Messages

71

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 31, 2011, 08:16:47 AM »

WOW! Awesome Ebay Find Hood!

So you use the smooth stepper with that sucker? Wow i bet it really flys!!!

72

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 31, 2011, 07:39:53 AM »

What drives do you have that will handle 2.5MHZ??? That's crazy! It seems i don't really have a choice. Like you said if i did a multiplier of 1 (instead of 4) that would absolutely kill my speed and require a lot of bandwidth (4 times more). The machine works really well how it is, so i can't complain at all!! The resolution is amazing, and i cant complain about the speed cause for how big it is, its speedy!!

I have these servos:
http://www.kelinginc.net/KL34-180-90.pdf

According to this cnc machinery building manual by Siemens, many power supply builders will go 10-15% higher voltage to accommodate like you said for lack of efficiency, voltage drop over long wire runs, etc. I do however have the amperage below the maximum.

Let me know what drives you have. They sound expensive haha.

73

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 30, 2011, 09:09:34 PM »

I think i will keep it @ 4x. It seems to give me a good amount of speed and the resolution as you stated is very very small.

I also remembered the "top speed" in the servo spec sheet is listed @ 3200rpm @ at a voltage constant of 90VDC. I have a 105VDC power supply.

That is an additional 16% voltage, which i have been told by a few industry professionals is a common practice to do.

If voltage and speed are a perfect linear relationship then that would mean i would have an extra 512RPM, giving me 3712rpm max.

What would my new servo max speed be if limited by my driver? I tried to do the math but it gives me a funky number in return.

Larry says-
"I don't recommend a 1X setting as the drive error is usually a few counts. 4X  gives the same resolution as the Line count.
since 1000 line, and with quadrature they are 4000 counts per revolution,"

So even with 4x setting on, i am still getting 4000 counts per revolution or only 1000?

74

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 30, 2011, 07:48:24 PM »

Larry saved the day again! He confirmed what we thought. It was set to 4x.

With no jumper on , you set the j command in the drive.
With jumpers on the j setting is set by the jumper.

EG : with no jumpers on, j5 sets 5 encoder counts/step.

I don't recommend a 1X setting as the drive error is usually a few counts. 4X  gives the same resolution as the Line count.
since 1000 line, and with quadrature they are 4000 counts per revolution.

75

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 30, 2011, 06:32:01 PM »

Page 30 for commands and 32 for step multiplier.
http://www.larkencnc.com/dloads/viper-manual.pdf

Would the "enter step size" command be what i need to look @?

76

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 30, 2011, 06:29:12 PM »

*i had no jumper (sorry typo)

77

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 30, 2011, 06:28:25 PM »

AH HA! Look what i found. Remember how i said i had jumper in the step multiplier?
Well apparently programmable step multiplier must not mean 1X. Below it states "any size"!
It must be a default setting in the drive that i have to configure i bet.. I cant find the command to do it though.
You have to use hyper terminal and RS232 to program the drive.


-  1 ,2 ,4 ,8   s te p   mu ltip lie r  (o r  a n y  s ize

78

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 30, 2011, 06:09:32 PM »

In the Viper manual it does state this:
125Khz max step rate.

"The viper can handle up to 625Khz
encoder frequency (assuming good cableing )"

Even more confused!!

79

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 30, 2011, 06:03:54 PM »

Support from US digital got back to me today. I have 1000Line count encoders, with 4000 quadrature counts.

"The "CPR" or counts per revolution is the number of lines on the disc. The "PPR" is the number of pulses in quadrature (x4) it gives per one revolution".

Regardless if i use a smooth stepper or parallel port my Viper drive max is 125Khz.

That means my servo speed max would be 125,000khz / 4,000 pulses per revolution x 60 =1875 RPM

My X and Y axis both have a 10:1 gear reduction so the output gear would turn @ 187.5 RPM.

The Z axis has no gear reduction and is linked to a .1" pitch lead screw: 1875 rpm x .1" = 187.5 ipm max.

My Y axis has a 1.25" output gear. 187.5RPM x 1.25" x 3.14 = 735.9375 IPM MAX.

My X axis has a 1" output gear. 187.5 X 1" x 3.14= 588.75 IPM MAX
-------------------------------------------------------------------------------------------------------
Max servo rotation speed: 1875RPM with 1000 line encoders @ 4000 counts per revolution in quadrature. 125Khz, limited by driver.
X axis: 588.75 ipm
Y axis:735.9375 ipm
Z axis: 187.5 ipm

These are my current mach setttings: They don't seem to match what i have calculated.
X axis: 3191.931756 steps per inch @ 700IPM (10:1 gear reduction) (1"output gear *i think*) (1000CPR encoder)
Y axis: 2491.704346 steps per inch @ 499.98IPM (10:1 gear reduction) (1.25" output gear *i think*) (1000CPR encoder)
Z axis: 10,040.73425 steps per inch @ 49.998IPM (No gear reduction directly linked to lead screw) (1000CPR Encoder)

80

General Mach Discussion / Re: Mach 3 Driver test. Results for 3 computers, which is best? (PICS)

« on: March 30, 2011, 09:28:59 AM »

I will be machining aluminum sheet/plate.

OOO so take all those numbers then divide them by 10 i see. opps!

1000 Line encoders (4000 count quad)
X: 1"/ 4000/10=.000025"
Y: 1"/ 4000/10=.000025"
Z: .1"/4000/10=.0000025"

Since the Y axis has a 1.25" gear instead of the 1" gear how does that affect things?