Sunday 20 November 2016

How to File

There are loads of things to read on the internet, but how to use a file doesn't seem to be one of them. Everybody who can really file has been shown how to do it and has had plenty of practice. Like all hand skills it's really done in the brain. It's a surprisingly meditative experience.

The first thing to know is how to hold a file. Both your thumbs are on top and your fingers are curled around underneath. You press down with your thumbs and pull up with your fingers as though you are trying to bend the file. Of course you don't really bend the file but you have to pretend that you are. As best as I can understand it you are putting pre-load on your muscles and tendons so that you don't snatch or jerk them as you move the file.
Stand with your front foot underneath the vice.

  • Press the front of the file onto the job and wiggle it around until you are certain that it is flat against the workpiece.
  • Clear you mind, for the next couple of seconds there has to be no thought in your head other than pushing the file forwards smoothly and keeping it flat. Try to imagine a point at exactly the same height as the job and push the file smoothly towards it.
  • Lift the file up, bring it back and put it down again with the front of the file touching the job. Don't draw the file backwards, the teeth are only strong in the push direction.
  • Repeat.

Every few stroke you need to check your work. Have you removed enough material? Have you taken more off at one edge?

Every few dozen strokes you might need to clear swarf (called pins) from the file with a card (a very fine wire brush). If you are filing something soft like aluminium you can discourage the pins from sticking to the file by filling it with ordinary blackboard chalk.

It's impossibly easy to remove material from the edges and much harder to get it from the middle. Only try to file the middle of the job and the edges will happen naturally by accident.

This is what I made, its a 1/2" square drive extension to reach onto the nut on the ball joint between the upper wishbone and the upright on the front suspension of my car.

It's impossible to file something perfectly flat. When I started I was putting a crown on every surface with a radius about like a grapefruit.  Since my brother -who's like a milling machine- gave me this lesson it's somewhere between space-hopper and igloo.

Richard "or just buy one" B

1 comment:

  1. That looks like a lot of filing right there, I would have liked to have seen the pile of swarf sorry pins.