Special thread screw supplier

McMaster is very good about special ordering stuff. They'll get back to you right away w/ a yay or a nay. MSC will also, but I don't know how hard they try.

If you don't need exactly 1/4-80, but are looking for just a super-fine thread, Metric Multi-standard in Elmsford, NY (Westchester county) might have something, or they might be able to point you elsewhere, as they are pretty knowledgeable.

Curious, tho, as to what a 1/4-80 bolt would be used for.

Have you tried your local Fastenal? I have had to order special threads, but they get 'em in a day or two.

Pete Stanaitis

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Hunter wrote:

"Proctologically Violated©®" wrote in message news:DjoVh.3$ snipped-for-privacy@newsfe12.lga... | McMaster is very good about special ordering stuff. They'll get back to you | right away w/ a yay or a nay. | MSC will also, but I don't know how hard they try. | | If you don't need exactly 1/4-80, but are looking for just a super-fine | thread, Metric Multi-standard in Elmsford, NY (Westchester county) might | have something, or they might be able to point you elsewhere, as they are | pretty knowledgeable. | | Curious, tho, as to what a 1/4-80 bolt would be used for. | -- | ------

It is for an adjustment assembly on a project I'm working on...sort of like a micrometer screw but only more capable of finer adjustment per division of screw rotation without incorporating a vernier scale. I already have the

Thanks.

Would seem easier to use a larger diameter barrel. A 1 inch diameter barrel would yield the same result with less trouble

| > It is for an adjustment assembly on a project I'm working on...sort of like | > a micrometer screw but only more capable of finer adjustment per division of | > screw rotation without incorporating a vernier scale. I already have the | > 1/4-80 tap but I need the screw or bolt to go into the hole. | >

| > Thanks. | >

| >

| Would seem easier to use a larger diameter barrel. A 1 inch diameter | barrel would yield the same result with less trouble

I understand what you are saying but this assembly has space limitations and I practically only have, at the most, 1 cubic inch of volume for everything to fit.

Because of thread tolerances, 1/4-80 is an oddball thread. If you just need 80 turns/inch, a differential screw with #10-32 and 3/8-24 threads (both standard sizes) has 1/(1/24-1/32) = 96 turns/inch. You fix a #10-32 stud to the moving widget, put a 3/8-24 threaded hole in the fixed gimcrack, and your adjustment knob rotates a tube with 3/8 exterior threads and #10 interior threads.

An 80 thread/inch screw has .012" threads, which (70 percent cut) means about .009" of actual metal/metal contact; it can be jammed with a tiny spec of dust, or strip out with minor force applied. It's gotta be accurate and clean as a micrometer to work right. I'd advise avoiding it.

#10-32 and 1/4-28 works out to 224 turns/inch, if you need it.

| > (wants a 1/4-80 screw for adjustment purpose | > ...this assembly has space limitations and | > I practically only have, at the most, 1 cubic inch of volume for everything | > to fit. | | Because of thread tolerances, 1/4-80 is an oddball thread. If you | just need 80 turns/inch, a differential screw with #10-32 and 3/8-24 | threads (both standard sizes) has 1/(1/24-1/32) = 96 turns/inch. | You fix a #10-32 stud to the moving widget, put a 3/8-24 threaded | hole in the fixed gimcrack, and your adjustment knob rotates a | tube with 3/8 exterior threads and #10 interior threads. | | An 80 thread/inch screw has .012" threads, which (70 percent | cut) means about .009" of actual metal/metal contact; it can | be jammed with a tiny spec of dust, or strip out with minor force | applied. It's gotta be accurate and clean as a micrometer to | work right. I'd advise avoiding it. | | #10-32 and 1/4-28 works out to 224 turns/inch, if you need it. |

Hmmm...that sounds interesting. I have to think hard to get the full concept of what you are saying. It might just work. Thanks.

Yes, I've been a strong proponent of differential screw technique for many years. I first saw it used on an optical device about

According to Hunter :

The main trick is to consider how much travel range you need. A differential screw requires a lot of travel of the intermediate part to get a small motion for the final controlled part. But as long as you don't need much travel, it can give nice fine control.

Enjoy, DoN.