A Simple Tip For Gluing Those LED Filaments

[Boylei] shows that those little LED filament strips make great freeze-frame blaster shots in a space battle diorama. That’s neat and all, but what we really want to highlight is a simple tip [Boylei] shares about working with these filament strips: how to glue them.

Glue doesn’t stick to LED filament strips, so put on a small piece of heat-shrink and glue to that instead.

The silicone (or silicone-like) coating on these LED filament strips means glue simply doesn’t stick. To work around this, [Boylei] puts a piece of clear heat shrink around the filament, and glues to that instead. If you want a visual, you can see him demonstrate at 6:11. It’s a simple and effective tip that’s certainly worth keeping in mind, especially since filament strips invite so many project ideas.

When LED filament strips first hit the hobbyist market they were attractive, but required high operating voltages. Nowadays they are not only cheaper, but work at battery-level voltages and come in a variety of colors.

These filaments have only gotten easier to work with over the years. Just remember to be gentle about bending them, and as [Boylei] demonstrates, a little piece of clear shrink tubing is all it takes to provide a versatile glue anchor. So if you had a project idea involving them that didn’t quite work out in the past, maybe it’s time to give it another go?

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A Little Pigment Helps With Laser Glass Engraving

The range of materials suitable for even the cheapest laser cutter is part of what makes them such versatile and desirable tools. As long as you temper your expectations, there’s plenty of material to cut with your 40 watt CO2 laser or at least engrave—just not glass; that’s a tough one.

Or is it? According to [rschoenm], all it takes to engrave glass is a special coating. The recipe is easy: two parts white PVA glue, one part water, and two parts powdered titanium dioxide. The TiO2 is the important part; it changes color when heated by the laser, forming a deep black line that adheres to the surface of the glass. The glue is just there as a binder to keep the TiO2 from being blasted away by the air assist, and the water thins out the goop for easy spreading with a paintbrush. Apply one or two coats, let it dry, and blast away. Vector files work better than raster files, and you’ll probably have to play with settings to get optimal results.

With plain float glass, [rschoenm] gets really nice results. He also tried ceramic tile and achieved similar results, although he says he had to add a drop or two of food coloring to the coating so he could see it against the white tile surface. Acrylic didn’t work, but there are other methods to do that.

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Towards Solderless PCB Prototyping

When we think of assembling a PCB, we’re almost always thinking about solder. Whether in paste form or on the spool, hand-iron or reflow, some molten metal is usually in the cards. [Stephen Hawes] is looking for a solderless alternative for prototyping, and he shows us the progress he’s made toward going solderless in this video.

His ulterior motive? He’s the designer of the LumenPNP open-source pick-and-place machine, and is toying with the idea of a full assembly based just on this one machine. If you strapped a conductive-glue extruder head on the machine in addition to the parts placer, you’d have a full assembly in one step. But we’re getting ahead of ourselves.

[Stephen] first tries Z-tape, which is really cool stuff. Small deformable metal balls are embedded in a gel-like tape, and conduct in only the Z direction when parts are pushed down hard into the tape. But Z-tape is very expensive, requires a bit of force to work reliably, and [Stephen] finds that the circuits are intermittent. In short, Z-tape is not a good fit for the PNP machine.

But what [Stephen] does find works well is a graphite-based conductive glue. In particular, he likes the Bare Conductive paint. He tries another carbon-based paint, but it’s so runny that application is difficult, while the Bare stuff is thick and sticky. (They won’t tell you their secret formula, but it’s no secret how the stuff is basically made.) That ends up looking very promising, but it’s still pretty spendy, and [Stephen] is looking to make his own conductive paste/paint pretty soon. That’s particularly appealing, because he can control the stickiness and viscosity, and he’ll surely let us in on the secret sauce.

(We’re armchair quarterbacking here, but the addition of a small amount of methyl cellulose and xanthan gum works to turn metal powder into a formable, printable metal clay, so it might make a carbon paste similarly adjustably sticky.)

We love the end-goal here: one machine that can apply a conductive paint and then put the parts into the right place, resulting in a rough-and-ready, but completely hands-off assembly. You probably wouldn’t want to use this technique if the joint resistance was critical, or if you needed the PCB to stand up to abuse. There’s a reason that everyone in industry uses molten metal, after all. But for verifying a quick one-off, or in a rapid-prototyping environment? This would be a dream.

We’ve seen other wacky ways to go solderless before. This one uses laser-cut parts to hold the components on the PCB, for instance. And for simply joining a couple wires together, we have many more solutions, many thanks to you all in the comments!

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A person putting a screw into a CNC spoil board on the left of the image. Their drill is chartreuse and black. Clamps hold a rectangular board down at all four corners. The spindle of the CNC is just visible on the right hand side of the image.

Workholding Options For The Beginner CNC Operator

Designing a file to cut on a CNC is only part of the process. You also have to keep it in place while the machine does its work. [Garrett Fromme] walks us through five different work holding techniques.

Since every project is different and stock material can vary from thin veneer to much larger pieces, there’s no one right work holding method for every project, and not all methods are applicable to all materials. A vise is great for small projects that need to be held very securely and won’t be damaged, vacuum tables can make switching pieces quick in a production environment, fasteners will hold a piece securely at the expense of your spoil board, clamps are fairly versatile but fiddly to setup, and tape and CA glue are quick but require more consumables.

