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Author Topic: Spindle RPM feedback, not low enough.  (Read 14647 times)

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Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #10 on: January 23, 2013, 06:23:41 PM »
Hood I apologize don't mean to confuse the issue, It's probably more me being pedantic more than anything else. In my thinking, if it works at 40rpm it should at 2000rpm but doesn't and vise versa.
For some reason I'm assuming that something is not quite right in the setup, so I go off reading all these other threads where they used multiple slots and timing and capacitor's with bells whistles and jam & scones for morning tea to make it work.
If I'm being unrealistic, please say so, maybe it just wont give me low and high rpm or the full spectrum.
I still have not tried at max RPM which is 2000.
Thanks
Katoh
Cheers
Katoh

Offline Hood

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Re: Spindle RPM feedback, not low enough.
« Reply #11 on: January 23, 2013, 06:29:37 PM »
Set Index debounce to Zero and see if you get the RPM correct above the 100rpm up to top speed.
I dont think there is a problem with your input, I am thinking it is the parallel port driver and the way it does things.
Hopefully Rich or someone else that uses the parallel port will say if they have the same thing.
Hood

Offline RICH

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Re: Spindle RPM feedback, not low enough.
« Reply #12 on: January 23, 2013, 08:01:19 PM »
It's been a long time since actual testing but need to find my notes on the subject.

I use 53 rpm on one of my lathes and i know that The Sherline was used below that.

more after i do some looking into my vaults......
RICH

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #13 on: January 24, 2013, 02:09:22 AM »
Hood I tried what you suggested, setting the debounce at 0 and and seeing what I got .
I could not get a constant reading at all, then I started from 1 and work my way up on the debounce, it took to 41 to acheive a stable reading at high rpm.
Something sounds a bit screwy now.
Thanks Again
Katoh
Cheers
Katoh

Offline Hood

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Re: Spindle RPM feedback, not low enough.
« Reply #14 on: January 24, 2013, 03:07:55 AM »
Is this Index Debounce?
Yes that does sound weird if it is as on any system I had anything over 0 would degrade the reading and anything near 10 would not be readable at all. Maybe things have changed in the driver since I use the parallel port but cant see it.
 Tell me a little about your wiring, ie I think you said its shielded, where is the shield connected? Can you try another input on your breakout?

Hood

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #15 on: January 24, 2013, 03:59:31 AM »
Hi Hood
That's definitely Index Debounce, I'm using pin 15 as the input on the bob, the wiring is shielded, actually its 4core shielded microphone cable, nice cable you can buy by the meter from Jaycar in Oz. The grounding of the shield is from one side only, the other is capped off as close as I can to the the opto, say 2" or 50mm. The grounds are all common as with the neg side of all power supplies all run from separate buss bars or points.
Ill include a couple of pics.
The only thing that I can think off  at the moment, is my spinning disk is made from a CD, maybe reflection, refraction, or just do the locomotion (bit of humor here) but I have read that with the opto I'm using it makes no difference if its a reflective surface or not. I have painted my black anyway.
As I said in prior posts the BOB picks up without a problem every pulse sent by the opto, just mach cannot define it. Maybe I have to go for timing instead of index, maybe a different input pin would do better, maybe Peter Homman could shed some light on this its his bob's I'm using?
Cheers
katoh
Cheers
Katoh

Offline Hood

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Re: Spindle RPM feedback, not low enough.
« Reply #16 on: January 24, 2013, 04:24:34 AM »
Timing can not be used now as far as I am aware. Changes were made in the driver quite a while ago. I have looked for the info Art posted about Timing not being any better than an Index but as yet can not find it, I was sure I had copied it so I wouldnt forget, seems I have forgotten where I stored it ;D

 We will see what info Rich comes back with, hoepfully he will be able to test.
I think you have said but just to make sure, are you using the parallel port for this machine?

Do you have a second parallel port that you could input the signal via so that it goes direct rather than through a breakout board? Just be carefull if you do that that your power supply is either taken from the computer or the 0v are tied to computers 0v.

Regarding DC supplies 0v being grounded, I have never done that although I hear of people doing it.

Hood

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #17 on: January 24, 2013, 05:10:29 AM »
Timing can not be used now as far as I am aware. Changes were made in the driver quite a while ago. I have looked for the info Art posted about Timing not being any better than an Index but as yet can not find it, I was sure I had copied it so I wouldnt forget, seems I have forgotten where I stored it ;D

 
Hood

Yes I don't what it is but I seem to have the same problem lately, "do you think we are just getting old" heaven forbid, because I still feel like I'm 28, only problem last year I felt like I was 21?


Regarding DC supplies 0v being grounded, I have never done that although I hear of people doing it.

Hood


I think you misunderstood me there, the ground and the neg or both separate but all power sources have a common Neg source through a common buss bar. The same way you would wire a boat if that explains anything?
If you look at the photo control box, you will see a group of contacts say 1/3 of the way up, the green is the earth bus bar connect to earth, the red is isolated 5v power supply, the blue is isolated 12v power supply, the black is the neg bus bar containing all the neg sides of each power supply into one point, then the neg side to each BOB is taken from here. All positive sides or active sides are separate for each power supply.

I forgot to post the pics in the last post so here they are.
Yes I'm using 2 parallel ports and 2 BOB's one is for inputs only and the other for motor outputs including spindle.

Thanks Again
Katoh
Cheers
Katoh

Offline Hood

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Re: Spindle RPM feedback, not low enough.
« Reply #18 on: January 24, 2013, 05:37:39 AM »
Ah ok I see now what you are meaning and that is how I would do things with maybe one exception, I would be using normal Earth Din rail terminals which would  connect the base plat of the cabinet to Earth, might be worth trying connecting an earth wire direct from the Earth terminals to the base plate.
Hood

Offline RICH

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Re: Spindle RPM feedback, not low enough.
« Reply #19 on: January 24, 2013, 06:49:49 AM »
Katoh,
What version of Mach are you using?
Found most of my notes.....quick look at over  100+ pages of stuff.
Good grief.......I will post when sorted out.
Hope to try low rpm's tonight.

Later,
RICH