Hi Tom
Yes I did see your thead, I will post on there once I can make the pictures bigger. Reply on your thread but what lead/ballscrews are you using?. i think the main response to your question is power... Belt drive and rack & pinnion require high power motors and give a low resolution.

With regard to identifing the beam, mine was easy as the burnt out chair was next to it with Stanna written on it...........