Repairing A Gear With A Candle (and Some Epoxy)

March 19, 2024 by 19 Comments

You have a broken gear you need to fix, but there’s no equivalent part available. That’s the issue [Well Done Tips] faced with a plastic gear from a lawnmower. While we’d be tempted to scan the gear, repair the damage in CAD and then 3D print a new one, we enjoyed hearing about his low-tech solution. In addition to the write up, there’s a video showing the process you can watch below.

The idea is pretty simple. Using a piece of pipe and melted candle wax, he prepared a mold of an undamaged section of the gear. Then he cast epoxy resin in place to recreate the missing pieces. There are a few tricks, like putting holes in the remaining part of the gear so the epoxy flows into the existing part. Depending on the gear’s purpose and original material, you might be able to just use it as-is. However, you could also use the repaired gear as a template to create another mold and then cast an entire gear from resin or even metal if you can cast metal.

You can argue whether resin is better or worse than PLA, but of course, it depends on the kind of resin—photopolymers are different from epoxy resins you’d use for this sort of thing. If you think you might like to make your new gear out of aluminum, you might find some inspiration in a previous post.

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Utility Mat Turns Waste Epoxy Into Useful Tools

February 9, 2023 by 46 Comments

Epoxy is a great and useful material typically prepared by mixing two components together. But often we find ourselves mixing too much epoxy for the job at hand, and we end up with some waste left behind. [Keith Decent’s] utility mat aims to make good use of what is otherwise waste material.

The concept is simple yet ingenious. It’s a flexible mat that serves as a mold for all kinds of simple little plastic workshop tools. The idea is that when you have some epoxy left over from pouring a finish on a table or laying up some composites, you can then pour the excess into various sections of the utility mat. The epoxy can then be left to harden, producing all manner of useful little tools.

It may seem silly, but it could save your workshop plenty of nickels and dimes. Why keep buying box after box of stir sticks when you can simply make a few with zero effort from the epoxy left from your last job? The utility mat also makes other useful nicknacks like glue spreaders, scrapers, wedges, and painter’s pyramids.

We’ve seen other great recycling hacks over the years too. Video after the break.

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Casting Custom Resin Buttons For The Steam Deck

January 26, 2023 by 11 Comments

If you play games on multiple consoles, you’re probably familiar with the occasional bout of uncertainty that comes with each system’s unique button arrangement. They’re all more or less in the same physical location, but each system calls them something different. Depending on who’s controller you’re holding, the same button could be X, A, or B. We won’t even get started on colors.

Overhearing her partner wish the buttons on his Steam Deck matched the color scheme of the Xbox, [Gina Häußge] (of OctoPrint fame) decided to secretly create a set of bespoke buttons for the portable system. There was only one problem…she had no experience with the silicone molding process or epoxy resins which would be required for such an operation.

Toothpicks were used to make channels in the mold.

Luckily we have the Internet, and after researching similar projects that focused on other consoles, [Gina] felt confident enough to take apart Steam’s handheld and extract the original plastic buttons. These went into a clever 3D printed mold box, which was small enough to put into a food vacuum container for degassing purposes. The shape of the buttons necessitated a two-piece mold, into which [Gina] embedded two channels: one to inject the resin, and another that would let air escape.

The red, green, blue, and yellow resins were then loaded into four separate syringes and forced into the mold. It’s critically important to get the orientation right here, as each button has a slightly different shape. It sounds like [Gina] might have mixed up which color each button was supposed to be during an earlier attempt, so for the final run she made a little diagram to keep track. After 24 hours she was able to peel the mold apart and get a look at the perfectly-formed buttons, but it took 72 hours before they were really cured enough to move on to the next step.

[Gina] applied the legends with a sheet of rub-on lettering, which we imagine must have been quite tricky to get lined up perfectly. Since the letters would get worn off after a few intense gaming sessions without protection, she finally sealed the surface of each button by brushing on a thin layer of UV resin and curing it with a flashlight of the appropriate wavelength.

There are a fair number of steps involved, and a fair bit of up-front cost to get all the materials together, but there’s no denying the final result looks phenomenal. Especially for a first attempt. We wouldn’t be surprised if the next time somebody wants to head down this particular path, it’s [Gina]’s post that guides them on their way.

The Best Threaded Holes For Resin Parts

November 1, 2022 by 21 Comments

Threaded inserts are great for melting into FDM prints with a soldering iron. The process isn’t so simple for resin prints, since they don’t generally soften with heat. Off course, you can also print the threads directly, screw a bolt into an un-threaded hole, or tap a hole. Following his usual rigorous testing process, [Stefan] from CNC Kitchen investigated various ways of adding threaded holes to resin prints.

After establishing a pull-out force on PLA using threaded inserts (205 kg) and tapped holes (163 kg), [Stefan] tested parts printed with Prusament Tough Anthracite resin. Un-threaded and tapped holes failed at 44 kg and 55 kg respectively, while printed threads were almost twice as strong, reaching 106 kg before breaking. Stephan also tried gluing inserts into the parts using resin and CA glue. The resin didn’t cure properly in the opaque parts (6 kg) while CA was comparable to plastic threads, failing at 52 kg.

