UPDATE: Since this post, Aaron Bleackley, the creator of Wild Gears, has bought his own laser cutter to produce the gears. It cuts more finely than the cutter at Ponoko, where he used to have the gears made, i.e. the jagged edges produced by the cutter’s movement on the X and Y axes should be much reduced. Shop Wild Gears at this link.
More from Jay Heyl, who has provided some great ideas for Wild Gears storage. Jay has noticed that the laser cutting of the gears leaves an edge that is not perfectly smooth; it’s very slightly jagged, like steps on the X and Y axes, or like a pixelated edge if you blow up a digital image. I took out my jeweller’s loupe to look at some gears and I can see these lines, and I can feel their texture with a fine tool. You can kind of see it inside the holes and on the sides of the teeth in this photo:
Not satisfied with this edge, Jay writes:
I have one other rather geeky “modification” I’ve done to many of my Wild Gears…. smoothing out the stair step edges left by the laser when the gears are cut. These can cause an irregular movement as the pen slides around the hole and result in the lines having jagged sections. The stair step on the gear teeth can make the gears not slide against each other as they should. This can make the larger gears stick when using the outer holes and can make the smaller gears jump around. The stair steps eventually wear down from use but it can take a very long time for them to become anywhere near smooth.
Enter the diamond coated burr bit set. This set was less than $10 from Amazon.
This sloped conical burr (right) is a perfect fit for the small pen holes. You can do it totally by hand, simply rolling the bit between your fingers while sticking it in the pen hole, but that will likely wear your hands out pretty fast. I put the bit in a cordless drill and set it to screwdriver mode to slow the bit speed. Run the bit into the hole all the way to the end of the diamond section. Just a quick in and out is sufficient. I do all the holes from one side of the gear and then turn it over and re-do them from the other side.
You do need to watch what you’re doing when using the drill. These bits are covered in diamonds, the hardest natural substance known to man, and acrylic is not remotely close to the hardest substance known to man. With a short span of inattention you can turn a nice round pen hole into something more like a pen slot. This bit isn’t bad because the conical shape helps it center itself in the hole and it’s almost the perfect diameter. Quick in, quick out, you’re good to go.
None of the bits in this set is a perfect fit for the larger pen holes. I use one of the barrel bits and slide the gear around the bit when it’s inserted in the pen hole. I try to keep the gear moving so I don’t get the hole out of round. A couple moderately slow passes around the hole will knock the high points off the stair step and make the pen feel much smoother. You don’t need to get it perfectly smooth. Just knock down the edges and the pen won’t jump as it moves around the hole. You do need to be careful about keeping the gear perpendicular to the bit or you can take material off the rim of the hole and leave the ridges in the middle.
Smoothing the gear teeth takes two passes, the first with one of the medium barrel bits to deal with the outer portion of the teeth and then another with one of the smaller barrel bits that can fit down further between the teeth. The thing here is to watch that the gear is perpendicular to the bit so it takes a bit of material from the entire width of the teeth.
You don’t have to smooth both the gears and the rings. As long as the stair steps have been removed from one, the teeth will slide together smoothly. Imagine you had two staircases, one turned upside down on top of the other. They obviously won’t slide against each other very well. Replace one staircase with a sheet of plywood and the plywood will slide along the edges of the stairs. Same thing with the gears and rings. Doing both should make it a bit smoother but I haven’t found it necessary.
With all of these it’s probably a good idea to start doing it totally by hand until you have a feel for it and some confidence that you aren’t going to mess things up. Do a few holes and then try them with a pen. I think you’ll notice the difference, particularly if your gears are brand new. Ironically, the burr bits will probably leave a slight burr around the edges of the holes and gear teeth. Put the gear flat on a piece of paper and slide it around for ten or fifteen seconds. That will remove the burrs and make the gear feel smooth when drawing.
So if you’re seeking perfection, you might want to try what Jay’s been doing. The diamond burr sets even come in different grits, so a person could totally geek out getting the edges smoother and smoother. Or find out for yourself where the Law of Diminishing Returns applies. Feel free to share in the comments if you try this.
More from Jay Heyl coming soon.