13mm Bolt Head Knob

I made a six foot long marking gauge and used 8mm bolts to fix the 1/4" sliding rods (approx 500mm long). I threaded those bolts into the timber timber support rail and they didn't turn so easily. So I made a bolt head thumbwheel knurled knob thing to make it easier! ;)

Here 'tis. Made for metric bolts here in Australia. Printing with a scale factor I imagine you could make it fit practically any hex bolt head size.

Then again, it's not real hard to do the design but hopefully it saves you a bit of work.

I printed these knobs and with a gentle tap of a hammer the 13mm hex head bolt went went straight into the recess. I didn't have to mess about with additional clearances or scales or anything. I'm putting that down to luck, lack of shrinkage of print material, a smidge clearance in the design although I forget exactly what it was. I could open the design again but I'm doing something else and got sidetracked into uploading this thing!

Cheers.