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View Full Version : Roughing/Finishing End Mill



bborr01
11-20-2012, 01:11 PM
Hi Guys,

The recent thread about roughing end mills got me to thinking about an end mill that I got recently but not tried yet. It is a Weldon KPA-24-5 crest cut. 3/4 inch diameter, 4 flute, M42 HSS, cutter that it is designed to rough and finish at the same time.

The one that I have is kind of dull but I tried it and it seemed to work fine, no long stringy chips when side cutting. A friend of mine that owns a fairly large cnc shop showed me a similar cutter a couple of years ago and told me that they are fairly expensive at about $50+ each but he said he made enough extra in productivity to pay for the cost and still come out ahead. I think the ones he was using were carbide and he was flying through some CRS at a pretty good clip, better than 1/2" DOC. Very impressive.

Here is the one that I have and a test cut. The first half of the cut was dry and the second half with coolant. And like I said, it was kind of dull.
http://i400.photobucket.com/albums/pp89/bborr01/20121120_105256.jpg
Has anyone else used these and if so, what was your opinion of them.

Thanks,
Brian

Toolguy
11-20-2012, 03:07 PM
They work OK, not as well as the corn cob style. I have never had one that left a finish good enough to call finished. If I'm using a roughing cutter I plan on following it with a finish cutter. There are other rough/ finish cutters that give a better finish. One kind is like a regular endmill with chipbreakers every so often on each cutting edge. Those usually leave horizontal lines. Another kind has rough and finish flutes alternating on the same end mill. I have not used that kind yet, but it should (theoretically) give a good finish.

oldtiffie
11-20-2012, 05:10 PM
Finish off with a fine (0.005") "climb" cut as a lot of the "marking/scouring" is from chips pulled back into the cutter with normal cutting.

beanbag
11-20-2012, 05:21 PM
Roughing cutters CAN give a good surface finish - on the bottom, but not really the sides.
I think if you have good chip clearing capabilities, you don't really need a roughing cutter.
My understanding is that they aren't as popular anymore in the CNC world. It is things like coatings that drive productivity gains.