Messages

1041

General Mach Discussion / Re: Perfect Square?

« 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

1042

General Mach Discussion / Re: Perfect Square?

« 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

1043

General Mach Discussion / Re: Perfect Square?

« 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

1044

General Mach Discussion / Re: Perfect Square?

« on: August 25, 2009, 08:57:50 PM »

ger21,

Question for you. I've also used Autocad for 10 years since acad 14. If you have a drawing with 3 or more views ,
 how do you do ordinate dimensioning without moving the UCS to each view? I've learned cad on my own, and I know theres lots I don't know, so please clue me in.

Thanks
Ed

Sorry Ed but I can’t help you right now

During my working years I definitely knew much more than now but I was never an ace in Acad. I just knew enough to assist my clients. It has been almost 10 years since I touched Acad and I only started last April when I got interested in the CNC.

I have all the manuals for V12 and looking up the subject I found an exercise with 14 pages describing how to do ordinate dimensioning in a machined bracket. I don’t have a flat bed printer to scan the pages but if you want I can take a picture of each page like the sample attached and send them to your email.

If you agree, I can’t do it before the weekend.
Nicolas

1045

General Mach Discussion / Re: Perfect Square?

« on: August 25, 2009, 07:26:06 PM »

Unless someone has a machine that is identical to yours then no one can say what your settings will be, just too many variables.
 Your velocity and Accell seem reasonable, not fast but again not that bad.

When it stops do the motors just squeal?
 Do your motors get hot?
Do the drives get hot?

Hood

Now I understand and its fine, I will manage one way or another the motors settings. Thank you for commenting on the Vel / Accl, at least I know that I'm in the ball part

Yes the motor squeal, I'm not sure but I think is only one motor that stalls, either the X or Y

Never touched the motors or drives so I dont know if they are hot. I will verify tomorrow.
Nicolas

1046

General Mach Discussion / Re: Perfect Square?

« on: August 25, 2009, 06:10:27 PM »

Decreased the velocity on X & Y to 35 and did what is in the pic. Better than before but stopped in the last couple inches of the code (see attached)

No drop in the voltage

Can someone tell me if my motor settings looks reasonable or there is not such a think as reasonable?

There is no other method except by trying to set the motors to an optimum setting?
Nicolas

1047

General Mach Discussion / Re: Perfect Square?

« on: August 25, 2009, 04:40:41 PM »

Looking at the axis settings your on inch's, 36" <m/min so I would have thought that's ok and Acc 2! Does it ever get upto speed?

You may be hitting soft limits, do you zero the axis and is the table size setup (can't remember which tab that is).

Normal use is to have the table size setup and have the soft limits on. Zero axis (ref all) before doing anything when the machine is first turned on.
You then clamp down you stock and drive the axis to a point you determined in your cam, usually bottom left, and press each button to the left of the DRO.
You should then be able to look at the table view to the right and it will show a white line around with you gcode lines in blue, if these blue lines are inside the white line you will be fine, other wise you'll get a warning that your code goes out of the table limits.

I'm quite tipsy at the moment on our second bottle so hopefully I've said it all right

Steve

Guess the second bottle must be Gin, cheers to you mate....

To my opinion it does get up to speed especially when she makes circles she is pretty fast on the X & Y axes. As for the rest you described all is done correctly.
Nicolas

1048

General Mach Discussion / Re: Perfect Square?

« on: August 25, 2009, 04:34:12 PM »

Ah ok so its only when you are running code? If so then what happens if you jog two at once or MDI a two or three axis move?
 Check your power supply is not dropping in voltage when moving axis together.
Hood

Yes it only happens when I run code. I did a simple square code and it was fine. I did the dwg RICH told me yesterday (Square, Triangle & Circle) and it was good but when I do a dwg I made which has a lot of half circles inside a square it gets stuck half way thru (file attached).

When I jog 2 axes at once, all works well. MDI also works well

Never payed attention to the DCV meter I have to see the voltage. I will have a look and post back results.
Nicolas

1049

General Mach Discussion / Re: Perfect Square?

« on: August 25, 2009, 03:28:02 PM »

Acme screws will have a lot of friction compared to ballscrews so it could just be that your motors are not big enough. Try reducing the velocity and accell and see if it helps.
 Hood

But why the axes work fine when I jog the motors and they get stuck "SOMETIMES" when I make a drawing?

I will try reducing the vel & accl as you said
Nicolas

1050

General Mach Discussion / Re: Perfect Square?

« on: August 25, 2009, 02:42:30 PM »

What kind of drives are you using?

Sorry Gerry dont know what you mean by "drives"

Motors are Keling stepper motors with 8 wires and wired as unipolar

The 3 drives for the 3 motors are Probotix  http://www.probotix.com/stepper_motor_drivers/ProboStep/
I have set the steps on the drives to half step and in mach (steps per) to 4000
Hope that is what you want
Nicolas