Half moon 1/4-20 clamp or draw bolt

Work in progress. Additional testing still needs to be done. I'll open up the license after some testing.

Update

Use the “short” version. It provides some much needed clearance.
 

Important Dimensions

• ¾" plywood (nominal)
• 1" hole 5/8" deep (minimum)
• ¼" cross drill (minimum)
• ¼"-20 Hardware 
• 100% infill prints under 15 minutes
• Add fully parametric .f3d model

Original
I designed this spacer to create a custom adjustable router template with flush top. It is a half moon so items can be clamped to T-Track.  It can also be used similarly to a countertop draw bolt. Just tighten the nut with a box wrench to clamp everything together. See examples below

¼"-20 is the standard hardware for T-track in the USA. I apologize for the messy mixture of imperial and metric dimensions but it really couldn't be helped. 

The eccentric center hole allows it to be used in a blind hole with ¾" (19.05mm) plywood. For best results, use a 1" Forstner bit with at least a 5/8" hole depth for this clamp. You may need to drill the hole slightly deeper depending on the hardware selected, not all nuts and washers will fit a 5/8" depth. Cross drill with ¼" drill bit (7mm could also work) at centerline. It is designed to be a little loose to allow for minor drilling misalignments. The 24mm diameter half moon will have 1.4mm clearance in the 1" (25.4mm) hole. The 7mm (0.275") through hole give clearance for ¼ bolts. It should also work for M6 hardware. 

No supports needed. Remember to use enough infill to get the best compressive strength. This is still a light duty part. Don't expect ¼-20 to be strong enough to hold a countertop together.


Example Router Jig and functionality
https://www.woodpeck.com/woodpeckers-variable-router-jig.html

Example Draw bolt

https://www.amazon.com/Rok-Hardware-Countertop-Connector-DRAW312BOLT/dp/B092CJTSGJ?th=1

Experimental notes to self:

Test out M6 Hardware to see if it is too loose. 

Test Cap Screws with ball end Allen wrench to see what other clearances are needed for faster operation

Test crushing of shorter version. 

Create 1 ½" and 2" versions.

Included an experimental 5/16-18 version for 5/16" Tbolts. It will require a through hole in ¾ ply due to the larger nut diameter. I doubt it has enough room to tighten the nut in a 1" hole. Adjust for actual plywood thickness instead of nominal