G 320 tuning w/scope

Hello all, I am in a quandry over getting to the test pins on the 320. there is a hole provided but, looking into hole i seem to see the optional jumper pins and no sign of the test pins. i'm assuming i must take my driver loose from heetsink, clear off the thermal paste, and find screws on backside in order to get off cover for hooking up the oscilloscope ? My 320's were pasted and mounted when i received them and so i haven't seen the back side, is there an easier way that i'm not seeing yet ? (chair)
Nearly forgot that any and all usefull sugestions here would be greatly appreciated, like remount with paste for testing ? this could get messy ! what else am i missing ? !

After mounting my Gecko's on my heat sinks and noticing that I couldn't access the test point, I also had to remove them from my heat sink, open each of their covers, and solder a small wire onto the test point. I wasn't too happy about it either. It looks like they did not update the case when they changed the board layout.

-Matt

Hi Mcarvey, That surely sounds like a very good idea ya got there and i just might do it, I just got off the phone with Aaron Moss of IH, and he has set me right on many naging questions i have had and some commponents i needed to get and wire in etc. butt ! His method is doing it by ear and feel and he made it sound so darned easy that i may just return my oscilloscope (channel 1 won't stabilize!) and get my money back. Then again, i may keep the scope and later when i have time i may just solder in the tag wire and see just how close the ear and feel method come to critical damping !

So does that mean that a scope is not a requirement? I know the manual gives instructions for tuning without a scope. I am proud owner of first G320! Will arrive soon, eBay for 60 bucks total!

In other words, do I need to buy a scope or not? I would like to have one, but they are a real trick to buy used, I can do without the headahe for the time being. Have most people that read this tuned with or without a scope?

Hello Halfnutz, I have talked to Aaron at IH extensively about tuning the drivers as well as other stuff and he does it by ear and feel, i have been learning this process the last two days and its not difficult. The tuning is to get it to run smooth, and what i am seeing is this = turn off damping and drive axiz full while turning up gain till it jumps, the smooth band will be noticable, then turn up some damp till best run, then stop ! I've done this a bunch lately as i adjust gibs too, then i test with an indicator to see if it looses any motion, you may do small changes with gain and damp till it sings smoothly, all without a scope. I do plan on getting another scope from Norvac today its a velleman at $140. and try that too. I feel that i'm pretty darned close tho right now and could probably leave it well enough alone, Butt ! I've enjoyed doing this tuning process so far and have learned plenty. I would like to know if the scope can be attached in another way for the tuning process, i think it can ! Maybe ? I think ' I hope well we'll see >

I tuned my motors by hand/ear and they seem to work fine. The Z axis was a bit tricky. Swinging that big ole 250# head around was a challenge but, more current, less limit, a bit of tweaking and the system is humming a beautiful tune.
I do own a scope but it's use was mainly for checking encoder outputs and checking for noise. I did intend to use the scope to tune the g320's but it just doesn't seem to be worth the trouble.
Good Luck.
Bill

Bill,
Have ya tried testing the drive with an indicator too after tuning ? I found that in increments of .1 or .01 that with a back and forth motion it could loose some motion, thats when i'd try some tweaking of driver and gibs. i don't think i'm done yet, but we'll see. once i get this done then its tramming time to get the column true to "best condion" and start making some chips. OH, still haven't hooked the hitachi up for spindle yet. Oh well, soon enough i'll be making some chips.

Great! Thanks for reply's. I will try it without a scope and see what happens!

Well, I got her moving,and tuned to a reasonable degree. At least its moving the gan try back and forth, and not losing steps, as well as settling immediately and not hunting.

The thing I'm puzzled about is the overall speed. If I connect this motor and screw combination to the 48VDC power supply I'm using directly it flies. Very fast.But the gecko, when running with Mach2 at 12500 SPI just barely moves it at a slow crawl. Of course I can get it to move faster by increasing the Steps, but then I am out of calibration. I geusse that is why the G 340 was created, but this is so slow I cant imagine being able to use it, unless I do some mechanical gearing. What I want to know, is where is all my power going? Why does the thing move so slow with the Gecko, and how do I increase the power being delivered to the motor?

Any help would be appreciated.

Any advice on how to get more power through the Gecko? I have one running but it is very slow, but if I hook the motor up directly it moves fine. Any attempt to increase speed by the gecko adjustments or by increasing the feed rate cause it to error consistantly.

I have noticed that the 5Volt supply is very sensitive to under/over powering. If the supply isn't exactly 5volts the system wont run right.

sorry halfnutz, i can't answer your question but i have another one. do you need to tune the servo in both forward and reverse? also are you tuning it witha computer hooked up or with a pulse generator? if you are using a computer i have mach 3 and what command do you give it to go forward and reverse? if using a pulse generator how do you reverse the motor?

sorry for all the silly questions
thanks
Jerry

Runner, Yes I will need to tune in both directions, but at present I am dead as I burnt up the encoder on that actuator. I am using mach3 and was able to get it to work OK, but it seemed like it was holding back, not putting out all that it had. I will try again once I replace the encoder, I must have hit it with too much power and cooked the light source. I have another one I did this too also.

Halfnutz,

I have Mach3 set up at 10K steps per inch and I can get 150 ipm rapids. The theroretical maximum I could go up to is 200 ipm with the motors and power supply I have, but that would require a 35kHz pulse rate and my computer can only handle 25kHz.

When you program a rapid move along a single axis, what is the feedrate that Mach2 shows? If it seems low, maybe the maximum speed in 'Config>Motor Tuning' is too low.

The other thought that I have is that the current limit of the Gecko is set too low. When you hook the motor directly to the power supply, it can get all the current it needs. But when you hook it to the Gecko, and if the current limit is too low, the inertia required to start moving the axis will cause the drive to fault out every time.

On my machine, I opted for a G320 because I had no use for the multiplier feature of the G340. While it does increase speed, it also decreases the resolution by the same factor. Depending on what you use your machine for, the reduced accuracy might be OK.

Make sure that the 5VDC supply is regulated.

Good luck,
Chris Kirchen