Wobblycogs CNC Mk1

[WandrinAndy]

What I'm struggling with now though is how to mount the SBR20 to the extrusion. In the image above I've centred the rail but it doesn't matter where I put it the rail lines up really poorly with the extrusion. Has anyone managed to find a good solution to this?

I followed a similar thought process Wobbly... I've seen folk suggest bolting thick flat bar to the extrusion and then in turn attaching the SBR20 to the flat bar, but IMO that partly negates one of the main benefits of using extrusion... relative ease of assembly.
Also just a quick caveat that the SketchUp 45x90 component... certainly if you are using one of mine, sorry... may not necessarily be accurate enough for this kind of accurate line-up exercise.

I'm so tempted to just give up and use profiled rails but the extra cost is off putting to say the least.

Agree, the costs are horrendous. Although it looks like Zapp is now also offering, in addition to the Hiwin range, a value for money range of linear precision profile stuff.... LSK or summat, that I think is about 25% cheaper than Hiwin?

I'm finding that there are sooooo many tradeoffs in any DIY CNC design.... That it's worthwhile setting aside plenty more time than initially anticipated :-)