I thought the hacksaw was the "crude" part, but sure you could use sanding paper. But it is very hard nylon, so you'll be at it for a while. The Dremel bit I used was also just sandpaper on a roll, but it went a lot quicker than manually grinding sand paper over the ring:

I managed to find a website that still had the 45x45° DEDA compression ring. When I compare it to the original Velobuild compression ring it looks very similar, but it is +/- 0,5cm higher. I will go for the sanding route with a bosch orbital sanding machine.
Did you manage to get a smooth, flat and parallel surface with the hacksaw and the dremel, because this seems nearly impossible to me?

[img]My problem seems to be that the height of the c-ring is too small. When I tighten the  top cap, the dust cap gets pressed down onto the head tube from my frame, and not onto the c-ring, which results in my handlebars getting stuck and unable to steer...
In order to fix this problem I ordered some microspacers to put onto the c-ring (see picture).
I had to cut the microspacers though, so they would fit the C-form from the C-ring.
This way I can tighten the top cap without the dust cover getting pressed down onto the top of the head tube.
I wonder if the problem lies with the C-ring (height too low), or the top bearing sitting too low into the head tube ...
Anyhow, I have a bad feeling about the (cut) microspacers and the c-ring, so I would rather have a new C-ring which requires no microspacers. Anyone now if the latest update for the C-ring changed anything on the dimension (height)? 

edit: another possible cause of the problem might be the dimensions of the bearings or maybe top and bottom bearing got switched? Anyone know if the top and bottom bearing have other dimensions and could be installed incorrectly (switched)?

OK, any way that I can report this to an admin to resolve this problem? There is not alot of information on this website on how to report problems. 

For some reason or another, the topic "VeloBuild Headset Play Issue Using Separate Stem/Handlebar: Resolved."  is corrupted.
From page 4 on it has become unreadable. Page 1 to 3 are still readable. What is also strange is that when you're not logged in, page 4 is still readable.
I also noted that it is possible to still add replies by reacting to messages from pages 1 to 3.

Who should I contact to resolve the problem?

I think you have the old C ring and could benefit from using the new one which has a smaller cut out and no tabs. If you email VB they should sort you out.

I received the microspacers today, so I dismantled my headset and it seems like I have the revised compression ring (without the tabs). I installed three microspacers and the problem is solved now. I have cut a piece from the microspacers so they fit on the compession ring.
So it seems that the problem is not resolved with the new compression ring. So my guess is that maybe the dimensions of the compression ring are not consistent, or the dimensions of the steerer tube are not consistent... Velobuild  really needs to do a thorough root cause analysis on this issue!!!

I am also suffering from the headset play issue and ordered 0.25mm microspacers, hoping this will resolve my problem. But because the c-ring has two tabs (see attached pictured), I wonder how this microspacers will fit onto them ? Do I need to drill two holes  in the microspacers in order to fit them onto the two tabs?