Squeezing struts

[Pbruce]

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Hey guys, I’m struggling with squeezing strut ends to accept fittings. Trying to get this done so I can get out of a borrowed hangar and back into my garage.

Here’s what “Tips” says about squeezing the strut ends: “Make up a spacer that’s about 3/16” thinner than the fittings and insert inside the strut while squeezing. This is to make sure the flat surfaces inside the strut remain parallel. Just tighten the vice until the opening is a little too small to let the fitting slide in. Release the pressure on the vice and see how much the strut springs back by sliding the fitting in. Keep repeating that process until, with no pressure on the vice, the fittings slide in with a snug fit.” image_9191.jpg

I’m just starting to squeeze, following this instruction to the letter. But as I squeeze tight enough to get close to the oak spacer block, the trailing part of the strut compresses more easily than the leading part. I’m afraid to go further, since it’s noted that you need to keep the flat sides parallel when squeezing, but that is not happening.

Seeking assistance. Thanks in advance. Picture attached. Hard to see but the gap along the right side of the spacer block is almost twice as wide at the bottom as it is on the top. It goes away when releasing the vice, as I haven’t squeezed it hard enough to affect permanent change.

[davzLSA]

Im not saying to do this but I talked to a guy who did and his airplane is now flying and he has had no problems with it. But what he did was milled the thickness of the strut fitting down about 1/8 of and inch. He said they slid into the struts with no problems and he did not have to squeeze the strut in a vice.

[Pbruce]

Ok thanks Dave. My strut fittings are already narrow. I ended up making blocks of progressively less thickness and then squeezing the strut onto them in succession. It has worked. Doing it all in one go might have worked too, but I wasn’t confident.

I’m planning on squeezing the bottom of the struts, but shimming the top in order to lessen the possibility of the aileron cable contacting the strut. Looks like it takes a bit more than 1/8” to fill the gap between the fitting and the strut. I wonder why they just didn’t make the fitting the same thickness as the inside of the strut. Maybe the bar stock they mill it from isnt available in that size.

[Utah-Jay]

Is this a QB kit? Do QB’s need this process?

[zkelley2]

Just get some shims that are the same size as the fitting, shim as needed. I think I used .100. No reason to potentially destroy or weaken a strut.

[Rollie]

I'm pretty sure you don't need to do this on the newer kits, I believe it was about two or three years ago that the factory started providing finished struts, along with the wings drilled to the fuselage and some other nice improvements

[Pbruce]

Yes to both. Although I suspect you could do the job with shims top and bottom to make up the extra depth between the inside walls of the strut extrusion and the machined end fitting. Honestly, squeezing the strut end turned out to be no problem. I had just kind of convinced myself it wasn’t working. It probably took me all of ten minutes to do the second one. Easy.

Any time you squeeze that extrusion, the flat parts of the inner walls seem to flex in more toward the trailing part, (the thin part of the teardrop. They tend to get more parallel when you place a proper sized hardwood block (1/4” thinner than the fitting) inside the extrusion and then squeeze hard.

[Mark Goldberg]

Make sure you squeeze about 1 ft of the strut end. Not just the very end. Wood blocks on both sides to not scratch up the strut. This has been done by hundreds of builders successfully. You should be fine. I have never used something in the middle of the strut. I just squeeze and release until it is a decent fit with the wing strut end. Better to sneak up to what you need rather than over squeeze it. Mark

[Pbruce]

Tips said to do 4”. Since mine were done when I saw your post, I went back and squeezed another 4” while the fittings were bolted in for a total of 8” I will be taking them apart for cleaning, final de-burring, and corrosion priming. I’ll give them another squeeze at that time if the fit isn’t quite tight. I used shims at the top of the strut instead of squeezing to provide more clearance for the aileron cable.

[svyolo]

I just used a bench vise with new aluminum angles on the jaws so I didn't scratch the struts. I squeezed down to the actual fitting, slid the fitting out, and slowly squeezed a bit more, and released, until the fitting was snug. Easy to do on a vise as you can visually see how much more to rotate every try.

Support the strut so it stays in place as you release pressure.