Facing on a mini-lathe
Facing is one of the most basic lathe operations. Most jobs on the mini-lathe start off by cutting off a bit of stock to the required length. I don't have a bandsaw, or any fancy cutters... I just use a reciprocating saw with a metal blade.
The cut end of the job will therefore be a bit rough. The first task is to make this end nice and smooth.
As you can see on the right, the end of the job in the mini-lathe is far from flat. making the end smooth and flat is called facing. This is simply a case of moving a tool back and forth taking off a small amount of metal until the end is flat.
The steps are roughly as follows:
- Mount the job in the chuck. TRy you best to mount it so that it its sides are parallel to the bed of the lathe. I find the best way to do this is to tighten the chuck enough to hold the job and turn the lathe very slowly, lining up your eye with the edge of the side of the job and the bed of the lathe. Then gently tap the job until its spinning in line with the bed. Then tighten the chuck fully.
- Mount the facing tool in the lathe. I angle is slightly so that the business end of the tool is angled in towards the chuck a bit. Make sure the tip of the facing tool is level (or a tiny bit above) the centre line of the lathe.
- Wind the carriage back so the tool is clear of the job, and wind the slide in so the tool tip is roughly level, but a tiny bit outside, the edge of the job.
- Turn on the lathe to a slow-medium speed.
- Wind the carriage in very slowly until the tool starts to "tap" on the end of the job. Lock down the half nut lever and lock the carriage in position.
- Now turn the carriage handle to the right so it takes up any slack... the tool will probably stop tapping at this point.
- Wind the tool towards the chuck with the topslide until the tool starts to bang slightly on the end of the job.
- Don't touch the topslide, and slowly wind the cross slide in, moving the tool across the face of the job. It will keep knock the whole way across, just taking the high points off the rough surface.
- When you get to the middle, wind the cross slide back again until the tool is clear of the job.
- Then move the tool a tiny bit closer to the job with the top slide - about 5 thousandths.
- Then repeat the in-out motion of the cross slide to move the tool across the face of the job, taking a bit more off the high points.
- Repeat until the end is completely flat. Finish off with some very shallow cuts (1 or 2 thou) to make a nice smooth finish.
As with most lathe operations, it is a balance between lathe speed, tool motion speed, and depth of cut to get the job done quickly and efficiently without stalling the lathe or damaging the job.
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