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  1. #81
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    Quote Originally Posted by cameraman View Post
    Spent many hours on one of those breaking all kinds of steels and 'Uni" (back in the day).

    @Milland thanks posting that link earlier about pull studs.


    Really dumb question here :

    1. Do these pull studs work harden through use ?


    If the is YES,

    Then the pull stud you buy is not the same as the pull stud after many thousands of cycles of use.

    IF narrow diameter pull stud work hardens then it means it's tensile yield strength goes up, BUT the material becomes less elastic, less ductile , essentially more brittle. Which means when it does fail and "They do fail" it will fail in a more catastrophic way under higher loads.


    so...

    2. How often should one be replacing one's pull studs on a 30 taper machine , before they fail ?

    3. Also kinda interested in the materials science between the cheap pull studs vs. the more expensive ones ?

    I'm not part of the 30 taper taper- mafia but have always been BBT 30 taper "Curios" ;-)
    To get "work hardening" you need plastic deformation. The only plastic deformation I see is at the gripper ball contact points. It looks like the neck diameter should be 7 mm. If the drawbar force is 700 lb, then the axial stress in the neck is nominally 12 ksi. That won't cause plastic deformation and work hardening even in A36 steel.

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  3. #82
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    Quote Originally Posted by rklopp View Post
    To get "work hardening" you need plastic deformation. The only plastic deformation I see is at the gripper ball contact points. It looks like the neck diameter should be 7 mm. If the drawbar force is 700 lb, then the axial stress in the neck is nominally 12 ksi. That won't cause plastic deformation and work hardening even in A36 steel.
    I agree that static linear loading would be unlikely to cause failure (really bi-directional colinear forces carefully applied relatively slowly), but shocks/ shock loading and bending / (nearly imperceptible) bending moments can/could cause failure.

    The pendulum machine that milland cites breaks steel dowels with ("V" cut into them for about half their diameter, and the weights and momentum are not "Insane" by any means to create a concentrated shock/ shear force to break the test sample. [That machine measures the energy taken to break the sample at a concentrated point.]. ).

    __________________________________________________ __________________________________________________ ____________________


    For example even in spring steels . keep bending them under relatively low (cyclical) loads they will fracture and break without warning (usually nucleating around some sort impurity / funky inclusion, internal stresses start to nucleate around certain points. ).

    _________________________________


    Is that really the maximum draw bar force 700 lbs ? [Not doubting you just curious ].

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    Quote Originally Posted by Mickey_D View Post
    I took an old long BT-40 coolant through stud, clamped it in a pipe vise, and beat on it with a 2 pound ball peen hammer for several minutes. It marred but did not break or bend. I dismounted one of the other Maritool studs and it fractured in the same way as the one out of the machine with a fairly light strike. We are going to do some more later today and put it up on Youtube so everyone can see how they are failing.
    For a guy who “isn’t trying to trash Maritool,” you seem pretty hellbent on trashing Maritool as hard as possible.

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  6. #84
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    Quote Originally Posted by gkoenig View Post
    For a guy who “isn’t trying to trash Maritool,” you seem pretty hellbent on trashing Maritool as hard as possible.
    Hold up here. If the studs he tested failed as readily as it seemed (easy brittle failure, no ductile behavior) it is a useful bit of info. It's why I asked if he had non-Maritool studs of the same size he could test in a more reliable/repeatable manner (pendulum impactor).

    Yes, it's bending over tensile loads, but still relevant if it turns out the other studs bend before breaking.

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    No experience with Maritool, but I gotta say this thread rubs me the wrong way.

    You say you're not trying to drag Maritool through the mud, but you DO realize that's EXACTLY what you did by starting this thread? This is like posting a 1 star review while saying 'you'll keep everyone updated'.

    Lets pretend they did screw up. If it was me, posting about the failure with their name attached for the world to see is the LAST thing you MIGHT do after all efforts to resolve it with them have been exhausted. It sounds like you started typing before the spindle even cooled off....

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    Quote Originally Posted by M.B. Naegle View Post
    No experience with Maritool, but I gotta say this thread rubs me the wrong way.

    You say you're not trying to drag Maritool through the mud, but you DO realize that's EXACTLY what you did by starting this thread? This is like posting a 1 star review while saying 'you'll keep everyone updated'.

    Lets pretend they did screw up. If it was me, posting about the failure with their name attached for the world to see is the LAST thing you MIGHT do after all efforts to resolve it with them have been exhausted. It sounds like you started typing before the spindle even cooled off....
    Yup, I'm sure the battle shields & walls are going up as we speak.

    Lawyers have been briefed, moves are being planned.

    And this is sad.

    To the OP I ask "If these pull studs were bought from China, would you pursue the
    manuf the same way ?"

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    I would be far more interested in ultimate tensile and yield than a Charpy test. How about a basic hardness test? Start simple right? While I would assume they are within hardness spec it always pays to check the simple stuff first.

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    Quote Originally Posted by cameraman View Post
    .......2. How often should one be replacing one's pull studs on a 30 taper machine , before they fail ? .....
    All the pullstuds used on my 30 taper Mori Seiki are from 1995-1996......

