DIY Surface Grinder For Making Precision Parts At Home

March 13, 2015 by Rich Bremer 31 Comments

Surface Grinders are machines that can make a surface of a part very flat, very smooth and very parallel to the face of the part that is mounted to the machine. Surface grinders usually have a spinning grinding wheel suspended over a moving bed. The bed moves the part back and forth under the grinding wheel removing an extremely small amount of material at a time, sometimes down to just a ten-thousandth of an inch (o.0001″) in order to make a precision part.

[Daniel] is a tool guy and wanted a Surface Grinder. He didn’t need a super-accurate commercial grinder so he decided to make one himself. It’s a doozy of a project and is made up of quite a few other tools. [Daniel] already had a mini CNC mill and decided this would be a good platform to begin with. The mill was rigid and already had automated X and Y axes, after all. For the grinder motor, nothing made more economical sense than to use a regular angle grinder, but there were two significant problems. First, no company made wide grinding wheels for an angle grinder. [Daniel] had to modify his spindle to accept an off-the-shelf surface grinding wheel. The second problem is that the new grinding wheel had a max RPM rating of 4400. The angle grinder can reach 10,600 RPM. In order to slow down the angle grinder, a speed control was taken out of an old variable-speed router and integrated with the angle grinder. Problem solved. A mount was then made to attached the angle grinder to the Z axis of the mill.

A magnetic chuck mounted to the mills bed is used to hold down metal work pieces. There is a lever on the chuck that when moved in one direction it creates a magnetic field to hold a ferrous piece of metal firmly to the chuck during machining. When the lever is moved in the other direction, the part is released and can be removed from the Surface Grinder.

To use his new Surface Grinder, [Daniel] creates a CNC g-code file to move his work piece back and forth underneath the grinding wheel. Being able to control the depth of cut and feed rates with his CNC machine removes human error from the grinding process and leaves a consistent finish on the part. Check out the video after the break.

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Broken Bread Maker Rises Again, Drives Tool-Sharpening Turntable

March 12, 2015 by Kristina Panos 6 Comments

Poor [makendo] had seven broken bread makers lying around, all with failed paddle drivers. Since they also all have big motors and other useful parts in them, he decided to turn one of them into a powered tool-sharpening turntable.

First, [makendo] salvaged the motor, the gear, and the thick circular glass window from one of the bread makers. He cut a platter from plywood the size of the glass window, chamfering the edge to fit the gear. Next, he built a housing from scrap plywood, separating the motor from the platter with a crosspiece to keep the motor free from dust. A large magnet on a hinge collects metal powder from the system quite effectively. The sharpener spins at about 200RPM: fast enough to do the job and slow enough not to get hot.

According to [makendo], the sharpener restores bevels nicely but doesn’t make edges”scary sharp”. To that end, he used a toaster oven door as a base for a series of micro-abrasive grits of sandpaper as a finishing rig. In order to sharpen his chisels uniformly, he made a jig to hold them firmly in place against either the powered turntable or the fine sandpapers.

[Thanks for the tip, Scott]

Spectrum Analyzer On The Cheap

March 12, 2015 by Bryan Cockfield 27 Comments

Provided you have an NTSC-compatible TV you can build yourself a really inexpensive spectrum analyzer. From there you just need one trivial piece of hardware to complete this build. [Bruce Land] has come up with a spectrum analyzer that shouldn’t cost any more than $5, if that’s what’s been keeping you from adding this tool to your workbench!

The spectrum analyzer is based on a PIC32 microcontroller which was previously proven in his Oscilloscope project. [Bruce] has managed to squeeze quite a bit out of this robust chip; the spectrum analyzer has 450 kHz bandwidth and runs a 256 Hz TV display and can output over 30 updates per second. The microcontroller runs the Fast Fourier Transform (FFT) to do calculations, with great results.

[Bruce] notes that the project was based on TV framework from another project, and that the FFT was added on top of that. Be sure to check out the source code on the project site if you’ve been on the hunt for an inexpensive spectrum analyzer, and if you need something with more processing power but only slightly more money, check out the FFT that runs on the Raspberry Pi’s GPU.

[James] Multiplies His Floor Sander By Four

March 11, 2015 by Adam Fabio 19 Comments

Hackaday contributor and new homeowner [James Hobson] had a dilemma on his hands. He had rented a commercial drum sander to begin a floor refinishing project. Like many before him, James was a bit too aggressive with the drum sander in places. The uneven stripes didn’t show up until the sander was returned and the floor was stained. Renting the sander again would be an expensive prospect. There had to be a better answer…

That’s when [James] put on his [Hacksmith] cape and got to work. He built himself a DIY floor sander (YouTube Link) using four Ryobi orbital sanders, some scrap wood, and a bit of ingenuity. [James] screwed the four sanders to a plywood sub plate, then added a top plate with a handle. He even gave the sander its own outlet strip so he wouldn’t be dragging four power cords behind him.

