Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Dbl_Tap on May 25, 2013, 01:16:18 PM

Title: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 25, 2013, 01:16:18 PM
I recently received a Chinese CNC http://salecnc.com/catalog/product_info.php?cPath=21&products_id=59&osCsid=gosj62io17t8qoku4tp0ti1704 (http://salecnc.com/catalog/product_info.php?cPath=21&products_id=59&osCsid=gosj62io17t8qoku4tp0ti1704) the XJ 1325.

I have switched over to Mach3 because of the endless issues I was having with their software and controller. I switched using a CENTIPEDE controller etc http://ksilabs.com/ (http://ksilabs.com/) and Sergey has gone above and beyond helping me switch over the boards, even helping me reprogram my VFD to work properly and I am 90% of the way there.

The problem I am having is I'm definitely losing steps so I need to tune but the Chinese salesman knows almost nothing about the technical aspects of the components. He was able to give me the steps, at least he says they are the right ones, but beyond that they are no help. And when I ask about Step Pulse and Dir pulse they have no clue what I'm even asking.

So far what I know is I have:

X & Y steppers are 96.01536 (they called them pulses)
I have two motors on the Y
Both X&Y motors are 86BYGH450B-060-15J and are 1.8 deg pitch
The Z step is 160, 1.8 deg pitch same motor part number but ends at the B. Nothing I can find shows this part number with nothing after it but the motor shows it is 4.3A 0.55Ohms  6.0mH

Sergey at KSILabs modified my XML and it is working a little better than what I had but on the last thing I tried cutting the Z cuts kept getting progressively deeper and suddenly plunged down about halfway through the board.

Any help at all would be greatly appreciated. I've had this ,machine for 3 weeks now and haven't been able to successfully use it yet.
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 25, 2013, 08:04:50 PM
Can you attach the xml you are actually using so I know I am looking at the correct config :)
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 25, 2013, 08:37:02 PM
Hood, did it not attach?
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 26, 2013, 03:47:42 AM
I was under the impression that was the one direct from Sergey that you attached. I really need to see the one you are using as it may have slight differences in it which would mean I am looking at something that may or may not be on your system.
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 26, 2013, 01:47:22 PM
He took mine and helped me modify it so I am using it. He fixed some things I had done and it is working better than my original configuration but it wasn't his file.
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 26, 2013, 03:51:15 PM
I'll paste what Sergey said after looking at my config file:

"Your axes settings -- those look totally bogus to me. First of all
motors turn very slow at their max speed. Something's fishy here -- either
steps per inch are wrong or maximum speed is way too low.

Acceleration, on the other hand, is simply astronomical :) No wonder you
motors are loosing steps. And it was kinda like infinite on Z axis so it was
supposed to go zero to sixty in zero seconds...

I put some rather conservative values there and made X axis a bit faster (Y
and Z are left where they were) so you could be able to test and compare
them.

For acceleration your first shot should be at axis accelerating from 0 to
full speed in something like half second. You can clearly see this time in
Motor Tuning dialog when you drag that horizontal "Acceleration" slider.
Then, if it worked, you can start gradually increase acceleration until your
machine started loosing steps. At this point you back off a bit and you have
your system set for maximum performance. The same is also true for speed."
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 26, 2013, 05:01:59 PM
Ok but the xml you attached has the last user as Sergey Kubushyn so unless you have Sergeys licence file then that is not the xml you have installed but rather the one you got from Sergey.
There is no point in me looking at that xml as I do not know if it is exactly the same as the one you are using at the moment.
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 26, 2013, 05:20:11 PM
I called it that so I would be able to switch to another one with a similar name if it didn't work. If it makes it less confusing I can remove the sergey part from the name of the file but it is the one I'm actively using
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 26, 2013, 05:39:03 PM
Ok thats better, it wasnt the name you called it, it was the info in the xml that said Sergey was the last user whereas this one has you as the last user so it is a different file. I have also just checked and there are differences between the two files, in particular the Z axis settings.
That is why I was wanting the file you are actually using as it means I am not looking at something that is different to what you actually have loaded.
I will look through the xml  more thoroughly in a bit and see if I can find any issues.
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 26, 2013, 05:40:43 PM
Thanks Hood. I just hadn't changed anything in it while using it last time. I did right before attaching it this time.
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 26, 2013, 05:41:06 PM
This is probably related but what could be causing the following in the attached picture?

In the bottom cut zero was just above the plywood surface and marked at 1st zero. As it cut the z got progressively deeper a small amount each line until it plunged deep. Once I stopped it and hit go to zero it moved to the spot marked zero after and was buried in the wood.

