Yes! Thank you!

Thanks for following along!

I'd thought about something that stuck up, but then it couldn't be printed flat on the bed. The thing that is really preventing flexing is the curvature of the handle itself.

@@PotterybyKent mhm okay. In that case, maybe holes for dowel pins or wood screws could do the trick. Have you considered finishing the surface with filler, sanding and spray coating with lacquer?

I was going to add some screw bosses to hold it down to the bottom plate if plaster was leaking. Those could serve the double purpose of points to pull on. However the tape worked well enough so I left them out. As far as finishing the surface, yes I have several other videos showing how to smooth the surface. However for this handle it wasn't really needed. You already need to clean the (small) seam line so most of the handle is gone over in that process. Also by the time it transfers to plaster then to slip and then fired (and shrinks), and with glaze, pretty much most of the artifacts from printing go away.

@@PotterybyKentYou could have the handle part actually go past the bottom plate instead of stopping on it. Have some key holes that are open on the side that protrudes past the plate. Then you slide into these holes 3D printed keys that have a slight taper along the length so it’s actually a wedge. Think of how some old tables are held together with nothing but wedge pins. This would hold the handle part in tight, have more to grab from when removing, allow to be printed flat, and no need to use tape. Just slide out the keys and it should all easily separate.

@chadvoller Thanks! I was considering something like that - in particular as a way to not need the tape. However the other consideration is so plaster doesn't leak and I think the jog in the bottom is actually helping in this case. I could put that geometry in the handle part but that would increase the thickness.

Yes it's working great now!

Thanks a lot!

Thanks!

I actually did have an idea here! But it's not a table - something to clip onto the mold itself.

@@PotterybyKent The advantage of a little shake table would be that you could run multiple molds at the same time! Since you need at least 2 molds per handle AND you could use it for any of the molds you make in the future.

I actually have a pretty big shaker table. However most people using Shape Cast don't so I've tried to show practices that everyone can use easily.

I haven't found that to be the case with the slip I'm adding, the moisture content, and proper drying. However if you've had issues or are concerned at all, it isn't a bad practice. For thrown pots and pulled handles it is very much a good idea since it reorients the clay particles.

@@PotterybyKentthank you for your response. I really enjoy your channel!

@@Heartwing37 Thanks so much!

There's enough space to grab on without touching the plaster, but not a lot! I think there is some room for optimization here, but it is also good enough to make useful molds. I've had several other people successfully make them at this point which is always fun to see!

Thanks! I'd like to know the etymology there. I know it's derived from latin / old French but not sure when the sound changed in this context.

It very much is not only the draft angle as I had them in some of my previous iterations. This is different than injection molding because the plaster actually grows slightly. And yes there are several ways to help knock out the bubbles however with such a small mold I didn't have any issues here.

Thanks. I'll need to take a look. But I've ver deliberately been looking at a process where the molds can be reused many times. Also, since the clay needs to be removed once slip cast, undercuts are still a fundamental issue.

Thanks!

It's mostly about tradeoffs, your process and your logo. Currently I'm using an underglaze stamp I made (I 3d printed a mold and poured silicone in it). I've also used a 3D printed stamp to make an impression but my slip casting clay body isn't very plastic so getting the timing right was tricky and why I switched. I do use it on my thrown pots. I have videos on my channel for both. I have yet to cast in my logo - I think doing so would require a much larger logo than I'm currently using since plaster is pretty delicate. It is something I want to explore.

@@PotterybyKent just tried to make a casting with the logo into a single non-collapsible shape and the results are always different, so today I will print an blank mug and a separate stamp. Thanks for the answer!

Happy to help!

That is an interesting thought!

I thought this too! inside the spur cups of the handle model you could put a rib across it, something you can grab with a pair of needle nose, since it's a little tough to get out with the fingers.

You wouldn't want a rib that spanned side to side as that would limit flexibility. What comes to mind would be pairs of horizontal tabs with a hole for something like snap ring pliers to get into. That would let you pull the walls together slightly. The downside of this is that this inner mold is printed rather thin so it can flex, and therefore those tabs might break easily (and adding reinforcement is counter productive given the need to flex). And it would likely require a new tool. For those who already bought the molds, I'd love feedback on this aspect of the design.

@@PotterybyKent Those are good points, makes sense that you want the plastic to flex and not the plaster. What about something like printing TPU?

Most people can't print TPU easily and the surface finish is way worse which is a problem since it transfers into the pot eventually. My last couple videos (and the comments) go through a lot of the tradeoffs and considerations if you're curious.

Because the plaster is specially designed to absorb water from the slip to form the solid clay. That moment of water is a key part of slip casting.

Yes you probably could. The nice thing is if it's working with PLA it'll likely work with many things.

I am selling them (and also using them myself!). shapecastmolds.com

@@PotterybyKentthank you! Buy some now…

@@Heartwing37 Great!

You mean create a mold with the handle attached to the body already? There are several reasons. One is this allows you to mix and match. However more fundamentally, I've seen very few slip casting molds with handles integrated. My guess is that the shrinkage of the clay might cause it to get stuck around the plaster for handle if you aren't careful about clay body selection and design of the forms.

@@PotterybyKent Thank you for the info! Very helpful

Not needed luckily!

Yes, others have used that approach to destructively remove the print. Luckily by just being careful pulling it out it can be reused.

Unlike metal casting the plaster is actually reused many many times (maybe 50) to make pots. And reuse of the 3d print is also an explicit design goal as well. In fact production potters will actually invest in silicone molds so they can make many paster molds to scale up production. By reusing the 3D print, that is no longer needed.

@@PotterybyKent Didn't mean it to in any way detract for the work you are doing. I have experience with plaster slip casting molds, and I believe you did an excellent job of designing your mold for reuse, and the design process you followed was great with the taper needed to remove the 3d print also needed to remove the slip casting. Where the other method seemed to be relevant was the lower quantity of plastic needed, faster 3d print times, and the use of heat to ensure the plastic was softened to enable easy extraction from the mold. But, It obviously has the negative of not being reusable. I am curious how reusable the 3d prints end up being, and if another material like TPU might make them easier to extract.

No worries. I suspect it wouldn't take many reuses to make up for destroying the mold, and here you need 2 per handle. As far as TPU, the problem there is the surface finish (and it being tricky to print doesn't help others using these molds as well). It actually isn't that hard to extract - just takes a bit of patience.