Backplate

[Steve355Participant @steve355]

>>do you have suitable gears for a fine-feed?

Yes, see the gear chart above, there’s a medium feed setup and a fine feed. I had the fine feed gearing on the machine for a long time. Problem is, it’s really hard to install these gears. It requires accessing bolts on the banjo that are really hard to get to. It’s a real pain. I dream of a Myford with a quick change gearbox!

[John HaineParticipant @johnhaine32865]

Install an ELS and never change a gear again?

[Howard LewisParticipant @howardlewis46836]

For a fine feed you need to set up a train, probably a compound one with the smallest gears driving the largest, such as 20 : 80/25 : 75/30 : 60 on the leadscrew . That would give a feed of 0.0052″ per rev of the chuck, with a 8 tpi Leadscrew.

If you can substitute additional 20T gears for the 25 or 30, the feed rate will be even finer. Anything of the order of 0.004″ per rev should be satisfactory.

For a good finish, have a sharp tool, set right on centre height, and use a minimal depth of cut, say 0.001 or 0.002″. Ideally, a very slight radius on the nose of the tool should give a really fine finish

But don’t let the radius remove the cutting edge of the tool so that actual contact is below centre with the actual cutting edge, now clear of the work! Radius all the front of the tool!

When meshing the gears, start with the Leadscrew mesh, and run a sheet of paper through it to give about 0.003″ clearance, minimum. Having clamped that stud in place, set the next mesh, by moving the first stud to set the mesh.

Once that backlash is set, the mesh with the Driving gear can be set by swinging the banjo.

In this sequence, the meshes will be correct, and the stud clamps more easily accessible, before clamping the banjo to give the correct Driver : first Driven backlash.

Since there will be two Idlers, the Tumbler Reverse will need to used to ensure that the saddle moves towards the chuck.

HTH

Howard

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