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    I'm still waiting on pics of the work-holding.
    And, some nice macro shots of the side of the part showing the witness marks impacted in the material from the part being lifted out of the vise.
    Until all the evidence is on the table, this is not the pull studs fault. Innocent until proven guilty.

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    Quote Originally Posted by Vancbiker View Post
    All the pullstuds used on my 30 taper Mori Seiki are from 1995-1996......
    Oh my, I was just getting ready for high school

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    Quote Originally Posted by wheelieking71 View Post
    I'm still waiting on pics of the work-holding.
    And, some nice macro shots of the side of the part showing the witness marks impacted in the material from the part being lifted out of the vise.
    Until all the evidence is on the table, this is not the pull studs fault. Innocent until proven guilty.
    All the evidence will never be here. Does anyone know if the holder was dropped at some point in the past, landing on the pullstud? Or if the holder was crashed previous to this setup? Point being there could be a million different causes for this failure.
    One thing for sure....if any brand of pullstud was failing on a regular basis it would be widely known. One failure by one user out of thousands makes me think user error, not mfg error.

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  19. #92
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    I have always been really happy with all the toolholders, pullstuds and endmills I have bought from Maritool. Never a problem, Everything is perfect. Tooled up several 40 taper machines using Maritool stuff and regularly buy consumables.

    Threads like this make me grumpy.

    It takes A LOT of composure for me to deal with shit like this when a customer of mine pulls something like this on an internet forum. Like we speak on the phone or there's emailing or the best- When there has been no communication whatsoever- I don't even know there's an issue. If you want to be in business you have to take any kind of customer service issue seriously to the extreme and YOU DO, but then the customer turns right around and claims you told them to shove it.

    It makes me lose a little faith in humanity every time this happens to me. Which is not often, but it does.

    All you can do is stay on top of where people discuss your stuff on the interwebs and do your absolute best to calm down the customer and find some kind of resolution while everyone watches and picks it all apart without knowing half the facts or processing all the information given.

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  21. #93
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    Quote Originally Posted by JMC View Post
    All the evidence will never be here. Does anyone know if the holder was dropped at some point in the past, landing on the pullstud? Or if the holder was crashed previous to this setup? Point being there could be a million different causes for this failure.
    One thing for sure....if any brand of pullstud was failing on a regular basis it would be widely known. One failure by one user out of thousands makes me think user error, not mfg error.
    All true. But, a good forensic examination of the part/fixture could tell a whole different story than a broken pull-stud.
    My point is: every single aluminum part I have ever loaded in a machine, comes out with some kind of witness marks on it from being clamped.
    Whatever marks are on the side of that part will/could tell a whole lot about this event. This is evidence that needs to at least be considered and examined.

    EDIT: just to cover my ass. I am not taking sides with my posts. Nor am I saying I feel it was, or wasn't, the stud that failed.
    I am just saying, there IS more info that should be made public if this thread is going to be public. Which it is.
    I for one would like to see the rest of the info because I own one of these machines. And, use some of the same studs/holders.

    The very first thing I would have looked at had this happened to me would have been the part/fixture.

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  23. #94
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    This thread has turned into a witch hunt that is going down the wrong road ... After reading for the last few years about pull studs busting on brothers machines I really don`t think its the brand or the re seller of the pull studs that to blame . The one factor that has stayed the same over all the busted studs is the machine itself .. Cat40 spindles have around 1,600 LBS retention and the brothers BT30 spindles only run about 400 lbs retention ,,, the second that tool comes loose in the taper shits going to hit the fan "FAST"

    I have had Fadal cat40 spindles get as low as 700 LBS retention and the tools start chattering and sounding like crap even with light cuts at 6K RPM ... so here guys are trying to run 10K with a tool weighting close to a cat40 tool with 1/4 the retention ...

    I think someone needs to start making a list of all the brother machines that have busted pull studs . I do not recall ever seeing a post about Fanuc robo mills busting studs and there is more robo mills in service that brother machines .

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    Quote Originally Posted by Milland View Post
    Hold up here. If the studs he tested failed as readily as it seemed (easy brittle failure, no ductile behavior) it is a useful bit of info. It's why I asked if he had non-Maritool studs of the same size he could test in a more reliable/repeatable manner (pendulum impactor).
    I'm not saying that there is no validity to this test. I'm also not saying that the pull stud might not be the culprit here.

    What I am saying is that posting to the largest machining forum on the internet with such a salacious headline, then following it up with what would likely be just as salacious a headline in a YouTube video doing quite sloppy "testing," is hardly the strategy someone trying to not trash a brand would do.

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  27. #96
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    Quote Originally Posted by D.D.Machine View Post
    I think someone needs to start making a list of all the brother machines that have busted pull studs . I do not recall ever seeing a post about Fanuc robo mills busting studs and there is more robo mills in service that brother machines .
    You don't hear about Robodrills with broken pull studs because the vast majority of them are in production shops. Andy and his team simply whip Methods ass when it comes to selling into job shops and low-scale manufacturing environments. That means two things:

    1- All the shops with Robodrills are not posting on public internet forums about their secret sauce production methods, or their trials and tribulations with these machines the way Speedio owners do.

