Torque for ER20 and ER32 collets

I have a shiny new-to-me Tormach mill and I'm ready to start breaking end mills and splashing coolant all over the room, hopefully with some usable parts emerging at some point.

Pardon the completely naive newbie questions -

How much torque should I be applying to tighten ER20 and ER32 collets? Does the end mill shank diameter matter?

Should I add anti-seize or grease or oil to the threads of the TTS ER collet holder that grips and squeezes the collet?


Maritool sells a torque wrench (for $168) and a wrench head for ER20 collets for another $57 and a different wrench head for ER32 collets for another $57, but that seems like a lot of expense and precision for a guy like me who just wants to make big pieces of aluminum into smaller pieces of aluminum without an end mill slipping out and flying across the room.

Their FAQ page suggests oiling the holder's threads and using 50-55 ft-lbs for ER20 and 90-110 ft-lbs for ER30 ... with the caveat to reduce torque value 40% when clamping on shanks 30% smaller than the collet's maximum capacity. I have a set of ER20 collets that includes 1/16" 3/32" 1/8" 3/16" 7/32" 1/4" 5/16" 3/8" 7/16" 1/2"

70% of 0.5" is 0.35" which is between 5/16" and 3/8" so I assume this means
30-33 ft-lbs for 1/16" 3/32" 1/8" 3/16" 7/32" 1/4" 5/16"
and
50-55 ft-lbs for 3/8" 7/16" 1/2"

All that info is about right except maybe oiling the threads part. If oiling do it sparingly. On a machine of that power potential, I don't believe you're going to need to worry too terribly about pulling tools out of collets due to heavy cutting. Just decently tight will work for most. The higher the helix on the tool the greater potential for pullout. People usually freak when you say you torque your ER32 to 100 lbs. Anyway... just-tight should be about right. No need to totally crank on them. Just keep an eye on the first 45 degree or more helix tool you use. That'll learn ya whether you've got it right or not.

hy, try bearing nuts ... they will protect your collets, and also they are more responsive when tightening, due to less friction : this means that what you feel has less ' noise ', thus represents better how much grip will be there; also, with such nuts, the tightening curve is smoother

if possible, avoid torque wrench for these collet sizes, and try to develop your skills

just like gentlegiant said, if you push an endmill too hard, it will pop-out anyway ... don't try to avoid that by overtightening, but lower your specs, or, if you wish to push your specs, then use weldon holders ( or whatever else, depending on buget ) / kindly :)

ps : keep the threads clean, air blow should do it ... no need for extra caution with er25 er32 ( since they are like bricks if used with minimal atention ), but only with little ( <=er20 ) or precision collets ( like those ones for gang spindles )

Techniks, a manufacturer of ER collets, has a torque chart at https://www.techniksusa.com/product/...pecifications/
The concern for pullout is valid but in my experience the weak point is the TTS holder in the spindle rather than an ER collet and the actual tool.

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in my experience the weak point is the TTS holder in the spindle

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Same here!

The more chatter you have, and the bigger your cutter is, and the thicker the cut is, the more risk there is of pull-out of the holder from the R8 collet.

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Originally Posted by jwatte

Same here!

The more chatter you have, and the bigger your cutter is, and the thicker the cut is, the more risk there is of pull-out of the holder from the R8 collet.

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I'll third this one. If you hear what sounds like odd chatter pay close attention to your holder. A disaster might be about to happen. My vise has marks in it from a lesson learned.

I was wondering if the new shorter collet may help with this problem, an r8 is only a single angle collet and it ideally grips over the whole shank but in actuality mine only grips on the bottom 1/8" of it or so. maybe with the tts face contacting the spindle and the 1/8" contact point moved up the shank of the tts by an 1/8" or so maybe this will help who knows??

Someone (Keene?) did some tests that indicated that solid shanks on TTS holders increased the grip of the R8 collet. Does anyone have further information on that observation?

Forget the torque wrench.
You'll distort the collets, create ridiculous runout and destroy the holders like this guy did (check out the second photo):
https://www.cnczone.com/forums/torma...ml#post1997966
The mechanical advantage given by the combination of the thread and taper are huge. Your tools aren't going anywhere. Just tighten them hand tight with the wrenches provided by Tormach - you don't even have to crank down on them. The Tormachs just don't have the power to worry about tools pulling out of the holders, and as already mentioned you should be paying more attention to making sure the TTS holders won't be pulling out of the R8 collet.
Step

Step is right on all counts in my experience. Never had a tool pull out of an ER collet with just hand tight on the wrenches. Have had an occasional near miss (hey, why is that cut getting deeper!!) when the R8 collet wasn't tight enough.

Thank you all, I appreciate the replies.

A shameless plug...... This will allow you to be consistent in your torque.

https://coolcncstuff.com/collections...tening-fixture

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Originally Posted by smokediver576

A shameless plug...... This will allow you to be consistent in your torque.

https://coolcncstuff.com/collections...tening-fixture

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I like your warning flags also :)
btw nice website

I never did like the TTS system......at the same time I've never had to use the TTS system as I have ER32 collets in chucks that have ISO20 tool holders, but the concept is one that relies on brute force by the friction grip of the collet to hold the round shank of the TTS tool in the R8 collet.

