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Author Topic: BT30 spindle from scratch - with power drawbar and ATC of course  (Read 411888 times)

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Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #80 on: September 01, 2012, 06:39:03 AM »
The guy you are talking about would likely be Dave DeCausin (sp?) one of the founders of Fadal.

Yes the drive is a DSD but it needs to be capable of Indexing, the standard drives wont do that.

I talk via the PLC and  the ladder has most of the integration in it for the unclamp/rotate/clamp timing. If you simply just wanted to index you could simply have some inputs and it would index to the selection you called.
The inpouts are seen in the drive as follows
Pre-Select 0  = 1
Pre-Select 1 = 2
Pre-Select 2= 4
Pre-Select 3 = 8
Pre-Select 4=16
Pre-Select 5 = 32


So as you can see depending on which inputs you use you can select any of the 64 index positions, well really only 63 as index 0 is not really valid for this operation.

You also need an input set up as Start Index and likely Start Homing, also you may have Reset Drive or whatever. The drive has 8 digital inputs but the nice thing is you can set them up for multiple uses. That means if you are doing an operation that requires two inputs you dont have to waste two inputs if they can legally be seen by the drive at the same time, for example you could have the start Index set up with the Presets.


Have attached a few screenshots of the drive setup, first shows the Index presets I have set, have opened the first three positions so you can see the configuration in the drive.
Next is the Inputs, as you can see I only need 4 presets as I only have 12 positions so there is no need for me to double up on the inputs.
Last is the outputs setup.

Heres a vid of my first tests with the turret I made from scratch (well curvic coupling wasnt home made ;) )
http://www.youtube.com/watch?v=hRTfxuXf6yk


Hood
« Last Edit: September 01, 2012, 06:51:16 AM by Hood »

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #81 on: September 01, 2012, 08:43:10 AM »
Very nice. Thanks for taking the time to explain.

So you are using digital inputs. Mitsu has both digital inputs and you can also talk to the drive, but thru RS422, so a converter is needed. I have acquired the converter, but it is still in a box . . . somewhere . .

I also have a couple of Copley drives and they are straight RS232 serial and have a text based command set. Very easy to use, but no digital input option like the Mitsu. Each has its plus and minus.

You have given me a lot of good info to think about as the ATC project grows closer. I will have the spindle done soon.

Q: if you don't mind sharing, how are you locking the turret?  It appears to be very heavy and takes a moment to settle. Do you have a damper on it?

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #82 on: September 01, 2012, 09:56:59 AM »
The turret plate is 305mm dia (not including the bar/drill holders which are not in that vid) and 60mm thick but not sure of the weight but its heavy ;D
It locks down onto a curcvic coupling and the clamp/unclamp is by hydraulics, no damper.
 In these vids I didnt have a keyway broached in the upper pulley and it moved around slightly (I was waiting on a broach the right size arriving but couldnt wait to test ;D ) so I had a delay set in the PLC before clamping to make sure it settled before clamping.
Hood

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #83 on: September 02, 2012, 08:04:18 PM »
Thanks again for the info, Hood. You and BR and Himmy and many others need to be recognized occasionally for the vast amount of time you all spend helping others.

So Kudos to all and please know that it is much appreciated.

Quick update on the spindle. Spindle proper is completed except for grinding the bearing pads and drill/tap for the drive dogs.

Progress photo here:

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #84 on: September 04, 2012, 04:25:10 AM »
Couple more progress photos:

The latest addition to my 'mini machinign center' is the horizontal spindle. Here making quick work of the bolt patterns and countersinking.



Final fix on the friggin' spring stack. I despise these things.



Housing parts:




And finally the whole gang in a 'family' photo:



Some detail items and final assembly and the spindle is complete.

« Last Edit: September 04, 2012, 04:31:58 AM by simpson36 »

Offline BR549

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #85 on: September 04, 2012, 09:34:14 AM »
HIYA Steve,  looking good. A couple of questions.

Do you plan to preload the bearings? or let them float?

Is your spring pack release mechanism going to put full load on the bearings?

(;-) TP

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #86 on: September 04, 2012, 11:48:30 AM »
The lower bearing is dual row angular contact and is preloaded. It is ABEC3. The spindle nose has a threaded retainer, so if I chose to use separate ABEC7 angular contact set, the retainer would clamp them together (preload is already set on these bearing sets). In either case, the upper bearing is pressed in (lightly) to the case and floats on the spindle (snug). The housing is steel, to the expansion difference will be only the delta in temp from the spindle to the case, which will be minimal.

A C3 top bearing would probably have enough clearance to not need to float, but I did not do the calculations on it because I elected to float the top bearing anyway.

The lower bearing will take the full force of the release, but it is well within the static load spec on the bearing. Again, I have not done calculations to quantify, but I would not be surprised if the force required to fault the Z axis is greater than the release pressure. 400 watt motor thru belt reduction to a relatively fine thread ball screw. The new mill will have a 750 watt Z axis motor because the head will be much heavier.

Edit: incidentally, I am of the opinion that the big CNC manuf spec a certain finish on the Belleville springs. If I could do so, I *might* be inclined to use them again . .  unless the cost was prohibitive. I will never use off-the-shelf commercially available Bellevilles again for this application. In fact, I am considering selling this prototype BT30 and making a larger spindle  . . . for which I would be able to use the coil spring.

« Last Edit: September 04, 2012, 11:54:25 AM by simpson36 »

Offline BR549

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #87 on: September 04, 2012, 12:33:40 PM »
Steve what holds the lower  bearing bearing set snug in the spindle housing?

In the old days we coated the bevells with high zinc grease and never saw a problem with years of service between change outs. Sometimes that rougher looking surface is better at holding the lube than a super slick finish.

Lookin Good,  (;-) TP

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #88 on: September 04, 2012, 08:21:28 PM »
The lower bearing is pressfit on the spindle and in the housing. I use Loctite 609 bearing set as well if it is a steel bearing in an aluminum housing. I will use that here as a precaution. Mechanicallty there are pins that prevent the bearing from moving and lastly, I have decided to preload the upper bearing in order to take the release stress off the main bearing. So altogether I think that is 4 methods of retaining the bearing.

This wraps up the spindle project. If anyone is interested in purchasing this prototype then I will build a larger one, otherwise I will use it in the new mill as-is. PM me if interested.


Here are progress shots of the completed spindle. All that remains is the drive pulleys, which attach to the steel clamp collar shown.

Two sets of holes in the clamp collar are to mount items above and below the collar.



From the front, you can see the Labarenth seal and the mounts for the drive dogs.


« Last Edit: September 04, 2012, 08:23:11 PM by simpson36 »

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #89 on: September 05, 2012, 03:07:49 AM »
You were talking about the finish on the disc springs, have you had them plated or is that the way you got them? The only ones I have ever seen have no plating at all and are black (maybe some sort of  passivation?)

The way the cylinder and springs are designed on the Beaver mill is quite nice I think, spindle, drawbar and cylinder are all in one unit thus no pressure on bearings at all as far as I can see.
Hood