Steve from the Nova Labs CNC shop asked me to make a pair of wrenches that could be used with a torque wrench to properly tighten ER collets: an ER25 hex wrench and an ER20 notched (spanner) wrench. The shop's existing wrenches didn't have a torque-wrench-compatible drive, so collets were being snugged down by feel rather than to spec — not great when you want repeatable clamping force on tooling.
Steve sent over a DXF to start from. I brought it into Fusion and beefed up the geometry in a few spots that looked underbuilt, laser-cut a prototype from thin scrap to check the collet/tool engagement, and later 3D-printed a second prototype once I was more confident in the final dimensions.
Before committing to material, I had an agent run a strain analysis on the design at the target torque (roughly 77 ft-lb — I believe that's the ER20 spec, though I'm not entirely certain) to make sure the thinner sections wouldn't yield or flex enough to throw off the actual clamping torque. That analysis is what drove a couple of the geometry changes.
Final parts are 17-4 PH stainless, laser-cut to shape on my fiber laser.
They're surface-ground before and after heat treatment (mostly for appearance), and heat-treated to the H900 condition for strength.
I laser-engraved the tool type on each wrench with my smaller galvo fiber laser and filled the engraving with orange nail polish — orange being Nova Labs' color.
Here's a short video of the galvo laser engraving the ER20 wrench.
Wrenches are done and headed to Nova Labs.
