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Author Topic: Spindle RPM feedback, not low enough.  (Read 14243 times)

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Re: Spindle RPM feedback, not low enough.
« Reply #40 on: January 27, 2013, 07:32:07 PM »
Hey Katoh, I was playing around with my little MicroMill today and hooked up a C3 index card.  It works great all the way down to 36 rpm.  Below that & my KB speed control gets jerky.  36 rpm is VERY slow by the way!  The top speed is a bit under 3100 but I'll get it up a bit higher later when I take the back cover off the enclosure and dial up the top speed pot on the KB.  They have quite a bit of adjustment range and I don't think I'll hurt the motor running the spindle at 4000 or so since my cycles will be short.

I checked the accuracy by warming up the spindle/motor/control for 10 min or so and carefully adjusted the pot (the mill has a manual speed control pot) to 60 rpm.  I  clicked on my stop watch and counted the hole in the disc going by a mark 60 times and clicked off the stopwatch....just about dead nuts 60 seconds showing.  Haven't checked the top speed with my digital tach yet but I'll bet it's right on.

At 35-40 rpm the LED on the diag screen pulses every 2nd or 3rd rev even though the C3 LED is dead solid so what Hood said about Mach/screen refresh is definitely true (as if there was a doubt if Master Hood pronounced it to be so.) ;D

I cut down a CD to 3 1/2" and drilled a #12 hole about 3/16" in from the edge of the disc to the center of the hole and painted the disc black.  I couldn't tell any difference between 0 and 1 on the debounce setting.  I'm using the parallel port on an old Dell P4 800mhz and a cheap, non opto-isolated B.O.B.  My ORAC lathe has a CNC4PC C11 B.O.B. with a C3 index card and it works great down to a crawl as well.  I have tested the top speed on it with the tach and it's within 10 - 20 rpm at 2000.
Milton from Tennessee ya'll.

Offline RICH

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Re: Spindle RPM feedback, not low enough.
« Reply #41 on: January 27, 2013, 08:07:23 PM »
Dickeybird,
Thanks for taking the time and posting as I have been out and about for a number of days.
RICH
Re: Spindle RPM feedback, not low enough.
« Reply #42 on: January 27, 2013, 08:32:04 PM »
No prob Rich, it feels pretty good for a change to successfully get a project working that I set out to complete.  Pretty simple stuff to ya'll but dangit, I can find more ways to screw up things!!  I'm sure next weekend I'll be back to business as usual. ::)
Milton from Tennessee ya'll.

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #43 on: January 29, 2013, 07:25:39 AM »
GDay Dickeybird, Rich
Sorry for some reason I never got notification that you had posted. weird?
Dickeybird if I bypass the BOB I get much the same results as you, which only points to the BOB. I'm waiting to here back from Peter Homman to see if he can shed some information on this or maybe he has a special pin that needs to be used or some other setting that needs to be set. But without going through the BOB I get an accurate reading anywhere from 41 to 2000rpm tested fine but I still need a index debounce of 5, not to shabby I thought. Considering I had to add a cap to a few inputs to stabilize them, its not to bad.
Cheers
Katoh
Cheers
Katoh

Offline otpco

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Re: Spindle RPM feedback, not low enough.
« Reply #44 on: February 02, 2013, 05:49:43 PM »
Katoh have you heard from Peter yet

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #45 on: February 03, 2013, 01:09:14 AM »
No all quite on the southern front! Maybe he's on holidays still?
I don't really want to go cutting and moving single cables yet,to bypass the BOB especially if there is an easier work around,
Cheers
katoh
Cheers
Katoh

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #46 on: February 07, 2013, 01:17:57 AM »
Gentlemen
It has come time and cannot wait any further, so I took the easy fix method. I removed the parallel port cable from the BOB and and simply removed cable 15 and the last common cable, drew them back through the plug and simply bypassed the BOB.
I reconnected the the opto cables to those I removed, but I re-connect to the Bob only the common, just to make it common? Does that make sense?
Anyhow with the Index debounce value of 1 I have accurate rpm feedback from 41rpm to 4000rpm. Fantastic that's all my wiring done! "hooray"
Now I'm simply left with two jobs on the lathe itself, one being the cover for it, and the other looking at coolant. Once they are finished I will post some happy snaps of my latest project, all working.

Tooling I'm looking at the moment at quick change toolpost, and indexable carbide tools positive rake only, preference would be DCMT inserts. What would you suggest for a CNC lathe 10x22" the only hitch spindle power is only 1hp, the machine takes 12mm/1/2" holders, plus an internal and external threading bar.

Many thanks
Katoh
Cheers
Katoh

Offline otpco

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Re: Spindle RPM feedback, not low enough.
« Reply #47 on: February 13, 2013, 07:29:53 AM »
Any reply from Homman re the board wireing . I think I am having the same type of problem 

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #48 on: February 13, 2013, 07:36:22 AM »
No nothing, I will send him another email, actually I would like to now the solution also, I don't think the bypass as I have done is correct method.
Cheers
Katoh
Cheers
Katoh
Re: Spindle RPM feedback, not low enough.
« Reply #49 on: February 13, 2013, 03:34:21 PM »
Hi Katoh,

Sorry, I had not been monitoring the forum for a while and have been a bit busy.

I'll have a read through the thread and see what I can find.

What index sensor are you using?

Cheers,

Peter

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Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com