Retention Knob issue between BT30-1 and 2

[jim r]

I have a new to me Miyano TSV 35 mill. No tool holders came with it. The manuals call for the P30T-2 retention knobs as it dose for the other TSV35 and TSV33 that I have. These other two machines work fine with these 30 degree knobs as the manufacture calls them, but the industry calls them 60 degree. The issue is when the tool holder is pulled from the spindle at tool change. A few times it has been violent enough to pop the holder out of the tool hands grip, and error the machine. More often the snap will just error the machine. Most often it is just an uncomfortable snap. I have measured the studs and they are within tolerances. Have run the same tool holders through all 12 of the tool positions. Have run a dozen plus different tool holders in this testing. I adjusted the tool knock out point, which was only .007 out of the tolerance zone. I can even see the taper release before the stud release so it is not the tool holder taper sticking.

There is no consistency with it. Running the same tool holder through a tool change over and over can give different results on each pull. Even coating the stud in more oil then it would normally see, it had only little effect. Being now, days into this mess I tried something most say not to. I put in a tool with a P30T-1 retention knob. These have the same dimensions except they have a 45 degree angle to them. The outcome? As soothe as silk. Of course I tried many more of the 45 degree studs in old and new tool holders and all change perfect.

So now I'll start with two questions:
Is there something vary wrong with the pull stud collet and guide?
Or did someone in the past maybe change out the pull stud collet and guide with the wrong parts?

 

[DavidScott]

My first thought is drawbar travel, as in maybe you don't have enough. Too many bellville washers, the spring is tightened down too much, or the urethane bumper in the air cylinder has disintegrated. Not that I know that machines specifics.

On further thought, if you have the correct knockout travel then you have enough drawbar travel.

 

[Vancbiker]

In general, popping tools when unclamping is a misadjusted unclamp mechanism. When the drawbar is pushed downward to release the knob it needs to actually push the end of the knob to break the fit of the taper. A lot of 30 taper machines use a cam or lever mechanism to unclamp the tool. Typically those mechanisms will have some stroke adjustment ability to set the knockout stroke. .5mm is a often used dimension for knockout.

 

[tc227]

I thought brother was the only one with the 60 degree pull stud.

 

[DavidScott]

I assume this machine uses caged balls for the pull stud gripper. Perhaps it is the sleeve that directs the balls when gripping the pull stud?

 

[jim r]

I did adjust the knockout. It was .007" out of it's range when first measured. The direction that it was out was pushing it farther then it was suppose to push. My first adjustment took it to far out the other way. It still wasn't any better or worse with pulling tools. It is now set near the mid point between it's limits. And those limits are only .016" apart. That is close to that .5mm tolerance. This machine dose use an arm with a cam to activate the knockout. Both the cam and bearing are clean and the return spring for the arm is strong.

I believe these machines use ball retention and not fingers. So I would think that they would need to move completely out of the way for the stud to release and not try to force it past the balls. Otherwise they would be pressed hard against the outer collar. I do have the basic spindle drawings from the manuals, they are just not a close up of this area. If any one can confirm that or has a diagram of what they call the collet and guide for the miyanos, I would appreciate having it.

So another thought. What if one of the ball bearings in the collet has shattered. I can certainly see it not wanting to slide out of the way. That would certainly make it pull differently each time. And I do remember reaching up beyond the taper and coming out with a few vary tiny hard crumbs. Guess I need to get out the bore scope and try to get up in there for a look.



If new machines were cheep and old machines never broke, life would be great.

 

[jim r]

I assume this machine uses caged balls for the pull stud gripper. Perhaps it is the sleeve that directs the balls when gripping the pull stud?

Yes , I think that is the case. So I would think the balls would need to move completely out of the way for it to release. So I do need to get a look see up in there.

 

[jim r]

Well the balls (3) look good. Unfortunately I don't have a 90 degree adapter for the bore scope so I have no idea what the races look like on the cage. Still does not make any sense why it pulls so hard.

 

[jim r]

So it has been a couple of mounts using the P30T-1 retention knob, a 45 degree angle instead of a 60 and have had no issues. Knowing that it is an incorrect fit according to the manufacture, I can not suggest that others run like this. Just wanted to give an update to how it is going.

Unfortunately that machine is now dealing with a 920 error code.