Thanks

Hi Chris,
  Super!  I've read/viewed just about all your offerings and haven't found an answer to a question I've been pondering throughout.
This may be a silly question..but:
When you create your pieces in wax for later fitting of stones and such, what percentage do you make the wax model bigger(if at all) to allow for casting shrinkage so finished cast isn't too small.

Again, I've recently 'discovered' your output and, having hand crafted jewelry in the past, am simply in awe of your work!

Many Thanks!
 John Bloy in Wisconsin

the reason i never discuss that is because its a complex question depending greatly on the post casting production that will be required on the piece.

If i am simply producing a piece that will be cast and finished directly i usually allow around 1.5% to 2% to allow for the small shrinkage that happens at cast time, but if its going to be vulcanised and recast the cats really out the bag, and up the tree, with the wifes best bacon bits and the pastors wig...

cutting masters and allowances in the original model can vary greatly with as many iterations as their are jewellers. rubber moulds have linear shrinkage for example so scaling has to be directional as well as general etc etc etc.. but metal mould processes are completely different again.. so .. no easy answer im afraid ....

too complex to cover in a single mere post, and a great many boos on lost wax casting cover all these issues

Thanks Chris,
  I take it then, outside of the general numbers you gave, that experience would account for your mold-making techniques.
    You've obviously mastered all the complex issues you mentioned regarding shrinkage from wax to metal.

 Thanks again,
John Bloy

here are some pics from the next rhinocam video im on, simple flip works and 4 sided multi index.

a few more,

Folks.. from time to time I get to cut rings for Colin(colwax), and man, let me tell you , he designs some lovely one, but !! BEEEEEEG!!!

Most we are not able to post but this one I gotten his permission to post with, so I have decided to do a video tutorial for Rhinocam on this one too.

Without further ado


A sneak at the paths involved, 4 tool changes and heap of paths, this will be in video, the rest is methodology , the only thing more interesting about this job is that it features a hollow head, ie: its not cut through to the finger and has a thin sleeve inside, so accessing those hollow area from the top at various angles was a fun exercise


Split a bit of signet tube off,

onto the conical cone clamps

onto the lathe to cut a lip to fit Niko/Kens fixture

Cut that lip!

Move lipped section into Niko/Kens fixture and Core the fingersize

Move it onto the Minitech and leave the rest to Mrs Botha

Roughing Pass with 3.17 End MIll

Image of pass setup

Result of Roughing Pass

ToolChange to 0.8mm BallEnd and finishing pass as rotary

path representation from RhinoCAm, noteuncut areas,

Result of Finishing Pass, uncut areas clearly visible and inaccessible wit 0.8BE even as a index due to tool cut depth

Index pass with 10 degree pyramid using half of extract curve from Rhino Model, and A rolled 16 degrees to right

representation of path

repeat to other side reversing angle

And Voila!

Now for the inset art section roughing 3.17 EM

and paths represented


and result then DROWNED in oil and finished

as per this path with 0.076mm tapered cutter

resulting in this GLOP.... off to the ultrasonic..


and the final results!




and after casting I assume this wil happen

Very nice job Chris,...you too Gert.
  Room in there for a bit of a "stash" eh ? 


RC

lol ya now you mention it.. i see  a new line of jewellery.. Stash Rings

lol ya now you mention it.. i see  a new line of jewellery.. Stash Rings

In this case, i just might begin to wear jewelry!