DIY Build of Aluminium CNC Wood Router without Workshop & Tools

[WandrinAndy]

As I've never made much of any mechanical rotating thingies before, the whole aspect of Timing Belts and Pulleys was a worry. But now that I've absorbed the relevant postings on the forum... particularly thanks to Jazz's pics... it seems quite simple.

I am again thinking of using RM1605 ballscrews for maximum possible resolution and torque and then gearing 2:1 to achieve "longer pitch" and speed. I understand this will increase load on, and reduce life of, certain components... but it somehow still gels better in my grey matter than doing it the other way around. Please persuade me if the other way is really the far better balanced solution... afraid I can't quite get my mind around that... yet?

On the X-axis will use 5mm pitch 15mm wide HTD Timing Belts and HTD5M-15 Timing Pulleys - 16T [o.d=28mm] and 32T [o.d=54mm] from http://www.beltingonline.com/5mm-htd-timing-belts-4575.

On the X-axis the Ballscrew pulleys will be 16T and Stepper pulleys swappable between 16T and 32T as a start :

- Stepper pulley bores modified to be 8mm and with 1 off M4 grubscrew hole
- Ballscrew pulley bores modified to be 10mm and with 1 off M4 grubscrew hole

Each idler will be made of two bearings 8mm i.d x 28mm o.d x 9mm wide from http://stores.ebay.co.uk/xtremesportandleisure-uk-online?_trksid=p4340.l2563 sandwiched between large washers serving as guides on each end.

Two quick questions please -

- Apart from asking Chai to machine F increased to say 30mm for coupling, does Chai grind the small flat on the shaft for the grub screw to grip and stop the pulley spinning or is that something I would have to do?
- Are M4 grubscrews about the right size for 8-10mm diameter shafts?

The costs are mounting... but after my massive shock at the cost of profile-rails and bearing-blocks, these components seem comparatively cheap!

Thanks,
Andy