The project continues apace with more turned parts. Again, these will need to be heat treated however at least I get to work with a fairly standard 5/16″ BSF (British Standard Fine) I cannot say I never work with imperial threads as all of the last weeks screwcutting was imperial and the time consuming part is always the clocking in as opposed to the screw cutting itself. Oddly, I do tend to work in metric for some imperial threads and as an example the 20×1/2″UNF thread so often seen on the end of barrels and used to attach a sound moderator starts off as a 12,70mm diameter to me and finishes at around 11,00mm for a class 3A thread (External) I say around as the ultimate diameter is down to the part I am attaching to the end so you could argue it is not really a class A thread.
I am sure some of you have shouted ‘Gotcha!’ confident now that you know what I am making. Good idea in principle however I think you will find this is the wrong thread.
All will be revealed over the next couple of weeks.
Firstly, Happy New Year, at this stage I could say my resolution is to write more however I have already failed on that count. Anyway, lets hope for a better year than the last. Here in the UK we are locked down for the third time which means no face to face customers unless they are essential users. Internet sales are OK though and we have already shipped to the USA and Sweden on multiple occasions plus theUK of course.
Screws- I am quite looking forward to this as it is an imperial job and I seldom if ever work in imperial. I need to make a batch of ‘Coned Head’ Screws and the drawing calls for them to be hardened so I will make a small handful and bung them through the HT oven, if all is OK I can make a few more, around 60 is where I need to be with some to spare/drop in the swarf bin/mess up along the way. The pitch is 38.48 TPI which would be a nightmare usually, however I can program this pitch on the big lathe and a 4,0mm collet seems to be my go-to for so many projects on both the lathes (Strikers and Optilock screws spring to mind) The thread angle is 47.5 degrees so not one I hold however carbide inserts are but a telephone call away. The slot will be done with a slitting blade held on an arbor with a collet on the manual lathe and I have a little 1MT Jacobs chuck that is held in a standard tool holder for holding the screws. The threads do not need to be timed so I can just wind the slide in with plenty of lubrication.
A sliding head lathe would be nice right now!
The project? You can probably guess what it is already and this is your first spoiler, however I will not admit to it until everything is finished and works as planned…