The Hacky Throttle Repair That Got Me On The Road Again

Old cars are great. For the nostalgia-obsessed like myself, getting into an old car is like sitting in a living, breathing representation of another time. They also happen to come with their fair share of problems. As the owner of two cars which are nearing their 30th birthdays, you start to face issues that you’d never encounter on a younger automobile. The worst offender of all is plastics. Whether in the interior or in the engine bay, after many years of exposure to the elements, parts become brittle and will crack, snap and shatter at the slightest provocation.

You also get stuck bolts. This was the initial cause of frustration with my Volvo 740 Turbo on a cold Sunday afternoon in May. As I tried in vain to free the fuel rail from its fittings, I tossed a spanner in frustration and I gave up any hope of completing, or indeed, starting the job that day. As I went to move the car back into the driveway, I quickly noticed a new problem. The accelerator was doing approximately nothing. Popping the hood, found the problem and shook my head in resignation. A Volvo 740 Turbo is fitted with a ball-jointed linkage which connects the accelerator cable to the throttle body itself. In my angst, the flying spanner had hit the throttle body and snapped the linkage’s plastic clips. It was at this point that I stormed off, cursing the car that has given me so much trouble over the past year.

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Ask Hackaday: How Do You DIY a Top-Octave Generator?

One of the great joys of Hackaday are the truly oddball requests that we sometimes get over the tip line. Case in point: [DC Darsen] wrote in with a busted 1970s organ in need of a new top-octave generator, and wondered if we could help. He had found a complicated but promising circuit online, and was wondering if there was anything simpler. I replied “I should be able to get that done with a single Arduino” and proceeded to prove myself entirely wrong in short order.

So we’re passing the buck on to you, dear Hackaday reader. Can you help [DC Darsen] repair his organ with a minimum amount of expenditure and hassle? All we need to do is produce twelve, or maybe thirteen, differently pitched square waves simultaneously.

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Motor test bench talks the torque

Salvaging a beefy motor is one life’s greatest pleasures for a hacker, but, when it comes to using it in a new project, the lack of specs and documentation can be frustrating. [The Post Apocalyptic Inventor] has a seemingly endless stockpile of scavenged motors, and decided to do something about the problem.

Once again applying his talent for junk revival, [TPAI] has spent the last year collecting, reverse-engineering and repairing equipment built in the 1970s, to produce a complete electric motor test setup. Parameters such as stall torque, speed under no load, peak power, and more can all easily be found by use of the restored test equipment. Key operating graphs that would normally only be available in a datasheet can also be produced.

The test setup comprises of a number of magnetic particle brakes, combined power supply and control units, a trio of colossal three-phase dummy loads, and a gorgeously vintage power-factor meter.

Motors are coupled via a piece of rubber to a magnetic particle brake. The rubber contains six magnets spaced around its edge, which, combined with a hall sensor,  are used to calculate the motor’s rotational speed. When power is applied to the coil inside the brake, the now magnetised internal powder causes friction between the rotor and the stator, proportional to the current through the coil. In addition to this, the brake can also measure the torque that’s being applied to the motor shaft, which allows the control units to regulate the brake either by speed or torque. An Arduino slurps data from these control units, allowing characteristics to be easily graphed.

If you’re looking for more dynamometer action, last year we featured this neatly designed unit – made by some Cornell students with an impressive level of documentation.

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Terrible RC Transmitter Made Less Terrible

It should probably go without saying that we’ve got nothing against the occasional bout of elaborate troubleshooting and repair, in fact it’s one of the most common things we cover here. As it turns out, people aren’t overly fond of being fleeced, and there are a lot of smart people out there who will put a lot of work in to keep from having to toss a favorite piece of gear into the trash. We can’t fault them for that.

But we have to say, we generally don’t see those kind of elaborate repairs for something brand new. Unfortunately, that’s exactly what [Marek Baczynski] had to do when trying to review the new iRangeX transmitter for his YouTube channel “dronelab”. He found a transmitter that was so poorly designed and constructed that he had to address a laundry list of issues to make the thing halfway tolerable. As you might expect, he’s not suggesting anyone go run and pick this one up.

The biggest problem is a fundamental flaw with how the gimbals are constructed. Due to poorly mated surfaces between the potentiometer and the stick itself, the accuracy of the controller is very low. The potentiometers don’t even return to zero when the sticks are released. Some tape was used to tighten up the connection and make the controller usable, but such poor tolerances are hard to forgive when accurate control is essentially the whole point of the device.

