Method of joining for chuck key?

[Chris VParticipant @chrisv]

I have been admiring this chuck key and as I need a couple thought it would make a nice project sometime. Thinking about joining the steel stem to the brass handle I had thought of turning and reaming tapers but seeing the small end at the top of the handle I think from my limited knowledge this would not be particularly efficient at griping, the taper being too steep.

Bearing in mind its a key so needs to be secure how do you suggest they might have fixed it originally?

Chris.

[Chris VParticipant @chrisv]

How would they have, how should I??

[Martin ConnellyParticipant @martinconnelly55370]

Is it pinned through from the side?

Martin C

[Chris VParticipant @chrisv]

Thanks Martin, I meant to add that was my thought first but I see no evidence of a pin…

[Simon CollierParticipant @simoncollier74340]

Total guess, but knurled and driven on?

[Chris VParticipant @chrisv]

Hmm well that might work ok but for something of obvious quality I would expect something more certain to secure.

Similarly I suppose the end of the shaft could be peined into a countersink and then finished off flush, but again I thin there must be a better engineers solution?

Chris.

[Robert Atkinson 2Participant @robertatkinson2]

The part of of the shaft inside the handle may be square, splined or similar (or even threaded) with small round post at the end that was peened over.

An X-ray would reveal a lot, how friendly is your dentist?

Robert G8RPI.

[Kiwi BlokeParticipant @kiwibloke62605]

Tapered, square-section shaft and hole, round shaft end peened over, to hold it in?

[Martin KyteParticipant @martinkyte99762]

Whats wrong with using soft solder? I would do a taper fit, tin the steel and wipe with wire wool and sweat the two pieces together.

regards Martin

[Swarf, Mostly!Participant @swarfmostly]

At least one well-known brand of padlock uses a brass pin through the brass body to secure the assembly of its 'innards'. The brass pin is driven in and then filed and linished flush on both flanks of the body. If this is done properly, 'you can't see the join'! (I and my fellow pupils actually had to assemble such a padlock as part of a 'Locksmithing Acquaint Course' several years ago. )

You could use the same technique but polish the handle rather than settling for a linished finish.

Of course, the shaft of the key would need to be a good fit in the handle and the pin should be the same grade of brass as the handle so that their colours match.

Best regards,

Swarf, Mostly!

[Nick Clarke 3Participant @nickclarke3]

The brass crosspin sounds good, but you could also draw the shaft into the handle with a cheesehead screw in a close fitting shallow counterbore and linish down the head flush when tight.

Shaft to be keyed, squared, tapered or loctited to taste as well if desired.

[Gary WoodingParticipant @garywooding25363]

What's wrong with threading it and using Loctite?

[Martin ConnellyParticipant @martinconnelly55370]

Robert, I suspect your X ray suggestion is a bit tongue in cheek, however I think you need a bit more oomph for the X-ray than you get from dentists' or even hospital machines. The ones used for metal parts in industry are hidden in bunkers with big heavy sliding doors and sand in the gap of concrete cavity walls. They also use long exposure times compared to x raying body tissues. I think there are some suitable NDT companies based in airports for obvious reasons so your idea would work if you could get friendly with one of their employees. Otherwise pipe manufacturers who do their own NDT may be a good bet, I know of at least one with X ray facilities.

Martin C

[John HaineParticipant @johnhaine32865]

Posted by Robert Atkinson 2 on 28/05/2020 12:51:19:

The part of of the shaft inside the handle may be square, splined or similar (or even threaded) with small round post at the end that was peened over.

An X-ray would reveal a lot, how friendly is your dentist?

Robert G8RPI.

If my dentist has an x-ray machine that would image through solid brass I'm not going back!

[Kiwi BlokeParticipant @kiwibloke62605]

Robert Atkinson beat me! Dental X-rays won't penetrate – they are too low energy. Also, I think you'd need higher energy photons than general medical diagnostic X-ray gear provides. You could try your local radiotherapy centre, perhaps. You'd need an energy where the attenuation coefficients of Fe and Cu/Sn were sufficiently different to allow them to be distinguished. I once had a cello put through a hospital CT scanner – that was interesting, but another story!

[Chris VParticipant @chrisv]

Brilliant!

I had in my mind dismissed a brass cross pin as not strong enough but as several of you seem to think that would be ok I think that would be my preferred method. Of course a steel cross pin could look nice too, matching the top of the shaft, but clearly that's not how this particular example was made.