[Fromme] does a quick demonstration of setups with these different methods and their limitations, which is a great place to start for the beginner CNC operator. Just like 3D printers, CNCs are a far cry from the replicators in Star Trek that can automagically create what you ask it to, but proper workholding lets you waste less material and operate the machine more safely.

Our own [Elliot Williams] had a look at how CNCs aren’t as automated as you think. If you do need some CNC clamps, you might try these printable parametric clamps, or if you want something more beautiful, give these metal toe clamps a go.

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Tech In Plain Sight: Super Glue

Many inventions happen not by design but through failure. They don’t happen through the failure directly, but because someone was paying attention and remembered the how and why of the failure, and learns from this. One of these inventions is Super Glue, the adhesive that every tinkerer and engineer has to hand to stick pretty much anything to anything, quickly. Although it was a complete failure for the original uses it was developed for, a chemist with good memory and an eye for a helpful product created it in a process he described as “one day of synchronicity and ten years of hard work.”

Super Glue was initially invented in 1942, when the chemist Harry Coover was working on a team trying to develop a clear plastic gun sight that would be cheaper than the metal ones already in use. The team cast a wide net, trying a range of new materials. Coover was testing a class of chemicals called cyanoacrylates. They had some promise, but they had one problem: they stuck to pretty much everything. Every time that Coover tried to use the material to cast a gun sight, it stuck to the container and was really hard to remove. 

When the samples he tried came into contact with water, even water vapor in the air, they immediately formed an incredibly resilient bond with most materials. That made them lousy manufacturing materials, so he put the cyanoacrylates aside when the contract was canceled. His employer B. F. Goodrich, patented the process of making cyanoacrylates in 1947, but didn’t note any particular uses for the materials: they were simply a curiosity. 

It wasn’t until 1951 when Coover, now at Eastman Kodak, remembered the sticky properties of cyanoacrylates. He and his colleague Fred Joyner were working on making heat-resistant canopies for the new generation of jet fighters, and they considered using these sticky chemicals as adhesives in the manufacturing process. According to Coover, he told Joyner about the materials and asked him to measure the refractive index to see if they might be suitable for use. He warned him to be careful, as the material would probably stick in the refractometer and damage it. Joyner tested the material and found it wasn’t suitable for a canopy but then went around the lab using it to stick things together. The two realized it could make an excellent adhesive for home and engineering use. Continue reading “Tech In Plain Sight: Super Glue”

Exploring Woodworking Mysteries With Strain Gauges And Raspberry Pi

If you’re not a woodworker, you might not have heard of the “45-degree rule.” It goes like this: a clamp exerts a force that radiates out across a triangular region of the wood that forms a right angle — 45 degrees on each side of the clamp’s point of contact. So, to ensure that force is applied as evenly as possible across the entire glue joint, clamps should be spaced so that these force triangles overlap. It’s a handy rule, especially for the woodworker looking to justify the purchase of more clamps; you can never have too many clamps. But is it valid?

Myth busted?

The short answer that [ari kardasis] comes up with in the video below is… sort of. With the help of a wonderfully complex array of strain gauges and a Raspberry Pi, he found that the story isn’t so simple. Each strain gauge lives in a 3D printed bracket that spaces the sensors evenly along the wood under test, with a lot of work going into making the test setup as stiff as possible with steel reinforcement. There were some problems with a few strain gauges, but once he sorted that out, the test setup went into action.

[ari] tested clamping force transmission through pieces of wood of various widths, using both hardwoods and softwoods. In general, he found that the force pattern is much broader than the 45-degree rule suggests — he got over 60 degrees in some cases. Softwoods seemed to have a somewhat more acute pattern than hardwoods, but still greater than the rulebook says. At the end of the day, it seems like clamp spacing of two board widths will suffice for hardwoods, while 1.5 or so will do for softwoods. Either way, that means fewer clamps are needed.

A lot of woodworking is seat-of-the-pants stuff, so it’s nice to see a more rigorous analysis like this. It reminds us a lot of some of the experiments [Matthia Wandel] has done, like load testing various types of woods and glues.

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The Sweetest Glue In The World

Perhaps we’re not alone in having a penchant for gummy sweets, but we have to admit to never following the train of thought shared by [Lost Art Press]. Upon finding that a hide glue ingredient was raw gelatin obtained from a confectionery company, they stored away the knowledge and eventually tried making some glue using Haribo Goldbears from a gas station.

Melting the anthropomorphised sweets in a pot with a little water produced a thin glue, which was tried on a couple of bits of wood. The test joint duly stuck together, and after a few weeks for it to set it was time to test it. Simply hitting it with a hammer caused the wood to fracture, but using more traditional hide glue dissolving techniques with water or alcohol gave the expected result of parting it.

So a pretty usable hide glue for woodworking can be made using gummy sweets. We think it’s pretty cool, but perhaps given how easy it is to buy either the real thing or a PVA-based alternative, that this is one for the MacGyver file. Should you ever find yourself stranded in a gas station unable to save the world for want of a bit of glue then now you have the crucial bit of knowledge. Until then, leave out Haribo Goldbears alone!

Thanks [Aaron Tagliaboschi] for the tip!