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Designing production machine: need air activated something to grab 8-32 screws

Alberic

Cast Iron
Joined
Jan 15, 2011
Location
SF Bay
HI guys,

So I'm ponderating making a custom machine to increase (or ease) our production.
What it needs to do is grab an 8-32 screw, and hold it still while the end is ground.
They come in two lengths: 0.500" and 0.188". And they come by the thousand...

My thought is to come up with something like a 5C air chuck, with a tube of screws feeding in from behind. Move a setting block in front of the collet, open collet, press screw out (somehow) against stop block. Close collet, grind (somehow).
Open collet, eject, move in front of stop block, rinse, repeat.

A full-on 5C air closer is much bigger and heaver than I really need for this.
Does anybody know of anything smaller that would fit the same bill?
What do normal production companies who need to hang on to screws (for whatever reason) use?
I know there are powered screwdriver systems that will autofeed screws for assembly. What are those called? Where do you find them?

Are there any companies that specialize in screw handling gear? I figure I can't be the only one who needs to mess with the ends of lots of screws, so *somebody* should make something close enough, if only I knew where to look.
(Yes, I've spent a whole lot of time bouncing around Google. I just can't find the right search terms apparently.)

What we're doing now is screwing the screws into steel plates, surface grinding, then unscrewing. Works great, but takes forever to screw and unscrew. About 30 seconds to actually grind a whole plate though.

My goal is to automate this. I can design and build the machine, even using an air chuck if I have to, but I'd really like to find a smaller, lighter solution. Doesn't have to be 5C. Just needs to grab an OD of about .200", so ER16 would work, or anything else in that range, if somebody makes a thru-spindle chucker in that size range.

Anybody have any suggestions?
Thanks,
Brian
 
Before anybody suggests it, yes, I've had custom screw houses make these things for me. (Several of them)
We're currently talking 8 month or longer lead times, not-entirely flat tips, and the last batch didn't even pass an 8-32 thread gauge. (After 6-8 month wait.)
These are mission critical for us. I can't deal with the lead times, so we have to do it in house, based on stock OTS screws.

Regards,
Brian
 
A few options come to mind.

1) You have an existing process that works; screw the screws into a plate and then put them on a surface grinder. There are off the shelf solutions for automatically feeding and inserting screws. Have an off-the-shelf robotic screwdriver put the screws in the plate.

2) You have two sizes of small screw. There are companies that will set up old-school cam-driven screw machines as turnkey machines. Buy two, one for each size, leave them tooled up and run them when you need screws.
 
How many screws are you currently doing at a time with your grind plate? How many grind plates do you have? You could get about 1000 screws on a 6x10 plate.
 
Before designing something custom, I would try the following with your current process:

"Screw presenter". These guys can be incredibly cheap (couple hundred bucks) and save huge time versus fumbing around with screws. Plus, if you do end up designing custom automation, chances are a screw presenter will be the first step in your machine anyway.

Instead of a solid plate, take a series of ground square bars and bore a hole though each end. Take some shaft stock and turn a thread on both ends. Stack the bars ising the shaft stock, and secure them with nuts. Drill and tap a few hundred or thousand holes into that plate, with each hole straddling a seam between the bars.

Run your screws into that, grind like you are now, then instead of unscrewing a thousand screws, put the whole contraption over a tray, unscrew the clamping nuts, separate the bars and watch all the screws fall out.

Obviously, number the bars and put them back together in the right order so you always have two halves with the same thread start.
 
Before designing something custom, I would try the following with your current process:

"Screw presenter". These guys can be incredibly cheap (couple hundred bucks) and save huge time versus fumbing around with screws. Plus, if you do end up designing custom automation, chances are a screw presenter will be the first step in your machine anyway.

Instead of a solid plate, take a series of ground square bars and bore a hole though each end. Take some shaft stock and turn a thread on both ends. Stack the bars ising the shaft stock, and secure them with nuts. Drill and tap a few hundred or thousand holes into that plate, with each hole straddling a seam between the bars.

Run your screws into that, grind like you are now, then instead of unscrewing a thousand screws, put the whole contraption over a tray, unscrew the clamping nuts, separate the bars and watch all the screws fall out.

Obviously, number the bars and put them back together in the right order so you always have two halves with the same thread start.

Adding to this, you may be able to eject the screws by having springs on headed dowels so you never mess up the order. Basically pull the two halves apart, drop screws and spring back.
 
