Page BottomSometimes it's a Good Thing to have a common chain driving, or being driven by, a small cheap sprocket. The larger crank sprockets are useable, often have a standard ID hole in them, and are easy to remove also. You can get bike chain in major department stores in the usa, no specialty store needed. Usually, the bike you remove the rear hub or tire from also came with a chain,
Here's the jig i made up to hold the tire (or just the hub) upright and sturdy enough to pound rusty threaded things off of it. I have one end of the angle steel on a 4x4 block of wood because i decided i prefer a slight tiltback to the tire as i
It's made of 2inch wide by 1/4 inch thick plate for the long pieces across the face of the wheel, and 1.5 x 3/16 bits for the "hinge" at one end. Everything is welded, except the floating hinge pin, and it's got a nylock nut on it. The 2ft piece of angle is 2x2 by 1/4 inch. The whole things is quite sturdy, and will grip the big sprocket of every hub i
Click on it to open a larger pic in a new tab.
Closeup of gripping a hub on a wheel. The vertical flat stock has two pins sticking out the back, made of a grade8 1/4 inch bolt with the threads cut off it. The vise grips make it easy to place the piece to hold the long arms tight on the big sprocket. It's inherently going to fit any normal large bike sprocket, based on where i clamp that plate. |
I prefer the two C clamps, they make the jig more resistant to twist than one grip, but you can use anything you have. The pins out the back hold the force of the arms trying to spread, so not alot of clamping is needed. Here it is with the hub/wheel removed, still gripping the big sprocket. The pins are short enough to not impact the next sprocket in on the hub. |
This is a plain ole piece of steel to pound on. You want to contact as much of the tooth as possible. Even tho the teeth are hardened, and this steel bar is common 30kpsi, it's still possible, however unlikely, to
The steel bar is soft enough to be molded by the tooth, which can be good and bad. Don't let the bar get deeply slotted, or it will bottom out on the hub and deflect
Click on it to open a larger pic in a new tab.
On all three pics below, you can cut the ring, or the first sprocket, or both, with a fiber reinforced abrasive disk in a Dremel / Moto type of rotary tool. I would not use the thinnest non-reinforced disks on this, those thin disks are quite fragile. I had to cut all but one ring i ran across, but then all my hubs sat outside for over a year. Click on a pic to open a larger version in a new tab.
Here's the small sprocket off after some pounding. Note it's internally threaded on a flare of the plate the sprocket is made of, and the hub tube has an external thread. This first sprocket is the only one threaded. Thankfully! |
See that ring outside the smallest sprocket? It's incredibly annoying when rusted up, because it won't come off as easily as the sprockets do. There's two versions, this one you can see a little thin hub sticking out beyond it, so this one is internally threaded, like the sprocket to the left is. None of the sprockets on this hub is threaded. |
This is an externally threaded ring. You can see where i cut it several times, so in the event it was severely stuck, it might collapse down away from the inside of the hub's threads, and just fall out. It didn't collapse, but after cut it threaded out easily. You can see the hubs with the lock ring have much thinner small sprockets. |
I'm sure there are specialised tools to do this task, feel free to buy them if you like! I made my jig because i believe i could not pound on the tools i saw available, and as you can see, these were really rusted up.
Pile of sprockets. Note the spacers in the pile, i'd rather keep them than toss them out, because i may want to build up a two-speed drive sometime, or just need a round spacer. |
Sprockets on a stick. While you can get bike sprockets in one-tooth increments, you're still likely to get duplicates with every hub you take apart. |
Page Top