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Author Topic: BT30 spindle from scratch - with power drawbar and ATC of course  (Read 408521 times)

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Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #500 on: February 13, 2013, 05:43:59 AM »
Progress is creeping along on finishing up the ATC. The last tasks are to put the sensors on the various parts that I want to monitor. Sensing the vertical position of
the arm proved to be a vexing problem, but the solution to that dilemma also provided improvements on some other aspects of the actuator that I was not completely satisfied with.

The photo below shows the new cylinder mount. Previously the cylinder mounted to the head on a heavy bracket. This required very close alignment to prevent the shaft from binding as is slides thru the gearbox. This new arrangement eliminates that separate mount by attaching directly to the gearbox. This not only guarantees alignment, it also provided for a single attachment point to the head and completely encloses the shaft. The cylinder has a magnetic piston and the position is readable by external adjustable sensors as shown in the photo. There will be a second sensor at the top of the cylinder to read the 'UP' condition. The shaft below the gearbox will be covered by a corrugated rubber bellows.

The cylinder pictured was intended to be only temporary and for feasibility and testing, but the performance seems perfectly adequate, so at this point I am inclined to leave it in place.

There was a question earlier about the shaft 'slamming' at the end of its travel. This cylinder has internal rubber bumpers at each end of the stroke that cushion the sudden stop. The air inlet and outlet fittings on the cylinder have needle valve adjustment for flow, so the speed (although not the force) can be adjusted.

I am very well pleased with this arrangement and will be duplicating the magnetic sensing method on the pod tool release cylinder as well. It is an expensive solution, but one that will prove reliable in a difficult environment.

There remains only one interlock and associated sensors for the tool pod release function. . . . and make 4 more tool pods for the carousel. Most likely I will use a solenoid actuator and optical sensor in this case.

I will post a picture of that last interlock when it is finished and that will complete the mechanics of the ATC, leaving the most complicated task of the whole project; the control software . .  which I would say is about half done. I'll make another video of the testing once these last tasks are completed . .  no ETA on that.

« Last Edit: February 13, 2013, 05:51:53 AM by simpson36 »
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #501 on: March 10, 2013, 01:45:09 PM »
Thought I'd toss out a "teaser" video of my new teeny, tiny power drawbar.  Works like a charm - capable of >30 ft-lbs torque on the drawbar.  Servo-controlled.

http://www.youtube.com/watch?v=QkkYabNx3Kg

In the video, it's mounted on my knee mill, for testing purposes.  It will very soon go on my new CNC bed mill, which I just received on Thursday.  The bed mill version includes a built-in spindle lock, and spindle sensor, so the PDB can't be engaged if the spindle is powered.

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #502 on: March 11, 2013, 10:39:47 AM »
I have been working on the control side of things so there is not much to report on the hardware. As I mentioned earlier, the control scheme is really the more difficult part of the ATC project. The prototypes in this thread are being incorporated into an all new CNC converted IH milling machine and the controls will have the ATC fully integrated. I will only be posting here  the portions of that project that are directly related to the BT30 spindle and the ATC.

To that end, I have just completed the computer, motion control setup and interfacing for the project. On Ray's recommendation, I went with the K-flop board over the smoothstepper. While the Kflop board is far from the 'plug and play' that I was hoping for, eventually (with very prompt, accurate and well targeted support from Dynomotion on their Yahoo group) I did get it going. A major caveat with the K-flop is that 'most' of it is 3.3V only. I got caught with my pants down on this because I only read the K-flop spec to the point where it said '5V tolerant', however, when I went to integrate the board and read the entire spec, I discovered that only a few of the pins are 5V tolerant and the rest are 3.3V ONLY, which was bad enough, but they also are limited to a tiny 10mA current. I now have 7 different boards and many of them had to be redesigned to work with the K-flop, and I had to make up a special batch of boards for this project . .  a rather large task that I had not anticipated.   :'(
 
Although there is essentially zero cutting time on the system, so far it has not exhibited the USB smoothstepper's bad manners, so I am encouraged that it will be a good solution for the initial MACH3 support as well as hosting some or all of the ATC control in the future. The K-flop is running a total of 7 axis; 3 linear, 3 rotary and the servo powered spindle.

At this time, my InTurn™ 4th axis motor controller is hosting the ATC controls. The motor controller has a multi task board (swapaxis, digital signal synthesizer, line driver) that is mounted in the CNC computer so for the sake of simplifying the external cabling, I ran all of the controllers cables to the CNC computer. From that central point, all of the cabling runs to two large enclosures which house the EIGHT Mitsubishi AC servo drives and a bank of 12 relays. From the enclosures, one set of cables goes to the head and include the spindle servo cables, the ATC cables and all sensor cables. The second enclosure has a set of cables that run to the mill base and contain the X,Y, and Z axis, the InTurn™ 4th axis, 5th axis servo cabling as well as relay and sensor cables.

The first step in the overall task is now completed. I fabricated an aluminium 'mezzanine' plate to mount the motion control board and all of the supporting interface boards. This is mounted in a large server case with the dozens of wires collected into SIX connectors on the back of the case. In the planned arrangement, the computer will be on or near the floor with approx 6 feet and 10 feet cable runs to the two wall mounted drive enclosures. Cable runs from the enclosures to the mill will be 8 to 10 feet. All of the servo cables are Mitsubishi factory made parts. Pneumatic valves and mechanical solenoids run at 12V and the optical sensors and limit switches run at 24V to help with noise immunity.

I am very happy to have the electronics portion (which I do not enjoy) completed so that I can now move on the the mechanics of the conversion (which is the fun stuff).  

This is the mezzanine with all of the goodies installed and wired up, but without the external connectors



Next is the completed setup final install and running



This is the back of the server case showing the 6 DB25 connectors needed to get all of the wires where they are going.



