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Author Topic: BT30 spindle from scratch - with power drawbar and ATC of course  (Read 400101 times)

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Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #550 on: September 27, 2013, 05:51:51 PM »
I really think it s more likely the springs are broken or weak as I do know they have never been replaced in at least the last 10 or so years.

Bellevilles loose tension over time (sometimes a failrly short time) that is a fact and is one of the disadvantages that I was looking to get away from with the coil. I agree with you and BR that most likely you will need a new stack, but you won't know that untill you get inside. If the gripper is coming off, you can check that easily  from the outside. It would be sort of a bitch if you tore the whole thing apart and then found out the gripper had unthreaded.

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Dont really want to have to dismantle bearings etc but I have found a PDF from McBroom Industrial Services that mentions removing bearings   . . . .

After reading the scary tech stuff from the bearing manuf, I made sure that there is room behind the bearings to get a puller in there and reach the inside ring. Some AC bearings can be separated, but if the OD of the inside ring is sitting against a larger OD, you still can't get a puller on it, so you are left with heat/cold as the remaining option for getting it off undamaged.

Please post back here if you do dig into that spindle so that I will get notified. My new spindle project starts in a few weeks, but I may take it to a bigger forum since there is not very much participation here. In any case, I would want to follow your 're-springing' effort.

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #551 on: December 28, 2014, 12:09:40 PM »
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Please post back here if you do dig into that spindle so that I will get notified. My new spindle project starts in a few weeks, but I may take it to a bigger forum since there is not very much participation here. In any case, I would want to follow your 're-springing' effort.

Sorry Steve, forgot all about you asking this and was only reminded when someone PM'd me asking if I had ever done the springs.

I got hold of some drawings from a German guy that does retrofits ( http://www.cnc-steuerung.com/umbau-einer-chiron-frasmaschine.html ) I had seen he had done a retro on an FZ17 and asked if he had the manuals, he didnt but very kindly drove to the person that owned it and took some photos of the relevant pages. (I have since also recieved some scans of a manual from a guy in South Africa who has a machine that is very close in build number to mine)

Anyway, although it was not identical it was very close including the disc spring sizes and amount, so I was able to see how to haul things apart. It was actually very simple, remove 6 M6 capscrews from the nose and pull out the spindle, pressing the drawbar release more or less pushed it out for me.
I replaced the springs and it was  better but still only about 600lb if I recall, this was still way lower than I was expecting but was actually the force expected with the size and amount of springs, so something was strange. I then studied the drawings a bit more and I then saw why the actual force was not too important.
The drawbar is precision made and according to the drawings  has a length of 298.7mm  -0mm +0.1mm and the 2 ball bearings are also precision, grade 3.
I stripped things back down again and all was in spec with the drawbar which surprised me as it is almost certainly the original, the sleeve and the the drawbar top also seemed fine but the balls had a slight amount of wear so I replaced them.
Anyway if you look at the pic below you can see that the balls effectively lock the tool in place as they are constrained by the outer sleeve and the top of the groove in the drawbar head is tight against the ball. This means that really the spring force is not  an issue as all it has to be is sufficient to make sure the tool holder is pulled tight enough into the spindle for the ball to lock everything in place. It also means that the air is sufficient to operate things rather than having to go hydraulic.

Hood

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #552 on: December 29, 2014, 01:25:43 AM »
Hello Hood.

Thanks for the update. That is quite some detective work you accomplished to dig up all of the info on your spindle.

Using balls as a 'latching' mechanism is clever indeed. I see where the precision would be needed in order to stay within the very narrow dimensional range where the mechanism would work.

I have made a half dozen or so spindles now and the die spring is working well. What does not seem to be working is keeping a spindle for my own use. So far I have been unable to accomplish that . . .  :'(

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #553 on: December 31, 2014, 05:05:42 PM »
Its always the way Steve, well thats if you are making things to sell that is :-D

Just finished a new VDI turret for my lathe but its mine, all mine  :D

Hood

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #554 on: January 01, 2015, 05:34:23 AM »
Its always the way Steve, well thats if you are making things to sell that is :-D



Appropriate season . . . you know the 12 days of Christmas song?;

6 BT30 spindles, 5 Tail Stock II, 4 Pneumatic actuators, 3 InTurn™ Ultra's, 2 ATC's and a Partridge in a pear treeeeeeeeee!

