Mike's Journal

electronics, engineering, entrepreneurship

Adjustable (slotted) arm on the quill collar

We took a piece of aluminum bar and made an arm that comes out radially
from the quill collar.

It's inset so the bottom of it is flush with the bottom of the collar.
All that protrudes is the two screws. This was important to make sure
the arm wouldn't interfere with our work when milling.

It's distance is adjustable radially via the slotted path for two hex
cap screws.

We used a dial indicator and measured a deflection of about 0.002" at
the end of the arm under a heavy hand-applied force (maybe 50 pounds or
so). Hopefully this means the deflection under the drag of the slide
will be negligible!

The end is threaded radially, which is where the digital caliper will
attach.

(download)

Quill collar for 1220XL

We've been working on making a new collar to fit around the mill quill on our Smithy CB1220XL. We started with a 4" diameter by 3/4" long piece of 6061 aluminum. After a bunch of facing / turning / boring / milling / drilling / tapping / sawing operations, we've successfully made the part. We had great results with lathe accuracy, able to get diameters finished to within roughly +/- 0.002" of target.

The outer diameter is arbitrary. The larger bore diameter must fit snugly around the quill collar for a press-fit -- it is then tightened with the two hex-cap screws as shown. The smaller bore through the piece must clear the rotating spindle, but must remain close so as to provide a chip shield for the thrust bearings just within the collar.

We ran into lots of issues with work planning, some of which were due to the reduced work volume of the machine, but most of which were simply due to our original paper design taking insufficient consideration of things like obstruction by the drill chuck, tool cutting lengths, etc.

But it works! It goes on snug and is quickly tightened via the two screws. This replaces a plastic cap included with the machine. However, this version gives us the opportunity to add a Z-axis digital read out (DRO)... stay tuned!

(download)

We're making chips on the lathe and mill!

We've been busy getting tooling, and finally have been able to do some
basic lathe and mill work!

The backlash is pretty terrible (perhaps 0.020 inches), specifically for
use as a mill, so we have to move toward DRO very soon.

(download)