[Runner4404spd]

i've been running my IH for a while now and it seems like the x and y are doing fine. the z on the other hand is giving me some fits. i had tuned the axes by ear initally and they seemed to work ok. i recently went back and tuned with a scope and tightened things up.

my mach settings are

x acceleration 9 top speed 120
y acceleration 9 top speed 120
z acceleration 7 top speed 100

on my geckos i have the limits on x and y set to 75% and the z limit is set to 100%.

the damp and gain for the z axis i had to reset really low in order to not get any oscillation when sitting idle. then when i moved i had to lower it some more. not really a problem, or so i thought. i finally got it to a position where it would move quietly on the z axis and i thought i was good. went to run a program and the z axis faulted. (i have a built the circuit specified in the gecko manual with 3 leds and 3 reset switches. this way i know what faults and it also triggers an e stop so the whole machine stops when a fault occurs.) anyway, i reset the fault, rehomed and re ran the program. almost at the same spot in the program, i smelled a plastic burning smell and shut the machine down. the smell seemed to be coming from the z axis motor.

so now i'm back to square one on figuring out where my problem lies. the program that the z motor got really hot running was a simple side milling application where it would hold position then step down in .075" increments. so there is clearly something going on here. i am starting to wonder if the drive itself isn't bad? tomorrow i will be adding capacitors to the encoder inputs, as well as a capacitor across the power input to the geckos. other than that i'm kind of at a loss for why this is happening.

[Al_The_Man]

See this thread also.
http://www.cnczone.com/forums/showthread.php?t=96488
Al.

[Mariss Freimanis]

Runner,

That isn't good; you will hurt your motor.

Disconnect the motor from the load (remove the toothed belt or coupling to the machine). Run the motor and see if it still gets hot.

Motor stays cold: This means your motor is OK but it is miss-geared to the load. A mechanical overload is heating the motor. Increase your reduction ratio because you are exceeding the motor's continuous torque rating.

Motor stays hot: This means either your motor is damaged or your motor inductance is too low.

Mariss

[Runner4404spd]

I apparently didn;t catch it in time and the motor is smoked. i will need to order another one tomorrow. these motors are sold as part of the IH kit and should be more than capable of moving the head assembly. i'm slowly working through the issues of this kit and using it as a learning experience. alot of the issues come from an inexperienced assembler.

[BobWarfield]

My Z was definitely the most finicky servo to tune on my machine.

I'd be a little bit careful not to "over tune" the Z. Give it a little margin for error.

Also, I run the gibs pretty tight. My machine will fault pretty soon in the morning if I forget to give it the one shot oil. Don't know if you have one shot, but the Z seems very sensitive to needing lube!

Cheers,

BW

[Runner4404spd]

My one shot oiler was working, i do have an automatic oiler on my mill. the system cost about $600 but it was well worth it. it constant circulates oil into the ways. i forget the actual cc output but its pretty low.

i received my new 850 oz/in motor from keling inc today and will be installing it tomorrow. i'm going to steal your install technique bob, i just need to make the right height adapter. i also need to remove the encoder and the top plate of the z axis so i can remove the stock 640 oz/in motor.

[Cruiser]

My experience with a warming servo on my IH was mostly due to two things.
One was the gib was tooooo tight !
second was the gain & damping was involved to an extent that the motor was more like in a state of stall while at rest. This is obvious if you can hear an audible buzzing of the motor while at rest. I backed off till the motor went quiet and the motor cooled down right off. If the gain and damping is too involved the motor can get quit warm even when disconnected from machine. This is referred to as being set "too tight".
When I reset my drives, I will adj while in motion then sit there and listen to the machine while at rest and if any audible clicking is noticed I will just nudge the drive back till it goes to near perfectly quiet and If I hear maybe one click per Minuit I may just put incremental movement in one direction or another and see if click goes away. If it is for the most part quiet at rest I say it is done. Then, I set the accel / decel and velocity rate in mach for a suitable performance. The accel / decel is best left in the range where you can just barely hear it accel. If you go for instantaneous accel you are likely pushing the limits too much. 5to7 for z and 7to9 for x and y is a good range, and should make for a smooth running machine. I tried tuning with a scope and always ended up reducing it to quiet ! Hope to be of at least a little bit of help. If not I like to hear myself once in a while just to make sure I'm still alive.
My present task is to correct an initial mistake that I made. I am dropping my 2 pole motor for a 4 pole and dropping my L200 for an SJ200. I am looking at obtaining usable low end torque and a higher top end. It is proving to be a bit of an expensive change over but well worth it in the end.

