AVOR – a steel-framed medium-size router

[Neale]

Just to give a better idea of what I was cutting, and why I thought that CNC would be a better way than milling manually...

This is the "finished item", as shown in Fusion 360. It's all now cut and waiting final assembly.

And this is an exploded view. Not quite as good a view as F360 only explodes "components" and some of my components actually consist of several pieces that are not separated here.


My technique varied slightly as I went along. I started with more-or-less rectangular tabs and slots, with fillets in the internal corners to soften the tool motion while cutting. The resulting corners needed relieving with small files before assembly. Eventually, I realised that I could machine appropriate clearance fillets, so tabs had small semi-circular cutouts at the base and slots were given semi-circular ends. In practice, with a structure like this it is only the flat faces of the tabs and slots which locate; the tabs can slide sideways a little as this position is actually constrained by the way that the pieces butt up against each other. You can see the different techniques in various places in the exploded view.

As ever, I don't recommend that you try to copy me too closely, but it's an indication of the art of the possible if you are both careful and lucky.

[Neale]

Another little sample item, cut with the router. Remember that the machine was designed and built for cutting wood, up to quarter-sheet size. This item is a prototype engraved master for a lapel badge for my local model engineering society. A member offered to lost-wax cast these provided that someone could make a master, and as the only one present with any kind of CNC capability, I was volunteered.

This was a first attempt to see if it was possible. The overall size is 20mmx10mm, and the engraving is about 0.75mm deep. Done with a 30deg included angle carbide V cutter. Although it looks a bit rough in the picture, remember just how small this is! The top surface of the engraving also looks a bit rough as it is the original surface of the drawn brass bar. I was only interested to see if I could achieve the detail needed in this test piece. I have recently completed a larger version, about 35x17mm, which is rather better, and where I have also skimmed the top surface to get a decent finish. The toolpath was generated by Vectric Vcarve, with the design traced from an original bitmap copy which needed a bit of manual clean-up.



The original investment in decent ballscrews and Hiwin rails was justified, I feel.