Build a pneumatic metal engraver for cheap

Several months ago I happened upon a YouTube channel called "Shaun Hughes Hand Engraving". His artwork is fantastic, but he also has a few videos describing how to build an air-powered engraver. Simple AND cheap?! I can't resist something like that. The pump modifications and the engraver were completed in a single evening and cost less than $40 total.

The air pump must be modified to produce air that oscillates in two directions rather than a constant flow in one direction. Air pumps are built using a set of two (one-way) valves. In this mod, the holes used as air passages for the first one-way valve were threaded and plugged with screws. The second one-way valve was then removed completely and replaced with an aluminum washer to maintain proper spacing. The modifications are easily reversible to restore it to normal inflator operation if needed.

The engraver is connected to the pump using aquarium hose. A brass barb fitting and bushing adapt that hose into a 1/2" copper elbow, which then connects to the copper cylinder. If I did it over again I would not use copper pipe from the hardware store. It was out of round enough that I had to squash it around a bit in the vise before the piston would fit perfectly. I chose it because it can be easily soldered and because it has no internal seam.

Inside the cylinder is a spring, a piston, a spacer, and an end-plug where the graving bit attaches. The spacer was used to tune the operation after cutting the spring to length.

The tool I use in this video is not shaped or sharpened correctly! Graving cutters normally have a particular geometry that I didn't attempt to reproduce. This project was just a quick proof-of-concept for fun, so I know it's not an ideal setup. I have a few more designs in mind, including some which don't require an oscillating air supply. Perhaps I'll try those next...

Thanks again to Shaun Hughes for sharing the tool concept, and for the enticing artwork. Metal engravings have a very cool, distinct appeal.
https://www.youtube.com/user/express375
What do you think? Have you made a similar engraver? Did I miss anything obvious in my attempt? Can you think of a way to bring the cost down even further? Leave a comment!

Видео Build a pneumatic metal engraver for cheap канала This Stuff I Do