Cut Your Own Gears With This DIY Machine

You can buy gears off the shelf, of course, and get accurately machined parts exactly to your chosen specification. However, there’s something rugged and individualist about producing your own rotating components. [Maciej Nowak] demonstrates just how to produce your own gears with a homemade cutting tool.

The cutting tool for the job is an M16 machine tap, chosen for the smaller flutes compared to a hand tap. This makes it more suitable for cutting gears. It’s turned by a belt driven pulley, run by a small motor. The workpiece to be cut into a gear is then fed into the cutting tool by sliding on a linear bearing, with its position controlled by a threaded rod. The rod can be slowly turned by hand to adjust the workpiece position, to allow the gear teeth to be cut to an appropriate depth.

The method of action is simple. As the tap turns it not only cuts into the workpiece, but rotates it on a bearing as well. By this method, it cuts regular teeth into the full circumference, creating a gear. Obviously, this method doesn’t create highly-complex tooth shapes for ultimate performance, but it’s more than capable of creating usable brass and steel gears for various purposes. The same tool can be used to cut many different sizes of gear to produce a whole geartrain. As a bonus, the resulting gears can be used with M16 threads serving as worm gears, thanks to the pitch of the tap.

If you find yourself needing to produce tough metal gears on the regular, you might find such a tool very useful. Alternatively, we’ve explored methods of producing your own sprockets too, both in a tidy manner, and in a more haphazard fashion. Video after the break.

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Sharpies And Glue Sticks Fight The Gummy Metal Machining Blues

“Gummy” might not be an adjective that springs to mind when describing metals, but anyone who has had the flutes of a drill bit or end mill jammed with aluminum will tell you that certain metals do indeed behave in unhelpful ways. But a new research paper seeks to shed light on the gummy metal phenomenon, and may just have machinists stocking up on office supplies.

It’s a bit counterintuitive that harder metals like steel are often easier to cut than softer metals; especially aluminum but also copper, nickel alloys, and some stainless steel alloys. But it happens, and [Srinivasan Chandrasekar] and his colleagues at Purdue University wanted to find out why, and what can be done about it. So the first job was to get up close and personal with the interface between a cutting tool and metal stock, to observe the dynamics of cutting. In a fascinating bit of video, they saw that softer metals tend to fold in sinuous patterns rather than breaking on defined shear planes.

Source: American Physical Society.

Having previously noted that cutting through Dykem, a common machinist’s marking fluid, changes chip formation in soft metals, the researchers tested everything from Sharpies to adhesive tape and even correction fluid, and found that they all helped to reduce the gumming action to some degree. Under their microscope they can clearly see that chips form differently once the cutting edge hits the treated surface, tending to act more brittle and ejecting rather than folding. They also noted a marked decrease in cutting force for the treated metal, and much-improved surface finish to boot.

Will Sharpies and glue sticks enter the book of old machinist’s tricks like gauge-block wringing? Only time will tell. But for now, this is a pretty fascinating bit of research that you might be able to put to the test in your shop. Let us know what you find in the comments.

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