Flyin'Bryan

Flyin'Bryan

Well Known Member
I have a series of 3 pics to share that show the assembly of my forward spar halves to the HS810 and HS814 support angles. I used my pneumatic squeezer to dimple the holes in the flange of the forward spar per the plans, and I counter sunk the angles per the plans as well. I am concerned about the less than desireable fit that I am seeing between the HS 810 angle and the forward spar flange when I cleco everything together. Can anyone tell me if this is normal, or do I need to do something to correct this obvious bulging problem before I prime and start riveting everything together?

I have already tried countersinking the angle just a small bit more to try to allow the dimple to seat better, but its not quite working out the way that I want it to, and I am afraid to drill out any more material from the angles. Any info is appreciated.

Pic 1 - Assembled
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PIc 2 - Close up with the clamps squeezing things together
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Pic 3 - Clamps off - only the clecos are holding the assembly, and gap is noticably larger..
otj2hv.jpg
 
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I had some trouble too with judging the depth of counter sinking to take dimpled components. Try making a small "dimple template ie a small piece of metal say no more than 2" by 2", same thickness as the spar, drill and dimple it and locate its dimple it in the countersunk hole. Can you "rock" it with your fingers? Its quite easy to feel. If the template rocks then the countersink isn't quite deep enough.

Hope that helps,

Chris
 
Bryan, I had this same issue on the VS spar. Looked very similar to your pics. I drilled out all the rivets, countersunk just a bit more and riveted again. Turned out much better the second time. Also, I've heard some say you can't overdimple, but with the pneumatic squeezer I'm not so sure. I completed the same step you're on about a month ago. I did back the squeezer off just a bit and my spar seems to fit better in the 810/814. Good luck with your build.

Skyking90200
RV8
Emp.
 
skyking902001 said:
Also, I've heard some say you can't overdimple, but with the pneumatic squeezer I'm not so sure.
Skyking90200
RV8
Emp.
Click to expand...

You are the second one to caution me about this - will certainly take the advice! I followed the instructions for setting the dies, which said to tighten the dies up to the point where they still turn but are snug. Seems to work OK on the 3/32 dimples, but the 1/8 inch dies sure made a large dimple. And yes, before anyone else asks, I am sure that I used the correct size dimple die. Is it possible or even wise to back rivet the dimple out of the metal and redimple it again, or might this weaken or distort the metal too much? With recent talk about tails falling off of airplanes, I want to be cautious about this.
 
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Danny7 said:
is there a cleco missing? I mean is there a hole there without a cleco?
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Danny, yes, left the cleco for the next hole in the series off, so that I could "simulate" setting the rivet by using the clamps. the problem area is isolated to the hole with the dimple and the countersink.
 
chris mitchell said:
Try making a small "dimple template ie a small piece of metal say no more than 2" by 2", same thickness as the spar, drill and dimple it and locate its dimple it in the countersunk hole. Can you "rock" it with your fingers? Its quite easy to feel. If the template rocks then the countersink isn't quite deep enough.

Hope that helps,

Chris
Click to expand...

Chris, awesome idea! I guess I should also head off to HD to get some thick angle as well. I had been almost religious about testing things on scrap before doing the real thing, but I did not have any thick angle scrap laying around at the time, and so I went ahead and just sqeezed it. I did manage to get the countersink dialed in to the point that the rivet would sit absolutely flush inside the countersunk hole of the angle, but obviously that was not good enough for the dimple, so that's when I stared going a bit deeper.
 
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Flyin'Bryan said:
Chris, awesome idea! I guess I should also head off to HD to get some thick angle as well. I had been almost religious about testing things on scrap before doing the real thing, but I did not have any thick angle scrap laying around at the time, and so I went ahead and just sqeezed it. I did manage to get the countersink dialed in to the point that the rivet would sit absolutely flush inside the countersunk hole of the angle, but obviously that was not good enough for the dimple, so that's when I stared going a bit deeper.
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nothing wrong with using HD angle for experiments, just remember you will use angle for mounting brackets all over the place and while mounting something isn't very highly stressed, the angle you get from HD or other places might not be structural. look for a radius on the inside corner. I have a piece of angle i got for a home project from lowes and it has no radius.

do not un-dimple a piece and then re-dimple it. that is asking for stress cracks
 
OK. I have nixed the re-dimple idea from existence. I have countersunk the angle a little bit more, and this seems to be taking care of the problem. Also looks to me like I still have sufficient material thickness in the angle for the rivet shaft. One more click on the microstop and I think everything will be sitting flush.

