I AM SCREWED !!!!! I mean I am REALLY screwed !!!
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... trying to order brand new H/W nuts and screws to replace all the rusty ones in my Tek 575 curve tracer.
It's a nightmare.. have to learn all the English screw related stuff, my goodness
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Luckily the mechanical parts list gives the description of every screw and nut and washer so I Googled to understand how to decipher what all the numbers and acronyms meant. I think I kinda got it now... a pain, but I am getting there.
So it looks like :
1) First number : diameter... for sizes up to and including '10', it's a lot of fun : you have to multiply the number by 0,013" then add 0,060" to it !?
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
For sizes above '10', it's simpler, the diameter is expressed directly as a fraction of an inch.
2) Second number is number of TPI.
3) Third number is length, in fraction of an inch.
Then we have a 3 letter acronym like "BHS" or "PHP" (no BD nothing to do with computers !), which code the type of head you want.
- Middle 'H' is invariable and just means "HEAD".
- The first letter codes the shape/looks of the head, can be (F)lat, (P)an (cake), (R)ound, (T)russ, or (H)ex.
- Last letter codes the type of screw driver you need : (S)lotted for a flat screwdriver, or (P)hilips.
I found a picture showing what the various heads look like from the top and from the size, helps.
"Truss" sounds like a weird word... looks like a round head but large and very very flat....
So I would say the rusty ones in my 575 are mostly slotted pancake heads, and Philips Truss heads.
I also need some nuts with a built-in "External star lock washer "....though I guess I could compromise if need be, and just use a standalone lock washer + normal nut, as it would do just as well and once assembled you wouldn't be able to tell the difference anyway...
I also might need the odd countersunk head here or there.
I assume the length is expressed the same as in Frog land ? That is, for a flat head, the thickness of the head is NOT included, but for a countersunk head, it is included ?
Unfortunately the service manual does not have an exploded view of the 575, so I don't know the dimensions/type of the screw that I need. So will have to remove them first and measure diameter and length and TPI, how fun.
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For the diameter, should not be too difficult, as according to the parts list there are only a few different ones : 4 or 6 or 8 or 10. So I can just run the numbers to figure out how millimeters that equates to. Then I can just measure the diameter of my screws with calipers and see easily what imperial size that matches.
However to figure out the TPI, I would need a TPI gauge ! Anyone can recommend a decent cheap one on the web ?!
![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif)
According to the parts list, 90% of the screws are 32 TPI, and a few are 40 and one is 26.
Then... the hard part : WHERE can I freaking buy all that stuff online ?! You can find screws on Ebay but trying to find the exact screw for each and every one that I need, might be fruitless yet waste hours of my time, plus I would have to pay shipping several times probably !
Would be cool if I could find a website of some screw manufacturer where I could buy direct from, and just tick of few boxes to configure exactly and quickly all the different screws that I need, and pay shipping only once. Problem of course is mostly that finding such a vendor in FRANCE for IMPERIAL screws and nuts, is... a waste of time probably. And even if it existed, they would probably charge extra since it would be out of their main line of products...
So I would need I guess a place in the UK ! So please all my TEA friends in the UK.... do you know of such a website/vendor ?!
Last problem: I don't know what kind of FINISH Tek used for their screw ! 60 years later they are all dull at best, but mostly al rusty, so it's hard to know for sure ! I have one Tek scope that looks about decent, and the screws on its outside, that hold the cabinet/chassis together, look like they have a light coloured finish, and kinda shiny. I would say it looks like a "normal"/standard finish, but I don't know the technical term to search for that corresponds to a "normal" screw !
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