shaping 18ct yellow tubing

[ajda]

I want to shape a piece of 18ct yellow gold tubing (4mm OD, 0.5mm wall) in a similar way to this piece of silver. With the silver it's easy enough to do by pinching with round nosed pliers, going gradually and annealing carefully. I've only worked a little in 18ct gold - any advice for doing it neatly and avoiding splitting?

8458

Alan

[Dennis]

An unusual request Alan and having previously done it with silver, you are already the expert on this. However 18ct will be harder than silver, even when annealed.

If I were doing this without prior knowledge, I would have one more go with silver or cheaper tubing from a model shop. I would start it with pliers, possibly large handymans wire cutters. Then I would see whether I could improve it by laying it flat, inserting a blunt table knife and rolling it. No idea whether this would give a better result, but experimentation is part of the process. Dennis.

[ajda]

Thanks Dennis. I thought the main difference would be hardness - I recently read a comment from a goldsmith who described working with silver as like working with butter. I've had several goes at this with the silver tubing - actually doing the same shaping operation as I plan for the gold, but for a quite different purpose (sounding enigmatic, I know, but I'll post pics/details of both further down the line), at the same time using the silver as a test run for the gold. I've been studying Cookson's datasheet on 18ct yellow gold and making comparisons with what I know - so, for example:

Annealed Hardness 120 +/- 10 HV
10% reduction of area 150 +/- 10 HV
20% reduction of area 180 +/- 10 HV
40% reduction of area 215 +/- 10 HV

Argentium, by comparison is around 50-60 annealed and up to about 120-150 fully hard.

It also says "May be cold worked up to 70% thickness reduction between anneals" - for Argentium up to 60% reduction is recommended.

So, I've got some theoretical understanding and some experience with silver to relate it to... but I guess I'll need to play with a lot more before I really get a feel for it. I just hoped someone might look at my picture and say, hey presto, here's a simple foolproof method for doing that. I suppose I'm nervous about getting started - £300 worth of gold just arrived in the post and there's not a lot there. I can't really afford to get it wrong, whereas with the silver it doesn't matter - I just melt down any botched attempts and make something else with them.

Ah well, I shall grit my teeth in the morning, take up torch and pliers and see what comes...

Alan

[ps_bond]

I'd be inclined to fill the tubing, either with pitch or Woods metal. Could then use a punch & pitchbowl (or sandbag) and chase in the groove, or get carried away and make a small smithing magician (AKA a butcher).

Or go with the pliers.

[ajda]

I'd been wondering about filling the tube to give it some support on the inside - probably a sound idea, though I didn't know what to use. So, different types of pitch... Wood's Metal... I've not worked with either... what would you recommend for a novice?

Smithing magician/butcher... that's a new one to me - I've just been asking Google about it - I might not try making something specific for this task but I can see lots of future possibilities there... Right now if you could lend me a magician of the Harry Potter kind that would be great.

I've left myself one week (busy already) to do something pretty complex that I've not done before in materials I'm not very familiar with. Deadline pressure works well for me, so that may be no bad thing. It's for a family member, so there's room for forgiveness (I hope) if it all goes pear-shaped, but obviously I'd like to get it right.

I will post pics here when it's done, even if it's a pear...

Alan

[ps_bond]

Pitch probably has more additional uses than Woods metal; you could either use traditional asphaltum pitch (um, or roofing pitch in a pinch) or a soft pine rosin-based pitch (often "German Red Pitch"). David Huang uses microcrystalline wax when chasing vessels, including his pure gold one; I've started trying that for some of mine - candle wax might work, but I suspect it'll fracture more. Worth trying to see though, work with what you have. I'd be leary of trying low temp solder, even if it is lead-free. You might get away with it if you soot the inside of the tube; it shouldn't wet gold, but sod's law takes precedence.

