Help finding screw - 10-32 thread, half thread, set screw

[belwar]

Does anyone know where I could find an allen head set screw.. 10-32 thread, but with only half the screw threaded? Im looking for the bottom half to be threaded obviously. Total length 1.125 or 1.25. threaded length 0.5"

Im looking to see if its available out there...

[David King]

You could cut the head off a hex head or socket head bolt. They sometimes only have the first 3/4" threaded and then straight for a bit.

I googled "threaded pin" and came up with this:
http://www.nzmeccano.com/115.php
I think meccano threads were all 10-24, I used to have a set.

[jonson]

known as a shoulder bolt/screw over this side of the pond.

[Bruce Johnson]

When you say half threaded, do you mean that the unthreaded part is full diameter, with the Allen hex socket in that end? Or do you mean that it's like a normal Allen setscrew, but with half turned down to a smaller diameter?

In either case, you're probably looking at doing a machining operation on a stock screw, or having it made up custom. I don't think you're going to find something like that off the shelf.

Attached is a picture of some special jacking screws that I make up from 1/4"-20 Allen setscrews. The tip is turned down in a lathe. Is this the kind of thing you're thinking about?

[Possum]

....

Nice job!

[jonson]

You can always give these guys a call


Stock Drive Products / Sterling Instrument-Directories

[rudutch]

McMaster-Carr

[David Schwab]

Does anyone know where I could find an allen head set screw.. 10-32 thread, but with only half the screw threaded? Im looking for the bottom half to be threaded obviously. Total length 1.125 or 1.25. threaded length 0.5"

Im looking to see if its available out there...

You know I looked, right? I couldn't find anything, so I just used fully threaded set screws.

If wouldn't be hard to thread some rod, but I don't know how you get the hex hole in the end.

[David King]

You need a rotary broach to make the hex hole. The tooling isn't cheap unfortunately.
http://cgi.ebay.ca/SOMMA-ROTARY-BROA...mZ280055746293
I'd stick with a slot if at all possible. If you just need a few, I have a geometric threading die for my lathe which will thread to the same length every time but I'm not set up to do the slot, you'd need a screw machine for that or just a Dremel tool set up in a simple wood fixture that slides each screw into the edge of a cutoff disc.

[David Schwab]

Matt... There's no reason to do it anyway, unless you are having the whole thing made the same way. Why bother? If the head isn't the same, just go with a regular set screw.

[stingray_65]

A slot in a screw for a regular screwdriver is not simply a slot ( a propper one at leats isn't)
a screw slot has a 5 degree taper and matches the profile of a regular screw dirver.
not to say it wouldn't work, or that i've not done that before.

there is a file called a Knife edge file. this is used for cutting or correcting screw slots and can be bought at most tool supply stores for less than $20 for a high quality nicholson brand.

I usualy start the screw slot at 2/3 depth by cutting with a dremel or other tool, then open it up with the knife file.

you will be amazed at the difference.

Ray

[stingray_65]

If i were to slot a 10-32 screw I would first be sure to NOT use an allen head screw as stock material.

most allen screws are made of a very hard steel alloy that doesn't lend itself to easy hand work.

find a grade 3 bolt. this is hard enough to accept a screw slot and soft enought to hand work.

a grade 5 may work, a grade 8 is too difficult. stay away from stainless steel too, some grades work harden and will cause you much grief.

to cut your slot by hand use a hack saw blade. but not just any blade, make sure the blade does not have a "wavy" tooth offset (look down the teeth, the waves are obvious). find one with a standard offset. use one with at least 24 TPI or more. 32 is best bet as there will be 3 teeth at any time on the screw when you cut.

if you have a disk or belt sander, flatten the tooth offset down on both sides. you only need to sand down an inch or two because you wont want to stroke that far. you won't be needing kerf relief because you wont slot that deep.

cut on the push.

now to hold your screw.

get a propper sized nut, cheaper and softer grades preferred.

start on one of the hex points and cut to the nut center.

deburr the cut on the inside threads with some 80 grit sand paper.

thread the cut nut over the screw an you can now clamp down on the flats that are 90 degrees from the cut and the screw will be held without damage in your vise.

I have a tupper ware bowl full of nuts I've made like this. they are sooooo! handy!

after you cut your slot you can take a piece of 80 grit sand paper and fold it over a piece of card stock to make a make shift knife file.

test fit with a regular screwdriver.
Ray

[belwar]

David S,

You know I think I might go to the work of having those screws made. I'm going to have a couple of people quote it out and see what I come up with. I actually like the idea of using that small 1/16th allen screw.. It gives you lots of mass at the head, and eliminate cover scratching from a flat head. I'd split and order with you if you want some. I'd probably do a small run like 10-20k.

Whats strange is the pickup is all metric, but the screw is imperial!

If I do have a batch made, id want to have the screw analysed to find out the alloy. Could hurt, though its probably standard low carbon steel, possible quick machining steel.

[belwar]

I spend a few minutes tonight drawing the screw.. I imagine this doesnt exist.

David S - Does it look pretty accurate to you? am I missing any details?

Matt

[David King]

Apparently we don't like leaded steel for pickups? So says Mr Possum.
You can have any grade annealed and then burn some of the carbon out of it for good measure.

Ooh that looks pretty, I'd take a small pile of those off your hands if you decide to go big.
You should try posting that on http://rfqwork.com and see what sorts of bids you get.