Should the cross pin also be tapered, I don't suppose you can buy imperial brass taper pins..or can you?

Chris.

[Nigel BennettParticipant @nigelbennett69913]

We used to make carriage door handles at work by casting the brass around a steel spindle with suitable chunks chewed out of it to provide a positive drive and location. The pattern was "handle plus spindle"; the pattern was removed and a steel spindle carefully positioned and aligned in the mould. Very simple bearings on most older carriage door locks; just a 3/4"BSW thread to provide axial and radial bearing surfaces.

To veer off-topic slightly, the handles on the BR Mk.3 doors were interesting; initially they were stainless steel, threaded 3/4"BSW, but they suffered misalignment problems. Later ones were fitted with plain journal bearings attached to the lock. Fitting the lock-plus-handle assembly involved first wangling the handle through the hole in the door, before securing the lock on the inside of the door with screws. Early handles – a lever type – suffered from twisting, due to the massive inertia caused by the handles whipping when the door slammed. (It is a rack-and-pinion arrangement which gives a positive visual clue to the door not being latched shut.) We had to change the material to a heat-treated grade normally used for turbine blades. The balanced dickie-bow type on Mk.2 and earlier stock didn't suffer from the problem, and a lower-spec stainless could be used.

And don't ask me about providing inside handles to slam door locks on Mk.3 stock…

[old martParticipant @oldmart]

Threading and using Loctite as recommended by GW would work, it would take more than the strength of the hands to break the bond. 270 would do.

[Chris VParticipant @chrisv]

Thanks Nigel B, casting the brass onto the shaft seems like that could well have been the way this key was made, I like it, but won't try that at home!

Cheers

Chris.

[Chris VParticipant @chrisv]

Or for that matter the tapered parts and soft solder, though I'd personally prefer a cross pin, not that Ive tried that before!

[Mick B1Participant @mickb1]

It's genuinely pretty, but as a lathe chuck key it seems to me to have a number of drawbacks:-

It's short, with limited leverage

It's heavy. If anybody starts the lathe with it in the 'ole, it'll make that much better a ballistic projectile.

It's not well balanced – I think it might feel awkward in use.

It's soft – after a year or two's regular use, it might look as if it's been chewed by a steel puppy with carbide teeth.

But hey, if you like it…

[Chris VParticipant @chrisv]

Thanks Mick B1,

Yes all good & valid points, though the chucks I 'need' them for are drill chucks that will mostly be used in the tailstock.

Regarding wear, is SAE 660 bronze more difficult to turn than CZ121 brass? And is it generally a harder material, ie likely to dent less????

Chris.

[Nick Clarke 3Participant @nickclarke3]

Posted by Chris V on 28/05/2020 13:56:54:

Brilliant!

I had in my mind dismissed a brass cross pin as not strong enough but as several of you seem to think that would be ok I think that would be my preferred method. Of course a steel cross pin could look nice too, matching the top of the shaft, but clearly that's not how this particular example was made.

Should the cross pin also be tapered, I don't suppose you can buy imperial brass taper pins..or can you?

Chris.

Yes you can, but only in small sizes and with non standard tapers I suspect – clockmakers use them to hold clocks together.

eBay Brass Taper Pins

 

Regarding wear, is SAE 660 bronze more difficult to turn than CZ121 brass? And is it generally a harder material, ie likely to dent less????

It all depends what you want to dent with it

 

 

 

 

Edited By Nick Clarke 3 on 28/05/2020 15:25:45

[Chris VParticipant @chrisv]

Ah yes I had seen and wondered what clock makers tapered pins were, I think they use them to secure the pillars to the plates like an engineer might use a cotter pin, only more refined!

[Mick B1Participant @mickb1]

Posted by Chris V on 28/05/2020 15:07:39:

Thanks Mick B1,

Yes all good & valid points, though the chucks I 'need' them for are drill chucks that will mostly be used in the tailstock.

Regarding wear, is SAE 660 bronze more difficult to turn than CZ121 brass? And is it generally a harder material, ie likely to dent less????

Chris.

I don't really know it – it's a leaded bronze that's said to be free-machining and resistant to wear. I've machined a fair amount of phosphor bronze PB102, and that's much tougher than CZ121, with a continuous chip and darker, more coppery colour. You need more clearance for tapping and good lubrication.

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