Hi Andy,
I had a link bookmarked with the part number for a car brake disk that could be adapted into a pier mount for the HEQ5. I can't find it at the moment, but will have a look when I get a chance.
In the meantime, Morten Frosth in Sweden used the same idea when he built his observatory. You can find all the details in his YouTube playlist:
https://www.youtube.com/playlist?lis...UQTFGzFSXjn9KQ
The pier adapter construction takes place in part 2.
Cheers,
V.