Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: N4NV on December 30, 2008, 04:35:52 PM

Title: Spindle RPM
Post by: N4NV 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

Title: Re: Spindle RPM
Post by: Hood on December 30, 2008, 04:50:16 PM

I have approx 10mm on 100mm disc.
Hood

Title: Re: Spindle RPM
Post by: Overloaded 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)

Title: Re: Spindle RPM
Post by: Hood 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

Title: Re: Spindle RPM
Post by: Overloaded on December 30, 2008, 05:11:59 PM

Hmm...been tryin....5 not yet delivered     .all looks good.....maybe you try me ?

Title: Re: Spindle RPM
Post by: N4NV 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

Title: Re: Spindle RPM
Post by: N4NV 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

Title: Re: Spindle RPM
Post by: Overloaded on December 30, 2008, 05:39:36 PM

Is your Index Debounce at "0" ?
And can you verify the actual rpm of the spindle ?

Title: Re: Spindle RPM
Post by: Hood 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

Title: Re: Spindle RPM
Post by: N4NV on December 30, 2008, 05:46:29 PM

Quote from: Overloaded on December 30, 2008, 05:39:36 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

Title: Re: Spindle RPM
Post by: N4NV on January 01, 2009, 10:19:46 PM

Now that I have the spindle RPM worked out, I tried some threading.  Other than the left handed thread I made, it worked well.  You can read more about it here:

http://www.cnczone.com/forums/showthread.php?p=546099#post546099

Vince