glue

26 Articles

Tech In Plain Sight: Super Glue

December 11, 2023 by 69 Comments

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

May 3, 2023 by 19 Comments

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.

Continue reading “Exploring Woodworking Mysteries With Strain Gauges And Raspberry Pi” →

The Sweetest Glue In The World

December 29, 2022 by 19 Comments

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!

Raspberry Pi Test Stand Tells You Which Glues To Use

April 7, 2022 by 6 Comments

Not all glues are created equal; or rather, not every glue is good for every application. But how is one to know which glue to use in which kinds of joints? The answer to that is not always clear, but solid numbers on the comparative strength of different glues are a great place to start.

To quantify what can ordinarily be a somewhat subjective process, there’s probably no one better than woodworker and hacker [Matthias Wandel], equipped as he is with his DIY strength-tester. Using its stepper-driven power to blast apart glued lap joints, [Matthias] measured the yield point of the various adhesives using a strain gauge connected to a Raspberry Pi.

His first round of tests had some interesting results, including the usually vaunted construction adhesive ending up in a distant last place. Also performing poorly, at least relative to its reputation and the mess it can cause, was the polyurethane-based Gorilla Glue. A surprise standout in overall strength was hot glue, although that seemed to have a sort of plastic yield mode. Ever the careful empiricist, [Matthias] repeated his tests using hardwoods, with remarkably different results; it seems that glues really perform better with denser wood. He also repeated a few tests to make sure every adhesive got a fair shake. Check out the video below for the final results.

It’s always good to see experiments like this that put what we often take for granted to the test. [John] over at the Project Farm channel on YouTube does this kind of stuff too, and even did a head-to-head test of epoxy adhesives.

Continue reading “Raspberry Pi Test Stand Tells You Which Glues To Use” →

Sawdust Printer Goes Against The Grain By Working With Wood Waste

June 13, 2021 by 28 Comments

Wood-infused filament has been around for awhile now, and while it can be used to create some fairly impressive pieces, the finished product won’t fool the astute observer. For one thing, there’s no grain to it (not that every piece needs to show grain). For another, you can’t really throw it on a fire for emergency heating like you could with actual wood.

But a company called Desktop Metal has created a new additive manufacturing process for wood and paper waste called Forust (get it?) that gets a lot closer to the real thing. It might be an environmental savior if it catches on, though that depends on what it ends up being good for.

The company’s vision is to produce custom and luxury wood products — everything from sophisticated pencil cups to stunning furniture, and to take advantage of the nearly limitless geometry afforded by additive manufacturing. Forust uses the single-pass binder jetting method of 3D printing to lay down layers of sawdust and lignin and then squirt out some glue in between each one to hold them together.

Although Desktop Metal doesn’t mention a curing process for Forust in their press release, post-processing for solidity and longevity is the norm in binder jetting, which is usually done with ceramic or metal-based materials.

Let’s talk about those wood grains. Here’s what the press release says:

Digital grain is printed on every layer and parts can then be sanded, stained, polished, dyed, coated, and refinished in the same manner as traditionally-manufactured wood components. Software has the ability to digitally reproduce nearly any wood grain, including rosewood, ash, zebrano, ebony and mahogany, among others. Parts will also support a variety of wood stains at launch, including natural, oak, ash, and walnut.

Beauty and workability are one thing. But this will only be worthwhile if the pieces are strong. This is something that isn’t too important for pencil holders, but is paramount for furniture. Forust’s idea is to ultimately save the trees, but how are they going to get sawdust and lignin without the regular wood industry — they want to be circular and envision recycling of their goods at end-of-life into new goods

We wondered if the wood waste printer would ever become a thing. You know, there’s more than one way to print in sawdust — here’s a printer that stacks up layers of particle boards and carves them with a CNC.

Images via Forust

Friendly Fiberglassing: Can Hide Glue Replace Epoxy?

September 11, 2020 by 40 Comments

Hide glue has been around for thousands of years, and some of it is holding wood pieces three thousand years after application. It is made from animal protein, so vegetarians may want to stick to the petroleum-based adhesives. [Surjan Singh] wanted to see if its longevity made it a contender with modern epoxy by casting a couple of fiberglass car parts with the competing glues. In short, it doesn’t hold up in this situation, but it is not without merit.

Musical instrument makers and antique restorers still buy and use hide glue, but you would never expose it to heat or moisture. To its credit, hide glue doesn’t require a ventilator. All you need is boiling water and a popsicle stick, and you are in business. [Surjan] writes his findings like a narrative rather than steps, so his adventures are a delight to read. He found that a car part made with fiberglass and epoxy will withstand the weather better than the alternative because heat and humidity will soften hide glue. His Saab 96 isn’t the right application, but since it is nearly as strong as epoxy once set, you could make other fabric shapes, like a flannel nightstand or a lace coffee table, and you could shape them in the living room without toxifying yourself

No matter how you want to work with glues and substrates, Bil Herd has you covered, and here is an excellent tip for a cheap degassing setup.

Stronger 3D Prints — Glue Or Carbon Fiber?

December 28, 2019 by 31 Comments

[CNCKitchen], like many others, is looking to make strong 3D prints. Using a high tech PLA bio copolyester compound, he printed a bunch of hooks in two different orientations. He used several different types of glue including epoxy and superglue. You can see the video of his results, below.

In addition to the glue, he used epoxy and bulk carbon fiber, again, in two different orientations. After several days of curing, he was ready to test.

Continue reading “Stronger 3D Prints — Glue Or Carbon Fiber?” →