Funnily enough, Jim Binnion & Chris Ploof have started marketing something similar for drawing down mokume billets in a hydraulic press. I'd probably just make one up from scrap though.
http://www.riogrande.com/Product/press-buddy-forging-kit-for-bonny-doon-mark-iii-hydraulic-press/115907

Added - video:
https://www.youtube.com/watch?v=2de_qgmTUAg

[Dennis]

I have wracked my mind from the beginning as to how one could support the inside. It would be quite challenging to fill 4.00mm tubing with a liquified substance and be sure it was completely full. Also messy to remove.
Tonight I found some electrical lead, where the plastic covered strands fit tightly into this size of tubing. By slightly bevelling the opening with a round burr and using a little lubricant, it can just about be screwed in.
If this improves the result, then by leaving some protruding at each end, it can eventually be removed by holding the tubing back against the front side of a drawplate, or hole in a piece of stiff metal such as brass and pulling with pliers-possibly the wire first and then the plastic.

A completely different approach would be to use two stubs of tubing, make about 6 short cuts in the end of each, stand them into a fitting hole in a doming block or plate and gently dome them shut. You have to go slowly, or they buckle. Also hold them upright with tweezers, to save your fingers.
Then use solder to obscure the traces of cuts, lay them touching in a groove made in a block, reheat and they will join. Dennis.

[ps_bond]

Agreed, it's not going to be the easiest thing to fill. Copper wire dissolved out with nitric acid would be another solution (no pun intended), but not everyone has nitric.

[ajda]

Dennis, your electrical cable idea could be the one. I'd been thinking about various things I might find to use in garage/kitchen/junk drawer, but worried about getting anything stuck inside the squished tubing - the fact that you could draw out the inner wires and thereby free the plastic outer from its tight squeeze could be the answer...

I'm tempted to get some pitch anyway, as I know I have other uses for that - and since I've got order something else from Cookson, I might just get a lump from them. They don't give much detail on the site about the different ones - would I be right in assuming these two are similar, perhaps different hardness?
http://www.cooksongold.com/Jewellery-Tools/Engravers-Pitch-450gm-Red-prcode-999-0099
http://www.cooksongold.com/Jewellery-Tools/Chasers-Pitch-Yellow-450gm-prcode-999-0104

Your idea of doming the ends of shorter pieces then joining them probably won't be practical in this case - I need to make 3 parallel grooves in two short lengths - but I also need to dome the ends slightly as well, so you've given me some useful clues there.

I probably wouldn't consider the copper/nitric acid route - not least because I think you have to have an EPP (Explosives Precursors and Poisons) licence nowadays for that - but out of interest, would nitric not also attack the copper content of a gold alloy?

I'm still thinking about the magician. I've got a small arbour press lying idle in the garage...

Alan

[ps_bond]

Dennis, your electrical cable idea could be the one. I'd been thinking about various things I might find to use in garage/kitchen/junk drawer, but worried about getting anything stuck inside the squished tubing - the fact that you could draw out the inner wires and thereby free the plastic outer from its tight squeeze could be the answer...

Reminds me of another trick - grab both ends and stretch the inner core, although I don't know if you'll get enough change in cross-sectional area to free it - it's probably that the necked-in section would fail first.


I'm tempted to get some pitch anyway, as I know I have other uses for that - and since I've got order something else from Cookson, I might just get a lump from them. They don't give much detail on the site about the different ones - would I be right in assuming these two are similar, perhaps different hardness?
http://www.cooksongold.com/Jewellery-Tools/Engravers-Pitch-450gm-Red-prcode-999-0099
http://www.cooksongold.com/Jewellery-Tools/Chasers-Pitch-Yellow-450gm-prcode-999-0104

Not familiar with either of those particular ones, sorry - but of the 2 I'd go for chaser's pitch first. Wondering about Polymorph, but it's quite firm.


I probably wouldn't consider the copper/nitric acid route - not least because I think you have to have an EPP (Explosives Precursors and Poisons) licence nowadays for that - but out of interest, would nitric not also attack the copper content of a gold alloy?

For a private individual, yes. Yes, it'll attack some of the copper on the surface but not to a significant degree.


I'm still thinking about the magician. I've got a small arbour press lying idle in the garage...

There're comprehensive plans around - LMK if you don't spot any, I'm bound to have some on file somewhere.

