Linuxcnc servo spindle encoder with pulleys

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02 Sep 2014 00:22 - 02 Sep 2014 00:23 #50591 by andypugh
It isn't impossible to make your own timing pulleys. I needed a very strange cup-shaped one for my X axis drive and made it myself.

For the round-tooth style belts you can drill a circle of holes then machine off the outer half.

I did it the hard way, setting my milling machine up as a hobber and buying a T5 hob from eBay.

In theory I could cut teeth on a blank you provided, but in practice transatlantic postage probably makes that impractical.
Last edit: 02 Sep 2014 00:23 by andypugh.

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03 Sep 2014 01:00 #50641 by nilrods
Andy,
Thanks, but your probably right on the trans-Atlantic shipping :)

I had seen one of your previous videos. It looked great!

I was actually planning to doing something similar in the future with a small old Atlas Horizontal mill(you might have just given me the push I needed to prioritize that). I had looked at some of the linuxcnc pages around that.

I assume you just use a decent number encoder on your spindle(something like 1024 or just more than just an index pulse). How to you gear the spindle to the rotary table? Do you just use some arc length function in Linuxcnc (like L=(pi*r*angle)/180) then apply by the number of teeth or something?

Thanks,
Chris

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03 Sep 2014 01:03 #50643 by andypugh

I assume you just use a decent number encoder on your spindle(something like 1024 or just more than just an index pulse). How to you gear the spindle to the rotary table?


The horizontal miller actually uses a resolver on the spindle, but I set up a vertical miller version using a home-made 25-slot disc and it worked fine.

Some details of the HAL setup are here: wiki.linuxcnc.org/cgi-bin/wiki.pl?Hobbing
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03 Sep 2014 06:47 #50656 by Zahnrad Kopf
Chris if I don't have the Hob you require you could purchase one, send me the Hob with a blank and I could Hob them for you if it comes to it.

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03 Sep 2014 15:55 #50671 by andypugh

Chris if I don't have the Hob you require you could purchase one, send me the Hob with a blank and I could Hob them for you if it comes to it.


This eBay store has quite a collection of toothed-belt hobs:

stores.ebay.co.uk/THE-TOOL-AND-TREASURE-...earch&_sid=384582008

(They are all described as gear hobs, but none of them are)

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03 Sep 2014 17:55 #50677 by Zahnrad Kopf
That is a dilemma! They are very nicely priced, but lacking VERY important information. So, unless the buyer does some serious research, they're almost useless. :) Timing belt Hobs usually come in ranges. 1 - 35 teeth, 36 - 58 teeth, etc... ( strictly as an example ) That's gambling at its finest! :)
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10 Sep 2014 06:44 - 10 Sep 2014 06:45 #50990 by Zahnrad Kopf
Back on the original topic, this fell into my lap today and I'm trying to find out if it might be a suitable replacement for our spindle encoders but cannot find any good information on it yet so do not know if it has an index pulse or not. It _DID_ come from a spindle with an orient function.





The only thing I can find is this - LINK HERE
Last edit: 10 Sep 2014 06:45 by Zahnrad Kopf.

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10 Sep 2014 15:15 #50997 by andypugh
You might be able to work something out from here:
www.heidenhain.de/de_EN/php/documentatio...w/file-0034/file.pdf

Especially page 73

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10 Sep 2014 17:21 #51009 by Zahnrad Kopf

You might be able to work something out from here:
www.heidenhain.de/de_EN/php/documentatio...w/file-0034/file.pdf

Especially page 73


Thank you,Andy.

Unfortunately, when I looked at that it appears that someone regurgitated a bunch a symbols and letters into a bag and then emptied the bag. But I stared at it while I drank my coffee and I _think_ it means that there _is_ an index pulse in there. Correct?

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10 Sep 2014 18:49 #51017 by andypugh

But I stared at it while I drank my coffee and I _think_ it means that there _is_ an index pulse in there. Correct?


It looks like 3 pairs of data channels, yes, so one ought to be an index.

Unless it is a commutation encoder, but then it wouldn't be marked as "incremental"

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