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Basic concept/the starting point

A project log for CNC Mill Conversion (RF30)

Makerspace Newcastle has an elderly, worn out RongFu RF30-clone mill. Let's freshen it up and CNC it :-)

david-pyeDavid Pye 03/26/2017 at 01:180 Comments

Makerspace has an RF30-clone mill (these are originally made by a Taiwanese manufacturer called Rong Fu), and rebadged and resold by a large number of third parties. This was very kindly donated by one of our members, Ben Shaw.

Ours is name-plated as the "MSC Industrial Supply Company" but there are a number of other resellers, including Axminster, in the UK.

Because of this, there are often incompatibilities between the machines, as each manufacturer has made customisations to their models.

It is a ROUND COLUMN mill - this means that you can adjust the height of the mill by undoing two bolts and turning the height adjust handle. But because it is a round column design, the quill will lose its' alignment in X and Y, as well as changing height. This is a bit of a disadvantage, but is not trivially easy to rectify.

Drive system
It is powered by the original single phase 240VAC 1.5HP motor, and has a belt and pulley arrangement to allow a variety of drive speeds.

The machine axes are as follows:

Y axis. Located most inferiorly on the machine. The lead-screw is left hand thread, and drives a brass casting with the lead-thread cut in it. This moves the Y axis along the machine's slides (front to back)

X axis - acme lead screw, brass lead-nut is bolted to the centre of the Y-axis table, the lead screw is anchored at both ends, and by turning the screw the table moves (left to right)

Z axis - coarse adjust, and a lockable fine-adjust with a worm gear driven by a Z axis handle.

Current issues

  1. Most of our members probably think in metric - this machine is imperial.
  2. The X and Y axis brass lead-nuts are worn out, leading to a lot of backlash (this means that when you change direction, and try to turn the table the other way, there is a lot of 'play' in the drive system, making it very hard/impossible to work out how far you have moved). Therefore, accurate drilling/positioning is difficult.
  3. It's a round column mill with the issues described above

We can address points 1 and 2 by a CNC conversion , involving replacing the leadscrews with a nice modern ballscrew and ball-nut, and stepper motor drive.

Point 3 is something we will just have to live with!

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