How close is too close with close tolerance bolts

BGordon · #1 04-18-2012, 06:54 PM

Good evening everyone,
I was working on my f104 bulkhead for my 7 and when I inserted the close tolerance bolts they were tight. Tight enough that it is going to take a mallet to insert them all the way, and after I install the wings to drill the rear spar and the mount coming off of the fuel tank it is going to require a mallet and probably a punch to get them out.
Is this normal? I know I am not supposed to ream or drill but I was wondering if others had this problem before I contact Vans.
thanks,
Brandon

bkthomps · #2 04-18-2012, 06:54 PM

so close that some people freeze them and then heat the holes before inserting them

Kyle Boatright · #3 04-18-2012, 07:06 PM

Don't use your close tolerance bolts for fit-up. Use hardware store stuff and only use the close tolerance bolts for final assembly. You may have to use a mallet then...

roee · #4 04-18-2012, 07:18 PM

Do not enlarge the holes. And do not use the close tolerance bolts for initial fitting. You will use those only once, to put the wings on for the final time, and they will hopefully never need to come out. And yes, you will need to lubricate, freeze, and tap the bolts in with a mallet. It's an interference fit, meaning that the hole is actually slightly smaller than the bolt, and it is supposed to be that way by design.

For initial fitting, use regular bolts that will slip fit into the holes (SAE or hardware store bolts are fine).

I believe this, and the whole wing fitting process, is described in detail in the builders manual. This is a critical area that you really don't want to screw up. So be sure to read up, ask questions as needed, and understand the process fully before you do it.

SteinAir · #5 04-18-2012, 09:18 PM

As others have said, you'll need to buy a second set, because you shouldn't use them for fitting....get some cheapo hardware store bolts and sand down a bullet on the nose and also to get rid of the sharp threads. When you finally put them in, a rivet gun is way quicker than a mallet!

Cheers,
Stein

frazitl · #6 04-18-2012, 09:44 PM

when you're ready to drill your rear spars. Our club has a special tool for rent that does a great job at drilling a quality hole for the rear spar attach bolt...

http://www.vansairforce.com/communit...ad.php?t=74770

Andrew M · #7 04-19-2012, 02:08 AM

AC 43-13.2B para 7-39 has some guidance.

Rupester · #8 04-19-2012, 09:46 PM

...go in even easier of you chuck them in a drill press and polish/sand with emery cloth. Then they work really easily for temporary locator bolts. that way you reduce the risk of galling the holes in the center section or wing spar.

Walt · #9 04-20-2012, 07:41 AM

Quote:

Originally Posted by Rupester

...go in even easier of you chuck them in a drill press and polish/sand with emery cloth. Then they work really easily for temporary locator bolts. that way you reduce the risk of galling the holes in the center section or wing spar.

I go one step further and grind the threads off to make "bullets" out of them. That way you will not damage the holes with the treads.