Is this a common problem? On my cast iron job I was using a nice new just bought 3/4" rougher end mill that I put in an ER32 collet and it pulled out over 1/2", put a nice mark in my previsouly virgin table and then broke. Got another new end mill and went back to the end mill holder to finish the last part.
Cat40-er32 was about 1" shorter than the cat40--3/4" end mill holder so I went with the less stick out is better aproach, and it backfired on me.
*Always* use std holders for roughing, especially hogging tools. Collets were not designed to take that kind of load. That is why the flats are ground into large end mills, you need the fixed screw to lock in the tool, creeping and pulling out will happen even then if you push the tool hard enough, only the screw acts as stop to limit the tool from exiting the holder. Always clean the spindle taper and check the tool's taper to keep running as true as possible. If the tapers are clean and the draw bar pressure is correct, things should be good. And then remains how you are feeding the tool, is the cut interrupted, is the iron good (high chrome content, bad Brinnell hardness all come into play, lead screw slack is a possibility. Sheesh, with all these considerations it is a wonder we ever get anything machined right, LOL! HTH, if not, just disregard all of the above and reduce the feedrate maybe?? Have a nice day Randy!
3/4" is near the very max. that an ER32 can hold also. Roughing in an ER collet is dicey enough, but at the max. capacity it really pushes things too far. We rough with 1/2" end mills (in aluminum) in ER collets, but we don't do it with an ER20, we do it with an ER32.
ER collets are made for precision; but not for maximum grip. TG and DA collets are made for neither. They're just cheap and convenient. Slippage during milling is always a problem with any of these types.
Set-screw type endmill holders are generally better for rough nilling, or even for finish work with cutters bigger than maybe 3/8". Here's a tip, though: When you install the endmill in the set-screw holder, tighten the screw just snug, then back it out maybe a quarter turn. Then, pull the endmill out of the holder as far as possible, so that the end of the endmill's flat that will actually prevent pull-out is engaged with the screw. Then tighten the screw fully. If you do the opposite, and push the endmill into the holder, it will still pull out a bit during cutting because the flat on the endmill is wider than the diameter of the set-screw.
When you need a good grip, but can't stand the runout that a set-screw holder creates - like if you're into serious roughing where runout will warp your chip loads and cripple your cutter's performance - then you'll want to look at milling chucks. These are specially designed collet type holders that give good runout, bunches of grip, and excellent rigidity and vibration resistance. They're more expensive than normal (TG, ER, etc.) collets; but the difference in performance is dramatic. Here are a couple examples.
?type=milling Heat-shrink holders are probably best; but the cost and trouble make them less than attractive, in my personal opinion.
Everybody has their own preferences, of course. And sometimes, what works best depends a lot on what you're used to, and how well you use it. I can't deny that there are lots of people who get good results with TG's. I just don't happen to be one of them.
With the shallower angle on the TG series they really grip in my opinion. The smaller size shanks, under 3/8" dia. don't go deep enough into the collet for good concentricity, even the single ended ones. For
3/8 and larger collets I haven't had problems with either concentricity or pullout. I've also seen TG collets with a plug that will engage the Weldon notch on endmills, this would effectively eliminate pullout problems.
As you say, different strokes for different folks.