wheel truing jig

This simple truing jig can be mounted to your frame with a zip-tie (I used the reusable kind to avoid having to cut it away in the end) 

To complete the jig you need: 
- M4 bolt of suffiscient length
- 2 x M4 nuts
- zip-tie for mounting to the frame
 

One of the M4 nuts just goes into the little slot on top of the print. Then you can put the bolt trough.
The tip part could be simply screwed onto the bolt in my print (it basically tapped itself). Depending on your tolerances you may need to widen the hole or use some glue to fix it in place. 

The second M4 nut isn't strictly needed but it can be used to fix the bolt in place.