Reclaiming Pye Fenman1 damaged knobs

[Yorkie]

Hi,

Many thanks for the kind comments in post #1 David. I'll dig out the knob pictures and put them on the appropriate thread.

Its a lot different to wood turning isn't it?

Kind regards, Col.

Thanks for you kind words Colin.

Yes, on a woodturning lathe you have more freedom to make shapes such as coves and beads, and don't have to worry about the tool being on the centre line of the workpiece as the tool is in your hand and you place it where you want it, and most woodturning work doesn't need to be too accurate unless its thread chasing or making a lid to fit a box. But of course, with a metalworking lathe, as with woodwork, 0.1 mm reduces the diameter by 0.2mm!

I think the trick with metal lathes is to take fine cuts unless roughing out, and of course with acrylic rather than metal, a slow turning speed is more critical due to heat generated by the tool.

I think the big issue with woodturning is that of a 'dig-in' due to not presenting the tool to the wood at the right angle (with the bevel running), and of course, the risk when hollowing, or coming through the side or bottom of a hollow form. But if it does, so what - it's just a bit of wood so its really no big deal.

All good fun eh!

It stops my kids from putting me in a home:D

[Yorkie]

With other diversions dealt with, I managed to find some time to start the restoration of my Pye Fenman1 today. My delight with the knob repairs was shortlived - as soon as I tightened them onto the control shafts, they proved no more robust than the originals and cracks started to appear, so it was back to the drawing board. My chum 'Old John' had mentioned that repair sleeves were often used on cracked knobs and as I had some 15mm ID aluminium tube, I decided to turn a new set of perspex knob adapators and to sleeve them with aluminum tube glued to the adaptors with Araldite, then when the glue had hardened, to drill and tap the adaptors to accept 4BA grub screws. It seems to have done the trick. I've attached a pic of a cracked adaptor, and a newly turned sleeved one. (looking a bit scruffy as I hadn't cleaned it up when I took the pic).

I've set about replacing several caps in the Fenman1, which includes the smoothing/reservoir caps - 2 x 32uF. One section was ok - the other didn't even move the needle on the ESR meter, and was basically open circuit. The original was held on the chassis with four twisted tags in slots, so I had to enlarge the hole through the chassis to give adequate clearance for the connections on the new cap, and to fit a circular clip to the chassis to support the cap. I've replaced several other electrolytics, and a couple of waxies. Not the easiest of chassis to work on because to get at the components which need to be replaced I've had to disconnect others to move them out of the way, then refit them.

It has the usual manky 2-core mains lead just tied in a knot to restrain it, so that will have to go. I'll repace it with a three core lead with a proper cable restraint.

[Retired]

Hi,

That looks more substantial David and fingers crossed it will work. I've never had any luck with gluing plastics but I hope yours is a success.

These small jobs quickly get out of hand but its fun to play around on the lathe. If all else fails could you make brand new knobs from scratch; it would be an interesting project?

The chassis sounds to be coming along nicely.

Kind regards, col.

[Yorkie]

I think you're right about perhaps making entirely new ones in this case Colin, though the front of the old knobs are all that shows from the front of the set, and I managed to skim them out so that when glued to the Perspex extensions, they're a nice fit, and seem to have stuck well.

Yes, I'm getting used to using the lathe, and have managed to make a few tools for the toolpost to suit my needs from 1/4" square HSS blanks bought off e-bay, and it's very satisfying to be making good use of what is really a relic of the past, but is still up to the task. I'm sure that if it could talk, it would have an interesting tale to tell about it's hundred or so years of life!

I managed to spend an hour or so on the chassis this mornnig, and so far have replaced four electrolytics and three waxies before we went to our keep-fit/swim session. Hopefully, I'll make a little more progress this afternoon. I had a wry smile while working on the chassis, thinking to myself that were the set in your hands, the chassis would be under the bench, and the cabinet ON the bench!

Whenever I look at old sets such as this, which has quite a high component count, I'm always amazed at how higgledy piggledy the layout appears to be. Very labour intensive to build and test and not very easy to repair. I can't help feeling that with all their expertise, the makers could have surely made sub assemblies on tagboards or whatever. True, in some cases, such as the front end, the desire was to keep wiring as short as possible, but even so, the overall appearance looks more like 'home-brew' rather than designed for assemebly line production. I'm sure they must have had it all worked out!

