|handheld case screws update|
Message #1 Posted by Ellis Easley on 31 May 2002, 2:34 p.m.
I have another lead on the screws for the handheld cases that we have been looking for. I should get some real Plastite screws next week!
I got the #2 X 1/2" plastic thread cutting screws from the website that Paul Brogger pointed out, that had #3 X 3/8 sheet metal screws. The #2's that I got are not what I hoped. They are 32 threads per inch, circular thread like a sheet metal screw, with a blunt end and a notch. I also bought an assortment of small sheet metal screws that unfortunately didn't include #3. I say unfortunately because as soon as I found the #2's weren't what I hoped, I wanted to kick myself for not ordering the #3's to see what they looked like! They sent a paper catalog and I went through it looking for some more items to make up a new order and found listed with sheet metal screws, a #3 X 5/16" with a footnote that said "Servo arm screw Type B - blunt end"! Sounds perfect! However, it doesn't show up on the website and when I asked for it in their search, the system said to call, so I did.
I explained to the gentleman what the screw is like that we are looking for and the HP description of the similar screws in the 97 card reader, #2-28, and my belief that the screws are "Plastite". He was familiar with Plastite, said it was a trademark for a patented idea for which the patent had expired and which is made by a number of manufacturers. He said "tri-lobular" is the distinctive feature of "thread rolling" screws of which there are "Plastite" for making threads in plastic and "Taptite" for making machine screw threads in metal. He verified that the #2 Plastite is 28 threads per inch and had a term for the maximum diameter - something like "encompassing circle" - that would be slightly larger than the measure I've been taking with my dial calipers, which for the #2 Plastitie is .089 inch. He also told me the diameter of a #3 sheet metal screw is .102 - .106 inch.
In the sheet metal screws that I got, the #2 measure .085-.087 inch diameter and have 32 threads per inch. The #4 measure .113 inch diameter and have 24 threads per inch. It may be that #3 have 28 threads per inch - I didn't get a definite answer on that - but the guy is pretty sure that at .102-.106 diameter they would crack a post intended to take a #2 Plastite.
The good news is that he is getting some #2 X 5/16" Plastite panhead phillips screws! They will be zinc plated. They should be just a few dollars per hundred - he couldn't give me a price today but I will call him next week when he will have them in stock. I will order some to make sure they are what we are looking for and post the results here.