abrasive

6 Articles

Have A Ball With This 3D Printed Sphere-Making Machine

February 13, 2024 by 19 Comments

Alright, everyone has 30 seconds to get all the jokes out of their system before we proceed with a look at this 3D printed wooden ball polisher.

Ready?

Theoretically, making a sphere out of any material should be easy. All you need to do is pick a point in space inside the material and eliminate everything more than a specified distance from that point. But in practice, sphere-making isn’t quite so simple. The machine [Fraens] presents in the video below is geared more toward the final polish than the initial forming, with a trio of gear motors set 120 degrees apart driving cup-shaped grinding pads.

Constant pressure on the developing sphere is maintained with a clever triangular frame with springs that pre-load the arms and pull them in toward the workpiece, but stop at the desired radius. The three grinding pads are fitted with sandpaper and constantly turn, wearing down the rough piece until it reaches the final diameter. The machine also supports more aggressive tooling, in the form of hole saws that really get to work on the rough blank. Check it out in the video below.

While we appreciate the fact that this is 3D printed, watching the vibrations it has to endure while the blank is still rough, not to mention all the dust and chips it creates, makes us think this machine might not stand up for long. So maybe letting this circular saw jig cut out a rough ball and using this machine for the final polish would be a good idea. Continue reading “Have A Ball With This 3D Printed Sphere-Making Machine” →

Home Brew Sandblaster Is A Junk Bin Delight

October 4, 2022 by 17 Comments

Opinions vary as to what actually constitutes a “complete” shop, but one thing is for sure: the more tools, the better. That doesn’t mean running out to buy a tool every time you have a need, of course. Sometimes you can throw together what you need from scrap, as with this ad hoc sandblaster. (Video, embedded below.)

Fans of junk builds — and we mean that with the highest respect — will want to pay special attention to [GARAGEUA]’s video below. It looks like pretty much everything he uses to make this sandblaster comes from the junk pile — bits of old plumbing fixtures, a blow gun that’s seen much better days, some old nuts and bolts, and even a deceased spark plug all make an appearance. That last one is perhaps the most interesting, since with some clever dissection the spark plug’s body and its ceramic insulator were used for the nozzle of the sandblaster. And best of all, no lathe was needed for this job — everything was done with a hand drill and an angle grinder. Check out the build details in the video below; you might pick up some useful tips.

We’ve featured even junkier sandblaster builds before, but this one is a clever way to save a few bucks and flex a bit on your mechanical ingenuity. If you need a sandblaster and it’s something you’re going to use again and again, by all means go out and buy one — we won’t judge. But rolling your own is cool too.

Continue reading “Home Brew Sandblaster Is A Junk Bin Delight” →

3D Printing Aids Metal Polishing

September 20, 2022 by 9 Comments

While a machinist can put a beautiful finish on a piece of metal with their lathe or mill, to achieve the ultimate finish, a further set of polishing procedures are necessary. Successively finer abrasives are used in a process called lapping, which removes as far as possible any imperfections and leaves eventually a mirrored smoothness. It’s not without problems though, particularly at the edge of a piece it can result in rounded-off corners as the abrasive rubs over them. [Adam the machinist] has a solution, and he’s found it with a 3D printer.

To avoid the rounded edges, the solution involves fitting a piece of metal or wood flush with the surface to be lapped, such that the pressure doesn’t act upon the corner. This can be inconvenient, and the solution avoids it by 3D printing a custom piece that fits over the entire machined object providing a flat surface surrounding the edges. We see it being used with a demonstration piece that has three separate surfaces in the same plane to lap,something that would have been challenging without the 3D printed aid.

Lapping isn’t a process we see too often here. But it has cropped up as an extreme overclocking technique.

Continue reading “3D Printing Aids Metal Polishing” →

Mechanisms: Abrasives

June 6, 2018 by 24 Comments

In our “Mechanisms” series, we’ve featured the fascinating bits and pieces that go into making our mechanical world work. From simple machines such as screws and levers, from springs to couplings, and even more complex mechanisms like zippers and solenoids, we’ve covered the gamut. But we haven’t talked about one of the very earliest mechanisms, captured from nature by our clever ancestors to do useful work like grinding grain and shaping materials into tools: grit, sand, abrasives.

Continue reading “Mechanisms: Abrasives” →

Fail Of The Week: The Semiconductor Lapping Machine That Can’t Lap Straight

May 21, 2018 by 34 Comments

It seemed like a good idea to build a semiconductor lapping machine from an old hard drive. But there’s just something a little off about [electronupdate]’s build, and we think the Hackaday community might be able to pitch in to help.

For those not into the anatomy and physiology of semiconductors, getting a look at the inside of the chip can reveal valuable information needed to reverse engineer a device, or it can just scratch the itch of curiosity. Lapping (the gentle grinding away of material) is one way to see the layers that make up the silicon die that lies beneath the epoxy. Hard drives designed to spin at 7200 rpm or more hardly seem a suitable spinning surface for a gentle lapping, but [electronupdate] just wanted the platter for its ultra-smooth, ultra-flat surface.

He removed the heads and replaced the original motor with a gear motor and controller to spin the platter at less than 5 rpm. A small holder for the decapped die was fashioned, and pinched between the platter hub and an idler. It gently rotates the die against the abrasive-covered platter as it slowly revolves. But the die wasn’t abrading evenly. He tried a number of different fixtures for the die, but never got to the degree of precision needed to see through the die layer by layer. We wonder if the weight of the die fixture is deflecting the platter a bit?

Failure is a great way to learn, if you can actually figure out where you went wrong. We look to the Hackaday community for some insight. Check out the video below and sound off in the comments if you’ve got any ideas.

Continue reading “Fail Of The Week: The Semiconductor Lapping Machine That Can’t Lap Straight” →

Bolt-Together Belt Grinder For The No-Weld Shop

November 21, 2017 by 19 Comments

Belt grinding offers a lot of advantages for the metalworker, and since belt grinders are pretty simple machines, shop-built tools are not an uncommon project. A bolt-together belt grinder makes this tool even more accessible to the home gamer.

With no access to a welder but with a basic milling machine and an ample scrap bin at his disposal,  [IJustLikeMakingThings] had to get creative and modify some of the welding-required belt grinder designs he found online to be bolt-up builds.  The key to a cool running belt grinder is for the belt to be as long as possible, and the 2″x72″ belt seems to be the sweet spot, at least here in the States. Machined drive and idler wheels with the crown needed for proper belt tracking were sourced online, as was the D-bracket for holding the two guide wheels. But the rest of the parts were fabricated with simple tools and bolted together. [IJustLikeMakingThings] provides a lot of detail in his write-up, and it shouldn’t be too hard to build a belt grinder just like this one.

Looking for other belt grinder plans to compare notes? Here’s a grinder with an even simpler design, but with welding required.