A standard Auto feed screwdriver that feeds from a feed bowl and screws into a curcular plate on a indexing turntable. As the table indexes the screw is ground on the bottom side of the plate (belt sanders?) Then annother screw driver unscrews the screw and drops it on a chute.
 
What kind of screw? a socket head cap screw (SHCS)? grade 5?
8-32
What is the incoming size and the finished size {.500, .188) with tolerance?

3place , +- .001?

We had a Cincinnati #1 grinder that could run about 600 to 1000 an hour with a parting wheel.

Likely a good fixture and a good quality abrasive chop saw could do the same

A vibrator bowl would be likely the start of a production process.
With a chop set up, I could likely run the screws as fast as a vibrator bowl could line them up.

I once knew a fellow who made a good living with a vibrator bowl and a drill press.

He had the drill & tap a very small part in the basement of a very nice house. The whole setup was about a 10 x 10 foot space. His shipping table was about as big as his manufactuering area.
 
Great production job for a person needing a job.

There are lots of people that need work.

We need to get manufacturing back into the US.
 
Great production job for a person needing a job.

There are lots of people that need work.

We need to get manufacturing back into the US.

What's the fully burdened rate these days for an entry level position ?

And figuring how many done by hand per hour, how much added cost per piece doing it your way ?
 
What is the volume of these need-shortened screws?
That might cost 50 cents each...at retail.

600 x a nickel would be
$30 per hour.

10,000 / 600 = 17-20 hours of work x $30= a $500 two day job..*I dont want the job.

I knew a fellow who was offered .50 each for sharpening a small drill, so could have made a bundle with high volume small drill sharpening, new they were around a buck each..

I figured out a sharpening method with a custom machine after the job was lost..but it was not offered to me.

But he could not make them match the new drill number of holes so missed the job.
 
HI guys,

They're Gd8 set screws, and there's no real length tolerance. We're taking about .020" off the tips, to get the tips dead flat, widen the contact area, and get the oxide coating off. (They end up going head-to-head with each other as part of a clamp to grab jeweler's saw blades.) (We make hand saws.)

As far as US manufacturing, yeah... that's what's making all the noise in the room behind me. All of our kit is made here in the US, even (most) of the screws. But we're also in Cali. *STARTING* wages around here are $15/16, going up fast, just to get a warm body in the door, nevermind anybody who actually knows anything. And I've been having real trouble finding anybody at any price.
But that's not the real issue. The real issue is twofold: (1) I've done that job. I figure I'd last about 2 days before my head exploded. I won't ask anybody else to do it if I can think of a way to do it better/faster. So I'm looking/scheming/plotting. And (2) If I can think of a better way, I've got better, less robotic things that my guys can be doing, that a machine can't. So I'd rather use them for that, if I can.

I really like the split rod, drop the parts jig idea. That's easy enough to make. I'll try it.
We're currently running 124 parts per jig. Keeps the size of the jig manageable, and lets us load them in reasonable times. (Four jigs per size. One cycle of jigs will stay in front of about 1.5 day's production, so we can keep at least a little ahead as we are now. I'd like it faster, of course.)

And thanks for the cobot idea. Probably not immediately, but worth looking at.

Anybody know if those screw presenters can handle set screws? (No heads to get a grip on.)

Many thanks,
Brian
 
With set screws I imagine any automated sorting will have difficulty keeping them facing the correct end up

The beauty of the existing process is they are hand screwed in so right end up

It is also the hell of the process

I wonder if you can buy screws like electronic components-on tape

I would love to get fasteners pre sorted facing the same direction

It would seem robotic assembly would like it even more

A quick google shows a bunch of stuff under assembly, maybe look at that stuff to get ideas on screw handling

The handling is the real bottleneck
 
Syntron (and other brands)vibrator feeders can easily bring parts to be all in a line in one direction, All parts come up the track, and the ones facing the wrong way are kicked back into the bowl. I built a machine that had 6 feeders, for bolts, nuts, and washers.

But putting them all in a row is only part of the job of sizing them.
If only 100 a day a simple manual operation may be good, that costs a few hundred bucks.

For a few thousand a day automation that may cost $10,000 might be due.



SYNTRON EB112 VIBRATORY BOWL-TYPE PARTS FEEDER | eBay
 
The quantity needed is still unknown but I can't imagine that many jewelers' saws are sold each day to make it a big number of screws.
 








 
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