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Author Topic: Spindle RPM  (Read 4975 times)

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Offline N4NV

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Spindle RPM
« on: December 30, 2008, 04:35:52 PM »
I am using a CNC4PC index pulse card.  The sensor is a photo transistor.  I think the problem I am having has to do with the slot with of the sensor disk.  I would like to know those of you who are using a photo transistor and a slotted disk for your RPM sensor, what slot width are you using in the disk.

Thanks

Vince

Offline Hood

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Re: Spindle RPM
« Reply #1 on: December 30, 2008, 04:50:16 PM »
I have approx 10mm on 100mm disc.
Hood
Re: Spindle RPM
« Reply #2 on: December 30, 2008, 05:01:27 PM »
Hi Vince, :)
I used this as a minimum them added a bit.
About a 5'' dia. disc w/.375" slot.
Better too wide than not wide enough.

Hood...you still Skypin' ? ?
The lights are on....but no ones home. ::)

RC 8)

Offline Hood

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Re: Spindle RPM
« Reply #3 on: December 30, 2008, 05:08:45 PM »
yep sure am RC but it has been said for a long time about me that there is "naeb'dy at hame  bar the fire an it's oot" ;)
Hood
Re: Spindle RPM
« Reply #4 on: December 30, 2008, 05:11:59 PM »
Hmm...been tryin....5 not yet delivered     .all looks good.....maybe you try me ?

Offline N4NV

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Re: Spindle RPM
« Reply #5 on: December 30, 2008, 05:14:45 PM »
My disk is 82mm.  I tried 3mm and I tried 10mm.  10mm worked better, but dropped out at 1000 rpm.  The math says it should be 7mm.  I'll try that.

Vince

Offline N4NV

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Re: Spindle RPM
« Reply #6 on: December 30, 2008, 05:34:32 PM »
So far, the max RPM I can read is equal to (slot width x100) + 100.  So at a 4 mm slot I am reading max of 500 rpm.  At the current slot width of 13mm I can read 1400 rpm max.  I have tried two different break out boards and two different index pulse cards.  I have tried setting the kernal speed in mach from 25,000 to 45,000.  At the rate this is going I am going to need a 70 mm slot width to read my max speed.  Is there some other setting in Mach that can affect the spindle rpm reading sensitivity?

Thanks

Vince
Re: Spindle RPM
« Reply #7 on: December 30, 2008, 05:39:36 PM »
Is your Index Debounce at "0" ?
And can you verify the actual rpm of the spindle ?

Offline Hood

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Re: Spindle RPM
« Reply #8 on: December 30, 2008, 05:39:57 PM »
What opto do you have? are they both the same type of BOBs? Have you tried wiring direct to the PP?
Hood

Offline N4NV

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Re: Spindle RPM
« Reply #9 on: December 30, 2008, 05:46:29 PM »
Is your Index Debounce at "0" ?
And can you verify the actual rpm of the spindle ?


I knew there was some setting I was missing.  My debounce was set at 100.  I set it to 0 and now everything works great.  I am using a 1 to 1 pulley and my VFD has an RPM display to I am able to verify the actual speed.  Thanks for all your help.

Vince