A Digital LCD Makeover For An Analogue CRT Spectrum Analyser

[Seb Holzapfel, VK2SEB] has a rather nice spectrum analyser, a Hewlett Packard 141T. It’s an entirely analogue instrument though, so it lacks some of the sophisticated features you might expect to see on its modern counterparts.

One feature the HP does have is a vertical deflection output that in effect allows the trace to be reproduced on an oscilloscope. [Seb] has taken that and applied it to an STM32F746 Discovery board with its associated LCD touchscreen to produce an interface for the HP that includes modern features such as trace normalisation and a waterfall view. Along the way he’s had to make a voltage level converter to render the HP’s scan output into a range acceptable for the ST board.

He goes into detail on his software for the project, which he is at pains to remind us is still very much a work in progress. He notes that the HP has a range of other outputs (on those “D” sockets that include co-axial connectors) that provide information about its band and scan settings, so there is ample possibility for further customisation.

If you are interested in this project then the code is all available via GitHub, otherwise you can watch his video below the break. He’s labelled it as “Part 1”, so we look forward to more on this project.

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Reamer Regrinding Using A Toolpost Spindle

How often have you wished you could reduce the size of a drillbit? [Ben Katz] has a bunch of projects in mind that use a tight-tolerance 22mm bore–but he didn’t have a 22mm reamer handy. Rather than buy one, he thought, why not regrind a larger one to the right size?

He first ground down the shank to fit in the lathe’s drill chuck. Once it was loaded into the chuck,  he reground the edge of a 7/8″ (22.225mm) reamer, reducing its diameter down to 22mm by spinning it on his lathe in conjunction with a toolpost spindle with a grinding wheel attached. The final diameter was 21.995mm—off by 5 microns!

[Ben]’s homebuilt spindle is a cool project in itself, and we publish a lot of posts about those handy tools. Check out our pieces on a brushless DC motor used as a CNC spindle, and this 3D printer outfitted with a spindle. Also check out [Ben]’s electric tricycle build we featured a few years ago.

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It’s An Angle Grinder! No, It’s A Floor Sander!

Faced with the potentially arduous task of sanding a wood floor, what would you do? Hire a pro? Rent the proper tools and do it yourself? Perhaps even shell out big bucks to buy professional grade tools? Or would you root around in your junk pile and slap together a quick and dirty floor sander from an old angle grinder?

That’s what [Donn DIY] did when looking at the wide expanse of fresh floorboards in his new sauna. Never one to take the easy way out, and apparently with a thing for angled gear boxes, [Donn DIY] took the guts out of a burnt-out angle grinder for his impromptu floor sander. A drill attached to the old motor rotor provides the spin, and a couple of pieces of scrap wood make the platen. Sandpaper strips are clamped between the discs, and as seen in the video below, the whole contraption does an admirable job.

We’ve seen lots of angle grinder hacks before, some useful, some silly. This one gets the job done and is a nice quick hack that speaks to the value of a well-stocked junk pile.

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Power Planer Brought Back To Life

Having the right tool for the right job is not always possible, but it’s an ideal that’s nice to try to live up to. The problem is that a lot of the time, the right tool is often very expensive. We have found lots of ways around this, though, from building our own CNC machines to finding new ways to electroplate metal. Sometimes, though, the right tool for the job doesn’t have to be improvised or built from scratch, it just falls in your lap.

Admittedly, [Sam]’s power planer didn’t literally fall into her lap, but she did pull this neglected tool from the garbage. With no idea what was wrong with it, [Sam] let it sit on the shelf for years until she finally needed it. Assuming there was a major problem with the tool, she set about replacing the blades and bearings only to find that the likely culprit behind why the planer was thrown away in the first place was a faulty switch. This was likely a deal and circuit-breaker for someone who would use it all day, but not so for someone who only needs it for occasional use.

While some might not consider this a “hack”, it is at least a reminder that one man’s trash is another man’s treasure, especially if that trash only needs new bearings and a switch. There are two lessons here: first, that tools aren’t usually beyond repair, and that it’s possible to find all kinds of tools in the dumpster from people who don’t heed this advice.

A Great Way To Make Quick And Easy Knobs

Here’s a great way to quickly and easily make attractive and functional knobs with no tools required. All you need is some casting resin (epoxy would do in a pinch), a silicone mold intended for candy, and some socket head bolts. With the right preparation and a bit of careful placement and attention, smooth and functional knob ends are only minutes away. Embedded below is a short video demonstrating the process.

These may not replace purpose-made knobs for final products, but for prototypes or to use around the shop on jigs, clamps, or furniture they certainly fit the bill. With a layer of adhesive fabric or rubber, they might even make serviceable adjustable feet for low-stress loads.

This technique could be extended to reproducing broken or missing dakaware or bakelite knobs. This, of course, would require an original, unbroken knob and a small silicone mold, but it’s still a project that’s well within the capabilities of the garage-bound hacker.

While we’re on the subject of knobs, don’t forget we’ve seen an excellent method of repairing knobs as well.

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Bringing A 50 Watt Laser Cutter To Life

This is the future and we live in a world of 3D printers and laser cutters. Have you ever pondered the question of getting yourself a laser cutter? Well [Erich Styger] just landed a 50 Watt Laser Cutter from AliExpress and has written up a detailed guide to his experience.

[Erich] had been wrestling with the idea of buying one for himself for some time but was put off by the difficulty in their operation. This changed when [Scorch] published the K40 Whisperer control software which allows for better control over these machines. With the hopes of an interesting weekend project, [Erich Styger] took a leap of faith and spent $900 on a model 4040 laser cutter.

In his blog, he goes through the steps in setting up the machine as well as calibrating the laser. With a plethora of images and a detailed look at each aspect of the leveling and testing, [Erich Styger] had a weekend well spent and a working K40 laser cutter for his workshop. But perhaps the more valuable part of the stories is the overall experience.

It was not a “what you see is what you get” order, but it did turn out to be a hacker’s “what you want is what you get” adventure. The machine didn’t look the same as the picture, it came with a burned CD-R with a box full of small parts (in addition to separate shipment of a USB thumb drive and silicone sealant), and there were some mechanical touchups plus a stuck switch requiring reassembly. He has done an excellent job of documenting from order to test-runs and the photos alone are worth taking a look.

Adding value to inexpensive laser cutters in an often-featured project around here. If you are looking for more details on these wonderful machines, be sure to check out more tales of Cheap Laser Cutters and our coverage of the K40 Whisperer software launch from last month.

Pouring 1200° Tea: Foundry In A Fire Extinguisher

Let’s face it — the design of most home foundries leaves something to be desired. Most foundries are great at melting metal, but when it comes to pouring the melt, awkward handling can easily lead to horrific results. That’s why we appreciate the thought that went into this electric melting pot foundry.

Sure, electric foundries lack some of the sex-appeal of gas- or even charcoal-fueled foundries, but by eschewing the open flames and shooting sparks, [Turbo Conquering Mega Eagle] was able to integrate the crucible into the foundry body and create what looks for all the world like a Thermos bottle for molten aluminum.

The body is a decapitated fire extinguisher, while the crucible appears to just be a length of steel pipe. An electric stove heating element is wrapped around the crucible, PID control of which is taken care of by an external controller and solid state relay. Insulated with Pearlite and provided with a handle, pours are now as safe as making a nice cup of 1200° tea.

You’ll perhaps recall that [Turbo Conquering Mega Eagle] has a thing for electric foundries, although we have to say the fit and finish of the current work far exceeds his previous quick-and-dirty build using an old electric stove.

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