C3 Mini-Lathe Metalworking Beginners
7x12 mini-lathe - Largest Job?
What is the largest job you can turn on a 7x12 mini lathe? Well, the clue is in the name. 7x12. This means that the distance from the bed of the lathe to the centre of the chuck is 7 inches. Therefore it is possible to turn something that is 7 inchs in diameter.
The observant among you will have noticed that the average mini-lathe only comes fitted with a 3 inch chuck. Unless you are machining a sponge, it is very difficult to fit a 7 inch ljob into a 3 inch chuck. The solution, as with many mini-lathe related problems, is to employ a bit of cunning.
How to fit a 7 inch job in a 3 inch chuck
I am working (occasionally) on a fairly long term project to make an equatorial mount. One of the components required for this is a pair of 6 inch diamter worm wheels. Nobody wanted to supply me with 6 inch disks of aluminium, however, a nice supplier did give me some 6 inch sqaure by half inch thick aluminium plate.
Here is the square bit of plate. The first thing I did was draw a 6 inch diameter circle on it using my compasses. Then, using nothing more sophisticated than a simple hacksaw, I chopped off the four corners. Then I drilled a hole down the middle using a mini-mill, and proceeded to mount this large plate on my mini-lathe.
If you want to face off anything bigger than 6 inchs, you do not have enough cross-slide travel to do it in one go, so I must be done in sections, adjusting the tool post holder between sections.
My series on making telescope worm wheel and gear sets shows a practical application of this approach.
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