[Mariss Freimanis]

Cruiser,

I think you are finding out servo systems need more care and attention to details than a step motor system. The performance is better but it comes at a price.:-)

Mariss

[Runner4404spd]

The input is always welcome cruiser. i had a silent servo until i decided to follow my own greediness and get a tighter setup. my x and y accels are set at 9 and it likes running there. the z before i messed with it was at 7 and it liked running there. i am going back to those setting with the new servo and i will post a follow up tomorrow after i get it working.

[Cruiser]

Runner, Its been many mornings since your last post on this subject !
I'd like to add one more thing to the equation that I have posted many times in other threads, and I am sure you saw it but !
Early on while setting up my machine I suffered with the setting of the gibs, versus the morning sticksion and the drive wanting to stall and fault out. I inspected my slide-ways and found some hot spots and gently stoned them. That is when I remembered the moly lube that I had somewhere. I cleaned the slides of the machine with solvent and found my moly and a piece of leather and rubbed in the moly so a stain was left behind, it is a faint stain but stain non the less. I then gave it a squirt of oil on top of each slide and run the machine to other extent and repeated. What I found is that I could increase my gib tension, increase the drive setting (accel) and had no more morning sticksion issues. I did however put the accel settings back where they were, it was just for testing. The moly will effectively cancel out the affinity of similar metals wanting to bond with each other in motion. It will last for a very long time if rubbed in, and will also assist the oil to hold a film on the surface of slide-ways, without being dried out during use.

[Runner4404spd]

Cruiser thanks for posting. i went and reinspected my ways, just so everyone knows i have one of the first new style mills. my x and y axis are ground but the z wasn't ground. it looks like the z axis was put in with a hammer and a chisel. its not even close to smooth. i think this is what was cuasing my problem from the get go. i did lap the ways, but probably should have done more on the z axis in the beginning. i did follow the steps aaron had on the website for lapping. anyway, i ended up switching motors, got it tuned in by ear and then i tightened the gibb like i normally would. i think for 5 days ran the axis up and down at rapid speeds and faster acceleration (12 as opposed to 7 or 9) after a few days of running i noticed the gibb was looser so i tightened it back up and ran it some more. the ways were lapped together and are now much smoother. this machine is definitely a work in progress but its coming along nicely. i've been cutting parts on it and its doing really well and repeating really well. the only thing i've had issues with is the z axis, partly this is my fault on assembly and tuning and partly that i got an early mill that wasn't completely ground, (i bought at the going out of business sale with no warranty implied.) anyway, i am happy to report that everything is going well and i will try and post some pics of the projects i'm working on. next will be a power drawbar to work with the 30 taper spindle. after that i will be working on an ATC.

[Cruiser]

The great thing about this iron is that it will break in, smooth out, and get better with time as long as a bit of TLC is applied and all is kept tuned. I have found that occasionally a bit of touch up is required with the gecko's as the iron smooths out. Mine is staying very consitant now that it is nearly run in, and the slide ways that I incorporated are doing their job and keeping load off of Z gib. Mine recently required some tightening up as it seemed to have become quite sloppy somewhere along the line. I was amazed as to how much it had loosened, I had to take up the rail adjusters a lot then almost as much with the gib.