ITS ALIVE

Ok... I still have a lot of work to do, but the Hurco KMB1 I picked up in
November 2010 finally came to life yesterday. Ok... one finger twitched
when stimulated with electricity. LOL.
I actually powered up the computer, motion control interface, breakout board
(with some on board functions also), and one of the servo drivers yesterday.
With a freshly installed 1000 line quadrature encoder on it I spun one of
the yet to be re-installed servo motors back and forth at speeds upto 1250
RPM with good position repeatability using a short g-code test program
running on the control computer. If the proximity sensors installed on the
mill are all still good and I don't have any oil line leaks I may actually
cut some parts with it in the next month or so.
1250 RPM is the speed necessary for the original factory specified rapid
speed of 250 IPM. I actually free spun the motors at 2000 RPM when testing
with direct uncontrolled power. With a 20% derating as reccommended by
Gecko that would mean a top rapid speed of 1600 RPM (upto 320 IPM) with this
setup. I'm going to set my programmed rapid speed down to 150 IPM until all
things are tested and working then bump it up with a full 500 lb load on the
table and see how it performs before settling on my final top speed. I'll
keep current low and allow for momentary overload rather than going for peak
current. If I get current or position faults during testing I'll drop speed
and/or acceleration back until I don't.
I still have a lot of work to do though before I start moving the table
under system controlled power.

Reply to
Bob La Londe
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YeeeeHa!
Good on ya!
Advise you leave headroom between the maximum error-free acceleration and your final 'top speed' declaration.
--Winston
Reply to
Winston
Yeah I was originally planning on just keeping it at 150, but I have a little Chinese CNC router I reconfigured recently that I ran all the way up to 600 IPM before it stalled. Then it was only after about 30 passes. I dropped it to 300 and left it there. Anyway, it kind of spoiled me for speed. LOL. Since the no load full speed of the servo motors on the mill is only 2000 RPM I'll never ever be able to run it as fast as I tested that router. Kind of amazing really when I think about it. The stepper motors machine is faster and always will be. LOL.
I think though as long as it catches up by the end of a rapid it should be fine. Cuts will always be much slower. Not much I can feed very fast with only a 3600 RPM spindle. I think even so I may stay at 150 for a long time. I want to make sure braking, limits, oiler, etc all work perfectly every time before I try to pick up any speed. Also, I want to make sure I have soft limits programmed and a slow down zone close to limit switches etc. I'll also want to establish a startup homing routine so I never actually hit the limits except when homing... and of course test EVERYTHING.
I know that no load testing isn't the same as pushing around a several hundred pound table, but the only time I saw the in position LED blink was on full speed reversals. That's not something you would ever have happen under normal machine operations when doing rapids. Never saw the fault light come on at all.
Today I unplugged everything and started wiring in stuff in its "permanent" configuration. I still want to add a drain circuit to my DC caps. The servo amps drain them a lot quicker than just idling, but still. I would never want to accidentally put a sweaty arm across the top of the big caps. I'm thinking maybe just a switched resister that shorts the caps anytime the door is opened.
I am considering cutting a hole in the door and putting a in a wire backed plexiglas or wire core safety glass panel in there so I can button it up and engage all the safeties and still be able to see all the LEDs.

Reply to
Bob La Londe
Yeah. I put some teeny tiny NEMA 34 steppers on my mill. They were the most I could afford at the time. I tested acceleration by physically pushing against the travel of each axis until I got an error. Crank down the acceleration and re-test etc etc. Eventually I got to a point that guaranteed travel even when I pushed against each axis with all my available guts. I set acceleration at 90% of that value and called it done.
Fun stuff!
--Winston
Reply to
Winston
Why a switched resistor? A simple 50k-100k 15-20 watt resistor will bleed off a cap in relatively quick fashion. The OmniTurn CNC lathes I use keep a resistor mounted across the caps just for that reason. Just use a cheap wirewound ceramic. You are working with about 100 volts DC..its not rocket science.
One bleeding-heart type asked me in a recent interview if I did not agree that "violence begets violence." I told him that it is my earnest endeavor to see that it does. I would like very much to ensure - and in some cases I have - that any man who offers violence to his fellow citizen begets a whole lot more in return than he can enjoy.
- Jeff Cooper
Reply to
Gunner
Awesome!
i
Reply to
Ignoramus19184
Funny, I basically tested the Taig, and the MAX NC that way. The Chinese router I didn't. Just tested it for position error with an indicator.
Reply to
Bob La Londe
Ok... I was doing some wiring last night. After testing the servo motor I disconnected it and started doing my "permanent" wiring. While I was standing there admiring my work I was thinking about the various inputs. A smoothstepper has the functionality of all the pins of two parallel ports, but it also has a set of inputs normally used for encoders that can be addressed like any other input as PORT 3. That gives me 15 inputs.
Since Mach doesn't tell you which limit was hit when you hit a limit switch I figured I would wire them all up to the same input. I will also use my limits for homing atleast to start.
Add in probing inputs and a few other misc stuff for various trouble conditions spindel speed etc, and I would normally have only a couple inputs left over. With those port 3 inputs however I have enough to hook simple switches up as jog switches for manual control other than the keypad.
At first I was thinking of some cheap Radio Shack momentary push buttons, but then I started thinking of other things I might be able to adapt. Maybe an old Atari joystick or something else. Then I started looking on Ebay for arcade buttons. I was almost ready to order some. One outfit has 2 HAPP joysticks and 14 buttons for about $40.
This morning I remember something I already had. Years ago we bought an arcade style interface to use with a PS2. I was never a serious gamer and my son didn't like the way it played so it got put in storage.
Its perfect. No its not a pendant, but I can make a little box shelf, mount it on the head of the mill, or hang it off one side of my keyboard tray. The exact location can be determined later. I suppose I can even make up a pendant style box I can hang on a hook out of the way when not in use.
Initial cost for testing the idea. Nothing.
Maybe I can add a pinball table and a tilt swinger to the machine. LOL.
Reply to
Bob La Londe
I was thinking of a lower value resistor to drain the CAPs really fast, although if I put the window in the cabinet door its not as big of a deal because I'll be able to see the LEDs and just not open it until they all go out.
Reply to
Bob La Londe
(...)
Go Bob Go!
--Winston
Reply to
Winston
My suggestion will kill the cap in under 10 seconds.
Gunner
One bleeding-heart type asked me in a recent interview if I did not agree that "violence begets violence." I told him that it is my earnest endeavor to see that it does. I would like very much to ensure - and in some cases I have - that any man who offers violence to his fellow citizen begets a whole lot more in return than he can enjoy.
- Jeff Cooper
Reply to
Gunner
Greetings Bob, Please let us know how well the Gecko servo amps work. I have three of them and have had good luck but I haven't yet really stressed them. Thanks, Eric
Reply to
etpm
In general I do not plan to work this machine to its full cutting load with a full 500 lbs on the table. I'll probably set my current limit for about 9 or 10 amps, but set the switches to allow for momentary max current. I will have around 160 lbs of vises on the table all of the time if my planned use of the machine remains the same. (4 screwless vises at 39 lbs 10.2ozs (apx))
I'll try to keep you up to date. If you are interested I do have a build thread going on CNC Zone here:
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The latest post shows pictures of the game controller I plan to gut out and use for manual inputs.

Reply to
Bob La Londe

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