Are All 2 Flute Mills Center-cutting?

[wawoodman]

I can't figure this out. Sometimes the description says centercutting, or plunge cutting, or something similar. But sometimes, it says nothing. I have found some comments that all 2 flute cutters are. Is this the case? I can look at the ones in my drawer, but when I want to order something online, I'm kind of at a loss.

A second question: if I want to make a groove deeper than the the cutting length, what's a good procedure?

 

[joshua43214]

dunno if they are all center cutting or not, my gut tells me no...

It is easy to tell if they are center cutting or not, a center cutting mill will have each cutting face coming to the center line of the mill.

The best procedure for cutting a groove deeper than the cutting length to get a longer mill, switch to an insert tool, or change the design. I did some side milling the other day that was deeper than the cutting depth. The mill rubbed a bit when I stepped down to the final depth but the finish came out fine for the work in question. Your mill should be smaller in diameter that the width of the slot anyway, so you can probably get away with just plunging out the slot to cutter depth, widen the slot to near final width, then plunge to final depth. Go back and widen to final dimension, it will probably have a bit of taper at the bottom.
I would not try to plunge deeper than the cutting depth on a slot the same width as the cutter, rubbing, chip ejection, flex, etc will cause problems.
No reason I suppose you could not grind the shank on the mill down a bit for clearance, just don't grind into the area that goes in the collet.

 

[Billh50]

No....If it doesn't say center cutting when buying then it is relieved just like a side cutting.

 

[JimDawson]

No reason I suppose you could not grind the shank on the mill down a bit for clearance, just don't grind into the area that goes in the collet.

I've done that many times. You can also buy endmills with a shank smaller than the cutter. But in general, I buy endmills that have the DOC needed for the job.
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[planeflyer21]

No. If you look at center cutting endmills, the flutes (or two of them on a 4-flute) meet in the center like a drill bit. The non-center cutting EMs have a small hole between the flutes, which I believe was for a center during the manufacturing process.

Edit: Wiki actually has a good photo of the end of some end mills, a 2-flute center cutting and two 4-flute, one of which is a center cutter: https://en.wikipedia.org/wiki/End_mill

Or you can peruse these: https://images.search.yahoo.com/sea...?p=types+of+endmills&fr=yfp-t-901&fr2=piv-web

 

[wawoodman]

I know what they look like! My question was about buying them on line, without a good description.

Thanks.

 

[JimDawson]

I don't ever remember seeing a 2 flute end mill that is not center cutting. I think you are safe in assuming that most are. 3 or more flute could be either, and are normally called out as center cutting or not.

 

[frostheave]

I called Enco about a year ago. They said if the description doesn't say center cutting, it is not center cutting.

 

[Billh50]

I have several new 2 flute end mills in by tool box and they are not center cutting. The smaller ones do not have a hole in the center but they are relieved just like any standard side cutting end mill. And if you think about it the bottom would be rubbing and quickly dull if it was center cutting and you used it to side mill as there would not be enough relief.

 

[4GSR]

I don't recall ever seeing a non-center cut 2-flute end mill. I know in my collection there are none and I have lots, many from dads shop that are over 30 years old. For two flute, I've always specified center cut when buying them, regardless. Four flute, same thing, if I needed center cutting.