Drill bit size?

s10sakota · Post by **s10sakota** » Sun Jun 17, 2012 6:16 am

Would someone please tell me what size drill bit to use for a #6 bolt?

I'm drilling the holes in the spar flange for the W-822 access plate.

Thank you!

Post by **bullojm1** » Sun Jun 17, 2012 7:10 am

Mark,

a #27 drill bit us used for a #6 screw. As always, test drill on a piece of scrap aluminum before you do it on the real thing! I had a really nice drill bit index guide I used to build my RV, but I can't find it anywhere. If I run across it, I will post it.

s10sakota · Post by **s10sakota** » Sun Jun 17, 2012 7:54 am

Thanks Mike.

Follow up question...

The instruction (I mean Vans brief almost worthless) manual says to countersink the holes in the spar for the inspection plates with a #40 counter sink bit.

But if I drill the hole first with a #27 bit so that I can fit a #6 screw through it, the #40 countersink bit will wiggle around in the hole when I try to countersink it. I tried this in a scrap piece and it came out terrible.

I could use some instruction here!

Thanks again.

lancef53 · Post by **lancef53** » Sun Jun 17, 2012 6:07 pm

If you have the larger bore countersink, you can just set it shallow, so it matches the -3 head. Otherwise, you will need to countersink starting with a 40 hole and step drill it to 27.

If you are installing a screw into the countersink, why a 40? Shouldn't it be for the #6 screw? Are you dimpling the access plate for the #6?

Post by **bullojm1** » Sun Jun 17, 2012 6:14 pm

Mark,

I believe the #40 countersink bit fits in the #6 nutplate and acts as a guide, from my recollection.

Here is a log entry for how I did it:
http://www.rvplane.com/?categoryid=3&dayid=146

Also, when you countersink, I got the best results by using an electric/battery drill on a very slow speed. The high speed air drill leads to a lot of chatter.

Best of luck!