[James] found that synthetic steel wool pads weren’t cutting through the floor very well, so he upgraded to 220 grit sandpaper. That did the trick, and the sander worked great. Now he won’t have to rent a drum sander when it comes time to refinish the first floor of his new house!

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Dirt Cheap Motor Balancing And Vibration Analysis

March 7, 2015 by Kristina Panos 7 Comments

Ever the enterprising hacker and discerning tool aficionado, [Chris] knows the importance of “feel”. As a general rule, cheap tools will shake in your hand because the motors are not well-balanced. He wanted a way to quantify said feel on the cheap, and made a video describing how he was able to determine the damping of a drill using a few items most people have lying around: an earbud, a neodymium magnet, scrap steel, and Audacity.

He’s affixed the body of the drill to a cantilevered piece of scrap steel secured in a vise. The neodymium magnet stuck to the steel interrupts the magnetic field in the earbud, which is held in place with a third hand tool. [Chris] taped the drill’s trigger down and controls its speed a variac. First, [Chris] finds the natural frequency of the system using Audacity’s plot spectrum, and then gets the drill to run at the same speed to induce wobbling at different nodes. As he explains, one need not even use software to show the vibration nodes—a laser attached to the system and aimed at a phosphorescent target will plot the sine wave.

Just for fun, he severely unbalances the drill to find the frequencies at which the system will shake itself apart. Check it out after the break.

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A Functional Sonic Screw Driver (Well, Kind Of)

March 6, 2015 by James Hobson 14 Comments

[Jerome Kelty] just finished building this awesome data-logging Sonic Screwdriver with his 6-year-old son [Sam]. The Halloween previous, [Jerome’s] older son had dressed up as the Doctor, which had inspired [Sam] to make his own Sonic Screwdriver — however he declared that his screwdriver needed to actually work!

They sat down together and decided what it needed to be able to do. [Sam] has a pair of hermit crabs, so they thought it would be handy to be able to measure the temperature and the humidity of their habitat. It needed a flashlight for obvious 6-year old reasons, and it had to make the right sound effect when you used it too!

[Jerome’s] first thought was to 3D print it, but was met with a resounding no: “It needs to be metal!”

So out came the sketchpad and they started designing it to be cut on the lathe, using a combination of aluminum, brass and wood.

Many weekends later [Sam] and his dad finished the body of the screwdriver and started work on the electronics. To keep it simple they used an Arduino Pro Mini 5V with a Sparkfun OpenLog to record all the data — and a handful of sensors of course!

After modifying the body a few times they finally got all the electronic guts to fit inside the screw driver. It features an SD card you can remove to see the OpenLog data, but as a “cool factor” [Jerome] also programmed in the temperature sensor to output to the RGB LED, so little [Sam] can point at things to determine how warm or cold they are.

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DIY Thermal Insert Press

March 6, 2015 by Ethan Zonca 38 Comments

You might not know what a threaded insert is, but chances are you’ve seen one before. Threaded inserts are small metal (typically brass) inserts that are pressed into plastic to give a strong point of attachment for bolts and screws. These inserts are a huge step up from screwing or bolting directly into tapped plastic holes since the brass threads are very strong compared to the plastic. The only major downside to these inserts is that the press to install them is incredibly expensive. Thankfully, [Alex Rich] came up with a cheap solution: a modified soldering iron mounted to an Arbor press.

Commercial threaded insert presses typically use ultrasonic welding or heat welding to fuse inserts with plastic. [Alex] chose the simple route and went with heat welding, which (as you might imagine) is way simpler than ultrasonic welding. To provide the heat, [Alex] mounted a 100W Weller soldering iron to the press, which he says handles the impact with no problem. Unfortunately the copper tips of the Weller just wouldn’t hold up to the impact, so [Alex] made his own tips out of some brass he turned on a lathe.

If, like most people, you don’t have the capability of making injection-molded cases, let alone an Arbor press on hand, you’re not out of luck! Using this same technique people have successfully added thermal inserts to 3d-printed parts using a soldering iron and much smaller DIY presses. Have any ideas on how you could use thermal inserts in your 3d prints? Let us know in the comments.