  
« Last Edit: March 11, 2013, 10:45:40 AM by simpson36 »
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #503 on: March 11, 2013, 10:47:02 AM »
Steve,

Looks good, but needs more wires!  :-)  You know Craig has his Bobs ready?  I got my two a few days ago - they look really nice.

What connectors did you use to connect to the KFlop?  I've never seen any like that.

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #504 on: March 11, 2013, 12:05:52 PM »
Steve,

Looks good, but needs more wires!  :-)  You know Craig has his Bobs ready?  I got my two a few days ago - they look really nice.


I was already pretty far along with the wiring diagram by the time the BOB was ready.  I had made a career out of this task already and was well into modifying the interface boards (to not instantly fry the K-flop's 3.3V 10mA pins) so the last thing I wanted was to rewind to add a new piece to the puzzle.

Craig had to make some decisions about I vs O and I would need to really compare his choices to my needs and see if there was enough of each flavor. On this project, there is a LOT of I/O and having a bunch of them pre-defined *might* present a problem, but I'll peek at that issue for the next project. I also need differential signals and relays that can drive coils and 24V isolated stuff and on and on blah blah blah, so if I decide to stay with the K-flop, most likely I will make my own BOB with all that stuff on it already. The incomprehensible tangle of individual wires is definitely a huge attraction, but alas we must occasionally yield to practicality  ::)

Certainly the BOB would be a big help to anybody doing a *typical* MACH install with 3 axis of single ended signals.

Quote
What connectors did you use to connect to the KFlop?  I've never seen any like that.


The connectors are just the mating parts for what is on the K-flop. I chose to use crimp pins for flexibility (read: fixing screw-ups). I prefer to use color codes and heavier wire than is available in ribbon.

Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #505 on: March 11, 2013, 07:22:42 PM »
Steve,

I've never seen IDC connectors that easily allowed using individual wires - just ribbon cable.  Where did you find those?

Regards,
Ray L.
Regards,
Ray L.
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #506 on: June 17, 2013, 10:41:54 PM »
Sure has been quiet here for a long time....

Not sure if you guts are up to speed on what I've been doing.  I bought a Novakon Torus Pro mill a few months back, and LOVE it!  And, I'm designing a PDB and ATC to fit all the Novakon machines.  The PDB is a few weeks from beta test, and I hope to get the ATC there by end of the year.  The PDB is a vastly improved version of my motorized drawbar, with a dedicated microcontroller to control the (rather complex) sequencing.  Everything fits very nicely inside the sheet-metal cover on the head, with the Grab/Release buttons and an LCD display mounted to the door.  This version has sensors so the firmware can verify nearly all operations, and it displays an error message on the LCD if anything goes wrong.  Like my other PDBs, this one also works equally well with TTS or straighy R8 tools.  Average time to grab or release a TTS tool is under two seconds.  It torques the drawbar to a very consistent 30 ft-lbs, so TTS pull-out is a thing of the past

Below is the final "production prototype" mounted on my machine.

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #507 on: June 18, 2013, 05:39:44 AM »
Typically I do not do 'conversions' but I have been busy building a CNC mill using the castings from a  new IH mill for one of my 4th axis buyers who also purchased the second prototype BT30 spindle, Drawbar actuator and the prototype ATC. This machine is 5 axis and has 8 servo motors.

One of the reasons I agreed to do this project was that it seemed feasible to come out the other side with a CNC retrofit 'kit' for this largest of the  'off-shore' square column bench mills. However, shoe-horning large precision ground pre-loaded (large ball nuts)  ball screws into this machine (even though it it the largest of its type) required so much machining of the castings that it became obvious that this is not a candidate for a DIY project. The IH column is open in the front so it had to be boxed in and linear guides were used in place of the dovetails.

I committed to this project so it will be completed, and it is an excellent platform for the BT30 spindle and ATC, but there will be no retrofit kit for the IH mill and this will be a one-time deal.

There have been no postings here because the progress so far did not involve the BT30 spindle, drawbar actuator or ATC, but that's about to change as the head is now completed and the BT30 spindle detailed in this thread (the second one actually) is now running. The owner chose a huge spindle motor for this machine which caused a lot of problems and required a lot of re-design of the head and drive components. That slowed progress considerably, but it's finally all completed and running.

Here are the videos covering progress on this project, axis by axis. The next video will cover the all new head which contains the BT30 spindle, drawbar actuator and ATC. The spindle motor is a 3,500 watt Mitsubishi AC servo running on three phase power. This next video should be up in a few days. The project wraps up in a few weeks when the owner comes to collect his new 5 axis toy.

http://www.youtube.com/watch?v=20l-HVgJtcc
http://www.youtube.com/watch?v=_sH8nBUxIV8
http://www.youtube.com/watch?v=b812wagyBW0

« Last Edit: June 18, 2013, 05:43:33 AM by simpson36 »
Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #508 on: June 18, 2013, 10:49:44 AM »
Steve,

Impressive, as usual.  Funny how 500IPM doesn't *look* as fast as it sounds.  Though it certainly seems fast when you realize your expensive new endmill is heading straight for that fixture bolt....

I hope to finally be starting on my new ATC build in the next few weeks.  It's been designed since about January, but I just haven't had the time to actually build it.

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #509 on: June 18, 2013, 12:48:20 PM »
Here is the head in its current condition. Actuator is not on the head in this shot. The motor pulleys are large diameter because if they were smaller, the tension would exceed the belt spec . .  even with 1" wide belts. That's a Big A$$ Motor.

Dual speed ranges are 1:1 and 2:1   MAX spindle continuous is 6,000 RPM with 'instant' speed of 7,000PM.