Messages

21

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: December 06, 2010, 04:32:02 PM »

Its progressing nicely, great work !

JH

Thanks JH. I was checking out your Bridgeport retrofit. That is an awesome build!!! I really like vintage iron, I wish I had thought to retrofit an old machine instead of building this machine.

22

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: December 05, 2010, 10:46:44 PM »

Couple pics of the Z axis getting a ball screw transplant and a few pics of the X axis.

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Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: December 05, 2010, 10:38:54 PM »

Been making some good progress on this build. Although, I suspect progress will slow considerably from here on considering how cold it's been here and I have no heat in the shop

Anyway, some of the work I got done:
Got wider belts for the y axis, the narrow ones were stretching a little.

Finished the X and Z axis. The X was easy after I figured out how I was going to do it The Z turned out to be a long project that involved purchasing a Bridgeport Series II mill to make the 3 plates that make up the Z axis. Then after I finally got the Z axis done, I had to change out the Acme screw/delrin nut combination to a ball screw due to a bad vibration from the acme screw.

Quick Z axis demo:
http://www.youtube.com/watch?v=dt9paSCZvhs

Pen plotting a part file with feed rates of 30 to 250 IPM and rapids at 600 IPM
http://www.youtube.com/watch?v=dbIUzRVaNq8

I guess the next project will be getting a spindle on this beast.

24

Galil / Re: Help! Anyone good at tuning Servos in Torque Mode???

« on: September 24, 2010, 11:12:08 PM »

The drives are Danaher model 20360. I don't know if they are "digital". I never noticed any place in the setup (software) where you would do PID tuning. I know they have a way of telling what motor is connected to them and that pre-configures the drive to run best with that motor. I think that only sets up the motor specs, like how many poles, motor voltage, things like that. There is no "autotuning" feature like some of the drives have. I suppose I could run them in step/direction mode, but isn't that kinda the same end result as running in velocity mode? In velocity mode the drive is doing most of the control and the Galil just makes sure it gets where it's supposed to be? In step mode the drive is doing all the control? I'm not sure I understand the diference between velocity and torque mode.

I know the Galil PID settings are nowhere near as touchy when the drives are in velocity mode. i can find a large range of settings that seem to work ok in velocity mode. In torque mode a small PID change makes a big difference. In velocity mode I still can't add any KI though.

In the Galil Tools program I can watch the scope and change the PID settings and the motor will make a move each time which in turn shows on the scope. So, what should the correct wave form look like? i know it should shoot up to position as quickly as possible and settle. But how can i prevent the motor from going in oscillation (which happens when I go back to Mach and try to run a G Code file). What should I be looking for? How should the motor sound? Should there be any overshoot before it settles? should I be looking at anything other then Reference Position vs Encoder Position?

is it possible the vibration from the drive belt teeth riding on a flat pulley combined with poor tuning could be causing the system to go into oscillation? That's one thing I was considering.

Thanks

25

Galil / Re: Help! Anyone good at tuning Servos in Torque Mode???

« on: September 24, 2010, 05:12:45 PM »

The best I could get it dialed into was around KD367 KP30 and if I add any KI at all it gets unstable. However without KI it comes to rest a little short of it's target position. I don't understand why I can't add any KI and still maintain any stability. It seems as if even a KI of 1 is too high.

With the above settings and KI set to 0 I can get it so it will rapid ok, but running a part program causes it to go into oscillation at some point in the run. I thought maybe I was trying to run the part program too fast so I dropped the feed down to a mere 10ipm but it still went into oscillation.  I did try using IL with a setting around 2.5 but that didn't help any. Less then 2.5 rendered KI ineffective.

I also tried 328, 19, 1 and several other variants.

what do you think?

26

Galil / Help! Anyone good at tuning Servos in Torque Mode???

« on: September 23, 2010, 09:52:33 PM »

Man!!! I am not having any luck tuning my servos thru Galil.

I have the Galil Tools program with the scope. I can get good movement if I set the servo drives up in Velocity Mode, but in Torque Mode (recommended by Galil for positioning systems)  I get bad oscillations no matter how I setup the PID.

Anyone have any pointers? What are the best signals to watch in the scope? I have been using Reference Position vs Encoder Position and tuning till I get a nice crisp rise with a little overshoot and quick settling out. Have the movement set to 2000 increments in 300ms. I can get a good tune in Galil, then when I go to Mach and run the axis it may be ok moving fast but oscillates badly moving slowly - or vice versa.


Should I just leave it in Velocity Mode? It does seem to overshoot about .003 before settling in Velocity mode. Maybe I could tune that out, I haven't tried.

27

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: September 23, 2010, 08:44:24 PM »

Couple pics of the Y axis drive.

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Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: September 23, 2010, 08:08:23 PM »

Worked on finishing the Y axis drive. After running the axis a few times, I think it needs larger belts. Sdpi didn't have the 25mm belts in stock, so I got the 15mm wide belts. I made the pulleys wide enough for a 1" belt. I machined the pulleys from pulley stock. The gadget you see holding the pulley on the shaft is a tapered hub. Fener Drives supplied those, very nice.

I do need to change that upper idler pulley so it has grooves in it for the teeth on the belt. I can't believe how much noise the belt makes going over that flat idler.

Quick video of me testing the Y axis drive.
http://www.youtube.com/watch?v=OORg43YlVoE

29

Galil / Wiring limits

« on: August 26, 2010, 10:21:06 PM »

First off, Please excuse my complete lack of understanding of electronics   Well, I understand some basic stuff but I'm very unsure of myself and don't want to destroy a very expensive Galil card and ICM 2900.   

Ok, I need to start the wiring on my mill project and I'm having some questions about some basic stuff. I have a ICM 2900 and want to wire the limit and home switches.

Questions...  Should the wiring for the limit and home switches be hooked directly to the Galil ICM 2900 or is there some sort of optoisolation that needs to be placed in between the ICM2900 and the actual limit switch circuit? If hooked directly to the ICM, is there any built in protection to the Galil card or the computer? Do I need to provide the limit switch circuit with a external power source? Do I provide power through a pull up resistor? And if so, how is that wired into the limit switch circuit?

Any help would be greatly appreciated, Thanks

30

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: August 25, 2010, 11:54:03 PM »

Couple more pics...