.71 KiB) Viewed 3516 times

...would be poor for wood routing in most grain orientations, save for one: end grain. It should work very well for that.

I image that the best end mills made for woodworking, in terms of optimum geometry, are those designed to do so by the manufacturer. I think only a few manufacturers, however, make end mills for woodworking use (Whiteside, Onsrud, Infinity, Amana...). What I don't know is whether an end mill designed for metalwork would serve perfectly adequately for wood or not.