Kearney & Trecker large iron conversion (WIP)

So - I thought I would start a thread over here about one of my projects.

We have a HMC with tool changer and pallets.

(Photo from the manual)
www.electronicsam.com/images/KandT/oldkandt.JPG

Current condition
www.electronicsam.com/images/KandT/DSCCurrent.JPG
Random pictures
www.electronicsam.com/images/KandT/conversion/

The existing control - all discrete components (yes germanium transistors) worked until a couple of years ago. The control finally smoked. Time for an upgrade to a new control.

Enter EMC2.

After annoying the developers with tons of questions - setting up a simple stepper machine with emc2 ( www.electronicsam.com/images/KandT/DSCgantry.JPG ) Emc will do everything we need it to. (and it has about 1000 more features than the original control :))

Now I am a big DIY'er - alway have been. The K&T has hydaulic servos. plus it is only 2.5 axis. (x and z share the same servo) we are going to hack in and install 3 dc brushed servos ( www.electronicsam.com/images/KandT/DSC_0242.JPG ). Now what to drive the servos with? Closed loop is a must.

One of the gurus on the emc irc channel had mentioned that he had used a h-bridge to run a servo. Emc2 has a Hal module (hardware abstraction layer) that is called freqgen (now there is an even better hal module called pwmgen). This module can be set up to output 2 pwm signals - one for forward and one for reverse - in proportion to velocity. So he had an h bridge hooked up to the pwm out - one pin for forward - one for reverse and read the encoder back in for position (another 2 pins). (parallel port).

This got a lot of people thinking. This guy made a servo etch-o-sketch using the same principle. emergent.unpy.net/projects/01142347802. He used a L298 as the h-bridge and also read the encoders back into the printer port.

Another emc developer converted one of his lathes to servos using the same L298 Bridge. He has had great luck with it so far. Very small following error. (he has not made a page on it yet but is going to)
Here is a picture of his servo mount
timeguy.com/cradek-files/emc/DSCN6290.JPG

So - what does a diy'er do? Make a 150v 20a h-bridge.
first try
www.electronicsam.com/images/KandT/servostart/almost.JPG

25th try (not quite that bad but it defiantly went thru some changes)
www.electronicsam.com/images/KandT/servo...rrentlimit/right.JPG
eagle files and such
www.electronicsam.com/images/KandT/servo.../latestcurrentlimit/
I have lightly tested it to 180v 22a or so. No smoke yet. Added from the original design - current limit, blanking, enable.
www.electronicsam.com/images/KandT/servo...ntlimit/mcguNI9R.jpg (meter reading 19.9A)

That is about where we are at. I will post pictures as we rip the thing apart.

sam

Some specs.

60 tool changer
Travel
X 38"
Y 36"
Z 24"
Table indexable to 5deg incr.

2 pallets

All ball screw and recirculating way bearings (tiko(sp) ways)

sam

Wow - this is an old thread that was forgotten..

We have come a long ways..

videos..

www.youtube.com/user/samcoinc/videos?view=0

The machine has been running awesome with linuxcnc and mesa. No complaints.

I still have to finalize the control pannel - but other than that.

random pictures..
electronicsam.com/images/KandT/conversion/

sam

Sam, amazing work.

Sam classicladder'm lost, good at everything else too, lol.

classicladder but not where to start.

it is a simple app that let you look at these links to see concerned.

www.linuxcnc.org/index.php/english/compo...ew&catid=38&id=23023

www.linuxcnc.org/index.php/english/compo...ew&catid=25&id=24135

any advice, tips, would be helpful.

thanks,

skunkworks wrote:

25th try (not quite that bad but it defiantly went thru some changes)
www.electronicsam.com/images/KandT/servo...rrentlimit/right.JPG
eagle files and such
www.electronicsam.com/images/KandT/servo.../latestcurrentlimit/
I have lightly tested it to 180v 22a or so. No smoke yet. Added from the original design - current limit, blanking, enable.
www.electronicsam.com/images/KandT/servo...ntlimit/mcguNI9R.jpg (meter reading 19.9A)

That is about where we are at. I will post pictures as we rip the thing apart.

sam

I had this same idea to replace the Fanuc DC servo drive(s) of my Kitamura. Use the parallel port or Mesa pwm to drive an H-bridge. Did the design work? Do you still use it?

Great info by the way.