KC3KNM

I’ve got a build thread going on TRF, so I figured it’d be easiest to copy and paste:

After getting my L1 back in June, I’ve been excited to start on my L2 build. I’ve decided to go with the Madcow Level-2.

The motor mount is going to be a little… different. I abhor aligning fins and don’t love making internal fillets. To get around this I’ve 3D printed an insert that the fins epoxy into. While it does add weight, it should make the entire assembly very rigid. It’s been printed with CF PLA @ 10% infill. The fins will be epoxied into the slots which I think will provide a very rigid bond when everything is sandwiched together.

I did have an issue with delamination on the lower end. The rest of the print seems to have worked out well, so I cut the problem area off, sanded square and laser cut a cap for it. As it was a 12hr print, I’d like to avoid going through that again. The issue was localized to that area as the rest of the print is rigid. I’ll keep an on eye on later prints and likely bump up my hotend temp (already at 230*C, so I’m not sure that was the cause), but in the end it’s more of an irritant than a real issue.

I’ve laser cut some spacers to allow the entire assembly to butt up to the Aero Pack retainer as well as some doublers for the stock centering rings. I’d like to fly this on larger motors later on, so the idea is to spread out the force instead of localizing it to the stock two centering rings. I’m not a mechanical engineer, but I’ve done something similar with a 3D printed mount on my IRIS and that’s stood up to an H550 very well with no signs of fatigue.

I wanted to provide a point to install my rail buttons to further up as well as provide a little support for the motor tube, so I’ve come up with this. It’s very rigid and should work well. I forgot to grab a picture after assembling it, but you can see it it glued up on the motor mount assembly photo.

This is where I’m at now. Waiting on some epoxy to cure before giving a good sanding and installing into the body tube. I’ll get a final weight of the assembly before install. I think it should provide a very solid mount, make the fins a breeze to install and hold up to some pretty large motors. We’ll see how that goes.

While the motor mount assembly was curing, I got around to cleaning up the slots in the body tube. They were too small and a little jagged. Took a rotary tool with a grinding stone and widened them a bit. They don’t need to be perfect as they’ll be filled in when I make my fillets on the fins, but at least the fins fit through them now.

Next I drilled the holes for the launch buttons. I just found the center between two fin slots, drew three dots along that line and used that to square a metal ruler to. Drilled the holes to match up with my mount.

Finally, I glued in the motor mount assembly. I first laid down a ring of epoxy where the shock cord mount ring was going to fall. I bought a telescoping magnet tool at Walmart and cut the end off. Replaced it with a 3D printed part that fits these makeup applicators I found on Amazon. They work really well when you need to apply small amounts of epoxy and with the telescoping handle it makes it super easy to lay fillets on rings down in tubes or to apply adhesive in hard to reach places without making a mess. Coated the bottom half of the mount in epoxy and slid it into the tube. After it was aligned I cleaned up the epoxy behind the mount. Finished by adding an epoxy fillet on the top of the shock cord mount.

Quick test fit of the fins… I’m really happy with this. Working on shaping them next.