    2- Those production shops are usually running very dialed-in programs, with very exotic automated/hydraulic/safety interlocked workholding.

    The only other factor that can be cited here is that almost all Robodrills come with BBT30 spindles (in the US). I'm pretty deep in the Speedio Instagram world, so I get a DM pretty much anytime someone busts a spindle (probably about 10)... None of them have been on Big+ spindles. Perhaps it is the 800lb drawbar force on BBT30? Or the impact of these incidents could be taken up by the face contact and not putting a lateral load on the pull stud?

    Having said all that, Robodrills have virtually identical pull studs. In the mixed fleet I work with (24 Robodrills from 2014-2018 vintage) and 12 Speedios (all 2019), they have been through 7 Robodrill spindles due primarily to crashes. One simply wore out. These machines run automated cycles 24/7/360 making a product everyone here probably owns. Spares are kept on-hand and swapped out by maintenance staff, and in this environment, it is all considered NBD. These machines fucking *print* money.

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    Well my two cents is the pull stud broke after whatever happened. I just cant imagine it breaking spontaneously, although I am sure they do occasionally. But what brand wouldn't? Like I said before, OP says "I'm going to Yamazen" what then? Are they guaranteeing no failure?? They going to buy a new spindle and do the install free of charge? I've had shit break, it happens, it is what we do....

    I dunno, the whole thing stinks IMO, even though I have never personally dealt with Maritool, all the people on PM that do have got my vote.

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  30. #98
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    Quote Originally Posted by D.D.Machine View Post
    This thread has turned into a witch hunt that is going down the wrong road ... After reading for the last few years about pull studs busting on brothers machines I really don`t think its the brand or the re seller of the pull studs that to blame . The one factor that has stayed the same over all the busted studs is the machine itself .. Cat40 spindles have around 1,600 LBS retention and the brothers BT30 spindles only run about 400 lbs retention ,,, the second that tool comes loose in the taper shits going to hit the fan "FAST"

    I have had Fadal cat40 spindles get as low as 700 LBS retention and the tools start chattering and sounding like crap even with light cuts at 6K RPM ... so here guys are trying to run 10K with a tool weighting close to a cat40 tool with 1/4 the retention ...

    I think someone needs to start making a list of all the brother machines that have busted pull studs . I do not recall ever seeing a post about Fanuc robo mills busting studs and there is more robo mills in service that brother machines .
    I've read a lot of your posts, and you have never ever been positive about Brother machines. I remember when you wanted one, and didn't get the deal you wanted. It's my opinion that it is not possible for you to be completely objective about Brother machines.
    I also remember when you were bashing Haas machines, and other machine problems you had.
    I'm glad you are now happy with Haas - but in the particular thread I think everyone reading your comments should be aware of your history and prejudice.
    This is not personal - It's just what I've observed.

    ETA: Since you've never owned a Brother, you are just guessing too. No matter what machine one has, it's important to recognize the limitations. Other people have opined in this thread that own a Brother. Their opinion carries much more weight.
    I use facemills, but I don't push near as hard as the OP in this thread. Crashing is always worse than the net savings compared to slowing 20 percent, making sure the part is clamped properly, etc.
    We don't know what caused this....

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  32. #99
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    Quote Originally Posted by Mike1974 View Post
    Well my two cents is the pull stud broke after whatever happened. I just cant imagine it breaking spontaneously, although I am sure they do occasionally. But what brand wouldn't? Like I said before, OP says "I'm going to Yamazen" what then? Are they guaranteeing no failure?? They going to buy a new spindle and do the install free of charge? I've had shit break, it happens, it is what we do....

    I dunno, the whole thing stinks IMO, even though I have never personally dealt with Maritool, all the people on PM that do have got my vote.
    That's my interpretation too...

    I'm a fan of Frank Mari's company and everything he's trying to do, amazing success story going from strength to strength and gaining serious capabilities at an incredible pace.

    I'm also sympathetic to Micky_D's plight as (If memory serves me right) he's had a bit of bumpy road with machine tool industry (MTBs) for unfixable failures and that have cost his operation serious $ in the past.

    Looking at the first set of photos it does not seem surprising that that pull stud design (in general) could fail at that point. It's a very small diameter to do what it needs to do (interesting 3d topography of the break) it appears.

    The question lurking in my mind is IF theoretically you had an indestructible pull stud (that could last a trillion cycles) what would the next sub system to be trashed beyond spindle replacement be ?

    Also lurking at the back of my mind is where and how (what points / surfaces) the tool holder taper contacts the spindle nose... I guess it's a bit late for that now that it's surfaces are trashed presumably ?

    __________________________________________________ __________________________________________


    Usually for "Catastrophic " things its a combination of three things in a specific combination (a combination that is normally regarded as exceedingly rare), remove any one of those factors and you don't have a disaster on your hands.

  33. #100
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    I have a question. If there are "high strength" pull studs for 30 taper - what are the other ones? Low strength? Why are they not all "high strength"?


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