Hi Mactec,

Thank you for your input.

I am currently trying to source the various components for this build; so far I have managed to pick up some brand new THK SHS45's with extra long carriages and the highest pre-load available that were originally destined for a DMG Mori mold making machine - surplus stock found on ebay. These will be used for my Z axis, I have also just bought a ballscrew from ebay that will be used on the Z axis; this is a 38mm diameter with 10mm lead. I don't know the accuracy grade, but the threads are ground and I am informed that it has come from a grinding machine, so am hopeful it will be reasonable. It also comes with bearings for end support. I am awaiting delivery of this. I was originally looking at 32mm diameter 10mm pitch ballscrews for the other axes but critical speed calculations appear to greatly limit the potential travel speed for such screws, so I am looking at larger diameter and pitch. I missed out on a 3820 screw for the bridge axis recently which is unfortunate, but I did notice that a picture of the nut appeared to show an oil line crimped off, so it may have been starved of oil. Unfortunately, I am not having much luck finding the longer linear rails that I need for the other two axes, and I am now leaning towards 45's for these as well. I did make an offer on some from Korea, but the shipping is prohibitively expensive it seems. I will keep looking for the time being, as I have other things to arrange, but may have to consider companies in the UK or cheaper rails from china until I can justify the expense of upgrading them. I'll take a look at TBI - do they sell directly?

In terms of the motors, I am considering the CTB servos used by badhabit in his excellent epoxy granite mill build here on the forum. He posted a manual of these servos in his thread which appears to be written in good quality English, and they are significantly cheaper than DMM and offer more power options - I was considering the 2.2kw motors (which happen to be the same power as those used by badhabit). I note that the delta servos only go up to 1.5kw in single phase (they do offer larger but I understand these are three phase). I intend to ask badhabit about his experience with these servos and whether they have any auto-tuning software but just haven't got around to it yet.

I hope to post an update soon regarding the next stage of this build concerning my approach to flattening the rail mounting surfaces, as I have some ideas for a slightly unusual approach.

Mike