I make 1/2", 3/4" and 1" solid wire fill end brushes that typically fit into die grinders that spin up to 20k RPM. The wire in folded in half around a steel pin then pressed into a steel cup. The cup is then crimped. This all takes place in a few seconds. The operator starts by placing a pin into a slot, a bundle of wire into a jig and a cup into a holder. After pressing two palm switches, the operation is automatic. Two hydraulic cylinders do all the work.The 3/4" and the 1" have a microswitch that detects a pin in the slot and prevents the machine from cycling. On the 1/2", the pin is so small that the microswitch detect system doesn't work very well, the pin is too small. (1/2" x 3/32")we're rethinking how to detect the pin better. Can we get a laser/photocell or something similar that will "see" this small of a part?If a brush gets made without a pin it will immediately eject the wire in a poof...NOT GOOD! The wire doesn't have a lot of mass and the tool's not up to speed yet so it's not extremely dangerous if you've got eye protection...who doesn't when using power brushes?

There are tons of optical sensors available that could do the job. Checkthe Digi-Key catalog for many examples. In particular look at the Omronmodules that include signal conditioning, so they just need power andoutput a logic signal. The issue you might have with these would be dirt/ debris buildup causing false positive detection.

How to detect a small pin

Jun 04, 2010 41 Replies

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Lloyd E. Sponenburgh 16 years ago

"Buerste" fired this volley in news:huidq9$bak$ snipped-for-privacy@speranza.aioe.org:

You need a copy of "Ingenious Mechanisms for Designers and Inventors"; the four-volume set.

There is a wealth of feeder/orientation/presence/absense sensing information there (including pin feeding mechanisms).

LLoyd

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Buerste 16 years ago

GOT IT! Great inspirational set. My favorite is "Geneva" mechanisms, built something to index knot bush disks using ideas from the book.

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