Designing A 360 Degree All Metal Hinge

Looking for a 360 degree hinge that had no slop was harder than [Mr. LeMieux] thought it would be. Add to the fact it had to be made completely out of metal with no plastic components — and basically fireproof. He was coming up blank.

You see, [Mr. LeMieux] is casting metal components, and needed a hinge to close two halves of a mold. When he couldn’t find anything commercially available, he decided to design his own. Using aluminum, he machined the two halves with an interlocking mechanism between the two. Essentially, it’s a 3-bar linkage, but if he stopped there, it would have too much slop. So he actually designed in two fixed gears that roll over each other — this ensures the hinge stays perfectly smooth throughout its entire range of movement — it’s actually quite ingenious.

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From Scrap To Sword: Casting Pewter

[TheBackyardScientist] has been living up to his name, this time by casting a pewter sword in his yard. Pewter is a soft alloy of mostly (85–99%) tin along with copper, antimony and bismuth. Older pewter castings often used lead as well. The great thing about pewter is its low melting point of 170–230 °C. At such low temperatures, pewter can be melted down on a common hot plate. Think of it as an easy way to get into the world of metal casting – no forge required. Of course, anyone who has been splashed with solder will tell you that hot molten metal always deserves a lot of respect.

[BackyardScientist] obtained his metal by hunting the local thrift stores. He used the “lost foam” method of casting, by carving a sword out of styrofoam. The sword was embedded in a 5 gallon bucket of sand with a riser to allow the mold to be filled. The pewter was melted on a cheap hot plate, and poured into the mold. The hot metal melts the foam on contact, simultaneously filling up the cavity left over in the sand mold. [BackyardScientist] was left with a solid pewter sword. It won’t hold an edge, but it is a great illustration of the technique.

Click past the break to see [TheBackyardScientist’s] video.

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