Messages

521

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: October 01, 2012, 11:06:22 AM »

Thanks Dave.

What your describe is exactly what I did, but when I clicked to post, it just hung. Maybe I did not wait long enough. Is it a long process? I have 6Mb/sec upload speed and I uploaded those and a few more to my site in only a few seconds.

522

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: October 01, 2012, 08:28:04 AM »

Could not get the thumbnails to work. Anybody have a quick 'thumbnails for dummies' course?

523

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: October 01, 2012, 08:03:03 AM »

So I have gotten lots of Kudos in this thread. However, sooner or later, we all take our 'turn in the barrel' and I thought I should reveal one of mine on this project. If I make a change to incorporate a good suggestion, I don't count that as a fail, but here is a clear SNAFU.

There are a lot  . . .  a LOT . . . of reads of this thread and not much participation, so I conclude there are a lot of newbees lurking around who don't speak up or ask questions. To those folks this post is dedicated. Even a well seasoned engineer does not always hit a home run each time up. Don't be discouraged if your project does not work at first. Just keep on truckin' and make it happen.  

OK, moving on to the fail. Below are photos of the claw that grabs the BT30 adapters and swings them around between the carousel and the spindle nose. The challenge in this part is to get it to snap over the adapter without excessive force (which may not be available from a small servo motor), and yet have a sufficient hold on the tool to function properly and safely (#1 priority). The current prototype meets those goals, but only up to a certain arm speed. For a typical DIY project, it would be completely adequate at a nice slow pace, but this ATC is slated for 'kick ass' performance and I do not want any impediments to that goal. Well at least not designed in.

The design shown works perfectly as expected, but the hold on the tool failed testing at the speeds I intend to run the arm. Sudden extreme decel at the end of the swing (the spindle nose) can dislodge the adapter (and whatever expensive and razor sharp tool it is holding). Finding a powerful spring that could be somehow mounted on the unusually shaped claw without interfering with other operations was a very big challenge. Ultimately as you see, I cut a channel to house the heaviest spring I could find. The swinging finger on the claw snaps smartly, but is unable to retain the tool during a sudden stop. There is no real estate on the part to allow for a larger spring and the back of the claw is off limits because it 'parks' against the mill column to clear the rotating carousel.

Result: back to the drawing board. Ashes to ashes, dust to dust and scrap to scrap. The claw started as chunks of 7075 scrap and it is now very expensive scrap.

The replacement design is completed, but not fabricated. The solution was to add a rocker in place of the swing finger. The rocker stays in either open or closed position via a high powered 'over center' spring plunger arrangement. Most important, the new claw has a positive mechanical lock. It can grip the adapter simply by moving over the groves in the same manner as the failed claw, but it is not able to release the tool until a mechanical interference is withdrawn. Similar in function to the interlock on the drawbar actuator.

Photos will be in the next post . . if I can figure out how to do the thumbnails.

524

Mach3 under Vista / Re: Which version of 7 for Mach3? Home? Pro? Ultimate? 32 bit? 64 bit?

« on: September 28, 2012, 08:03:20 AM »

FWIW, I do all of my development work on a Win7 pro 64 bit machine. It runs MACH fine and the brains, macros, screen macros and serial modbus all work fine  . .  so far as I can tell.

Caveat: I do NOT do any output from this machine, so I cannot speak to smoothstepper, or other external motion controllers that must be used since the PP driver does not work with 64 bit OS.

I have just started messing with PoKeys and it seems to work fine with 64 bit as well.

525

Mach3 under Vista / Re: Will MACH3 ever support 64-bit systems? Officially? FYI, it's 2010

« on: September 28, 2012, 07:49:06 AM »

If you want to use a 64bit OS for running a machine than you have to use an external motion control card.

Jeff, does the new ethernet version of the smoothstepper work with 64 bit Win7 pro and have you tested it with Win8 (32 or 64)? I have an SS that I got for cheap off the bargain basement quite some time ago. I hate that thing but am forced to use it in order to support customers who use it.  However, I have read good things about the new Ethernet version. You seem to be the go-to guy for smoothstepper, so I would buy from you if I take the plunge.

