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Author Topic: BT30 spindle from scratch - with power drawbar and ATC of course  (Read 402217 times)

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #320 on: October 21, 2012, 08:03:25 PM »
Here's a somewhat better video:  http://youtu.be/aDEgRS6PI60

Regards,
Ray L.
Regards,
Ray L.

Offline BR549

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #321 on: October 21, 2012, 08:45:40 PM »
HIYA RAY I noticed that something is PUSHING your spindle up and down. You can see movement of the actual spindle during the change.

Just a thought, (;-) TP
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #322 on: October 21, 2012, 09:00:30 PM »
HIYA RAY I noticed that something is PUSHING your spindle up and down. You can see movement of the actual spindle during the change.

Just a thought, (;-) TP

Terry,

No, not pushing, the quill is being moved intentionally as part of the process.  When loading a tool, I move the quill down 0.050", to make certain the TTS holder is pushed fully into the spindle, so it will seat properly against the spindle nose when the drawbar is tightened. After the drawbar is tight, I move the quill back to home position.  There is enough compliance designed into the system to accomodate this small motion.

Regards,
Ray L.
Regards,
Ray L.

Offline BR549

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #323 on: October 22, 2012, 12:56:14 AM »
GOTCHA, (;-)  Lookin GOOD , (;-) TP
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #324 on: October 27, 2012, 05:53:12 PM »
I've been making progress on the ATC - albeit slowly, due to interruptions.  The basic mechanism is proving quite reliable.  I've let it run random toolchanges for hours on end, running hundreds of toolchanges along the way, and it has never once made a mistake.  And that's running completely open loop!  Next week, I hope to get the sensors mounted, so the control program will be able to confirm that each commanded motion has actually fully completed.  With the sensor feedback, this thing should be pretty darned bullet-proof.

I have two other project I have to complete before I can actually put the ATC into service.  First, I need to complete the new telescoping Y/Z way covers.  The current ones are too wide, and prevent the ATC from going fully into its out-of-the-way park position.  The second is finally installing a spindle sensor, as I need to be able to ensure the spindle has fully stopped before doing a toolchange.  The sheet metal parts for the way covers are all cut and bent, so it's just a matter of about a days work to assemble them, and get them mounted on the machine. 

In the meantime, I've started making the "final" ATC parts, to replace some of the existing ones, which were made specifically as disposable prototypes.  I've re-made the pivot arm, and air cylinder attachments, and they came out beautiful.  The remaining work on the ATC is to re-make a few of the minor parts, mount the "skirt", connect up the door operating cable, and mount the sensors.  That will all take some time, but nothing really hard there.  I expect when it's all done, I'll either powder coat the whole thing, or perhaps just polish the aluminum.

Regards,
Ray L.
Regards,
Ray L.
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #325 on: November 09, 2012, 05:11:17 PM »
Progress on the ATC has, once again, been interrupted by higher priority work, but it is nearing completion.  I've just finished getting the "sensors" working, so all that's left is getting the door mechanism going, putting on the "skirt", and doing some minor clean-up.  The mechanism is working flawlessly.  In fact, it's been running continuous toolchanges since early this AM - nearing 1000 just today.  So far, no problems whatsoever.  And, now that the sensors are in place, I believe it will correctly detect any problems, and halt operation.  I've tried everything I could think of to make it fail, and it has correctly detected every failure I've thrown at it, and simply stopped what it was doing, until I manually cleared the error condition.

On a related note, the functionality of my machine has been expanding for years, and has gotten to the point that the wiring around the KFlop has become something of a rats nest, and I'm starting to run short on I/Os. A friend and I started designing a KFlop-specific breakout board, and in the process of defining what functionality to include on it, I came up with what I think is a great idea to greatly reduce the overall amount of wiring, and the amount of required buffering of signals.

The signals connecting to the KFlop basically fall into a couple of very broad categories. First is the special function and time-critical signals, like axis
drive outputs, Home/Limit/Probe/E-Stop inputs, and a very few others, which MUST be connected directly to the KFlop. These make up about 30-40% of the total signal count. The remainder are not at all time-critical, nor do they really NEED to connect directly to the KFlop. This group includes spindle and coolant controls, power drawbar and tool-changer controls, etc.

