Cnc Machining In Precious Metal

[JTR]

I've been a member for one day and already have my first question!

 

Can anybody recommend a UK based company who can CNC (CNClathe?) in precious metal? Perhaps a member offers this expertise?

 

Thanks in advance.

[ZeissIkon]

Any CNC setup should be able to work silver, gold, etc. as easily as it would brass or steel. Be aware, however, that CNC as a process tends to be wasteful of material; this doesn't matter much when you're machining off 60+ pounds of forged aluminum to make a billet wheel (in fact, it's cheaper to let the machine run and sweep up a big pile of shavings than to spend more time forming the blank), but when you're converting $200 worth of gold (or more) into fine shavings in the bottom of the machine cabinet it'll be another story, I think. To minimize the metal waste, you'd be best to start with a preformed part that's (very) close to the final machined dimensions (FWIW, gold should cold forge nicely, too).

[Inka]

Knowing what it is you want machined would be helpful, not so much the material as to the type of piece you're trying to create or modify.

Like ZI has pointed out, CNC machining can be very wasteful when large amounts of precious material are removed.

If you're just trying to get a small part precision machined with some small amounts of material removed, well that's a different story.

So what is it you're trying to do would be most helpful in helping you, only then moving on to the next step trying to help you find a place that can/will do this for you.

If it's a small item, only needing a small amount of milling, then even a good "Drill & Mill" with a precision X-Y table would do the job nicely and more p[l]aces available to have it done as well.

Edited October 6, 2009 by Inka

[FarmBoy]

Interesting topic. PM (precious metal) machining is as stated not much different than machining any other material from the mechanical side taking into account the material properties of what you are machining. I've machined platinum, silver, and gold for use in electrodes. It takes a bit of intestinal fortitude to start cutting on a small bit of stock that cost you three figures. The problem you will have is finding stock that meets your specifications. For electrodes we merely turn the rod stock we can get to the proper diameter then face it off and polish the ends after parting off the piece we need.

 

In case anyone asks, yes we save the turnings but putting a catch tray directly under the headstock.

 

You do want to find the stock that is as close as possible in size to your finished piece part and then avoid end mills since catching the shavings isn't easy.

 

I would not use a CNC machine to do this as mentioned but for other reasons. CNCs are not wasteful, the way we use them is. They do give a new meaning to hogging out a lot of material though.

 

Todd

[professionaldilettante]

Considering how much precious metals cost, you may be better off machining a piece of jewler's wax, and having it cast in the metal of choice. I would think that if it wasn't perfectly to dimensions, you could then just machine the critical areas, wasting the least amount of precious metal.

[JTR]

Hi Guys,

 

How rude of me to forget to reply, so long after my original post!

 

I managed to find a fantastic company in the UK who specialise in this type of work. After much development (and time) we're machining from various dimensions of tube, which are close to the finished size. It's all quite complicated but I think they're 99% complete!

 

Anyway, here's a sneaky-peaky: http://www.craftanddesigncouncil.org.uk/10-3DTechInnovation.html

[richardandtracy]

As a piece of jewelery, it is simply stunning. As a pen for regular use.. Umm. I'd be terrified to use it.

 

The shape looks almost perfect for a lost wax/investment casting, but CNC is a good option given the complexity of the shape.

I have often wondered if rapid prototyping can't be used to make lost wax patterns acceptably, so you benefit from the modern design technology but also get close to final shape very quickly.

 

What can we say other than 'Wow'?

 

Regards,

 

Richard.

[JTR]

As a piece of jewelery, it is simply stunning. As a pen for regular use.. Umm. I'd be terrified to use it.

 

The shape looks almost perfect for a lost wax/investment casting, but CNC is a good option given the complexity of the shape.

I have often wondered if rapid prototyping can't be used to make lost wax patterns acceptably, so you benefit from the modern design technology but also get close to final shape very quickly.

 

What can we say other than 'Wow'?

 

Regards,

 

Richard.

 

Hi Richard,

 

I'm glad you like it - that's just the silver prototype.

 

It certainly isn't a pure writing instrument for your pen buff. I like to think of my pens as a harmony between fine jewellery, objet d'art and exclusive writing instruments. So, a piece of investable, practical art. Something you'll invest in as an heirloom and I hope, appreciate as a precious work of art in its own right.

 

This model is not the sort of thing you'll write a novel with, nor a long letter - but perhaps large cheques and important, personal notes. Many collectors of this grade of product will perhaps never use them, although the parts form Heidelberg are top-notch and operate really smoothly.

 

And, you're not far off on the production side. A combination of milling, lost wax casting, RP and traditional goldsmtihing techniques. It's all laboriously hand finished and all my own custom, bespoke parts. The whole thing (apart from essential plastic feeder parts) are produced in precious metal, and made in the UK. The only part that aren’t are the nib and feeder which are sourced in Germany (EU).

 

Anyway, I'm glad you appreciate my passion (or is it my poison?!) and I hope to bring them to market in the near future. Watch this space...