I'll need to add quite a few caps to my shopping list for the BVWS stand at Golborne! I haven't tested the valves other than the filaments, which are fine, and when I've finished fettling the chassis up, will plug them in and see if they work. I have bought a NOS ECC85, because in my experience, they're invariably duff, and likely as not, being in the FM stage, are probably the reason that FM sets such as this one got pensioned off and put in the attic to be re-discovered decades later. I've also got a NOS magic eye for it.

It's nice to be getting on with a set restoration after so many other things I've been on with, and time spent away from home.

[Retired]

Hi,

You certainly know me David and yes the cabinet would have been first job for me with the "works" dumped in the front bedroom safely out of the way.

It is amazing that a manufacturer would go to great lengths to sort out the workings of a radio then as you say spread the components all over a chassis in what appears random order. Sub assemblies would indeed have been easy to assemble by unskilled labour but in those far off days labour didn't seem to be the issue it is now.

It shouldn't be long now before the chassis is fully working and I'm sure it is giving you a lot of pleasure whilst working on it.

My lathe too is a relic but even so it is fantastic what can be made on it with a lot of care and patience. Your little Lorch Lathe is beauty David and is capable of decent sized work; certainly anything associated with vintage radio/TV. It will also be very accurate. I'm so pleased you are using it and now buying tooling; the bug has bitten!! Have you ever done any knurling David as this is an interesting lathe operation and simple to do once the first knurl has been produced; I have two knurling attachments; one is much too big for the Myford but the other fits. On your lathe you might need to adapt a bit in order to mount the attachment but the lathe should be capable.

I certainly don't wish to steal your thunder David but here are the promised pictures of the large radio dial I recently repaired. The work was most interesting but the solution and method took a great deal of thinking about as I would only have one chance of success. I was very worried as I spun the dial to clean up the break and it took ages as I dare not put a decent cut on so just kept nibbling away at it. These dials as are the knobs from your PYE are very fragile and it is so easy to underestimate the power at your finger tips whilst using even a small lathe; chucks are heavy and don't take prisoners ruining the work if you blink

I've included a couple of pictures showing knurling in action and the finished knurl for those unfamiliar with the term or process.

I bet there is no stopping you now David that you are producing work on the lathe; perhaps a nice Colchester will be on your wish list for Christmas?

Kind regards, Col.

                       

[AlanBeckett]

Col, David,
Without wishing to divert this Thread into things Mechanical I prefer a clamp type knurling tool for small lathes and small sections. They put a lot less load on the bearings.
http://www.chronos.ltd.uk/cgi-bin/sh0000....ltd.uk%2f&WD=knurling&PN=Small-Clamp-Type-Knurling-Tool-with-Two-Pairs-of-Knurls.html%23a391201#a391201
Alan

[Yorkie]

Thanks for re-posting those pics Colin - that project really was quite a challenge, and the Tufnol seemed an ideal choice for the shaft that slips over the tuning cap spindle. I've not done any knurling since I was at school, when we all made the obligatory centre punches and what not. The clamp type knurling tool at the link Alan showed looked quite nifty, and inexpensive. The problem I have with my Lorch is that the centre line is only about 6mm above the toolpost, so I'm limited as the the size of tooling I can use, but of course small lathes such as the Unimat etc and those sold by the likes of Machine Mart are similar in scale to my Lorch, and have quite a following with model engineering hobyists, so small tooling for knurling must be available. I'll have to wait till the next Northern Model Engineering Show at Harrogate and have a chat with Chronos! I did buy a set of three inexpensive small tools at the last show, as you know, but they're above the centre line when in the toolpost and I later discovered that they're really intended for the ML7.

This thread underlines the 'make do and mend' concept that nothing is beyoned redemption with a bit of ingenuity and imagination, tempered with skill and patience!

The pressure is on Alan now, with his MM spindle project!

[AlanBeckett]

I'm working on a Post now, but if you're of a nervous disposition don't read it
Alan

[Mark R]

Nervous disposition? Crikey Steve P taught me I have every right to be nervous lol.

cheers Mark