Tool holder pull studs. How often do you replace? Have you ever had one fail?

[huleo]

Personally, I think I have looming concern in my head because I actually had one just snap years ago when machine was off overnight. Came in to a dropped tool!

I am thinking about replacing every pull stud we have but wanted to see if this is over thinking? My issue is of one actually fails in a cut, really bad things can happen, and probably trash the spindle nose, making refreshing studs a cheap investment!

IDK, just want to get opinions about it. Many of ours are TSC type, which adds to the weakness.

 

[M.B. Naegle]

I'd be interested in others experience as well. I've never considered them an expire-able consumable as we've never had one fail, but I could see them wearing out over time. We've had a couple machinists years ago who always advised to pull the tool out of the spindle at the end of the day and set it on the bench or table to be put back the next morning. IMO, any machine left for a long length of time should have the tool removed from the spindle, but that's less about pull studs and more about tapers settling together.

 

[mhajicek]

Which spindle taper, and how hard do you run? 30 taper studs are under-engineered and prone to failure.

 

[Vancbiker]

All my BT30 pullstuds are from 1995-1996. Never had one break. Most are Tecnara or Parlec with a few Command.

 

[Bobw]

I've had 2 break.. One was many many many many moons ago.. It was on a tool holder
that came with the machine, and we just used it.. And then all of a sudden it wouldn't come
out of the spindle. Had to push the button, and it took 2 guys on 2 pry bars to get her out.

The culprit.. OVER TORQUEING!!!

What broke??? The flange.. And when the flange disintegrated, the stud didn't have
any tension in it, and it got a lot shorter.. I really wish at the time I had put that sucker
up on a granite plate and measured how much shorter it was than it was supposed
to be...

Solution, we pulled all of our studs, and had them mag particled, 140 or so tool holders.
Not a single crack found in any of the other studs.

My second failure was just a few years ago.. 3/4" holder, with a really long 3/4" ball
mill in it.. It was on a Fadal VMC15, so it was just piddling along doing something
stupid, I might have just been piloting for a .754 reamer or something. The tool
came back up to the tool change position, and the tool holder fell out, without the
end of the pull stud attached..

First, I must say, that I do have some cheap shitty e-bay pull studs kicking around, I
REALLY thought I had them in only ER16 holders, holders that aren't going to get
worked hard.. I was WRONG!!!!!!!

It was a cheap shitty e-bay pull stud from years ago. It was cracked, it had been
cracked, you could tell by a little bit of rust and some discoloration, it was hanging on
by maybe a square millimeter of real metal.. I think I still have the threaded section
floating around, if I can find it, I'll post a pic.

I consider myself one lucky bastard that that pull stud let go when it did. I ate up a
lot of karma that day.

My pull stud thoughts.. DO NOT BUY CRAP!!! and if you do buy crap, put it on
tool holders that don't get a lot of stress. Small drills, little endmills, those kinds
of holders..

If you are nervous, have them mag particled.. Quality pull studs aren't free, I'm
pretty sure getting them mag particled is cheaper than buying new. If you are that
nervous, buy new ones.... GOOD ONES!!!!! not from E-bay.

And last, but not least. Install and torque them properly. Tighten until it starts to
loosen and then back off a quarter turn does NOT work for pullstuds. I don't even
think you need a fancy pull stud installing torque wrench, any machinist(mechanic) worth a
nickel can gauge it pretty good, and again, if you are nervous, double check your
feel with an actual torque wrench.. If you don't trust yourself to get it close by feel,
then buy the fancy adaptor, I'm not saying that there is anything wrong with that, because
there isn't. If I ever get a quarter million dollar machine, I'm buying the fancy adaptor.

Also look up the proper torque specs, its a LOT less than you think it should be.

 

[JonFinn]

I have had them break twice. First time was a cheap US Shop Tools stud (purchased before my time at the company). Once we started looking, we found there was a visible mismatch from manufacturing on ALL of this brand of stud and it broke right there during a facing cut. Trashed a $30k spindle. We replaced all of those brand studs immediately.
Second time was a good quality stud that had been over-tightened. Broke at the thread but fortunately during a small diameter drilling operation so just dropped in the coolant tank.
Buy good quality studs and install them correctly (correct torque, thread locker and o-rings for coolant through holders). Grease your collet fingers regularly and inspect for and dispose of any studs that show the first signs of wear.

 

[in2glamisgirl]

I have had one Cat 40 solid (Mazak/Fadal style) pull stud snap at the neck during a tool change recently.
I have replaced several that showed wear from the knob retention system, that is the sign that they have seen a lot of tool changes.
I have never had one fail during cutting.
This is from a library of over 400 tool holders many with coolant thru used in daily production, some of them are over 30 years old.
We do toss out several holders with their knobs every year, the common problems are cracked barrels on DA style, bell mouth on side lock, and worn or damaged tapers.

 

[DavidScott]

I have been running 30 tapers for 25 years now and the only ones I have seen break were home made and pretty poor at that. Nearly all of mine are TJ Davies and one of my spindles has 900lbs of drawbar force, which is pretty good for BT30. I think the biggest problem with BT30 pull studs is overcoming the draw bar tension and pulling the holder out of the spindle, which causes them to break.

 

[Stirling]

I had one break at in the thread relieve under the flange.
Was holding on by a half turn of the reliefs thread. Ran a program for days and upon u loading the tool something bought my attention.
Half turn and it fell out…. I got very lucky! The cracked face looked old…… the thread is still stuck in the tool holder waiting for my to one day salvage it maybe