Screw Counters for kits!

Guys,

wasn't too sure where to share this one. I'm a dork for tools and jigs - having seen how the pro's do it in bigger factories and dreaming of such fortune!

Anyway, a short video of a screw counting kit. I did try a fully arduino'd, stepper motor'd solution etc, until someone suggested I look at how pill counters used in pharmacies work!

https://youtu.be/QuuwH-HcmYU

Would love your feedback and ideas for design improvement. Nothing is ever "finished"

Far too complicated. I added a note to the video to suggest doing it they way they count notes and coins - by weight. He can just weigh 25 screws and note the value. Then just pour screws into the scales until you hit the weight and then pour them into the packet. You can even get scales with nice little scoops fitted on them like you would for baking.

Cheers

Ian

what Ian said... they even make scales that do the math...

JR

I have those scales (admittedly from aliexpress). Couldn’t trust them. Would miscount 22/23 instead of 25...

Rochey said:

I have those scales (admittedly from aliexpress). Couldn’t trust them. Would miscount 22/23 instead of 25...

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That is a recipe for some angry customers. It is most annoying buying something that requires 25 screws and only receiving 22 or 23.

I suppose you could calibrate for something like 28 to assure 25+. Kind of wasteful though.

I had a kit business back in the 70s so I hand counted lots of parts back then. 

A decent general purpose scale with adequate precision, and a pocket calculator can do the job for counting bulk parts.  We didn't have cheap precise scales like we do now (probably motivated by the drug trade).

To measure out 25 screws I would first weight 10 screws, divide that by ten to get an accurate one screw weight, then multiply that times 25.  I've done this to count bulk parts for inventory, more than accurate enough for that.

JR

This is how it is done in industrial applications:
https://www.rnaautomation.com/products/feeding-and-handling/vibratory-feeders/

Not sure you want to go to these lengths as this needs quite a bit of fiddling to get right, not an issue if one has a production line running for years on end, but for lower volumes, hmmm.
I'd go for an accurate scale, and make sure there's always enough screws in the kit, three screws excess (worst case) is not going to kill you.

Jarno said:

This is how it is done in industrial applications:
https://www.rnaautomation.com/products/feeding-and-handling/vibratory-feeders/

Not sure you want to go to these lengths as this needs quite a bit of fiddling to get right, not an issue if one has a production line running for years on end, but for lower volumes, hmmm.
I'd go for an accurate scale, and make sure there's always enough screws in the kit, three screws excess (worst case) is not going to kill you.

Click to expand...

Vibratory feeders/bowls are a common sight around factory automation for "odd component" insertion, sometimes they need to be designed specifically for the part. Modern automation with machine vision may reduce some of that complexity by helping a gripper see the part to orient it properly for insertion.

This is pretty much beyond the realm of kitting up parts for hand insertion.  The best use of factory automation by a kit company was from heathkit near the end of their previous incarnation. The would provide the kit of through hole resistors and (axial) capacitors on a sequenced tape. Inside the automated factory such tapes of sequenced parts would then be machine inserted into the PCB.  Back in the early days of machine assembly the components first had to be taped up on large reels by a separate sequencing machine, the sequencing machine held a lot of different parts but there was benefit to keeping the number of different values reasonable. This was a win-win for kit business because the components were loaded on the sequenced tape in proper order making it harder (but still not impossible) for the kit builder to screw up hand assembly.  :

Modern automation no longer uses through hole or sequencing, actually some of the later TH automation machines (like radial component inserters) didn't use sequenced tape either, but loaded up the tens of different parts on the final insertion machine.  SMD pick and place machines are likewise not sequenced, but hold tubes or reels of individual parts.

JR

All of the rack cases I get from Par-Metal seem to come with extra screws.  Perhaps they measure by weight with a + offset as well.

mjrippe said:

All of the rack cases I get from Par-Metal seem to come with extra screws.  Perhaps they measure by weight with a + offset as well.

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Screws in quantity are a fraction of a cent each, so no problem supplying a few extra JIC.

JR

JohnRoberts said:

Screws in quantity are a fraction of a cent each, so no problem supplying a few extra JIC.

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Until a bean counter decides there are huge savings to be made if you sell millions of kits...
BTW, kits are not only for the kit business,
All the factories I know have people preparing kits for manufacture.
Counting scales have reached such a degree of accuracy and such a decrease in price, I don't see the point in creating specific jigs.

JohnRoberts said:

Vibratory feeders/bowls are a common sight around factory automation for "odd component" insertion, sometimes they need to be designed specifically for the part. Modern automation with machine vision may reduce some of that complexity by helping a gripper see the part to orient it properly for insertion.

Click to expand...

It's true that sometimes they need to be designed specifically for each part, but they tend to help a lot in processes like the one you've taught us about automation. We worked with bowl feeders from https://tad-en.com/ and were able to improve line efficiency.