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Tool holders fall out of ATC arm coming from pots

Jacob Atwork

Plastic
Joined
Apr 21, 2023
Good afternoon (from the Midwest),

I'm having an issue where my tool holders will fall from the tool pot when the ATC arm swings over to grab them. Once the tool holder is free from the tool pot it just falls out of the ATC arm.

Here is what I have observed and what I think may be the solution,

-I can put a tool holder manually into the spindle just fine.

-From there I'll do a tool change.

-The ATC arm swings over and grabs the tool from the spindle (no issues here).

-The ATC arm swings over and puts the tool holder into the tool pot (slight issue here.)
The slight issue is that, after the ATC arm seats the tool holder into the pot. The ATC arm goes to pull away from the tool holder flange that's been seated and I can visibly see (and hear) a slight vertical shift (like .125") where the ATC arm separates from the tool holder flange. It's abit of a clunking noise

-From there I will try and bring the tool I placed back into the spindle.
The ATC arm swings over and looks like its working fine but as soon as the tool holder is free from the holding pot it just falls from the arm as it begins its pull down and rotation towards the spindle.


I'm sure this is a height issue with the ATC arm but I have never had to set this mechanical height that isn't like a machine reference inside the controller where you can change such references electronically.

Also, If anybody knows how I can command the ATC arm into it's positions that would be extremely helpful. I've tried to find the miscellaneous codes that allow me to swing the ATC arm into its stepped positions. I have found them in the Meldas manuals like M71-M77 but when I go to enter them in MDI mode the controller says they don't exist except for M71 (pot down) and M77 (pot up).

I will post a video of this happening too but not until Friday or Saturday when I'm on-site.

Thanks!
 
To better see what is happening I would manually, as in by hand, run the tool changer through its paces. The way I do this on my mill is to turn the motor that drives the tool changer with a socket wrench. It is part of the procedure of checking the heights and positions of the tool changer for both the pot and spindle. I don't think your arm should move vertically unless it is removing the tool holder from the pot/spindle.

This is something I would be calling my MTB service center for a PDF describing the procedure to make sure I knew what I was doing. Plus they may have dealt with this issue on this machine before and may have you check other things.
 
Is this machine new to you?

Is the machine set up for bt40 but you're using cat40 tooling? or vice versa?

Cat and BT holders are the same basic taper and may function in the spindle, but the flanges that the tool changer arm grabs onto are very different and they can't be interchanged.

if you do have the correct tool holder type, it could be the springs that clamp onto the holder as it rotates are broken or jammed.

However, the way you describe it sounds like its the wrong tool holder type, if the machine is new to you.




Edit: re-read it and see that you say it drops from the pocket, not the spindle. Are you sure it's the right pullstud also?
 
On my Hardinge (Bridgeport) the tool would get thrown when the swing arm rotated. There's a cam on the swing arm that is supposed to hold the tool in during swinging. The rod pushing the cam was sticking and I cleaned it off and all was fine.
 
Is this machine new to you?

Is the machine set up for bt40 but you're using cat40 tooling? or vice versa?

Cat and BT holders are the same basic taper and may function in the spindle, but the flanges that the tool changer arm grabs onto are very different and they can't be interchanged.

if you do have the correct tool holder type, it could be the springs that clamp onto the holder as it rotates are broken or jammed.

However, the way you describe it sounds like its the wrong tool holder type, if the machine is new to you.




Edit: re-read it and see that you say it drops from the pocket, not the spindle. Are you sure it's the right pullstud also?
Yes, the machine is new to me.

I'm using BT40 tooling which is what the manufacturer brochure calls out too but when I asked the previous owner about it he said he only ever used CAT40 tooling for the machine. I did some digging further in the manuals I received with the machine, and on the page that shows the spindle specifications it says I can use either BT40 or CAT40 which I thought was odd.

The ATC arm grabs it just fine out of the spindle but grabbing it out of the pot is a no-go. The tools sit perfectly inside the tool pots and the spindle. Nothing loose or suspect. The only thing is that it seems to be the ATC arm is at the wrong height and I need to adjust it manually by about .125". I've never had to do that though so not sure if that's the best solution.
 
To better see what is happening I would manually, as in by hand, run the tool changer through its paces. The way I do this on my mill is to turn the motor that drives the tool changer with a socket wrench. It is part of the procedure of checking the heights and positions of the tool changer for both the pot and spindle. I don't think your arm should move vertically unless it is removing the tool holder from the pot/spindle.

This is something I would be calling my MTB service center for a PDF describing the procedure to make sure I knew what I was doing. Plus they may have dealt with this issue on this machine before and may have you check other things.
This is what I was thinking too but I wasn't sure how to rotate the arm. I could maybe disable the servo motor to rotate it easier but I haven't looked into how to do this yet.
 
On my Hardinge (Bridgeport) the tool would get thrown when the swing arm rotated. There's a cam on the swing arm that is supposed to hold the tool in during swinging. The rod pushing the cam was sticking and I cleaned it off and all was fine.
Yeah, that's also something I was considering but the main issue seems to be my ATC arm not lining up with the tool pots.
 
No way you can use bt40 and cat40. They are way too different.

I can't believe it even sorta works. That's crazy!

Most machines can use both, but not interchangeably. You have to change the grippers. The grippers are specific to cat or bt and very different.
 
Did it used to work? Did the swing arm get hit hard? If so do what Jacob suggested. On my machine the motor (not a servo motor) has a shaft extension with a hex male profile that allows you to attach a socket and drive with a wrench.
 
No way you can use bt40 and cat40. They are way too different.

I can't believe it even sorta works. That's crazy!

Most machines can use both, but not interchangeably. You have to change the grippers. The grippers are specific to cat or bt and very different.
That's what I thought too! I was just figuring that I'm close enough that I needed to make some kind of obscure adjustment but I couldn't find any resources about it.

So looks like I may need to change the grip-end. Interesting. I'll try and find one and if the geometry looks like it's vastly different I'll have to give it a go. But before I do that I know a guy with some CAT40 holders. I'll see if those fit without issue.
 
No way you can use bt40 and cat40. They are way too different.

I can't believe it even sorta works. That's crazy!

Most machines can use both, but not interchangeably. You have to change the grippers. The grippers are specific to cat or bt and very different.
Any idea where I can buy these grippers? Idek what to call them in a search.
 
Yeah, if the arm is for CAT then that is your problem, and BT would be loose in a CAT arm. Photos of the arm end would be helpful. What machine, and any parts like this you would get them from the MTB, or make them yourself if nothing else.
 
Yeah, if the arm is for CAT then that is your problem, and BT would be loose in a CAT arm. Photos of the arm end would be helpful. What machine, and any parts like this you would get them from the MTB, or make them yourself if nothing else.
Can confirm, this was definitely the issue. I'd never had to swap out or even look too closely at the gripper plates that hold the tool flange in the ATC arm.

I have CAT40 gripper plates on my ATC arm. Swapping them out for the correct BT40 gripper plates.

Thanks for all the help you guys. Even though I now feel like this is super obvious I was able to learn something.
 
Can confirm, this was definitely the issue. I'd never had to swap out or even look too closely at the gripper plates that hold the tool flange in the ATC arm.

I have CAT40 gripper plates on my ATC arm. Swapping them out for the correct BT40 gripper plates.

Thanks for all the help you guys. Even though I now feel like this is super obvious I was able to learn something.

You probably need to set your Z reference position as well.

I would keep Cat40. Cat40 is hundredfold more common than BT40 in the US.
 








 
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