Broken #40 Countersink Cutter

[TJ_Slice]

Call me crazy, but I decided to stick with the kit and do rivnuts for the floor. While countersinking some of the holes, I broke off the nipple end of my #40 countersink cutter.

Has anyone else had this happen? It happened after I stopped countersinking, and wasn't paying attention when removing it from the hole. I must have torqued it a bit.

If it is something common, I'll order a couple of replacements, instead of just one.

[jaredyates]

It is really easy to break a drill bit in the smaller sizes. I have not broken the pilot off of a countersink yet. Are you using a cage on the countersink or just freehanding it?

[TJ_Slice]

I am using a cage. I'm sure the steel tabs are not easy on the cutters.

[David Swartzendruber]

I'm trying to think of why you would need to do any countersinking when installing a rivnut. Did you mean to say nutplate? I didn't realize you had to be crazy to install nutplates for the floorboards. That's what I did.

[TJ_Slice]

Yeah, I meant nutplate. I'm going to be glad I installed them when it's all said and done, but it's definitely not the easiest option.

[Bcone1381]

I think your countersinking for AN426AD3 rivets. They are the normal countersunk rivets. My build might have 1000 nut plates. 96 in each fuel tank alone. Save some energy and add a collection of NAS1097 rivets to your hardware inventory.

These countersunk rivets have a smaller head. I countersunk them with about 6 turns of a deburring tool because teh head is small so you dont go as deep. It allows you to countesin them into thinner material too becuase they are not as deep. All the rivets do is hold your nut plate. So strength of a normal rivet is overkill. You want NAS1097AD3-3, -3.5 and -4. Aircraft spruce is not carrying the AD3 size. Try Vans aircraft or Pegasus Auto racing.

[TJ_Slice]

Thanks, but too late. The replacement cutters showed up this morning, and I have spent the last couple of hours doing countersinks.