A while back, I bought a VistaCNC USB pendant, which I proceeded to rip apart, completely re-writing the firmware for the embedded PIC processor, and converting it from USB to RS232, so it could communicate directly with the KFlop. The code in both the pendant and the KFlop is dead-simple, and the pendant has worked absolutely flawlessly since the day I first put it into service months ago. It uses a very simple purpose-built serial protocol. My
new hair-brained idea is to expand that protocol to allow additional external processors to be connected to that same RS232 link, by either a daisy-chained or star connection, so that all non-critical signals can be moved completely off the KFlop to any number of external processors, each of which can then be located near the device it controls, connected by only a serial link, rather than a mass of wires. Each processor will be separately addressed, so it will accept messages targeted to it, and ignore all others. All processors will be able to send messages to any or all other processors, including the KFlop. Each will be able to accept commands from the KFlop, or other processors, and to send status message (e.g. - current spindle speed) back to the KFlop.

I will re-configure my system so that there will be one processor in the pendant (it's there now, and will just require a few minor tweaks to support the new protocol), another in the E-box for several basic machine functions (spindle controls, coolant controls, etc.), one for the power drawbar and toolchanger, and one for the control panel (this is, essentially the pendant from hell - a console with MPG, and a bunch of dedicated-function buttons...), so I can operate the machine without a mouse.

So, for example, if the user want to release the drawbar, the KFlop will send a message to the PDB/ATC processor telling it to release the drawbar. Once the operation is complete, the PDB/ATC processor will send a message back to the KFlop either confirming the operation completed successfully, or return an error code, indicating why it failed. Similarly, to turn on the spindle, the KFlop will send a message to the spindle processor, telling it what speed to set the spindle to. The spindle processor will set the spindle PWM, turn on the spindle, and send periodic spindle speed updates until the spindle is turned off.

I plan to use off-the-shelf Arduino processor boards, because they're dirt cheap (starting at about $10), highly functional, and available in a broad range of capabilities, with a wide range of plug-in I/O expansion boards. But, ANY processor could be used, as long as it supports RS232. Since each will be
controlling only "local" devices, there is little need to any extra buffering or isolation, further simplifying the wiring. This will reduce the current mass of
cables going from the E-box to the machine down to just the motor/home/limit/probe wiring, and a single RS232 cable, daisy-chained to the
processor boards on the machine.

Regards,
Ray L.
Regards,
Ray L.
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #326 on: November 27, 2012, 07:58:45 PM »
Finally had time to make a new Y/Z telescoping way cover (you can see it in the video) that clears the ATC, and all is installed and working perefectly:

http://www.youtube.com/watch?v=54s0aoAT37o

I've also got the new serial network working.  It's going to significantly reduce the amount of wiring on my machine, and especially reduce the number of connections back to the E-box.

All that remains on the ATC is installing the "skirt" and door, making a cover for the "works" on top of the carousel, and cleaning up the wireing and plumbing.  Functionally, it's already working 100%.

Regards,
Ray L.
Regards,
Ray L.

Offline Fastest1

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BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #327 on: November 27, 2012, 09:43:49 PM »
Nice work Ray! Looks like it is working very well.
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #328 on: December 02, 2012, 01:37:01 PM »
Wondering if you guys might clear up a thing or two for me...

A few pages back, their was a link to an ebay auction for a new BT30 spindle. I understand about how the bellville washers are compressed, and this releases the tool because the grippers release when the bellvilles are compressed. What I dont get is- unlike a turret mill (standard BP), the BT30 spindle appears to be fixed as it relates to Z. it appears that the spindle itself does not travel, but the spindle housing with all associated parts and air cyl must travel together? am I understanding this correctly?? VMC= travelling spindle housing, BP= travelling spindle (in) housing that is stationary?

So, it appears to me that other than creating grippers, a taper and a place for the spring stack, that the biggect issue is having an air cyl that will travel with the spindle on a BP, so that the relationship between spindle and air cyl is maintained fixed like it is on a VMC?

Following is an example of difficulty of not having air cyl/spindle relationship fixed-

Tools are held on table in carrier, BP spindle must descend to tool carrier height. this means that the air cyl must be able to either travel down significantly to actuate the release of the tool or be a fixed in its relationship with spindle like on VMC.

I do understand that having the air cyl travel up and down like an air power drawabar can(has) been done, but would it not be easier (less sensors/fixed hard stops) to just have the air cyl travel with the spindle and thus maintain the fixed relationship?

Also, the BT30 spindle in the ebay auction looks as if the air cyl actuation puts a load on the spindle bearings when it is actuating? is this correct?

Thanks,
Nate.   

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #329 on: December 02, 2012, 02:48:41 PM »
I would say the best solution is to have the cylinder travel with the quill. Few drawbacks to it though, one is its more complex and another is you will need more headroom.
The Beaver mill I have has a travelling Hyd cylinder and it works well, I can clamp/Unclamp at any point of the quill travel.
Haven't looked at the eBay auction mentioned as I couldn't see it in the last few pages and didnt search further. On my mill the cylinder outer screws to the spindle and thus there is no force exerted on the spindle bearings.
Hood