Step 8: Mill Something [FuddyMuckers]

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====== Step 8: Mill Something ======

Specifically I decided to try with a 0.1mm engraving cutter (from a cheap eBay pack of 10) into a bit of black anodised aluminium:

{{ http://fuddymuckers.co.uk/gallery/s/500/cnc/20190202_192109.jpg }}

And here's how it came out:

{{ http://fuddymuckers.co.uk/gallery/s/500/cnc/20190204_101900.jpg }}

===== All work and no play =====

So while I'm counting it as a success that I <del>milled</del> engraved something into a bit of aluminium it's clear there's a couple of things not right here.

The "trailing off" I'm ignoring for now as I'm fairly sure it's down to only clamping one end of the piece down.

The bigger issue is most obviously summed up in this section:

{{ http://fuddymuckers.co.uk/gallery/s/500/cnc/issue_1.jpg }}

See how the Y axis has drifted a fair bit? Not what you want!

Now, there was some adjustment to be had in the X axis dovetail guide (see the little brass nuts & grub screws) which removed a bit of play, but on re-running another test piece it's obvious the Y-axis has a fair bit of backlash in the lead screw.

Now, the Proxxon is not built quite the same as a larger industrial mill, so on the end of the lead screws are plain (although left-handed) nylock nuts and a brass washer to take the load (thrust, fnarr).

{{ http://fuddymuckers.co.uk/gallery/s/500/cnc/kt70_nuts.png }}

And here's what a real one looks like:

{{ http://fuddymuckers.co.uk/gallery/s/500/cnc/20190205_093935.jpg }}

Twiddling the motor revealed a lot of play in the Y-axis lead screw:

{{ http://fuddymuckers.co.uk/gallery/s/500/cnc/end_nut_play.png }}

So I tightened it up to take the play out. I also cleaned it up a bit while I was in there, and reversed the washer in the housing as the face was slightly worn by the nut.

{{ http://fuddymuckers.co.uk/gallery/s/500/cnc/20190205_111144.jpg }}

I'd say that's a lot better. Still not perfect, but a lot better. Certainly it'll do for now.

<WRAP center round alert 60%>
**WARNING**\\
I discovered later that over-tightening these nuts can lead to the thing binding up whilst working and ruining a work piece - the solution (other than care & lube) is to [[12-yo_dawg|mill new end pieces]] with actual ball-bearings in them.
</WRAP>


===== Yo Dawg, We Heard You Like Mills =====

This leads to one of the issues with tools like this - a great idea would be to mill some new end-plates that aren't plastic, and have a deeper pocket to hold an actual bearing. A bit like [[http://www.jarkman.co.uk/catalog/cnc/russmf70.htm|this guy did]], but of course that leads to taking the mill apart again...

So yeah - the problem with a mill or a lathe is you immediately think of ways to make it make better parts for itself and down the rabbit hole we go!

Edit: **[[12-yo_dawg|I gave in and did it]]** for various reasons.