Fail Of The Week: Casting A Bolt In A 3D-Printed Mold

Here’s a weird topic as a Fail of the Week. [Pete Prodoehl] set out to make a bolt the wrong way just to see if he could. Good for you [Pete]! This is a great way to learn non-obvious lessons and a wonderful conversation starter which is why we’re featuring it here.

The project starts off great with a model of the bolt being drawn up in OpenSCAD. That’s used to create a void in a block which then becomes two parts with pegs that index the two halves perfectly. Now it’s time to do the casting process and this is where it goes off the rail. [Pete] didn’t have any flexible filament on hand, nor did he have proper mold release compound. Considering those limitations, he still did pretty well, arriving at the plaster bold seen above after a nice coat of red spray paint.

One side of the mold didn’t make it

He lost part of the threads getting the two molds apart, and then needed to sacrifice one half of the mold to extract the thoroughly stuck casting. We’ve seen quite a bit of 3D printed molds here, but they are usually not directly printed. For instance, here’s a beautiful mold for casting metal but it was made using traditional silicon to create molds of the 3D printed prototype.

Thinking back on it, directly 3D printed molds are often sacrificial. This method of pewter casting is a great example. It turns out gorgeous and detailed parts from resin molds that can stand up to the heat but must be destroyed to remove the parts.

So we put it to you: Has anyone out there perfected a method of reusable 3D printed molds? What printing process and materials do you use? How about release agents — we have a guide on resin casting the extols the virtues of release agent but doesn’t have any DIY alternatives. What has worked as a release agent for you? Let us know in the comments below.

This Mask Will Make You A Psycho

Videos games are a cornucopia of project ideas well-suited to the talents of makers and hackers, and Halloween is as good a time as any to show them off! Reddit user [Tavarin], a huge fan of the Boderlands video games, whipped up a plaster mask — replete with glowing eyes — of one of the game’s signature enemies: the Psycho.

[Tavarin]’s secret to forming comfortable plaster masks is to open his jaw while the wrap is setting  — that way he’ll be able to talk without breaking the mask off his face. Hot gluing in and modifying a 60mm PC fan and a pair of lenses meant that the only thing standing between him and a lot of sanding to shape the mask’s details was a few layers of thick plaster mix.

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[Bil’s] Quest for a Lost Finger: Episode I

A little over a year ago I had a semi-gruesome accident; I stepped off of a ladder and I caught my wedding ring on a nail head. It literally stripped the finger off the bone. This was in spite of me being a safety-freak and having lived a whole second life doing emergency medicine and working in trauma centers and the like. I do have trauma center mentality which means, among other things, that I know you can’t wind the clock back.

hand9A few seconds make an incredible differences in people’s lives. Knowing that it couldn’t be undone, I stayed relaxed and in the end I have to say I had a good time that day as I worked my way through the system (I ended  up in a Philadelphia trauma center with a nearby hand specialist) as I was usually the funniest guy in the room. Truth be told they ask incredibly straight questions like”are you right handed?”  “Well I am NOW”.

So now I could really use a bit of a body hack, having seen the X-Finger on Hackaday long before I knew that I would one day work with them, I was hoping that we could get one to work for me. In speaking with a couple of the mechanical engineers on the Hackaday staff we decided to get [James Hobson] and [Rich Bremer] involved and that the best way to do it was to get a casting of my injured hand out to them.

 

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