[ajda]

A brief update: I've posted a couple of pictures here - http://www.cooksongold.com/forum/showthread.php?t=7595 - of my cricket ball and bails. To make the bails, I shaped one piece of tubing to fit tight over a smaller diameter tube, then soldered. I made it as one piece then cut through the centre. I tried several tools/methods and in the end reverted to my round nosed pliers for most of it. I did use the electric cable idea - actually it may not have been needed for support, but was a useful guide to squidging the tube evenly to make the grooves. Once I got the grooves to a certain depth it was easier to finish them with the outer in place on the inner piece. I'm pretty pleased with how it worked out - pity I can't say the same for the ball at this stage...
Thanks for the help and advice.
Alan

[Dennis]

You done good as they say across the pond and we are learning with you, Alan. thank you for posting, Dennis.

[ajda]

Thanks Dennis. I followed your lead and made each stage in silver before doing it in gold, except the last bit of soldering on the ball, as I was running out of time - and that's where it went wrong (mainly due to my lack of experience with gold, partly also a weakness in the design). I think there's a lesson in that. I'm going to remake the ball, but this time complete at least two in silver first to test out a couple of slightly different approaches. I think the balls would be quite saleable in silver - perhaps I'll do a range of sports, rugby, football, cricket, baseball, etc...
Alan

[Dennis]

I think the lesson, which I have never learned either, is not to go on for the finish when you are overtired. You might get away with it, or you might be set back to square one. Dennis.

[ajda]

True. I can't claim I was overtired, but I was definitely rushing. Also, I don't think my focus was quite right. You know that experience sometimes called "flow" when you're fully focused on the present moment and the task in hand? The trouble is, I had the thing already completed in my head and was already congratulating myself on a job well done. I suspect it's the same reason why the majority of car accidents are said to happen within a mile from drivers' homes. You can be fully focused on the road and the driving conditions for hundreds of miles; but close to home, feeling that you are already there, you let your concentration lapse and you think about what you are going to do or say after you're out of the car, you're on familiar roads and you leave the automatic pilot in charge for the final leg - then something unexpected occurs and you fail to re-engage and react to it... Something like that perhaps... An experienced goldsmith, working in familiar materials and perhaps on a task they've done many times before, would have got away with it - I just swerved and crashed the car. No insurance, either - fortunately no one was hurt!
Alan

[Dennis]

Very Good. Dennis.

[ajda]

On a brighter note, I think I got the shaping of the tube sorted this morning - at least for the larger diameter silver that I'm doing something else with. I found a suitable brass washer, profiled it with the Dremel and swapped it with the cutting wheel of a standard plumbing pipe cutter... works a treat.
8492

The painted nail, by the way, is part of my niece's attempts to tart up her "Uncle Alien" for Christmas...

Alan

[Dennis]

That's invented a completely new tool. Now I wonder what I could do with tubing like that?

[Tabby66]

I think the lesson, which I have never learned either, is not to go on for the finish when you are overtired. You might get away with it, or you might be set back to square one. Dennis.

I'm guilty of that Dennis, just thinking, oh I'll just finish this bit and I'll be done, only to trash the piece or make more work. If only I'd left the piece and done it when i was fresh it would have been done right and quickly!! Aaaagh!!

I like you're analogy too Alan, makes me think of when I'm trying to 'hurry', doing something because I have too much to do and ruining it because my mind is on what I have to do and not what I am actually doing!!


On a brighter note, I think I got the shaping of the tube sorted this morning - at least for the larger diameter silver that I'm doing something else with. I found a suitable brass washer, profiled it with the Dremel and swapped it with the cutting wheel of a standard plumbing pipe cutter... works a treat.
8492
Alan

Fab little tool Alan!!

[ajda]

There's a flaw in my tool - at least when shaping something as soft as annealed silver - because the guide wheels (on the opposite side to the cutting wheel) impress a mark on the tubing either side of the groove. You can see what I mean in the photos of my entry in the December competition - http://www.cooksongold.com/forum/showthread.php?t=7535&page=4&p=84884#post84884 - not that it matters much for these pieces...
Alan