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331  General CNC Chat / Show"N"Tell ( Your Machines) / Re: 9x20 Chinese Lathe Conversion on: July 21, 2012, 02:02:42 PM
Hi Hood,

I was not able to tune the spindle Sad Just looks like the Ultra 5000 has the wrong parameters for tuning a servo. Can't get it hold position and be stiff at the same time. Either can get it position tuned or be stiff. Put in an AMT programmable encoder instead of the original 1000 ppr one the other day. Set it to 2048 ppr and tried to tune it. Had only less than an hour to play with it, but it didn't feel any better. In fact may be even worse, but I am not sure. The belt, although pretty tight, starts behaving as a musical instrument string when I try to increase the position gain. And in the same time I get overshoot on position. The point when I am happy with the position gain and there is no overshoot, the spindle loses stiffness completely.

Regarding the plugin, yes, Greg sent me a version with quadrature signal for the spindle, but he said he didn't think it would solve the problem we were experiencing, but it would be nice if it did in some way. If you like to play with I can send it to you. It works very well here, and in spite of what Greg said I haven't been able yet to get any symptoms of the problem we were seeing with the spindle. SRO seems to be working fine as well as CSS. But I only had a few minutes to play with it.

Dan

Dan
332  Mach Discussion / General Mach Discussion / Re: Minor Threading Problem on: July 15, 2012, 01:47:28 PM
Hi John,

The number you arrived at seems to be right based on the mathematical formula for a 60: DOC = 0.5 x Pitch x tan60 ≈ 0.866 x Pitch ≈ 1.3

Dan
333  Mach Discussion / General Mach Discussion / Re: Minor Threading Problem on: July 15, 2012, 11:47:53 AM
Hood, I think it would depend on the tool tip radius. John's probably sharper (smaller radius) than yours.

Dan
334  General CNC Chat / Show"N"Tell ( Your Machines) / Re: 9x20 Chinese Lathe Conversion on: July 13, 2012, 12:48:50 PM
Thank you for sharing, Joe.

Dan
335  General CNC Chat / Show"N"Tell ( Your Machines) / Re: 9x20 Chinese Lathe Conversion on: July 13, 2012, 02:41:25 AM
Just watched your videos. You have one huge workshop there... and it looks so clean in the same time... I liked it. The lathe looks good too. In my opinion, with the Chinese stepper drivers, the motors or louder as compared to Gecko. And speaking of this, I would love to try out Granite Devices drives with stepper motors. They claim that they drive the stepper with a sine wave and I think it would make the motor run quieter and smoother. However, their drives are a bit expensive.

Dan

336  General CNC Chat / Show"N"Tell ( Your Machines) / Re: O3N250 on: July 10, 2012, 02:18:16 AM
You did a good work with screen set, Peter. I like the look.

Dan
337  General CNC Chat / Show"N"Tell ( Your Machines) / Re: O3N250 on: July 09, 2012, 02:41:03 PM
Looks good! Are you using a Pokeys or how did you implement the knobs?

What's the screen set you have there?

Dan
338  General CNC Chat / Show"N"Tell ( Your Machines) / Re: 9x20 Chinese Lathe Conversion on: July 04, 2012, 02:49:35 AM
You mean it fully stretches and contracts with the nut move? That's nice.

Dan

339  General CNC Chat / Show"N"Tell ( Your Machines) / Re: 9x20 Chinese Lathe Conversion on: June 30, 2012, 11:21:10 AM
Found the problem finally Smiley!!! It appears that Autotuning is seriously broken in the Ultra 5000. Once you have used this feature the drive goes crazy and is virtually impossible to tune. After using the Autotuning you have to reset the drive in order to get things back to normal.

No this crazy buzzing has stopped for me and I can at least try and tune the system Smiley

Dan
340  General CNC Chat / Show"N"Tell ( Your Machines) / Re: 9x20 Chinese Lathe Conversion on: June 30, 2012, 12:50:08 AM
Ah... no, it's the same with the 5000. Also have the step current there, but again no matter what (changing the step current as well) the autotuning gives same parameters.

I tried the inertia thing and it didn't make any difference at all.

I went back and removed the belt and so tried to tune the motor alone, but interestingly I was not able. Exact same values that worked for me before, didn't this time and I couldn't tune it any better than with the chuck together. Really have no clue what's happened.

Dan
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