Nanoic

Thanks for the image reference, those sizes are indeed correct as I have no received a M10 and M12 wing nut, the 12mm fitting on the eyepiece holder at the end of the bolt.

Since I'm unsure I've ordered a M10 and M12 wing nut on ebay. I'll reply with an update when it arrives which should be 3-5 working days.

I'm looking to get a wing nut as I don't have a wheel nut to secure my eyepiece to the centre bolt that connects the HEQ5 to the tripod. What size is the part at the bottom that holds the eyepiece holder? I don't own measuring calipers, just a cheap ruler and it looks to be roughly 12mm. This is the thicker end at the bottom. This video timestamped at 4:02 shows the component that I am looking to replace with a wing nut. I've attached an image with the labelled end of the bolt. Thanks in advance!