Custom Threaded Inserts for 3D Printing

There’s a variety of ways to add threaded holes to 3D printed objects. You can tap a hole, but the plastic isn’t always strong enough. Nut traps work, but aren’t very attractive and can be difficult to get exactly the right size. If you try to enclose them, you have to add a manual step to your printing process, too. You can buy threaded inserts (see video below) but that means some other piece of hardware to have to stock in your shop.

[PeterM13] had a different idea: Cut a piece of threaded stock, put nuts on the end and heat it up to let the nuts reform the plastic. This way the nut traps wind up the perfect size by definition. He used two nuts aligned and secured with thread locker. Then he used a hot air gun to only heat the metal (so as to reduce the chance of deforming the actual part). Once it was hot (about 15 seconds) he pulled the nuts into the open hole, where it melted the plastic which grips the nuts once cooled again.

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An Improved Table Saw Fence With Threaded Rod

Back in the bad old days, table saw fences were terrible. You would have to measure the top and bottom of the fence before each cut, just to make sure the fence was square to the blade. In the 1970s, [Bill Biesemeyer] invented a better table saw fence, one that was always square, and included a measuring tape, right on the table saw.

[Jer] wanted an upgrade for his table saw and came up with what might be the next evolution of the table saw fence. It will always produce a square cut, but unlike the 1970s version, this fence has repeatability. If you rip a board to 1″, move the fence, come back to it after a month, and try to rip another board to 1″, those two boards will be exactly the same width.

The secret to this repeatability is a threaded rod. On the front of the fence is a big, beefy piece of threaded rod with 16 threads per inch. On the fence itself is two nuts, cut in half, welded to the guide, with a lever and cam to lock them in place.

When the lever is up and the nuts are disengaged from the threaded rod, the fence easily moves from one side of the table to the other. When the fence is locked down, it locks to the nearest 16th of an inch, and only the nearest 16th of an inch. While that may seem a little large for a relatively expensive tool, this is wood we’re talking about here. There’s not much reason to make the resolution of this fence any smaller; wait until the humidity changes and you’ll have a piece of wood that’s the desired dimension.

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Fail of the Week: [Chris] vs. The Gorn

This week, [Chris] tips the scales but ultimately fails. He’s on the road, hacking through the Great White North and improvising from a poorly-lit echo chamber that happens to have a vise.

Knowing nothing about firearms (do you believe that?), he decided to build a BB cannon out of pure scrap. Several kinds of sparks fly, starting with a Hitachi drill-as-lathe and ending with a tiny cupcake sparkler. [Chris] proceeds to bore out some redi-rod by eyeballing it and offers helpful tips for course correction should you attempt same. Having centered the cavity, he drills out a tiny hole for a fuse.

His first fuse is of the crushed up match head paste variety. It burns kind of slowly and does not launch the BB. Naturally, Plan B is to make napalm glue to adhere Pyrodex pistol powder to paper. As you might imagine, it worked quite well. The wadding was singed, but still no joy. After packing her full of propellant, it still didn’t explode and merely burned out the blowhole. So, what gives? Insufficient barrel length? Should have used bamboo instead of redi-rod? Didn’t want it badly enough? Give us your fodder below.

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Building a cluster of iPaq PCs

[Steven Pigeon] got his hands on ten iPaq computers that a friend acquired through an eBay auction. The older machines were in good condition but the march of technology had left them behind as casualties. He’s given them new life by assembling a cluster. The first order of business was testing the hardware to make sure it’s working. [Steven] used memtest86+ that comes along with the Ubuntu distribution of Linux to find one bad memory chip in the bunch (a revelation that took 10 hours to discover on the slow hardware). He assembled the unit above with MDF as a support structure and threaded rod to hang the boards. He ended up with a beautiful module and his next step is to choose the operating system that will pull the whole thing together.

We find this build every bit as beautiful as the file cabinet cluster. It’ll be interesting to check back with him and see what kind of performance he can get out of it.

Cheap and easy top-down camera quadpod


We keep waiting for evolution to give us that third arm but in the mean time, this may be the solution for holding the camera while you document your projects. [DHagen] has made a four legged tripod (quadpod) for his camera in order to use it as a digital copy machine. We’ve spent many a night trying to get a steady and sharp video of an LCD or array of LEDs in action to document our weekend tinkering and this will make that all a lot easier.

His build uses materials that will total between $10-$20 at the hardware store down the street. A chunk of scrap wood is connected to the camera using a bolt in the threaded tripod hole of the camera. Two L-brackets are attached to the wood so that one is on either side of the camera lens. This leaves two mounting holes on either side of the lens to attach threaded rod using nuts. The assembly is capped off with a square of acrylic (plexiglas).

Quick and clean. It’s not the cheapest camera mounting solution we’ve seen, but it sure does a good job.