Securing that famous cluster

[mhorowit]

It's time to begin seriously thinking about how I'll immobilize that rotten cluster before I cut it out. Following VB's suggestion, I'll clamp all the tubing against a piece of plywood (actually, three pieces, since the cluster is in 3 planes).

Has anyone use plumber's metal strapping to hold tubing to the plywood?
If so, did you find simply laying a piece across the tubing and screwing down the ends was sufficient or did you find yourself wrapping the strapping around the tubing first? Or, making the equivalent of an adel clamp? - Mike

[N96337]

Re: Securing that famous cluster

Mike, I've used it and it works great! Usually when I have something like that to try to immobilize, I'l get the plywood up there, then take strips of wood or plywood and lay them along side the tubes on both sides, then use the plumber's strap to hold it in the "fixture". Gives it a bit more stability. Sheetrock screws are your friend!
JH

[NY86]

Re: Securing that famous cluster

...actually, three pieces, since the cluster is in 3 planes.

Suddenly I understand why Mike is asking so many questions. Mike, if you concentrated on fixing one plane at a time you'd probably be flying something a lot quicker!

[NC22211]

Re: Securing that famous cluster

Mike: When I've done fuselage tubing repairs, I have taken a block of poplar or other hardwood, drilled a hole thru it the size of the tubing I need to secure, or a hole just a little larger. Saw the wood thru the hole, slightly off-center, and cut the shoulders flat so the block of wood slides pretty tightly over the tubing, pressing it firmly to the plywood backer board. You'll have to putz around a bit with the block's legs to get a close tolerance fit between the block and the plywood. Screw it in place and the tubing is not going to move a bit when you cut out the bad stuff. I use hardwood and pre-drill the fastening holes. Pine 2x4's are handy, but they don't hold up. Make up a bunch of these clamping blocks and fasten them all around the plywood former. If your plane has had prior damage and you start cutting away some tubing, you'll be amazed at how much it tries to "walk around".

Now, this may be far from what you're talking about, but it may help you anyway. Bob Coolbaugh

[mhorowit]

Re: Securing that famous cluster

Mike: When I've done fuselage tubing repairs, I have taken a block of poplar or other hardwood, drilled a hole thru it the size of the tubing I need to secure, or a hole just a little larger. Saw the wood thru the hole, slightly off-center, and cut the shoulders flat so the block of wood slides pretty tightly over the tubing, pressing it firmly to the plywood backer board. You'll have to putz around a bit with the block's legs to get a close tolerance fit between the block and the plywood. Screw it in place and the tubing is not going to move a bit when you cut out the bad stuff. I use hardwood and pre-drill the fastening holes. Pine 2x4's are handy, but they don't hold up. Make up a bunch of these clamping blocks and fasten them all around the plywood former. If your plane has had prior damage and you start cutting away some tubing, you'll be amazed at how much it tries to "walk around".

Now, this may be far from what you're talking about, but it may help you anyway. Bob Coolbaugh

Hi Bob - That's my favorite technique; however, I'm trying quick and dirty.
I'd tried the plumber's strapping this afternoon and it seems to work well. By the way, if you don't have access to a band saw, you can do the same with two pieces of square hardwood trim. I sandwich a layer of masking tape between the two pieces, clamp them together, drill the hole (along the seam), and when I remove the masking tape, the hole is slightly smaller - making a tighter fit - Mike

[jdoran]

Re: Securing that famous cluster

Mike,

Why not just buy a dozen u-bolts at the hardware store?

Put them around the tubing and thru the plywood and tighten them up.

Mcmaster Crr has any size you would want.

[mhorowit]

Re: Securing that famous cluster

Mike,

Why not just buy a dozen u-bolts at the hardware store?

Put them around the tubing and thru the plywood and tighten them up.

Mcmaster Crr has any size you would want.

That's a great idea; just need to be aware that blocks give some protection against rotating along the plane of the plywood, but a U bolt won't unless you really crank it down; then you need to be concerned about scaring the tubing. - Mike

[NY86]

Re: Securing that famous cluster

Get some blocks of wood and drill then the size of the tubing. Cut then lengthwise with a band saw and clamp then around the tubes and to the plywood.