Single vs double end end mills

[Mr Ron]

What is the difference (if any) between single end and double end end mills? I thought a double ender would be more economical than a single ender. I checked prices and a double ender cost LESS than a single ender. It seems the cost should be the other way around. Is there any preference between the two end mills?

[tornitore45]

I asked the same a while back and the "village" opinion was negative due to the fact that as the collet sucks up the tool it may ruin the other end.
I use them because they cost less than two singles and by using 2 cents worth of care there is no problem.

There is a substantial difference of attitude, as it should be, between people making a living machining and a hobbyist financing the hobby out of discretionary income.

[John Hasler]

If the double ender costs less then it's more cost-effective other things being equal than the single-ender even if assume that the end that goes in the collet is ruined and never use it.

Can we assume that other things are equal, though? Can the cutter damage the collet? Is the grippable shank length too short?

[John Evans]

You sure it is not one double end mill cheaper than TWO single end mills ? I have both and have bought double end just for the cost savings but usually use single end mills. 6 of 1 -12 the 'tohger.

[mcostello]

More steel in two single end endmills.

[Harold_V]

mcostello pretty much nailed it. The double end end mill shares a common shank, thus there is less material in one than there is in two end mills of equal size.
I've been on milling machines since I started in the shop way back in '57. I have yet to do any damage to a double end end mill by the collet or draw bar. They are built to deal with such cutters.

I routinely use 3/4" double end cutters in my Bridgeport with the R8 taper. If they don't have any problems with the depth of the collet, you can rest assured that smaller end mills won't have, as they are correspondingly shorter, according to size. I can not address other types of collets. Could be some of them would be limited to single end cutters. I recall that the Cincinnatti Toolmaster I used to run wouldn't accommodate double end cutters due to the type of collet used, which I do not recall now.

H

[tornitore45]

John, I do not see any source where a double cost less than a single. A double cost usually less that TWO single.

[toddalin]

My take based on my ShopTask Tri-Power mill/drill/lathe.

I bought a bunch of mill bits here and most were double-ended. When I try to put them in my collets (R8s), it seems that they don't even go in to the smooth shanks and the collet is just grabbing onto the bit portion. This can't be right. I think that I now need to have all of these bits cut in two just to use them.

[whateg0]

What is the difference (if any) between single end and double end end mills?...

I can't believe nobody has said that the difference is in the number of usable ends!

I use an ER collet for almost everything. A 1/2" double EM won't fit in the collet holder. If I put one in, the inserted end hits the collet holder before I can put more than about 3/8" of shank in, so I am limited to single ended EMs. Some smaller ones would work like that, but for me using single ended is fine.

Dave

[Inspector]

Maybe just the place I worked but I recall the double ended cutters having "whistle notches" in them to fit in Weldon type holders and not in collet holders.

Pete

[John Hasler]

Cutters with Weldon flats work fine in my collets.

[whateg0]

The collet will straddle the Weldon flat. Not sure why that would be a problem. Most of my single ended em have a Weldon flat too.