Try This for 3D Printing Without Support

Have a look at the object to the right. Using a conventional fused deposition printer, how would you print the object? There’s no flat surface to lay on the bed without generating a lot of overhangs. That usually requires support.

In theory, you might be able to print the bottom of the sphere down, but it is difficult to get that little spot to adhere to the bed. If you have at least two extruders and you are set up to print support material, that might even be the best option. However, printing support out of the same material you are printing with makes it hard to get a good clean print. There is another possibility. It does require some post-processing, but then again, not as much as hacking away a bunch of support material.

A Simple Idea

The idea is simple and — at first — it will sound like a lot of trouble. The basic idea is to cut the model in half at some point where both halves would be easy to print and then glue them together.  Stick around (no pun intended), though, because I’ll show you a way to make the alignment of the parts almost painless no matter how complex the object might be.

The practical problem with gluing together half models is getting the pieces in the exact position, but that turns out to be easy if you just make a few simple changes to your model. Another lesser problem is clamping a piece while gluing. You can use a vise, but some oddly-shaped parts are not conducive to traditional vise jaws.

In Practice

Starting with an OpenSCAD object, it is easy to cut the model in half. Actually, you could cut it anywhere. Then it is easy to rotate half of it so the cut line is at the bottom of each part. That doesn’t solve the alignment problem nor does it help you clamp when you glue.

The trick is to build a flange around each part. The flanges mate with a few screws after printing so alignment is perfect and bolts through the flange holes can keep the parts together and immobilized while your glue of choice sets. The kicker is that I even have an automated process to make the design side of this trick very easy.

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Cardboard and Paper Gun Shows Off Clever Construction

This project by [blackfish] shows off a cardboard lookalike of an MP5 that loads from a working magazine, has a functional charging handle, and flings paper projectiles with at least enough accuracy to plink some red party cups. It was made entirely from corrugated cardboard, paper, rubber bands, and toothpicks.

In the video (embedded below) you can see some clever construction techniques. For example, using a cyanoacrylate adhesive to saturate areas of wood, cardboard, or paper to give them added strength and rigidity. The video is well-edited and worth a watch to see the whole process; [blackfish] even uses a peeled piece of cardboard — exposing the corrugated part — as a set of detents (6:56) to retain the magazine.

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Innovating A Better Printing Platform

Just because you have a fancy new 3D printer doesn’t mean that innovation should stop there. Almost everyone has had a print go foul if the first layer doesn’t properly adhere to the printing platform — to say nothing of difficulty in dislodging the piece once it’s finished. Facing mixed results with some established tricks meant to combat these issues, [D. Scott Williamson] — a regular at Chicago’s Workshop 88 makerspace — has documented his trials to find a better printer platform.3D Printer Steel Print Plate 1

For what he had (a printer without a heated plate), painter’s tape and hairspray wasn’t cutting it, especially when it came time to remove the print as the tape wouldn’t completely come off the part. How then, to kill two birds with one stone? Eureka! A flexible metal covering for the printing plate.

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Glues You Can Use: Adhesives for the Home Shop

A while back I looked at lubricants for the home shop, with an eye to the physics and chemistry behind lubrication. Talking about how to keep parts moving got me thinking about the other side of the equation – what’s the science behind sticking stuff together? Home shops have a lot of applications for adhesives, so it probably pays to know how they work so you can choose the right glue for the job. We’ll also take a look at a couple of broad classes of adhesives that are handy to have around the home shop. Continue reading “Glues You Can Use: Adhesives for the Home Shop”

Powdered Glue Activates when Squished

Sometimes a hack needs something more than duct tape. Cyanoacrylate glue is great, if you don’t mind sticking your fingers together. But it doesn’t stick to everything, nor does it fill gaps. Epoxy is strong, but isn’t nearly as convenient. The point is, one type of glue doesn’t fit every situation, and that’s why you have to keep a lot of options.  [Syuji Fujii] of Japan’s Osaka Institute of Technology (and his colleagues) have a new option: a glue that goes on dry and sticks when squished.

According to New Scientist,  the researchers rolled spheres of a latex liquid in a layer of calcium-carbonate nanoparticles. The resulting spheres are a few millimeters across and pour easily. When put under pressure for a few seconds, the nanoparticles are pushed inside, and the sticky liquid contacts the surface. The source paper is also available if you want to read the gory details. Or you can cut right to the video below to see it in action.

If you don’t think glue is a good hacking material, you don’t know [Kevin Dady]. You can even glue wires if you really hate soldering, although we’d rather solder.

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Tint your Epoxy Resin with Toner Powder

Epoxy resin is useful stuff. Whether for gluing stuff together or potting components, epoxy is a cheap and versatile polymer that finds its way into many hackish projects. But let’s face it – the stock color of most commercially available epoxies lacks a certain pizzazz. Luckily, [Rupert Hirst] at Tallman Labs shows us that epoxy is easily tinted with toner powder from a laser printer or copier.

Looking for a way to make his epoxy blend into a glue-up, [Rupert] also demonstrates that colored epoxy makes a professional looking potting compound. There’s just something about the silky, liquid look of a blob of cured black epoxy. [Rupert] harvested his toner powder from a depleted printer cartridge; only a smidgen is needed, so you should be able to recover plenty before recycling the cartridge. We’ve got to admit that seeing toner handled without gloves gives us the willies, though. And don’t forget that you can find cyan, magenta and yellow cartridges too if basic black isn’t your thing.

Sometimes it’s better to leave your epoxy somewhat clear, like when you’re potting an LED matrix for a pendant. But this neat trick might just spiff up your next project a bit.

[Thanks, Jake]

Welding and casting ABS

Anybody who has a 3D printer always has a ton of useless plastic lying around. Some of that plastic may be from useless baubles, but most of it is in bad prints, short bits of filament, and general scraps. [Luke] found an interesting way to put those ABS scraps to use, and ended up turning trash into valuable plastic parts.

Commonly sold as nail polish remover, acetone will turn anything made out of ABS into a puddle of plastic. [Luke] makes glue using the same process – he fills a small container half full of acetone and half with small bits of ABS. After a day or so, he has a nice thin glue that dries into solid ABS. [Luke] used this to create a 400mm long piece of extruded t-slot. We don’t know if it would be suitable to build a child RepRap from, but it would sure be an interesting experiment.

[Luke] also did a little bit of casting with his ABS glue. With a thicker solution of ABS and Acetone, he managed to make this ‘thing’. The entire process is explained over at Thingiverse, We can’t wait to see what can be done with this stuff.