I AM SCREWED !!!!! I mean I am REALLY screwed !!!
... 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
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 !?
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.
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 ?!
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 !