Micro Chainsaw Gets a Much Needed Nitro Power Boost

When life hands you the world’s smallest chainsaw, what’s there to do except make it even more ridiculous? That’s what [JohnnyQ90] did when he heavily modified a mini-electric chainsaw with a powerful RC car engine.

The saw in question, a Bosch EasyCut with “Nanoblade technology,” can only be defined as a chainsaw in the loosest of senses. It’s a cordless tool intended for light pruning and the like, and desperately in need of the [Tim the Toolman Taylor] treatment. The transmogrification began with a teardown of the drivetrain and addition of a custom centrifugal clutch for the 1.44-cc nitro RC car engine. The engine needed a custom base to mount it inside the case, and the original PCB made the perfect template. The original case lost a lot of weight to the bandsaw and Dremel, a cooling fan was 3D-printed, and a fascinatingly complex throttle linkage tied everything together. With a fuel tank hiding in the new 3D-printed handle, the whole thing looks like it was always supposed to have this engine. The third video below shows it in action; unfortunately, with the engine rotating the wrong direction and no room for an idler gear, [JohnnyQ90] had to settle for flipping the bar upside down to get it to cut. But with some hacks it’s the journey that interests us more than the destination.

This isn’t [JohnnyQ90]’s first nitro rodeo — he’s done nitro conversions on a cordless drill and a Dremel before. You should also check out his micro Tesla turbine, too, especially if you appreciate fine machining.

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3D-Printed Parts Torture-Tested in Nitro Engine — Briefly

Additive manufacturing has come a long way in a short time, and the parts you can turn out with some high-end 3D-printers rival machined metal in terms of durability. But consumer-grade technology generally lags the good stuff, so there’s no way you can 3D-print internal combustion engine parts on a run of the mill printer yet, right?

As it turns out, you can at least 3D-print connecting rods, if both the engine and your expectations are scaled appropriately. [JohnnyQ90] loves his miniature nitro engines, which we’ve seen him use to power both a rotary tool and a hand drill before. So taking apart a perfectly good engine and replacing the aluminum connecting rod with a PETG print was a little surprising. The design process was dead easy with such a simple part, and the print seemed like a reasonable facsimile of the original when laid side-by-side. But there were obvious differences, like the press-fit bronze bearings and oil ports in the crank and wrist ends of the original part, not to mention the even thickness along the plastic part instead of the relief along the shaft in the prototype.

Nonetheless, the rod was fitted into an engine with a clear plastic cover that lets us observe the spinning bits right up to the inevitable moment of failure, which you can see in the video below. To us it looks like failing to neck down the shaft of the rod was probably not a great idea, but the main failure mode was the bearings, or lack thereof. Still, we were surprised how long the part lasted, and we can’t help but wonder how a composite connecting rod would perform.

Still in the mood to see how plastic performs in two-stroke engines? Break out the JB Weld.

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Nitro Powered Rotary Tool

We really don’t know if the world needs it but we’re sure glad [johnnyq90] took the time to build one. We’re talking about a nitro powered rotary tool. Based on a Kyosho GX-12 nitro engine, commonly used in R/C cars, [johnnyq90] machines almost all other parts in his shop to make a really cool ‘Nitro-Dremel’. But success didn’t come at the first try.

The first prototype was made using a COX 049 engine but the lack of proper lubrication cause damage to the crankshaft. Because of this setback, [johnnyq90] swaps it out with a O.S Max 10 Aero engine he had lying around in the shop. That didn’t work out so well as the engine was quite hard to start. On the third try he finally decided to use the 2.1 cc Kyosho GX-12 engine to power up his 20.000 rpm tool. As noisy as one would expect and, from the videos it seems quite powerful too as it easily pierces through an aluminium block, cuts steel like a breeze, and breezes through other less demanding feats.

But [johnnyq90] is no stranger to nitro engines nor to Hackaday. In the past he built, among other things, a nitro powered cordless drill and showed impressive feats of machining in a micro version of a Tesla turbine. We wonder what’s next…. a nitro powered tattoo gun perhaps?

In the 20 minute video after the break, we enjoy watching the construction of the ‘Nitro-Dremel’, as well as other parts from two previously failed prototypes:

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Garbage can RC car Engine Powers Ridiculous Pencil Sharpener

Christmas has come and gone, and no doubt garbage cans are filling with toys that got but a single use before giving up the ghost. If you scrounge around, you might get lucky and score a busted RC car so you can be like [Mike] and build a completely unnecessary nitro-powered pencil sharpener.

This is one from the [Tim The Tool Man Taylor] “more power” files. To be fair, [Mike] acknowledges as much right up front, and as a learning tool for these super-powerful internal combustion engines, we think it’s a pretty cool project. After dealing with a seized cylinder on what looks to be a VX .18 engine rated at about 1.1 horsepower, [Mike] learns the basics of starting and controlling the engine. Once coupled to a pencil sharpener that clearly isn’t engineered to work at a bazillion RPM and jury-rigging a damper for the clutch, [Mike] fires up the engine and races through a pack of 10 pencils in record time.

As silly as this hack seems, it could come in handy if you decide to go into the colored pencil jewelry market at production levels.

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Twitter brain interface

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Just in time for the influx of sedentary Oprah viewers, [Adam Wilson] built a brain interface that allows you to post Twitter messages. The electrode cap monitors the user’s brain functions to determine where they’re looking. The display slowly flashes each letter in the alphabet. The user focuses on the letter they want and when it flashes the cap can pick up the resulting impulse. It’s a long process and the average user can only do ten characters a minute i.e. 14 minutes to use all 140 characters in a Twitter post. It’s interesting research and shows how far we still need to go with neural interfaces. The researchers note that Twitter’s forced brevity levels the playing field between locked-in patients and normal users. A video of the device in use is available on the NITRO blog.

Related: KanEye tracking system

[via @johl]