Easy plastic gear forming...
Posted: Thu Oct 29, 2015 7:13 pm
Hardly needs any words!
The set up.....
... and the result!
I think this plastic is ABS, I cut a disc of random size and mounted it in the lathe with spare change wheel mounted on an axle in the tool post.
The lathe was run at about 400rpm and the change gear pressed against it, of course the gear started to turn and I increased the pressure a little. After about a minute the sound changed somewhat which I assume indicated the plastic was getting hot and starting to soften, at that point I increased the pressure and in about 15 seconds or less the teeth were formed.
The blank does not have to be the same size as the gear and as far as I can see no matter what the size of the blank the teeth which are formed will always be shaped in true involute form. It should be possible to make gears with odd numbers of teeth (according to the diameter of the blank) and of course there is no need for any indexing devices.
BTW, this does not always work and it is easier with bigger diameters.
Now if I used a steel blank with an oxy/acet flame playing on the edge it might get hot enough to form the same way.....
The set up.....
... and the result!
I think this plastic is ABS, I cut a disc of random size and mounted it in the lathe with spare change wheel mounted on an axle in the tool post.
The lathe was run at about 400rpm and the change gear pressed against it, of course the gear started to turn and I increased the pressure a little. After about a minute the sound changed somewhat which I assume indicated the plastic was getting hot and starting to soften, at that point I increased the pressure and in about 15 seconds or less the teeth were formed.
The blank does not have to be the same size as the gear and as far as I can see no matter what the size of the blank the teeth which are formed will always be shaped in true involute form. It should be possible to make gears with odd numbers of teeth (according to the diameter of the blank) and of course there is no need for any indexing devices.
BTW, this does not always work and it is easier with bigger diameters.
Now if I used a steel blank with an oxy/acet flame playing on the edge it might get hot enough to form the same way.....
