IBM 5155 analogue display fault

[Tony Duell]

> 
> On Tue, 31 May 2005, Tony Duell wrote:
> 
> > If it was a particularly rare or significant machine, I might to that
> > with any components I had to replace (because they'd failed). I'd keep
> > the originals with the machine for historical reasons. But I wouldn't
> > replace anything I didn't have to replace.
> 
> What if Bristol Spline screws eventually become obsolete and the
> manufacturing of the tools ceases?  I know: you'll say "I have a lathe
> (and know how to use it) and would manufacture one."  Sure, we all have

Actually, a milling machine and dividing head would be useful, but you 
can do milling in a small lathe, and, yes, I do have a dividing head.


> lathes (and know how to use them).  But wouldn't it be easier if someone

Well, you could try asking somebody to make you one, or asking somebody 
if they have the right tool that you could borrow, or...

> had just replaced the screws with more standard varieties and kept the
> originals with the machine, tied to the inside case in an archival quality
> bag?

Alternatively, Jules has already proved you can remove these screws with 
pliers if you have to. Or you could drill them out (they even make LH 
twist drills for this sort of thing). Or many other ways to get them out 
if you had to and couldn't get the right tool. The point is to make as 
few mods as possible _now_. 

Are you suggesting that every Bristol Spline screw in every machine 
(5155s, Datamasters, IBM typewriters, Friden Flexowriters, etc) should be 
replaced now, just in case you can't get the right tool in the future. 
What about replacing all UNC screws with metric (after re-tapping all the 
holes) just in case inch-size spanners and allen keys cease to be 
available (they're a lot harder to find than Metric in many UK tool shops 
now). If not, why just replace them on machines you need to repair?


-tony