Sometimes ya win, & sometimes ya kinda win!

[Buckshot]

http://www.fototime.com/09B8A0B281FB4D2/standard.jpg

.................I was high bidder on these 2 'new in the tube' Hanita double ended 1" 4fl CC M42 endmills. In fact, the ONLY bidder. I have a real 'jones' for endmills.[smilie=1: The pair with shipping came to $34.50 total. A couple days after they arrived, late one evening I was in the livingroom reading, and PING! out of nowhere, and no way connected with what I was reading the thought hit me. I had no way to hold a DE 1" endmill :veryconfu

R8 collets won't, and I have R8 shank endmill holders for the larger sizes, and of mine, "double end" endmill capability ends at 5/8". I also have a set of ER40 collets, but the R8 chuck for them also will not handle them. I suspect I'll simply have to cut one end off, to use them as singles. It hurts to do that, but still two new 1" 4 fl endmills for $34 is still a good deal but not as good as FOUR would have been! Another lesson learned.

...............Buckshot

[seppos]

Make a bushing/holder cup from brass..

S

[theperfessor]

Have you checked with Enco or MSC for an extended reach Weldon style R8 tool holder? I had to get one in BAT40 for work when the same thing happened to me.

[dragonrider]

There are holders available for them. I don't like to use them because the endmill will not run true due to the set screw that holds the end mill in the holder. Cutting those endmill in half will pretty much render them useless in such a holder as they may not be long enough to reach to the set screw. I would cut one in half hold it in a collet in your lathe and attempt to turn a 3/4 inch shank. If these mills were induction hardened at the flutes only you may be able to cut them.

[Buckshot]

theperfessor ........... I was thinking of looking for something like that, but danged if I don't hate buying something like that for just these 2 [smilie=l: If I did that I'd have to get some more of'em to make it worthwhile.

dragonrider............ The endmills are hard all the way. I have ETM endmill holders (5/8, 3/4, 7/8, & 1") and the 1" holder has 2 setscrews. The lower of the 2 will catch the flat on the shank leaving the full length of the flutes useable. Maybe 4-5 years ago there was a thread on the Practical Machinists forum (maybe others since) dealing with the possible issue of the setscrew offsetting the endmill. The concensus ran favorably to using (quality) endmill holders vs R8 collets for larger endmills. The thread was lengthly, became somewhat heated in a few places :takinWiz: but I went with the concensus:razz:

................Buckshot

[btroj]

Another example of why I stay away from machine tools. This is the dark side of the shooting sports to me. It sucks you in and then the garage is full of "stuff".
Nope, not for me. I will just pay someone else to do what I need. I can then spend my time looking in awe at what some of you guys can make. The awe is not just in the end product but the process that was used to create something. It is in the design that some of the real genius comes out.

Buckshot, keep your mills. They would just lead me down a dark, dark path.

Brad

[John Taylor]

Cut them right at the middle and have four end mills.
I ran into the same problem on a ball end mill that was 1 1/8" with a 1" shank. I used a tool post grinder and took the shank down to 7/8" for the largest R-8 collet I had.

[JIMinPHX]

You see, now you need a cylindrical grinder. That way, you can cut the end mills in half, then grind the shanks down to fit in the collets that you have.:kidding:

Seriously though,
Tool holders for those things do exist, but they are hard to find, expensive & give poor performance.

The shank on an R-8 is less than an inch, so a collet is a non-starter. The largest R-8 that I have ever seen is 7/8" & as you probably know, they have a bad reputation for fracturing.

An extended Weldon type solid holder would stick out so far that your rigidity would be poor & therefore a 3/4" end mill would probably perform better.

Those end mills really belong on a machine that has at least a 40 taper. An extended 40 taper holder will have enough beef to pull a tool like that & do it some sort of justice. If I were you, I'd try to find a shop that runs larger mills & then swap them for some 3/4" end mills. With the price that 1" end mills go for new, you would probably find that someone who can use that mill will be happy to trade. Unfortunately, I don't have a 40 taper holder that is big enough to hold them or else I would make you an offer.

As for the debate about Weldon shanks being off center, my position is this: Yes, they do hold the mill off center, a little. In a good holder, you can not even measure the difference with a .0001" test indicator. The best holders grind the bore relief off center, towards the set screw. Even the cheap holders are usually good within .0003" or so. You need to be taking a reeeeeaaaaallly fine cut to even see the difference. If you are trying to work to 50 millionths tolerance or something like that, then it matters. In that case, you can either use a collet or grind the end mill in the same Weldon shank holder that you are going to use when taking a cut. The solid holders are superior to collets when taking a heavy cut or working in a tough material or when you need to stick the tool way out. Otherwise, collets work fine.

[Buckshot]

You see, now you need a cylindrical grinder. That way, you can cut the end mills in half, then grind the shanks down to fit in the collets that you have.:kidding:

Seriously though,
Tool holders for those things do exist, but they are hard to find, expensive & give poor performance.

The shank on an R-8 is less than an inch, so a collet is a non-starter. The largest R-8 that I have ever seen is 7/8" & as you probably know, they have a bad reputation for fracturing.

An extended Weldon type solid holder would stick out so far that your rigidity would be poor & therefore a 3/4" end mill would probably perform better.

Those end mills really belong on a machine that has at least a 40 taper. An extended 40 taper holder will have enough beef to pull a tool like that & do it some sort of justice. If I were you, I'd try to find a shop that runs larger mills & then swap them for some 3/4" end mills. With the price that 1" end mills go for new, you would probably find that someone who can use that mill will be happy to trade. Unfortunately, I don't have a 40 taper holder that is big enough to hold them or else I would make you an offer.

As for the debate about Weldon shanks being off center, my position is this: Yes, they do hold the mill off center, a little. In a good holder, you can not even measure the difference with a .0001" test indicator. The best holders grind the bore relief off center, towards the set screw. Even the cheap holders are usually good within .0003" or so. You need to be taking a reeeeeaaaaallly fine cut to even see the difference. If you are trying to work to 50 millionths tolerance or something like that, then it matters. In that case, you can either use a collet or grind the end mill in the same Weldon shank holder that you are going to use when taking a cut. The solid holders are superior to collets when taking a heavy cut or working in a tough material or when you need to stick the tool way out. Otherwise, collets work fine.

From what I recall of the debate was that an R8 shanked endmill holder was much more rigid, first, last and always. Inexpensive endmill holders were less accurate then direct fitting in an R8, so you had to weigh rigidity vs possible accuracy.

Then again, how accurate is the endmill you're going to use, to begin with? As you mentioned, bias honing of the endmill holder's bore WAS talked about also. People have their druthers, and ideas or thinking they've pretty much settled on, and THAT'S the way they'll do it. The only people who seemed to get anything out of the entire thread were new people like me, or those that hadn't already made up their minds. I have a set of R8 collets by 32nds, but I also have endmill holders in the larger sizes. I felt rigidity itself is a valuable asset in building accuracy.

..............Buckshot