How to fix a loose blind nut?

I'm in the process of finishing a Lazy Bee fuselage. I was bolting on the
engine mount after covering when one of the blind nuts popped loose. The
Bee is a real PITA when it comes to working inside the fuselage, and there's
no way I can get my hands inside. The blind nut has something inside that
makes turning the mounting bolt difficult. Any suggestions?
Thanks in advance,
Morris
Reply to
Morris Lee
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Try this...stand the Bee on its nose and carefully drop medium CA 'bombs' trying to hit the edges of the blind nut. If successful then carefully run a tap through the threads to clean up the obstruction.
Failing that, push the defective blind nut back and shake it out of the fuse. Run a string through the hole and use it to fish a new one into place.
Good luck !
Reply to
John Bonnett
On 8/12/2004 10:27 AM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:
Replace the blind nut with a new one. If you think the blind nut has stripped out the wood, check your local hardware store for blind nuts. The ones they have USUALLY have a substantially larger back (head ? ) to them so they will bite into fresh wood.
For installing the blind nut in a PITA location I do the following:
Insert a Vaseline coated bolt into the blind nut. The bend a piece of 1/32 or 1/16" wire to get to the underside (back) of the area then use a drop of thin CA to attach it to the back of the blind nut. Remove the Vaseline coated bolt. Use a LONG bolt with an OVERSIZE washer and thread the bolt through the hole and into the blind nut and tighten the bolt down to pull the blind nut into the wood. Then pop the wire off. If you can get to the back side of the blind nut, (I use a long piece of capillary tubing for this) reinsert the Vaseline coated bolt, then put some thin CA on the back side of the nut to "lock" it in place. The Vaseline prevents any CA from getting into the threads.
Hope this solves the problem.
Reply to
Ted Campanelli
Read more model magazines!
This has to be one of the most-repeated tips after the clothespin modifications.
What all of the tips have in common is fishing something through the firewall from the front (wire, nyrods, cable, weed-whacker string, etc), sliding the new blind nut on, then attaching some big thingy behind the blind nut and hauling it back through the fuselage to the firewall where, if your snake is strong enough, you can pull it far enough into the old hole to thread a bolt into it and snug it up.
If you're brave and have confidence in your snake, you can slather epoxy on the outside of the T-nut after protecting the threads with vaseline or some other grease.
I'm not good with T-nuts, so I go easy on the outside glue myself, but it does seem like a reasonable step to take to make sure that the thing stays put when you're done with the process.
Here's a shortcut I haven't seen or used myself, but I think it is worth considering: cut a hole in the firewall, centered between the mounting holes and large enough for you to get a finger in to help set the T-nut and get it threaded straight. Especially with a Bee, you don't need a solid firewall to keep the engine on the aircraft. Some big honking gasoline engines need a hole cut behind them through the firewall in order to clear their carbs, so the loss of some material from the center doesn't seem to be a big issue.
If you're anxious about the hole, cover it with some balsa or lite ply when you're done.
Some of the pattern guys use 1/8" aircraft ply for firewalls instead of 1/4". They mount YS engines to them, too. I haven't tried that myself, but I am convinced that a lot of our firewalls are overbuilt for the real needs of the airframes.
When you make a decision, let us know how it turned out!
Marty
Reply to
Martin X. Moleski, SJ
If you are concerned about the firewall, consider drilling it out and plugging it with a much larger dowel, using epoxy to glue the dowel in. Then redrill the hole for the engine mount.
To replace the blind nut, try this. Get a piece of Sullivan (or other) pushrod CABLE. Feed it through the engine mount hole, back through the fuse. Place a blind nut over the cable. Put a wheel collar, behind the blind nut, on the cable and tighten it down. Now pull the cable until the blindnut starts into the wood. Push the cable back into the fuse. Remove the wheel collar and the cable. Put a bolt with a large washer on the engine mount bolt and tighten, thus seating the blind nut. Remove the bolt.
Your plane has a light firewall, so don't pull too hard on the cable. It might take two or three attempts, but, this method takes the frustration out of replacing blind nuts.
Reply to
J_R
This has worked for me...
Push the old nut out... Push an appropriately sized of weedwhacker line thru the firewall from the front and thread a new blind nut onto it. Wet the flange of the nut with thick CA and pull into place... Let the CA kick and unthread the line...
Bill
Reply to
Bill Fulmer
Thanks to all for your suggestions! I got a bolt in far enough to get it pulled back flush against the firewall and then managed to dribble enough CA around the edge to hopefully get it stuck back. Again, I really appreciate the advice!
Morris
Reply to
Morris Lee
Advice 'r' Us. ;o)
Thanks for letting us know how it all turned out.
Marty
Reply to
Martin X. Moleski, SJ

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