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Dial screws sizes (Plus other telephone screw sizes!)

Started by Greg G., January 28, 2013, 05:02:20 PM

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Darkstar2006

Why do people with cell phones use "old phone" as their ring tone?

-Dave S.

TelePlay

Quote from: TelePlay on October 13, 2022, 02:32:28 PMThis is not a source for self tapping metal screws for plastic but it tells you everything you will ever want or need to know about them.

And, yes, the thread pitch is spaced greater than sheet metal screws to reduce the pressure on the plastic when screwed in.

https://engineeringproductdesign.com/knowledge-base/self-tapping-screws-for-plastics/


A further discussion of self tapping screws for plastic posts, with comparison images, is on this topic:

http://www.classicrotaryphones.com/forum/index.php?topic=27537.msg265564#msg265564


poplar1

#48
Quote from: TelePlay on May 22, 2023, 05:27:54 PMA further discussion of self tapping screws for plastic posts, with comparison images, is on this topic:

http://www.classicrotaryphones.com/forum/index.php?topic=27537.msg265564#msg265564


The guy who finally convinced WE Shreveport Works to get rid of the housings with metal inserts for machine screws calls them "insertless screws."  (Perhaps he said "insertless housings" instead???) There was resistance to this change, he said, but at some point, most of the new housings for modular sets (500, 554, 702, 2500, 2554, 2702) were manufactured for use with insertless screws.   (I think self-tapping screws are for sheet metal.)
"C'est pas une restauration, c'est une rénovation."--François Martin.

poplar1

Quote from: MMikeJBenN27 on May 22, 2023, 11:50:05 PMI would buy some from you!

Mike

Dial screws? Self-tapping screws? Insertless screws???

When replying, it would help if you would hit the quote tab at lower right of the message you are replying to -- which is not necessarily the latest reply. Then remove unneeded information in that post.
"C'est pas une restauration, c'est une rénovation."--François Martin.

TelePlay

#50
Quote from: poplar1 on May 23, 2023, 02:24:13 PM(I think self-tapping screws are for sheet metal.)

That article showed different types of self threading screws depending on the application to include the plastic being used.

The other type of such screw is the self drilling and self threading which are typically used in sheet metal applications. Those screws have a chisel point that punctures the metal and then the screw threads tap the metal hole.

The plastic self threading (tapping) screws don't have the chisel point but requires a proper diameter and depth of the molded hole to match the screw.

Too large of a screw would split the post and the depth of the unthreaded, molded post has to be deep enough to hold the small amount of plastic bits that come off when the screw creates the thread in the material.

There are a couple different "tap" styles for these plastic tapping screws but they all have about the same thread pitch and a design at the bottom to help center and start cutting the threads.

As for buying them, I think they are only available in wholesale bulk (thousands at a time).

The sheet metal type are commonly available in hardware and home building stores.

MMikeJBenN27

Sorry, I thought dial screws are all you had.  I would like some of those dial screws.  My glasses broke, and my new ones aren't yet ready, so it is very hard for me to read.

Mike

TelePlay


ka1axy

For onesies of oddball screws, I like BoltDepot.com Fair prices, great selection and shipping, while not free, is reasonable. They don't have 4-36, but last time I ordered some from here:
https://blacksmithbolt.com/products/4-36-x-3-4-slotted-round-head-machine-screws-black-oxide