Last Qs;

Ethernet SS co-exist with Windows network?
Ethernet SS co-exist with Po Keys?

526

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: September 28, 2012, 07:27:40 AM »

the trouble with R8 in a manual/semi auto change, is you need soo much more room under the tool to make the change.
The 30 or 40 taper allows you to take the tool sideways a lot earlier than the R8.

I do not know this for a fact, but my experience with the BT30 taper had led me to speculate that the R8 design has the concentric ring spaced relatively far above the taper in order to prevent the taper from racking due to inaccuracy in the drawbar straightness or thread precision.

If anyone has some reference material on the original R8 design goals, I would really love to see it.

527

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: September 28, 2012, 07:17:33 AM »

Making good progress on the ATC.  The whole carousel and "lift" mechanism is working now.  

Very nice.

The only advice I would offer is to put an upper support on the arm pivot pin. That is a long lever and when you get that carousel loaded with tools, it will put quite a moment load on the pin. Aluminum is not the best choice for the mount, in my view, due to the modulus of aluminum. Your mechanism moves a load vertically at the end of a long arm. This arrangement will induce significant vibration and aluminum has little ability to damp that. An upper support on the pivot pin would address both the moment on the pin and the vibration (bouncing) of the loaded carousel.

An upper support would convert the moment on the lower bracket to compression and put the upper bracket in tension. The pin force would be converted from moment to shear. Moment loads are a bitch to calculate, while shear is easy, so there is an ancillary benefit as well.

edit: one other comment; You probably already have something in mind for this, but just as an observation, the shafts running thru the arm at the carousel would benefit from bellows or a scraper type o-ring to keep the nasties (evidenced by the wall behind the carousel) from jamming the movement.

528

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: September 28, 2012, 07:00:20 AM »

Here is an interesting approach to a power draw bar:

They get by with only 600# drawbar tension, but they have a clamp collar that grabs the spindle nose to transfer torque for high power tooling. R8 is a vexing problam and while it would not be useful with an ATC, I think this is a very clever solution to speed up manual tool changes. Apparently so did the patent office.

Video: (there are several, but this will get you started)
http://www.youtube.com/watch?v=YaiZC93ASJ8&feature=relmfu
Comapny site:
http://mach-1tooling.com/

529

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: September 23, 2012, 03:37:07 PM »

DWalsh: caution about posting drawings . . . the teacher has a big RED pencil  . . .  a corner chair with dunce cap . . .  and possibly a wooden ruler  . .  and a paddle  

Do you really see anything wrong with that drawing?

Not at all. Just a joke based on the guys tauting me a few posts back. BR was the actual target, in a sense. I assumed you had read thru there and would get the tease. First rule of plumbing and so on. Sorry it was unclear. No offense intended.  

530

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: September 23, 2012, 02:29:01 PM »

Steve,

Just for your amusement, here is the current state of my ATC

Well, if I am to be amused, I must get out my RED pencil   . . . kidding, of course. Your work is always first class and logically conceived.

Interesting thing is that what you have is something of a hybrid between the typical moving carousel arrangements that I have seen and with what I am doing. You move the carousel . .  so far fairly conventional . . . .  but as always there is the 'Kabibble Twist' on it. You move it with an arm! That removes one of my objections to the travelling carousel concept . .  that being the carousel hanging over the table. This is the first arrangement I have seen with an arm swinging the carousel. Very clever indeed.

Couple questions if you don't mind (not to worry no RED pencil here);

1) Another of my quibbles with the DIY setups is lack of protection for the taper (or 'stud' I suppose in your case). Do you have any plan to protect those surfaces from swarf?  Do you consider that a must have or optional?

2) What kind of sensors are you planning? At what points in the process do you recon a confirmation is required before moving to the next step?

3) Probably you would get around to this eventually, but I am impatient so . . what will drive the Geneva?

4) did you make the holders in the carousel or are they a Tormach part?

5) Will you use a sparate PLC to control the sequencing or will it be integrated into your Kflop system?

6) How do you do the thumbnail - to - full size photos?