It's a good system for interchangeable tool holding, same as the Bridgeport R8 collets holding cutters in the spindle, but if you put heavy cutter loads on the friction grip it will pull down before the cutter pulls out of the collet.

The great expectation of the user is that they want to go to the extreme cutter potential for metal removal and so something has to give.
Ian.

By that definition then heat shrink tooling is also junk as it merely uses friction to hold the tool in place. Schunk Tribos is junk for the same reason then. How about milling chucks?. Nothing but friction. I think the more appropriate way to state it is that the capabilities of TTS are lower than some of the others but it's also been marketed and directed at lower power, less rigid machines.

Hi, what you are missing is that the TTS system is a spring loaded draw bar that applies tension to the collet to hold the tool shank in.

It depends on the amount of spring pressure the Bellville washers can exert on the drawbar, and correspondingly the extra amount of pressure you can then exert on the drawbar to slacken the collet.......something like a ton of pressure to do the holding and an increasing amount to release it.......that is a cock eyed way to hold something with less pressure for something as volatile as a cutter revolving at a high rate of knots and more pressure to release it when it's stationary.

My electric powered drawbar failed when the motor draw bar mechanism burned out and I had to resort to a manual mechanical device to release the draw bar........it was not in the order of a ton of force as it was a dead lock method not a spring one and that will never back off under load and release the tool......but that is a pull stud retention system.

Having a power draw bar a potential failure is the price you have to pay when you want a push button solution as opposed to tightening a nut manually etc to do the holding.

You can of course use a huge amount of extra force to pull the R8 collet up to make it grip more, but that is brute force in the extreme which means you must then apply even more force to release it.......the old fashioned nut and bolt method is fail safe.

You don't have that problem with a tool that has the pull stud retention method only TTS.

BTW...... Bridgeports have R8......the reason they hold cutters in tightly in R8 collets is because they are nut on bolt tightened and that is a dead force not a spring one.
Ian.

I don't think I missing anything but we may be arguing from differing viewpoints. I think we need to differnetiate between tool holder retention power versus tool holding retention power. I think we'd both agree that a BT30 pulled in with a threaded draw bar would be better than a pull stud and bellville washers. THe first being a pure mechanical lock and the other being a compression force that could be overcome by the forces of cutting. TTS wold be just fine if the drawbar threaded into the tool holder and not into the RB collet holding the tool holder. I think it's blending of those two to get to some thing capable of running out of tool changer is the drawback. As tool holder retention method I agree. It's less than optimal. A retention knob is slightly better but still at the end of a stack of bellvilles so still not a rigid but less likely to pull out from chatter and vibration. Having argued all that at some point you are getting down to a round smooth shafted tool being held in the tool holder by friction so the possible failure point moves down to the tool. Weldon flats are a mechanical and I guess could be deemed better than a pure friction hold but we know the problems with run out and balance for those as well.

Having said all that on the size machine that TTS is targeted at does it really create more problem than is solves for most folks. Chances are if the cut is heavy enough to pull the TTS tool holder down the machine is already twisted up like a noodle anyway or at the edge of it motor HP. The power draw bar may be the source of all it's problem as I never had a TTS tool holder pull down while using a threaded drawbar.

You are quite right in the capacity being worked....if it overcomes the holding force of the draw bar system it probably will do some damage elsewhere etc......provided the Bellville washers are assembled correctly and have enough force to pull up the bar.

I have a sneaking suspicion that if you get any resonant frequency vibration going up the drawbar it will cause an oscillation with the washers and could slacken them off.
Ian.

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Originally Posted by Kenny Duval

By that definition then heat shrink tooling is also junk as it merely uses friction to hold the tool in place. Schunk Tribos is junk for the same reason then. How about milling chucks?. Nothing but friction. I think the more appropriate way to state it is that the capabilities of TTS are lower than some of the others but it's also been marketed and directed at lower power, less rigid machines.

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The way I understand heat shrink tool holders, the idea is all about low tool run out. not pull out.
From my experience my most problematic tools to get good finish with and avoid chatter is anything mounted in a collet :)
I find my tts Weldon set screw holders have far less run out and give me a more consistent finish then tts collet held tools.
The only way to mitigate this is to clock runout and check everything you do with collet tools.

I dont worry much about tts pull out and just work within the machines design and power. Not hard with modern high performance coated cutters designed for specific materials combined with good controlled tool paths and adjusted speeds to get excellent results milling just about anything. As many demonstrate on youtube. You just have to do some testing.

Just slower then a 10 hp machine with ninja fast rapids that have so much power they could push my jeep thru the wall :)

So, what is all the fuss about then......tool pull down with TTS or cutter runout with any system?

I think you can get total cutter concentricity with all systems if you're lucky enough with your purchases but cutter pull down is a personal machine use thing.

That means TTS is not a problem at all......if it becomes one then machine application or maintenance is the answer.
Ian.