Yes, HD angle would only be for testing - never on the airplane. Perhaps I can order another set of HS810 and HS814 angles from Vans - never too late to start a spare parts inventory! Although these are a couple of parts that I hope that I never have to replace.:)
 
skyking902001 said:
Also, I've heard some say you can't overdimple, but with the pneumatic squeezer I'm not so sure. I completed the same step you're on about a month ago. I did back the squeezer off just a bit and my spar seems to fit better in the 810/814.
Click to expand...
You really can't over-dimple a hole. Once the dies bottom out, you aren't going any further. OK, maybe you could with a gazilion ton press and cause the metal to deform under the dies, but not with our little tools. I don't have any numbers of the force applied by a pneumatic squeezer, but I'd bet it's pretty close to what you could do with enthusiastic use of a hand squeezer.

By under-dimpling the hole, it may sit flush in the countersunk hole, but you are really just masking the fact that the countersink is not deep enough, and now your rivet will sit proud of the surface.
 
Checked Vans Documentation about countersinking

Yup, don't want proud rivets either - just want to be the proud owner of a flying airplane. :)

So I opened the front of the preview plans book last night and re-read what they said about having to countersink a bit more for exactly this same situation. Problem is, they said that "you may have to increase the microstop by a few clicks."

I understand that they can't get more specific than that due to different tool designs and so forth, and I have a feeling that maybe they are using an example for a 3/32 rivet when they make this statement, because I have had to increase my tool's cutting depth by more than "just a few clicks" to get it to finally seat the dimple correctly. Probably up to 8 or more now from where I started.

I make small changes, check the depth of the cut, and then refit the parts, and so on... It's just a little un-nerving to keep cutting away the hole. I'll try to put some pics of the countersink on the angle and and the dimple on the spar flange this evening.

Can't wait to have to do this many more times on the VS and beyond! All part of the fun I guess. :(
 
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Flyin'Bryan said:
It's just a little un-nerving to keep cutting away the hole.
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Yes it is, which is why you don't want to use your airplane for this purpose. Use a piece of scrap to get the countersink set correctly, then start using it on the actual piece. That's what scrap is for.
 
I have observed that dimpling different thicknesses of metal will create different dimples. Thicker metal will mean you need a slightly larger countersink to accept it, so you can't expect to set your countersink once and use it for all of your countersinking.
As said earlier, make a series of test pieces for different thicknesses of metal you will be using, kind of like the rivet gauges you see around, and use them to get the countersink set each time you start out.
The pieces must fit together perfectly, before you rivet, or they will not be right after riveting. If your countersunk hole needs touching up after using the countersink cage, you can always use the deburring tool to make it perfect, if you don't want to fool around with the cage settings.
Good luck.
 
Almost there...

So yesterday I chatted with Van's. They gave me the same advice to use the test template. I told him I had cut about a 2" x 2" piece and dimpled it and seemed as though it was seating correctly in the countersunk hole when I used it, but everytime I re-assembled the parts I still got the bulge. He suggested that I make a longer strip that would lay against the back of the angle and cover multiple holes instead of just the contersunk hole, so I could get a better idea as to the fit. I will definitely make the longer templates.

The other thing I did was to finally reach for a ruler to check the size of the dimple and the countersunk hole. Don't know why I did not do this sooner. Of interest is the fact that the dimple ends up being about .27 wide, and a measure of the edge of the counter sunk hole was just shy of that, confirming the reason why it won't quite seat correctly.

I drilled a little bit more, and now that the edges for both parts have about the same measurement, the problem is just about resolved. I am guessing one more click on the countersink and I'll have it licked. Even the extra depth of the countsunk hole seems to match up with the thickness of the dimple on the spar flange, so it looks like everything should fit together nicely. Of course the proof will be when I slam the rivet, which of course I will perform on the scrap first.

Only one mystery remains, and that is why the holes on the other angle, HS814 (the larger angle) seem to be just fine, and did not require any further drilling. I won't lose any sleep over it, but I don't understand why I needed to keep digging out the hole on the HS810, but not on the HS814. I will measure the 814 holes and dimples as well, just to see how they compare.
 
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