All I have is the stinking tree . . and it's dead.

The Partridge?

. . . . . tastes like chicken     :D

Just finished a new VDI turret for my lathe but its mine, all mine  :D
Hood

I visualize Vincent price wringing his hands and laughing maniacally.   :)

However, I can not visualize what it is that you built.

What does VDI mean?

Did you do a thread or video?

Oh yeah and HAPPY NEW YEAR  . . . To ALL

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #555 on: January 01, 2015, 05:44:22 AM »
Ah chicken is not too bad a taste, can think of worse ;D

VDI is Verein Deutscher Ingenieure, thiink it translates to something like Society of German Engineers ;D

It is a means of clamping tool holders into the turret via teeth. Below is a pic of the setup showing the completed turret, the wedges are exploded on some positions to show their make up.

Have a few vids but not done a write up yet.
This vid is it almost complete although I have since  altered the layout to have the gearbox on the turret rather than the motor.
https://www.youtube.com/watch?v=35p74Bf51u4


This one is me making one of the wedges.
https://www.youtube.com/watch?v=8CHhfy1CanM

There are a few others of the face and edge machining.

Hood

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #556 on: March 15, 2015, 08:31:44 AM »

Have a few vids but not done a write up yet.
This vid is it almost complete although I have since  altered the layout to have the gearbox on the turret rather than the motor.

Hood

Hi Hood,

Sorry I missed this post. I have not been on here in a few months. In here now because I'm porting my InTurn™ motor controller to MACH4. That project is completed and I made a widget and played with the screens a bit, but now time to get back to work.

Your tool turret is impressive! I was thinking about making a turret to go on the mill spindle nose to present tools to the 4th axis in this same manner . .

Also, I have upgraded the InTurn™ Tail Stock and it now slides along using dovetails on a fat piece of precision ground cast iron. It has 'precision' ACME  lead screw and provision to add a motor for a power lead. The mounting is now robust enough to carry a Tool Turret . . .  albeit not nearly as massive as yours.



  . . . . so I have a couple of questions about your design, if you don't mind.

How are you extending/retracting the turret and how are you locking it? Can't tell from the video or the 3D model.

 

You mentioned moving the 'gearbox' to the Turret's frame. Are you using a planetary?

Sorry for so many questions. I'll stop here for now, but I actually have more questions.
« Last Edit: March 15, 2015, 08:36:17 AM by simpson36 »

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #557 on: March 16, 2015, 12:00:20 PM »
I am using hydraulics to calmp/unclamp the turret, the lathe has them for the chuck and tailstock and it also originally used the hydraulics to work the turret completely by rack and pinion for rotating.
I am using a Hirth coupling on this one, it is the one that was on the original lathes turret.

Yes it is a planetary box, 25:1 if I recall, just what I had lying around.

Hood

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #558 on: March 16, 2015, 04:11:50 PM »
I am using hydraulics to calmp/unclamp the turret, the lathe has them for the chuck and tailstock and it also originally used the hydraulics to work the turret completely by rack and pinion for rotating.
I am using a Hirth coupling on this one, it is the one that was on the original lathes turret.

There is going to be a lot of torque on that turret when you start digging in those tools with a lathe that big. Are you pulling against a cone clutch or are there wedge shaped dogs in there somewhere or is there a friction plate?

You mentioned machining wedges, but for some reason I though those were for the tool holders.

I have a power chuck yet to install and it has a big hydraulic actuator, draw tube and the chuck itself is mechanical and operates on internal wedges. The hydraulics on the chuck is only something like 600psi, surprisingly low.



 
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Yes it is a planetary box, 25:1 if I recall, just what I had lying around.


That explains the similar sized pulleys.  :)  With the box on the motor, it is surprising that you would have that much bounce. Was that coming from the belt? Did moving the box to the turret calm it down?

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #559 on: March 16, 2015, 05:02:22 PM »
It has a Hirth Coupling, see pic below for half of the Hirth, other half on the turret body.

Yes the wedges are for holding/pulling the VDI tool holders into the turret plate.

600PSI is quite normal I think, if that is the Hyd pressure to the chucking cyclinder, mine runs at 35bar so about 500PSI


With the gearbox on the motor it meant the full torque was being passed via the belt, with it now on the turret the torque through the belt is very low as it just has to turn the input of the gearbox.