u/Wash_is_my_copilot

Hey folks, I’m seeking help with making a triangle pattern grid for kumiko. When making the notches for the grid pieces, I’m doing something wrong that is compounding. By the time I get to the end of longer pieces, they’re no longer close to matching up. I’m hoping for suggestions or solutions if anyone else has had this problem.

Pics:
- How it starts
- How it ends
- A previous piece I made where I didn’t have this problem.

Considerations:
- Im using a 30/60 degree sled with an adjustable key. Specifically Johnny Tromboukis’ design. (https://jtwood.works/products/jt-woodworks-kumiko-sled?variant=50441711550767)
- I’ve added a second miter runner to eliminate any side to side movement.
- Working with poplar.

The best explanation I can think of is I’m making slight bends in the strips as I put them on the registration key, and the variation is adding up over time. If that’s the case, though, I have no idea how to fix it.

Posting in case anyone else has experienced this and having suggestions. Short version: I'm unable to get my Kuna to fire with the Nexus lower installed, and it looks like the top of the hammer is hitting the buffer spring before the face makes contact with the firing pin. I'd welcome any suggestions or troubleshooting help.

Possibly relevant information:

- The Kuna fired fine ~200 rounds with the factory lower.

- When attempting to fire with the Neux installed, there's no visible mark on primers from the firing pin.

- There's visible wear on the top of the hammer. No visible wear on the hammer face.

- I've tried every variation of Rise Rave 140 trigger, TriggerTech AR 15 two-stage trigger, HBI buffer, factory buffer, HBI heavier spring, and factory spring. 

- Using a marker on the top of the hammer, all variations showed the same wear on top with factory buffer and spring showing the smallest wear mark. You can see this, and where I used a black marker for troubleshooting, in the pictures.

- Additionally, there's wear on Nexus lower, on the wall between the trigger well and magwell, with the wear on the trigger side. I can't tell if that's from the trigger or the bolt carrier hitting it.

I saw in another thread where someone had a similar issue and ground down the top of the hammer. Before trying something irreversible, I wanted to see if anyone else had solved this problem a different way.

I think the hammer is hitting the buffer spring is the most likely cause due to the wear on the top of the hammer (and nowhere else). That implies to me the top of the hammer is the only point making contact when the trigger is pulled.

The dark mark on the hammer is where I used a marker when troubleshooting. You can see the bright spot where the marker was rubbed off.

(Edited to add more info)