The other issues took a bit more debugging to figure out. The TX made an absolutely terrible screeching sound when turned on, but [Marek] was sure he was hearing a little bit of melody under the din. Putting the signal through the oscilloscope, he was able to confirm his suspicions. As it turns out, the buzzer used in the TX has a built in tone generator that was overriding the intended melody. Switching it out for a basic buzzer fixed the issue. Similarly, an issue where the radio wouldn’t turn on if it was recently turned off was tracked back to a resistor of the wrong value. Putting a higher lower value resistor in its place sorted that out as well.

It’s hard to imagine how this device made it out of the factory with so many wrong or unsuitable components, but here we are. Not that this would be acceptable at any price point, but as [Marek] points out in the video, it isn’t as if this radio is even all that cheap. For nearly $90 USD, it doesn’t seem unreasonable to expect something that actually works.

This isn’t the first time he’s put “cheap” RC hardware through the wringer. We recently covered his efforts to quantify latency in different transmitters. As the RC transmitter world gets increasingly competitive, detailed analysis like these help separate the real gear from the toys.

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The Most Utilitarian 3D Print Has the Widest Reach

3D Printing is often heralded as a completely new fabrication method, creating things that simply cannot be manufactured in other ways. While this is true, the widest reaching usefulness of 3D printers isn’t for pushing the limits of fabrication. The real power is in pushing the limits of manufacturing for individuals who need one-off parts.

The proof point is in the story shown above. A missing key on a keyboard could have meant an otherwise fine piece of hardware headed for recycling, but was saved by a single part printed on a desktop 3D printer. Multiply this by the increasing number of people who have access to these printers and you can see how using 3D printing for repairs will have a huge impact on keeping our gear in service longer.

We want to see how you’ve saved things from the rubbish pile. Show them off in Hackaday’s Repairs You Can Print contest. The best Student entry and the best Organization entry (think Hackerspace) will each win a high-end 3D Printer. But anyone can enter, with the top twenty entries receiving $100 credit for Tindie.

If you’re like us though, these prizes are just icing on the cake. The real reward is showing what some think is mundane but the Hackaday crowd believes is worth celebrating. Check out all the entries so far and join us below for a few highlights.

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Repairs You Can Print: Model Coal Car Fix

Model railways are a deep and rewarding hobby, and the mechanisms involved can be both surprisingly intricate and delightful. A great example that may surprise the unfamiliar is that of model train carriages, such as coal cars, that are capable of both receiving and dumping a load at various points on a model layout. This adds realism and, if we’re honest, just plain old fun.

When [Phil]’s father received his Lincoln coal car from eBay, it was unfortunately damaged, and incapable of dumping properly. Instead of throwing it away, a replacement part was developed and 3D printed. The part was iterated on until the coal hopper could dump and retract smoothly.

This is the perfect example of a tidy repair executed through 3D printing. The broken part was extremely detailed and would be difficult and expensive to repair or fabricate through other measures. However, through the power of 3D printing, all that’s required is a 3D modelling job and a few hours to print it.

It’s a great entry into our Repairs You Can Print challenge, and covers the fundamentals of modelling and iterative design well. Got a neat repair you’ve done yourself? Document it on Hackaday.io and enter yourself!

Repairs You Can Print: Racing the Clock for a Dishwasher Fix

No matter how mad your 3D printing skills may be, there comes a time when it makes more sense to order a replacement part than print it. For [billchurch], that time was the five-hour window he had to order an OEM part online and have it delivered within two days. The race was on — would he be able to model and print a replacement latch for his dishwasher’s detergent dispenser, or would suffer the ignominy of having to plunk down $30 for a tiny but complicated part?

As you can probably guess, [bill] managed to beat the clock. But getting there wasn’t easy, at least judging by the full write-up on his blog. The culprit responsible for the detergent problem was a small plastic lever whose pivot had worn out. Using a caliper for accurate measurements, [bill] was able to create a model in Fusion 360 in just about two hours. There was no time to fuss with fillets and chamfers; this was a rush job, after all. Still, even adding in the 20 minutes print time in PETG, there was plenty of time to spare. The new part was a tight fit but it seemed to work well on the bench, and a test load of dishes proved a success. Will it last? Maybe not. But when you can print one again in 20 minutes, does it really matter?

Have you got an epic repair that was made possible by 3D printing? We want to know about it. And if you enter it into our Repairs You Can Print Contest, you can actually win some cool prizes to boot. We’ve got multiple categories and not that many entries yet, so your chances are good.