PMC 3

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JanineB@7 wrote
on 28 Feb 2012 10:04 AM

Hi there,

Fired my first PMC 3 Pendant yesterday and it was a disaster. It looks like a BLOB !!!!!  I used my mini torch to fire the piece and do believe that when it started bubbling and the design dissapeared that I was in trouble..LOL

I decided that I would sand it and try to salvage the piece. When I tried to drill a hole in the pendant for a Bail it was so hard that I broke three drill bits..

Can anyone help me????

I do know that I should purchase a Butane torch for further designs, but I do not know why I cannot drill the piece???

Help !!!!

Janine

 

 

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Posts 10
on 28 Feb 2012 10:46 AM

Janine - I suspect that your drill bit is dull, or broken on the tip.  I would try a NEW drill bit, with a bit of lubrication: bur life or ivory soap.    You don't specify if you are trying to drill by hand or mechanically.  I would recommend using a drill, powered screwdriver, flexshaft/foredome or a drill press.  Using a drill press will also help apply pressure perpendicularly to the piece.

You should be able to torch fire your PMC with a mini torch - but, you have to carefully monitor the temperature.  It sound like you overheated the piece and it melted.  You can do that with a Butane torch as well.  The piece should glow salmony-orange for at least 2 minutes.  If it begins to glow red, or you see a shiny surface you need to pull your torch back IMMEDIATELY.  The bubbling could be due to moisture still in the piece - how long did you let it dry?  I don't know that I have ever seen silver bubble due to heat - it just becomes a melted blob in an instant.

 

Paula McDowell

Fire Dance Jewelry

firedancestudio@yahoo.com

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Tom and Kay wrote
on 28 Feb 2012 10:52 AM

Hi Janine, we are working on your problem and should have a response shortly.  We'd also like to use your question in our in-print column in the magazine.  Please email your full name, city and state to us at:  kbenham@cfl.rr.com.  Thank you for your question.

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JanineB@7 wrote
on 29 Feb 2012 7:03 AM

Paula,

Thank you for your reply...I use a Drill Press to drill my metals and stones. Wish I had a Flex Shaft, as it would be so much easier for some applications.

I dried my PMC3 for 24 hours and let it air dry on top of a piece of crumpled up Paper Towel.

When I was forming my design and shaping my Pendant I was not smart enough to use a bit of oil on my hands, work surface and clay.

When the piece started to bubble I immediately pulled the torch away and held it at a higher level. Not knowing how far away to hold it is going to be a wee bit tricky for the next attempt. I had so much fun designing the Pendant and my mind had gone wild with so many thoughts on what can be done with PMC Clay. To have my final piece end up looking like a BLOB was somewhat discouraging, but has not put a damper on my willingness to move forward with another attempt.

Thank you,

Janine

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deecaria wrote
on 29 Feb 2012 3:23 PM

That's exactly what I feared might happen with PMC and the main reason I haven't tried it yet. I have a hard enough time heating up a ring or some other piece of silver evenly when I need to solder that I didn't believe I'd be able to fire a PMC piece evenly enough. I guess it must take a lot of practice.

I think I'll probably save up to buy the kiln before jumping into PMC.

As for drilling, I'm no expert but if the pendant was thick the drill bit may have overheated too much and that's why it broke. Drilling a metal sheet is easy enough but I've had to drill thick half round wire and felt the need to stop and let the drill cool once in a while.

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Posts 100
Tom and Kay wrote
on 3 Jan 2013 9:38 AM

Janine, here's our response this was submitted for the March 2013 issue:  We did watch a PMC 3 torch firing demo a few months ago which we found pretty cool.  But just watching the demo doesn’t give us enough knowledge or experience to provide a solution to your problem.  A quick search online, however, led us to a .pdf document [www.metalclay.com.au/pdfs/TorchfriingPMCpdf.pdf] posted by Tim McCreight that first appeared in Studio PMC.  Tim’s article supplies the answers to your torch-firing problem:

 

         “For the record, it has always been possible to fire PMC with a torch.  The hard part was finding someone to hold a torch for two hours!  With the creation of PMC+ and PMC3, torch firing becomes a viable option.  Both of these products have firing schedules that are significantly shorter and at a lower temperature than original PMC.  Now we can make solid silver jewelry in only a few minutes.

