Years and years back as a young apprentice I really wanted to convert a manual bp to cnc. At the time I ended up going down the boring proprietary cnc route as the commercial work I picked up favoured more rigid purpose built cnc machines.

Anyway, I'm thinking about the old ideas again. My plan was to put the knuckle and swivel joint in the head to cnc control.

I devised a means of using tapered shaft bearings with large diameter thrust bearings to maintain a reasonable amount of rigidity. According to the bearing specs it would have been ok for about 80% of what the machine could have thrown at it.

Where I ran into a bit of a quandary was with antibacklash gearing. At the time (2002 ish) I couldn't find an antibacklash worm gear. I know some cnc tables use a direct acting toothed belt, but with the out of balance weight of the head that's kind of an accident waiting to happen. Yes I have previously encountered a Bridgeport without the worm screws fitted.

I'm wondering how things have moved on since then or if there's any other solutions that I've missed.

The projects I have in mind for this machine if I built it would be for machining lightweight low volume motorsport components. In particular I'd like to have a crack at machining single piece brake calipers and also structural dry sump conversions for mid engined cars. It would also be nice to hang engine blocks off the side of the table and swing the head over accordingly.

Machine would predominantly be used on aluminum and priority would be the ability to complete the tasks rather than ripping material off quickly. I've got no tolerances tighter than 0.05mm in mind.

Thanks in advance.

Greg