How to detect a small pin

Wouldn't a vacuum sensor tend to actively suck debris into the tiny hole giving false positives also?
Assuming this is an unpainted steel pin, how about two spring-loaded brass contacts (one at/near the bottom of the hole) and test for continuity? They would be essentially self cleaning, but would wear out periodically.
Just a thought.
I LIKE IT!
Reply to
Buerste
Loading thread data ...
I like this idea the best, I only have to have one insulated contact where the limit switch is and the machine as the other.
Reply to
Buerste
formatting link
Thanks Wes, the guys were talking about something like this, now we have a link.
Reply to
Buerste
******************************** The side of the pin
*********************************************** The blade is only 1/16" thick by 1/2" wide by 8" long. It rides in "U" shaped channels on either side.
Good thoughts! We see a variance of a number of grams in perfect brushes and the pins only weigh a few grains.
Reply to
Buerste
Without the pin in place, doesn't the ram pushing the bundle travel a longer distance? Could you measure ram travel as a check to see if the pin is there?
Good thought but the ram hits an "end of stroke switch" and the crimped wire has a variable density, it's springy.
Reply to
Buerste
(...)
OK then, how about a mini inductive prox sensor?
formatting link
$FILE/D06E2EC1101.pdf Parametric Search:
--Winston
Reply to
Winston
I would consider a snap-action switch whose lever sweeps the pin position, actuated by a solenoid. Cheap, rugged, reliable, not debris sensitive, and easy to fix.
Reply to
Richard J Kinch
On one project I used small prox switches to detect electrical terminals. If the prox switches wouldn't work for you maybe a photo-eye? IIRC Banner makes one called a pico-dot or something like that. There are also fiber optics for photo eyes that get very small.
formatting link
Notice the above has a 0.6mm sensing range, the pin has to nearly contact it to turn it on. May be able to fit up where the micro switches are.
Also fiber optics for photo-eyes...
formatting link
In most of my experience Prox switches are nice due to not having to keep them as clean as photo-eyes, and they are generally very reliable if you keep them from being destroyed (don't allow the ends to be worn off and mount them so they are protected).
RogerN
Reply to
RogerN
Just another thought. Could you hog ring the bundle? They use hog rings at the end of bungy cords to keep them from slipping throught he hook. Not sure about the automatic machines that put hog rings in place.
Reply to
Denis G.
Just another thought. Could you hog ring the bundle? They use hog rings at the end of bungy cords to keep them from slipping throught he hook. Not sure about the automatic machines that put hog rings in place.
I like the way you think!
Reply to
Buerste
I am going to try one of those soon. It is 0.09" thinner, I am running into a stacking issue sensing orings on a family of parts of different lenght and oring locations. The larger QS18 is bumping into the one above it.
Thanks!
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
Reply to
Wes
They can get quite dirty before they stop working. We had optical with small incandesant lights in card and check sorters in the 1960's. Ran for a week with no errors and only a vacuum of the transport couple times a week. Check reader ran 100's of checks a minute. Card reader ran 1000 a minute. Make the lens and light big enough and the light will make it.
Reply to
Califbill
Boy does that date you and me, also. The lights you mention usually had bulbs that were flat on the tip and that tip was actually in and part of the flight path of the card or check. The paper cleaned the bulb as it went past the bulb. On Burroughs equipment they were called BOLs, Beam of light. Don't remember what they were called on IBM equipment.
Then before light there were the wire brushes that would make electrical contact with a drum when a hole in a punched card was being read.
I programmed for the IBM 1419 check reader/sorter on IBM 360 model 30, then moved to a company with Burroughs medium systems check readers. Then to Burroughs/Unisys check reader/sorters that were controlled by Motorola 68005, 68010, and 68030 microprocessors. By then the checks were being read at 1,000 or 1800 documents per minute and from 4 pockets to 48 pockets.
Retired from all that in 1997, so don't know what they are doing, now.
Paul
Reply to
co_farmer
Thanks. I like dreaming up solutions based on things I've seen done.. But there's a big difference between an armchair quarterback like me and a real quarterback putting ideas into practice. I hope you solve the problem.
Reply to
Denis G.
I worked my way through college (EE degree) working on mainframe 315 systems for NCR corp. Then the Century 100 systems. Was a hardware guy who did some programming. Ended up designing embedded systems. Hardware and software. Disk controllers for System Industries (DEC) and disk drives for Maxtor and apps engineer on disk drives for TI and programming DSP's for TI and contract jobs. then retired after a Biomed employer screwed up. 8 years ago. Funny that I ended up as an EE was going to either be an ME or geologist as a kid. Dad owned one of the larger machine shops in the East side of the SF Bay area.
Reply to
Califbill
Thanks. I like dreaming up solutions based on things I've seen done.. But there's a big difference between an armchair quarterback like me and a real quarterback putting ideas into practice. I hope you solve the problem. **************************************
The funny thing is, the REAL problem is just training the operator to always put a pin in the damn slot!
Reply to
Buerste
How about the little optical relay like is used in an old semi mechanical mouse? There is a little wheel with spokes that breaks the optical source from the optical receptor. Reaction time would be the key.
Reply to
Bob La Londe
Huh? I had assumed that loading the pin was automated. Sounds deadly boring and thus error prone.
Maybe the better solution is to automate pin loading, and pull a vacuum through the blade to hold the pin in place, and also to sense absence of the pin (if one cannot develop the vacuum), with an air puff once per cycle to keep the vacuum port from clogging.
Joe Gwinn
Reply to
Joseph Gwinn
I had a vibratory bowl feeder feed pins through a tube but I could never get it to work right and gave up.
Reply to
Buerste
Yes, we're looking into optical sensors and there have been a lot of good responses, thanks!
Reply to
Buerste

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.