Thank you, Bep and Gaieus. I hope my brother-in-law will adopt sketchup for his business. It would be a great design and sales tool for him. We shall see. Some day I may have a go at creating some geology-realistic rocks. When I do I'll put them out here for anyone to use.

thanks for this information

Just to conclude this thread or my contribution to it, my problem appeared to be related somehow to using SU through a Linux machine that is remotely controlling a Windows PC where the instance of SU is installed and running. Not sure I said that right, but you probably understand. The system we use to provide Windows on a Linux desktop is Citrix, which I understand is not really a Windows emulator but actually a remote control of the distant Windows pc. However I also understand the same sort of problems with exporting animations happens with the Windows emulator Wine (I think it's an emulator), as reported in the link a few posts above. If this thread would fit better somewhere other than Newbie, then feel free to refile it.

the only aspects of inferencing you can change/turn off are length and angle snapping. Length snapping snaps geometry to incremental units when you create it. Angle snapping snaps geometry to angular increments when you rotate it. Generally i find it easiest to turn length/angle snapping of and just type stuff in to the VCB when i need precision.

FYI, the suits were impressed--enough to purchase the Pro if we needed it. Funny though, I have now tested this by comparison and I was using the cut-down free version all the time (well, except for the first 8 trial days). I never noticed anything go away after the first 8 days so I assumed I was just living with Pro on borrowed time--that's a newbie for you! Anyway I'm concluding at this stage of our use that we can get along fine with the freebie version and wait to pick up Pro at a later date. Thank you all again for the help you gave me getting through this. We are taking the exported animation to a trade show next week, where I suspect it may draw some attention.