Thursday, February 27, 2014

New Casting Project Enters Planning Phase - Needle Case

I have entered the SCA Midrealm's Pentathlon competition (PENT) in the past.  I see it as an Arts and Science competition which attempts to inspire participants to be more than a specialist in one arena.  There are five basic divisions one can enter into with regards to the A&S competition.  Each division is broken out further into categories.  (See the website for further details regarding the criteria.)  A pentathlon entry must consist of 5,6 or 7 entries.  The final score will be the highest 5 entries which span across at least 4 divisions.  This causes the participant to expand knowledge and expertise outside a single area of specialty.  OK, that's enough background.

I have decided to enter the PENT again for the 2015 season.  I have already completed the majority of one of my entries.  The greenwork shirt will be one of my entries.  I have started a collection of wood working tools.  Those will be another entry.  I have some plans for other entries but nothing that I'm willing to go on record with as of yet.  That is to say other entries other than the one on this post.

My first complex multi-part pewter casting project.  I have recently been instructed in the ways of pewter casting.  I have long wanted to develop more expertise in this area.  I have attended a couple classes and recently helped cast some coins for one of my favorite SCA events which involves lots of fake gambling with pewter coins.  While I have limited experience in the arts of pewter casting I have been thinking on this project for about 3 years or so.  I haven't actively done much planning… until now.

The project is a late period pewter needle case.  I previously had collected some images from inspirational pieces but have since lost my hard drive and have as of yet not recovered any of those images.

The basic style of the needle case is represented in the following image.

While I have been conceptualizing this design I wanted to keep a few design considerations in the forefront of my thought.  I want the finished piece to be aesthetically pleasing, functional and yet complex enough that anyone familiar with casting would easily see the complexity of the mold required..  I plan on making decorative designs on each of the six faces of the case.  I would like those designs to be recessed enough so that it is clear that any 2 part mold would not work.  I have worked through the overall design shape and layout of the stones required which I will outline here.

Here is a view of the shape and recessed areas of the case as well as a cross section view.

To achieve this design I plan on attempting a eight part mold for both the top and bottom.  I maximize the use of the soap stone I plan on trying a cutting layout for the six side pieces as depicted in the following image.

Once cut I can rearrange them into a rough barrel shape.

I can then smooth out the edges and drill holes for the register pins.  I plan on spacing out the register pins as shown in the cross section following.  While I haven't tried it yet I have heard that you can simply drill through two pieces and then pour molten metal into it.  The resulting metal once hardened will become your register pin.  This sounds like a plan but until I practice that approach this type of register pin is subject to change.  I may simply drill and insert brass pins instead.

The primary thing to keep in mind is that the pieces must match up consistently once assembled while still being easy to disassemble once the mold has been poured.

Once that portion of the mold is roughed out I can proceed with the top and bottom caps.  At this point I don't plan on doing any carving to the stone yet.  I want to get the overall pour layout finished first and then begin my carving.  I would hate to waste time carving a piece that does not pour well.  I plan on making a cap stone for the each end.  One end will have the sprue and the other end will have a wooden dowel inserted to create the hollowed out section of the case.  The cap stone will be cut to fit the six pieces and serve both as a cap and also as a retainer to hold the six pieces in place.

The cap on what will be the bottom of the case will have a sprue drilled into it. I will have to start small and then drill larger depending on how fast the metal can flow to all the cracks and crevices.  The cap on what will be the top of the case will contain a wood dowel. 

At this point the real fun can begin.  Once I can get a decent pour at this point I believe I can start taking away material from the stone to add to the design.  Up to this point the mold will be cut "small".  Keep in mind that as I remove material from the inside of the stone it will increase the metal which can flow to the case.  It will therefore thicken the resulting piece.  I want to start as thin as possible and get a good pour.  Once that is achieve I can carve the detail work which will thicken the resulting piece by adding embellishment that stands out from the surface.

Before I get along too far on carving my next step is to add the loops which will allow the case to be hung.  I have discussed a few options with a friend.  Some options discussed were:  1) A flap which could then be rolled up to form the tube after the cast cooled. 2) Drill out the hole after the pour.  3) Cast separately and then solder to the case when complete.  I have come to the conclusion that I would still like to do this in one pour with minimal post production work.  I would like to cut a recess which would allow me to put a small wooden dowel as a spacer.  Once poured the dowel could be cut and removed leaving the hanger opening.

The approach for the needle case lid will largely be the same except that the insert spacer for the hollowed out section cannot be simply a dowel.  The wooden spacer will have to conform to the same of the lower section of the case.  Since the lit must fit to the bottom it only makes sense that I begin with the bottom portion of the case first.

I think that is enough planning for now.  The next step is to buy some good solid stone and begin cutting it up.