Payback to this group

Okay, you guys (gals?) have been answering my questions and solving my
problems for about 5 years now. Time for possible payback.
Had to get a new roll of Mylar (ouch!) for the plotter. Now that I have
plenty, I am willing to make "division strips" for any and all. Give me the
diameter of your chuck (or any fixture), I will multiply by 3.141592 and
print you a strip of Mylar (very high linear stability) with any divisions
you desire. E.g., 360, 27, 231 etc. I can number the divisions, like on a
scale. I can probably print two scales (back to back on the same side), on
a single 1" strip.
This plotter prints very accurately (HP design jet 600)
Cost? Almost free. I send you the strip and you, after receipt, send me
equivalent postage.
If you want two strips, the weight is almost nothing.
HELP! I need ideas for shipping. Product must be rolled and not folded. I
need a source of cheap shipping tubes. I used to get 24"± tubes for about
$1, but I lost my source. Office Max, etc, want about $2.50 per tube. Wife
says use toilet paper tubes. I will check with post office to see if TP
tubes are not too small. If they work I should be able to get by with less
than 2 ounces. IDEAS FOR TUBES APPRECIATED.
This offer expires in about 2 moths because sig. other will want plotter out
of the living room and back in the shop.
Email me direct with your diameter, etc.
Ivan Vegvary
Reply to
Ivan Vegvary
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How about a film canister, put inside a small mailer? How wide are the strips, and can they be rolled that tight?
Reply to
Dave Hinz
A friend and I were just discussing ways to know the orientation of a telescope's equatorial mount. One guy wants to get 12" to 15" brass gears made and use rotary encoders. That'd work, but I was thinking that it could also be done electro-optically with a pattern on a disc or strip.
I'll ping him, see if he'd like to try this. I can generate a pattern in AutoCAD and save it as a .dwg file (R-12), .dxf (R-12) or adobe .pdf but I have no way of accurately printing it.
I wish I could figure out how those Chinese calipers get .0005" resolution. I took one apart. The features on the capacitive scale and reader are not nearly that small: the reader's strips are on .025" centers and the scale's features are .100" wide with spaces between them that look like they were routed with an .0125" dia (might be 0.5 mm dia) endmill.
Reply to
Don Foreman
"Don Foreman" wrote in message
Don, generate your Acad dwg, or I could do same. Be more than happy to plot it for you.
Ivan
Reply to
Ivan Vegvary
Heh.. film cannister. I was wondering a few days ago how I'm going to get supplies of those. They're becoming rare! Maybe he should use cigar boxes.
Dave H> How about a film canister, put inside a small mailer? How wide are the
Reply to
Mike Berger
People that make fireworks use cardboard tubes that are pretty cheap.
Reply to
Dave Lyon
The resolution is even higher. It is 1" / 20480. Theoretical. I get a few 1/1000mm out of them with overshampling and averaging.
Have you seen what I have added to my HP in the meantime? I didn't describe how the electronics work*). But I have put a lot of material how the signals look like and about the mechanical arrangement of the couppling and shielding caps.
See:
*
) Because I don't know. I have only a vague picture of it: It works with the vernier principle and it seems that it does enhance resolution by messuring the coupled voltage. I _guess_. Still have to laugh when I get remembered how much fun it was to use the HP-54645D Mixed signal scope. :-) Geee, and they sayed that I can keep it as long as I want. What a gem!
BTW: Hopefully at the end of this month, kits for my digital scales interface will be available.
Nick
Reply to
Nick Müller
Nah... you can still get them by the Hefty Bag full at any full-service film processing center.
Some amateur pyrotechnicians make tiny aerial shells with them.
LLoyd
Reply to
Lloyd E. Sponenburgh
I've got 2 ammo cans full of 'em, but as such, I'm getting low (film cans, not cigar boxes).
Reply to
Dave Hinz
Cool. I'll see if the guy responds. If he does, I'd be glad to send you a mailing tube with stamps on it. Just peel off the outer address label.
Reply to
Don Foreman
As a word of advice onthe encoding, look up "Gray code" techniques. the reason it's important is that in Gray code, only one bit changes at any transition. That makes reading the position a lot less prone to reading errors.
Just a thought...
Richard
Reply to
Richard Lamb
Encoders these days are incremental quadrature feeding a counter, not Gray code. Gray code made sense when the electronics were costly, but not so today.
Reply to
Richard J Kinch
Dumpster behind carpet shop or printing plant.
But I think you'd be better off coiling it into something like a 5 x 5 x 5 inch box at $0.18/each.
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If you really need tubes:
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Reply to
Richard J Kinch
Carpet store dumpster - full of tubes.
_-_-bear
Reply to
BEAR
Richard, thanks, I've tried carpet tubes, way way too heavy. But your link to 5" cube boxes is the obvious answer. Thanks for the link.
Ivan
Reply to
Ivan Vegvary
Ah. I guess I've dated myself. Just wondering if I got lucky...
Richard
Reply to
Richard Lamb
Gray code was used on aircraft reporting altimeters because it was easy to determine an error in coding. If any one bit was out the thing would report wierd altitudes in sequence.
John
Reply to
John
Why not small boxes. If you don't need 24" why buy them.
Post office has several sizes - but those are not high volume. (and a little pricey) Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
Ivan Vegvary wrote:
Reply to
Martin H. Eastburn
They were used a lot on simulators too, and the weird read outs were great for troubleshooting...
Reply to
Richard Lamb
Gray code is relevant to absolute encoders, not to incremental encoders. An absolute encoder will give correct position even if the encoder was moved during a power-down situation. However, a nonredundant n-bit binary sequence can be arranged so all adjacent states vary by only one bit, thus avoiding race conditions, and it is true that inexpensive silicon (e.g., a microcontroller or FPGA) can now easly convert those state codes to a monotonic sequence of values. Example: adjacent binary states from 0 to 7 would be 0,1,3,2,6,7,5,4. Elex can sort that out. It gets messier if there are 65,536 states (16 bits). Elex can still sort it out.
Mitutoyo uses a really ingenious scheme for absolute position reading of their digital calipers. Google it if interested. It's explained (in patentese) in a patent assigned to Mitutoyo. I think the HF calipers may have ripped that off, don't recall when Mitutoyo's U.S. patent was dated. I think the HF digital calipers, at $16.99 on sale, are an incredibly good buy. I have both HF and Mitutoyo and I see no difference in accuracy, function, feel or finish between them.
Reply to
Don Foreman

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