          Jewelers use a variety of torches, all of which deliver more heat than is needed to fire PMC.  People with experience in metalwork and a good idea for heat colors will be able to fire PMC+ and PMC3 with any traditional torch.  If a person is buying a torch specifically to fire PM, I recommend a small self-contained butane torch.  These compact torches are relatively inexpensive ($25-50) and are available from craft suppliers and jewelry supply companies.  In fact I even saw one at a kitchen supply company where it was sold to caramelize cremé brulée.  The torches are sold empty and filled (and refilled as needed) from a canister of butane that can be bought from the same suppliers, grocery stores or tobacconists.  Note that the standard torch is rated at 2000° F so it can melt PMC.  Some manufacturers sell a modified unit that heats only to 1650° F.

 

Torch Firing Process

 

     1.  Allow the work to dry overnight or drive off moisture with a hairdryer, coffee warmer or in a slow oven.  Torch firing is not recommended for large items.

     2.  Place the work on a soldering block or fire brick, which is in turn set on either a fireproof surface or something you don’t mind being singed (like a piece of plywood).  If you are working on the kitchen counter and the piece rolls off the block you don’t want to scar the countertop.

     3.  Light the torch and hold it so the flame is nearly vertical with the tip of the cone about 3/4” away from the work.  Within a minute, the piece will be enveloped in a soft flame as the binder burns away.  The flame will soon go out by itself.  Within another minute, the piece will start to glow red.  Continue heating until this becomes a bright and luminous color.  At this point, glance at a clock.

     4.  Hold this color as uniformly as possible.  For PMC+, hold it for at least 5 minutes. For PMC3, hold the temperature for about 2 minutes.  When the time is up, turn off the torch and allow the piece to cool at least until the red color is gone, at which point it can be quenched in water.  Or not—there is no advantage to quenching, other than the fact that you can examine the piece immediately.

 

Educate Yourself

 

          Here’s a test I recommend to anyone who intends to fire with a torch.  It takes a few minutes and requires the investment of a dollar or two in PMC, but it will go a long way toward understanding the process and building confidence.  Pull off a pea-sized bit of PMC+ or PMC3, split it in half, and roll out two small rods.  Follow the instructions above with one added step.  After the complete cycle, move the rods apart on the brick so you can focus on one of them.  Concentrate the flame on this rod in an effort to melt it, which might be possible even with the regulated torch. You’ll see a bright mercury-like skin form on the piece and the red color will become even brighter.  The edges will start to curl and the PMC will be drawn up into a ball.

          Make a mental note of what you saw. This way you’ll know the signs of melting, and you can withdraw the torch in time before damaging a piece you care about.  To complete the experiment, allow the other rod to cool and test it by bending, filing, burnishing, and polishing.  This will confirm that, sure enough, torch firing really works!”

 

Editors Note:  Tim McCreight is a Senior PMC Instructor for the Rio Rewards Certification Program as well as a metalsmith, designer, author, teacher and publisher (Brynmorgen Press).

 

The easiest way to eliminate breaking drill bits is to create the opening for the bail prior to firing.  However, to drill the metal after firing we suggest using a small drill press if you have access to one as it allows you to work more safely and smoothly than drilling by hand with a flex shaft.  Be sure to clamp your work piece securely to the press table so it doesn’t spin out of control possibly injuring you in the process.  Lubricate the drill bit with bur-life or beeswax.  Bring it down to the work piece and drill a little at a time so as not to build up heat causing the drill bit to bind.

 

If drilling with a flex shaft machine, make sure that the drill is running true – no wobbling – when chucked in the flex shaft.  The flex shaft must be held securely, fingers wrapped around and palm against the head of the flex shaft with the flex shaft held perpendicular to the metal piece being drilled.  Again, secure the metal work piece being drilled.  Run the flex shaft at low speed as high speeds create a lot of heat from friction and destroys the temper of the drill bit making it unable to cut through the metal.  Again, always lubricate the drill bit.

 

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