Door Sill Question

[Allen B]

Hello. I had a question regarding what others have done with fabricating supports for the main door window sill brackets. It seems like I have more than enough room for to create a support for the aft section of the former but the forward section is really tight with my build. There’s room for about a 1/2” bracket between the tab and the edge of the former. Is that sufficient space? I worry the bracket wouldn’t be very strong. Are people grinding the tab down to make room for a bracket? Lastly, I wonder about making a 2” wide bracket that sits underneath the tab and spans the entire distance.

Thanks in advance for any suggestions.

Allen

[Bcone1381]

My sense from your photo....

Don't grind down the nut plate tab. The bracket you made looks sturdy to me. The Bracket will put a shear load on each rivet that secure it in place. If its secured with 3 rivets, and if you calculate the shear strength of those 3 rivets you will have confidence in them. I bet its over 300 pounds shear strength. A triangular sheet could be added to tie in your bracket to the back two tabs, but I don't think you need it, as the the aluminum sill on my Patrol kit (2017 era) was plenty strong.

[Allen B]

Thank you for the reply. I feel confident about the aft section (the picture with the angle bent). My concern is the other picture. The forward attachment bracket. It seems like there’s not much room to attach anything without grinding down the 4130 tab. I can make a 1/2” wide bracket but that’s about it without removing metal and it doesn’t seem like that’s a sturdy solution.

[Allen B]

I suppose I forgot to mention. The material for the brackets is .050 2024 t3. Seems pretty tough to me.

[Astro John]

I ground off a corner of the tab and also made the bracket out of .050 aluminum. Without the bracket, the sill would flex just a tiny bit. It is very rigid with the bracket installed.

It is very similar to the older text manual/images on the Bearhawk website manual page, although mine has a tad more space between the tab and the bracket I made. Image #20 shows it.

https://drive.google.com/drive/folders/1IACnhKqTjuCIDamayCq9g-01WKVKWCPD

[Allen B]

Ok! I figured someone had ground it down. Thanks for the response. Any idea (roughly) the width of the front bracket?

[Astro John]

I can measure it when I get home later today. It's something like 3/8 at the tip and tapers to about 5/8 or 3/4. I 3D printed a small jig to trace out on the .050 aluminum.

[Allen B]

No need. Thanks. That seems to pass the sniff test with what I was thinking.

[FFTravism]

Here is what I did.


image.png

[Allen B]

Sounds like the consensus is to grind down the corners. Thanks everyone for the advice.