2nd try at cutting I lowered the Z velocity and let it go. It was still cutting just barely deeper each pass until it plunged and continued. When I sent it back to zero it went to the spot marked zero after and again buried in the wood. It did not run as far before unexpectedly plunging but I expected it to zero in the wrong place to the right of my 1st zero not the left of it.

Could it be velocity causing to to be off like this?

If so that still doesn't explain the plunging at random points in the same unchanged g-code file.

(edit: offending attachment removed, thread should be fine again - scottn)
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 27, 2013, 03:07:25 AM
Something wrong with this thread as I am not able to view the last responses, so not sure if this will show correctly.

Does your machine have servos or steppers? Do you have any information on the drives/motors? I looked at the site you linked to but good info is sparse.
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 27, 2013, 12:01:40 PM
Scott fixed it.

Steppers and the part numbers are in the first post.

I Did a simpler cut yesterday and it went much better. It was supposed to be 8" tall (y axis) and 6 1/4"wide (X axis). Ended up 8" exactly tall but 6 3/8" wide.

Going to try cutting it several more times to see how it does.
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 27, 2013, 01:41:08 PM
Ok easiest way, assuming you dont know the pitch of the screws or microstepping of the drives would be to use the Set Step button on the settings page. It will be as accurate as your measuring so if you have means of measuring accurately then you will get close.
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 27, 2013, 04:18:39 PM
Just got back from work so I'm going to give it a shot.

The spec sheet I was able to find for these steppers says the screws are 1.8 degree pitch.
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 27, 2013, 04:31:15 PM
I think that will be the motors it is referring to rather than the screws. Steppers are usually 1.8 degree or in other words 200 steps per rev.
But you also have microstepping in the drives to take into account and then any gearing plus pitch of screws.
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 27, 2013, 04:47:34 PM
Ahh, I'm learning more as I go along. My tech guy tells me if I can figure it out I can probable get the micro steps engaged and get even more precision but I'll wait until I get this nailed down first.
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 27, 2013, 05:26:26 PM
I would imagine your drives already have the microstepping set, depends on the drives but usually the Chinese drives have adjustable microstepping and it is set with dip switches.
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 27, 2013, 05:43:25 PM
oK, Maybe this is a stupid question but if I have metric steps from the CNC sales person and I have mm selected under "Select Native Units" when I run the step calibration and it asks for the distance to travel is it asking for mm?
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 27, 2013, 05:48:38 PM
Yes, basically it is asking for distance in Units, so if you are set in metric then a unit is a mm, if set Imperial then a unit is an inch, if its a rotary axis then a unit is a degree (well normally on the rotary, could be a rev depending on your setup )

Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 28, 2013, 01:01:46 AM
Well I wish I had noticed that setup menu before, would have saved me a lot of time :) Now I have got the X & Y tunes really nicely but I found my real problem; the Z axis binds as it moves up and down. My computer is about 10' away from the spindle so I didn't notice it til I was manually jogging the spindle up after it buried itself in the project yet again. As I was watching I could see it stuttering as it moved up and when I ran it back down it stuttered again.

So Now I get to pull the whole danged Z assembly apart and try and figure it out.

What is the best way to measure the two round bars it moves up and down on to see what needs to be adjusted?
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 28, 2013, 01:06:49 AM
Here are a couple pictures with the spindle removed. Even with the spindle out it still binds as it moves up and down.
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 28, 2013, 03:38:07 AM
I suppose the easiest method which is likely owned by most people is a digital caliper. If you hold one jaw on the ball screw and have the other on the outside of one rail, you can then measure at varing positions to get it running in line. You would likely be best to have a shim of some sort between the jaw and the ballscrew so that you are sure you are not measuring slightly in one of the ball tracks. If you then get one rail set that way and then the other then that should get things aligned pretty close.
 Of course that method will only work if you are sure the ball screw is actually in line in the first place, so it may mean you have to readjust the whole lot a second time.
 What I think I would do is set it up as described and then place a Clock (DTI) on the base with its needle against the Z  then raise the slide and see if the needle stays constant, if not then it shows you need to adjust the whole lot again to offset things.

Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 28, 2013, 05:24:19 PM
Thanks Hood. Before I get too much further into pulling things apart, could being too slow on that axis cause it to hang up? THat's what the sales guy in China that didn't understand anything about Mach3 when I needed specs is saying now that I'm saying there is an issue with their setup.
Title: Re: I could really use some help with motor tuning...I think
Post by: Hood on May 28, 2013, 05:28:29 PM
Unlikely, especially as you have steppers. Steppers produce the greatest torque at standstill and it drops off with speed so the slower you go the more torque you have. If going slow is stalling the stepper then going faster will just make it worse.
Hood
Title: Re: I could really use some help with motor tuning...I think
Post by: Dbl_Tap on May 28, 2013, 05:29:26 PM
That's what I thought, thank you :)