Chart of results
TLDR: Print your threads for best results

[Stefan] also tested regular ELEGOO Translucent resin. The higher hardness of the cured resin allowed the parts to hold on to around 100 kg for un-threaded and tapped holes, while printed threads reached 120 kg. Threaded insert glued with resin did better on the transparent parts thanks to improved UV penetration, but were very inconsistent. Inserts glued with CA performed about the same as on the Prusament parts, failing at 56 kg.

In an attempt to improve the performance of the inserts [Stefan] printed some parts with stepped holes to match the geometry of the inserts, which had the advantage of preventing the insert from falling through during gluing. It only made a marginal difference on the Prusament parts but boosted the strength of CA-glued inserts on the ELEGOO resin to 82 kg. Two-part epoxy was also tried, which matched the un-threaded holes in strength.

So for resin parts you’ll probably be best served by just modeling the threads in CAD and printing them directly. If you need to be able to repeatedly screw and unscrew fasteners in a hole without stripping, threaded holes with CA or epoxy might be a better solution.

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A transparent blue resin waterfall tabletop with a single wooden leg sits on a grey rug between two grey leather chairs.

Using The Sun To Turn Epoxy Into Furniture

October 29, 2022 by 16 Comments

Epoxy resins have been used to make some pretty cool furniture, but since it’s still a relatively new material, makers are still discovering new techniques to work with resin. [Cam] from Blacktail Studio may be the first person to bend fully cured epoxy using nothing but a form and the power of the sun.

Inspired by a friend’s mishap with an epoxy table left out in the sun too long, [Cam] wanted to see if he could purposely bend an epoxy sheet into an interesting shape. The tabletop was poured in sections to give an ombre look before being planed and given a preliminary surface finish. The epoxy sheet was then clamped onto a form made of kerfed plywood and left in direct sunlight on a 104°F (40°C) day. Once the sheet began to deform in the sunlight, ratchet straps and more clamps were added to conform the sheet to the bending form.

After letting the tabletop relax for a few days, [Cam] finished the surface with lots of sanding and an automotive polishing regimen. The epoxy was then attached to a single zebrawood leg to give a very modern-looking, waterfall-esque table.

More interesting projects with resin you might want to check out are this ocean-themed epoxy nightlight, how to degas epoxy on the cheap, or some techniques for cold casting with resin.

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Epoxy lenses

The Ins And Outs Of Casting Lenses From Epoxy

December 9, 2021 by 10 Comments

If you need a lens for a project, chances are pretty good that you pick up a catalog or look up an optics vendor online and just order something. Practical, no doubt, but pretty unsporting, especially when it’s possible to cast custom lenses at home using silicone molds and epoxy resins.

Possible, but not exactly easy, as [Zachary Tong] relates. His journey into custom DIY optics began while looking for ways to make copies of existing mirrors using carbon fiber and resin, using the technique of replication molding. While playing with that, he realized that an inexpensive glass or plastic lens could stand in for the precision-machined metal mandrel which is usually used in this technique. Pretty soon he was using silicone rubber to make two-piece, high-quality molds of lenses, good enough to try a few casting shots with epoxy resin. [Zach] ran into a few problems along the way, like proper resin selection, temperature control, mold release agent compatibility, and even dealing with shrinkage in both the mold material and the resin. But he’s had some pretty good results, which he shares in the video below.

[Zach] is clear that this isn’t really a tutorial, but rather a summary of the highs and lows he experienced while he was working on these casting methods. It’s not his first time casting lenses, of course, and we doubt it’ll be his last — something tells us he won’t be able to resist trying this all-liquid lens casting method in his lab.

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Faux Stained Glass Effect, With 3D Printing And Epoxy

April 22, 2021 by 14 Comments

Like the looks of stained glass, but not the amount of work, skill, and materials involved? Well, [Northern Geometry] shows how to sidestep all that nonsense and use a 3D printed frame, epoxy, and some alcohol-based inks to create a pretty good fake stained-glass effect piece of art.

A smooth polypropylene board is the key to a glassy smooth back.

[Northern Geometry] has played with this idea before, but shares some refinements and tips on getting the best results. One suggestion is to begin by securely taping the 3D printed frame to a smooth polypropylene board as a backer. Giving the cured resin a smooth surface is important to get the right look, and since resin will not bond to the polypropylene, it can be used as a backer to get that done.

Once the frame is mounted, pour a small amount of epoxy into each cavity and ensure it gets into every corner, then let it cure. The thin bottom layer of resin will seal things as well as create a glassy-smooth backing that is the perfect foundation for finishing the piece with colored resin as needed.

Once that is done, and everything has had plenty of time to cure fully, just pop the piece off the board. Check it out in the video embedded below, where [Northern Geometry] shows the process from start to finish.

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