Pye MM

[AlanBeckett]

A few updates to be going on with.

Attached is s picture of the back of the panel. It shows the 'pip' which supports the Tuning Capacitor spindle.

I've received the 1/4" Brass rod I ordered. I make the Diameter 0.240" - 10 thou down - which is a bit disapointing. It's slightly sloppy in the holes, and I may have to use Silver Steel to get a good fit. Anyway, I've got plenty of material to practice on.

The nuts and screws are 6BA. I've dug out my 6BA Taps - they look awfully thin - and ordered some drills.

After much measuring and pondering I've done most of a Drawing.
Attached is the provisional GA.
A few comments on that:-
1. I don't think that in general the dimensions are very critical. Provided the switch blocks lean on the contact springs it should work OK. However, I'll do some cross checking against the chassis - this was done from the corpse of the shaft.

2. The Detent square is at a slight angle to the flats for the switch blocks. I bet that wasn't popular with the DO Manager at the time. You can imagine the conversation: 'What do you mean it's at an angle? That's going to be expensive. What will the Toolmaker say? etc, etc' So, that's a problem to be solved. The end of the shaft with the Detent and the first flat is intact so it shouldn't be too difficult.

3. I can't find any evidence of a method of contraining the shaft longitudinally. Perhaps it's all done by the knob and the Detent, or perhaps there should be a circlip which I've lost. I'll wait until I've got a protototype.

That's all for now.

Alan

       

[Joe]

Thanks for the up-date.

- Joe

[Yorkie]

Thanks for the updates Alan. Do you think you're in with a chance to bring the finished (or unfinished) article to Golborne on Sunday?

[AlanBeckett]

Gentlemen,
I've cleaned up the English a bit.
I'm not sure I'll manage a prototype by Sunday, or I should say Saturday night, and I'd rather get it right than rush.
Alan

[Yorkie]

Well you are burning the midnight oil Alan, looking at the time of your latest post!

(Neat drawing by the way)

[AlanBeckett]

Another update :-

Comment on my incompetence first. I said that the brass measured 0.24" which both Col and Joe thought was unusual. They were right. I've re-measured it with my Digital Vernier, Vernier Vernier and trusty M&W. They all say 0.249". It's still a bit sloppy in the end bearigs, but I don't regard that as a disadvantage.

I've done a Drawing - see attached.
The main problem with it is the position of the switches on the spindle. After much measuring and sums the best I can say is that I'm not convinced about my Dimensions. Clearly there must be some tollerance built in, and I have only one unit. I think the best bet is a trial assembly so that I can mark up where they really should be, and then measure.
I also still can't find any eveidence of a circlip or other means of location.

So, I'm sorry to say that I won't be bringing a sample with me on Sunday

Alan

       

[Joe]

I always find trial and error and prototyping being the best way as measuring is how errors get in.

- Joe

[Retired]

Hi,

I felt sure this spindle had the circlip but I did say I wasn't positive. Better late than never though I've just remembered I was also working on my Triumph Colchester lathe at the same time and this was another spindle job.

The reversing switch had a broken main spindle and this too was a difficult one to replace and it was this spindle with the circlip.

On these lathes the chucks are taper locked and by switching the rotation can be instantly reversed without the lathe throwing the chuck. I only ever tried this once though because the Transwave 7.5HP converter powering the lathe made such a racket I thought it was going to explode.

Fortunately all my current projects are recorded on the digital camera and additional notes taken.

Out of interest whilst in the garage this afternoon I measured both my 1/4" Dia brass and silver steel rod using my digital vernier calliper and obtained a reading on both of 0.248".

Kind regards, Col.

[Joe]

Obvious question: At what temperature is it at the specified width? Steel rules are supposed to read right at 68° and it's been well below that of late.

- Joe

[AlanBeckett]

Col,

At least that's solved that conundrum, although it doesn't answer the question of what keeps the shaft in place. I'm sure all will be revealed when I make a new one.
My Chipmaster's chuck mount is a D1-3 Camlock, which can also be reversed 'on the fly', or at least that's the theory. I haven't tried and don't propose to

Undoubtedly the air temperature in the garage was well below the required 68. However, I made the measurements in the house to be on the safe side. The internal temperature currently shows 21 on the Stat.

Alan