3D mockup for 1940s Medalta Potteries ball pitcher

No molds have survived so we are going to start from scratch. We will use Fusion 360 and 3D prints in PLA to create a block mold to make a rubber case mold. Learning to draw this rewarded me with some new 3D drawing skills. The geometry of the lip is challenging. It appears the piece will need to be cast with a full top and the lip shape and pouring hole cut manually (as was done originally at Medalta Potteries). I will likely have to create a 3D-printed PLA template as a cutting guide to get the lip contour more correct and consistent than they were able to do. Although not on the original, we are going to include a foot ring for easier glazing and better stability during forming and firing.

Related Pictures

The importance of 3D printing the right way up

These are quarters of a block mold piece for a Medalta Potteries ball pitcher. The whole piece was far too big to print so I had to break it up into quarters. Quarter #1 (top right and bottom left) was made by shelling (hollowing) the whole thing in the CAD drawing process and quartering in the slicer. The other piece (top left and bottom right) was made by quartering and shelling each individually in the CAD software (Fusion 360). Quarter #1 has a dangling corner (front left of top right) so I had to print as shown so that infill would support it. Quarter #2 mates with a wall and that supports the whole curved mating edge (enabling upright printing). Notice also that the matting surface is not planar on quarter #1 (top right). And its inside surface as print artifacts. Quarter #2 was printed with the back-side down, thus only printed support was needed in the narrow channel where the rubber wall will pour. Surface quality is much better and it printed in 9 hours instead of 14 (these pieces are quite large).

The v2 ball pitcher is way too big to 3D print. What now?

This is a Medalta Potteries medium-sized ball pitcher block mold, version 2.0 - it has a more oval body shape. Upper left is the top section (actually, it is half of the top section, a base will fit on to create a three-piece working mold. There is to 3D print something this large in one piece in a consumer 3D printer. Even if it did it would require 50 hours of print time! Also, working surface quality is affected by the orientation of printing (especially if a surface is down-facing and on top of printed support). Further, a large print would almost certainly warp and corner-lift during printing. Cutting it into four pieces and hollowing them individually (in the CAD software, lower right) solved all the problems. Each of the pieces is still quite large, taking 10+ hours to print. But they can each be hollowed individually and rotated to the optimum position for the best finished surface (and print speed). It is amazing how well these four pieces fitted together. This approach really paid off because I made a mistake - and I only needed to reprint one of the pieces!

Bringing an old mechanical drawing of a crock lid back to life

This is an 85-year-old drawing downloaded from medalta.org. Medalta Potteries manufactured crocks, on a large scale, from the 1920s on. In this example, I imported the drawing as a canvas in Fusion 360, positioning it so the center of the knob was at the origin point. I traced the lid outline to create a sketch and then revolved that to create the 3D lid. This is part of a project to enable a potter to make lids to fit the old crocks.

Medalta Ball Pitcher

Here is an example of one that was for sale on Ebay. The inset bottom will be a challenge, for version 1 we will likely settle for a flat bottom.

Links

Projects	Medalta Ball Pitcher Slip Casting Mold via 3D Printing A project to make a reproduction of a Medalta Potteries piece that was done during the 1940s. This is the smallest of the three sizes they made.

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