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Offline kolias

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Re: Perfect Square?
« Reply #30 on: August 25, 2009, 09:31:44 PM »


Couple things. Is the current pot set correctly on the drives to match the motors?

And What voltage are you running at?

Do the motors sound "smooth", or do they sometimes sound rough at certain rpms?

I'm in the process of setting up my router using a Xylotex drive, and on my Z axis, with 1/2-10 acme, I'm currently getting 50ipm with an accel of 7. You should be able to set your accel much higher than 2.

If the motors sometimes sound rough, you could be seeing resonance. I made a damper for my Y axis, and increased velocity from 80 to 180 with a huge increase in smoothness, and accel set at 12. Although this is with 1/2-8 2 start acme.

I'm guessing you don't have the current adjusted right, possible. Also, try running in 1/8 step mode and see if it'll let you go faster, as microsteps allow the motor to run smoother.

Don’t know what “pot” means but a few days back I posted my motor settings in another thread and Hood had said that all was ok

The drives are rated for up to 42VDC. My power supply is adjustable 12-32VDC and it is set at 28VDC. My motors take 3.0A each wired as unipolar

Motors sound very smooth to my opinion.

I have played extensively with the motor tuning and as far I can see the 32ipm, 2 accel seems to be the best setting. Motors never stall and sound good. What slides do you have? Mine were V-Grooved bearings running on aluminum 3/4"x 3/4" x 1/8” angle but due to noise I made my own slides with UHMW material. Now I have less friction and it is silent. I will experiment tomorrow with your 50ipm / 7 accel.

No I don’t have any resonance. Some times when the gandry is in the middle of my 36” long Y axis I do get a bit but if I reduce the travel speed it is not there. I’m ready to make dampers too if the need arises but so far I see no need for them

I also did try all the microsteps on my drives but the one I have now (1/2) seems to be the best. But I have no issues to give it another try with 1/8 step.

Gerry my friend you are my man, it just clicked on me……… I have had problems with my drives and had to send them back for new ones and although I did check the current setting on the original ones, I completely forgot to set the current on the new ones. I will do that first thing tomorrow

Excellent comments Gerry, much appreciated
Nicolas
Nicolas

Offline ger21

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Re: Perfect Square?
« Reply #31 on: August 25, 2009, 09:38:03 PM »
Mine are roller blade bearings on pipe.

If you find that you haven't set the current, after you set it, try the other microstep settings. Also, turn the supply up to 32V if you can. The higher the voltage, the faster it'll go.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline kolias

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Re: Perfect Square?
« Reply #32 on: August 25, 2009, 10:36:03 PM »
Mine are roller blade bearings on pipe.

If you find that you haven't set the current, after you set it, try the other microstep settings. Also, turn the supply up to 32V if you can. The higher the voltage, the faster it'll go.

The only reason I did not set the power supply to 32VDC is that I could not find a DCV meter locally with a higher rating. The one I have not is max reading at 30VDC and so I went a bit lower. Perhaps later, if I need more speed, I will scrap the meter.
Nicolas
Nicolas
Re: Perfect Square?
« Reply #33 on: August 26, 2009, 01:17:24 AM »
ger21 , kolias,

Thanks for the replies. I do lots of drawings with ordinate dimensioning, and move ucs to my views. This has always worked for me.
Solid works and other 3d programs are a different story.
Kolias, Thanks for the offer , but I don't need the info.

Ed
Ed VanEss

Offline kolias

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Re: Perfect Square?
« Reply #34 on: August 26, 2009, 01:32:24 PM »
Thanks to Gerry for the tip, I checked the current on my drives this morning and it was set to about 25% of what I needed. Then I adjusted the current to specs and now I notice the big difference; did 4 drawings and she never stopped. I did play with the microstepping but I like best the sound and feel with 1/2 step.

Now that I have more current I also adjusted the velocity / accel. To 50 and 7 and it seems good. Probably I will fine tune it in the future as I gain more experience.

The only annoying problem is the wabble I get on my 36” long Y axis. As I said when the gantry is in the middle of the Y axis I get this annoying sound like “running gears with no oil”. The lines the machine draws at this point are straight, so it does not affect the performance – just sounds like a coffee grinder.

Does anyone have an easy fix for this?

The Y axis has a single Delrin nut (see attached pic)
Nicolas
Nicolas

Offline bowber

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Re: Perfect Square?
« Reply #35 on: August 26, 2009, 02:47:16 PM »
No both bottles were only wine, but it was the last drop of the 3rd that gave me the head ache this morning ;)

I have the same problem with my router, I have used 16mm tricoidal thread and brass nuts, the thread has room to move up and down in the nut while having little movement along the thread, when it gets in the middle and spinning fairly fast you get a squawking sound as the thread flaps around (technical term) and it can even lock up my axis.

I found the best method was to split the nut and compress it somehow, I know it's not an elegant solution but it works.

A better and much nicer solution is to have a brass nut and Delrin nut, turn out half the brass one and thread, turn down the outside of the Delrin one and thread to suit the inside thread of the brass one and then you have an adjustable backlash nut that should also help with the "flapping"

A temporary solution is to oil the tread as it stops the grabbing that causes the problem.

Or

As some one else has mentioned you could also add a damper, apparently these work very well

Steve

Offline kolias

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Re: Perfect Square?
« Reply #36 on: August 26, 2009, 03:09:20 PM »
I thought that Gin was the name of the game in UK; wine is for the blocks across the channel LOL

Thanks for the tips, I will keep them in mind. I have a few of my own and working on them.

When I’m done I will post the results
Nicolas
Nicolas

Offline ger21

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Re: Perfect Square?
« Reply #37 on: August 26, 2009, 05:33:53 PM »

The only annoying problem is the wabble I get on my 36” long Y axis. As I said when the gantry is in the middle of the Y axis I get this annoying sound like “running gears with no oil”. The lines the machine draws at this point are straight, so it does not affect the performance – just sounds like a coffee grinder.

Does anyone have an easy fix for this?

The Y axis has a single Delrin nut (see attached pic)
Nicolas



I get the same sound. resonance. I added a damper and it got perfectly smooth, and allowed me a 2.5x speed increase. I'm finishing up 2 more tonight, and I'll take some more pics. Here's the first one.

http://www.machsupport.com/forum/index.php/topic,12411.0.html
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline kolias

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Re: Perfect Square?
« Reply #38 on: August 26, 2009, 06:08:42 PM »
Nice machine Gerry,

Will be interesting to see how do you mount the damper to the motor shaft
Nicolas
Nicolas

Offline ger21

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Re: Perfect Square?
« Reply #39 on: August 26, 2009, 06:16:02 PM »
I have double shaft steppers. They mount on the back.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html