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Mach 3 Spindle rpm inaccurate
« on: January 15, 2011, 07:01:18 PM »
In mach 3, My rpm dro is inaccurate and varies greatly.

I know mach x pulsing  driver was updated for faster bus computers,
Did it cause lower bus speed computers to have inaccurate rpm or inconsistency even
with single pules disk?

Even thou I have a mill, I'm interested in threading using both a 60 deg lathe
cutter in a holder mounted on the table as well as mill threading and turning
using  4 axis  control.

as in these videos as examples

http://www.youtube.com/watch?v=gUw9XKjMfUg

http://www.youtube.com/watch?v=yU_SeEvSsqE

http://www.youtube.com/watch?v=pQ83XRgRCyg

hope not to get in trouble as the links relate to my post.

    Dell Dimension 8300
    Intel Pentium 4 3.20Ghz Hyper Thread
    1 GB Ram
    Windows XP Pro 5.1.2600 Service Pack 3
    Nvidia Geforce FX5200 128MB 1024x768x60Hz

Mach 3

     Licensed Mach 3
     Version R3.042.04
     Mach x Pulsing Engines 4-11-2010
     Version 5.50.0.0
     Pulse Frequency 24998 rock steady
     Time in Int. 4.2 to 5.2
     PWM Base +140

Cnc Machine

     MaxNc 10 Open Loop 2005
     Omron EE-SX 872 Optical Interrupter
     Sensor has electronic circuit signal conditioning
     Direct connect to printer port pin 15 port 1 (no bob, 5volt + and ground from
     MaxNc stepper control board, connections are verified good.)
     5.09 volts on pin 15 active pulse window on printer port buss
     .025 volts on pin 15 no pulse window on printer port buss
     clean o scope signal


Setting

     Index De bounce = 0
     Index pin 15 port 1 enabled
     TurnDiags - 1.00.1 NOT enabled

I would like to have the spindle rpm work right so the feed will
follow with rpm, If it's possible.


Thank you.

Richard
kb7cga

« Last Edit: January 15, 2011, 07:10:23 PM by KB7CGA »

Offline Hood

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Re: Mach 3 Spindle rpm inaccurate
« Reply #1 on: January 15, 2011, 07:10:09 PM »
Two things, first for threading lathe style you will need to have Use Spindle Feedback in Sync chosen, also you may need spindle speed averaging chosen for a steady RPM to actually show in Mach, all depends on your drive setup.
These options are from Config menu then Ports and Pins then Spindle Setup page.
Hood
Re: Mach 3 Spindle rpm inaccurate
« Reply #2 on: January 15, 2011, 07:17:35 PM »
Hello Hood

Spindle Feedback in Sync and spindle speed averaging are chosen.

m3 on a S500 I get a rpm of 5800 to 5990, not good in cnc land  :(

I should be more stable and at the correct rpm, that is more than 5300 rpm off .

Offline Hood

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Re: Mach 3 Spindle rpm inaccurate
« Reply #3 on: January 15, 2011, 07:18:35 PM »
Just looked at the vids, the last one shows thread milling, you dont even need spindle feedback for that as it just needs coordinated XYZ movement.

I will see if I can find a link to Simpsons machine, think you will like that :)
Hood

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Re: Mach 3 Spindle rpm inaccurate
« Reply #4 on: January 15, 2011, 07:19:46 PM »
You didnt have them chosen in the xml attached, are you meaning you have just tried them and its no different?
Try a small amount of index debounce then, 1 or 2 and see if that helps.

Hood
Re: Mach 3 Spindle rpm inaccurate
« Reply #5 on: January 15, 2011, 07:23:58 PM »
I do intend to thread mill soon when i can get the cutters, but for now, I was going to
use a 60 deg lathe cutter in a vice on the table like in the vid link I sent.

I just tried them with no difference. trying the debounce now.
Re: Mach 3 Spindle rpm inaccurate
« Reply #6 on: January 15, 2011, 07:29:50 PM »
 just tried a debounce change, here are the results.

start with m3 s500

bebounce 0  =rpm 5800 to 5990

bebounce 1  =rpm 117 steady

bebounce 2  =rpm 117 steady

bebounce 3  =rpm 117 steady

does the debounce interval affect any thing?

Offline Hood

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Re: Mach 3 Spindle rpm inaccurate
« Reply #7 on: January 15, 2011, 07:32:15 PM »
The steady 117RPM, is that the correct speed?

Debounce Interval is for all other inputs other than Index.

Heres the vid I was talking about earlier.
http://www.youtube.com/watch?v=NzY-OqckqpI&feature=autoplay&list=UL1xv603HHs3U&index=9&playnext=1

Hood
Re: Mach 3 Spindle rpm inaccurate
« Reply #8 on: January 15, 2011, 07:44:07 PM »
Cool video.

m3 s500 should give rpm of 500.

I don't have the option of mounting lathe tools on the spindle head as the stacked bearings
are in the way. cool move thou.

have a look at the second vid like in my post as it the same setup as I'm trying.

Richard

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Re: Mach 3 Spindle rpm inaccurate
« Reply #9 on: January 15, 2011, 07:46:33 PM »
Yes, have seen that before, also quite a few other similar ones floating around.

Ok so the Index debounce  is obviously not helping, not sure what else to suggest as its not normally a problem getting a speed reading.

What dia of slotted pulley do you have and how wide is the slot?
Hood