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Spring back dimple vs Normal Dimple
Hey,
So here's a good question for you fellow builders, I was in the process of dimpling my RV-9A vstab skin today and I had some Aircraft Spruce regular dimple and so I decided to give those a try since I don't have the spring back... Anyway, here is a picture of the finished dimpled hole with one rivet in... rivets seems to be perfectly sitting flat in the dimple and there is no deformation of the skin... ![]() What do you think, do you see anything wrong with using these? Is it worth to buy another set of dimple dies, and is there a big difference with the spring back? Anyone has any experience with the aircraft spruce dimples? Thanks |
I used reg/tank/springback...I could not tell much difference just looking. The tank appeared to be slightly deeper. Whatever you have looks good.
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I think the difference is what they call "marketing". :)
As long as the head sits flush to the skin, you are good. The tank dimple dies are just a bit deeper. |
A little hard to tell from the picture, but the rivet looks like it's sitting deeper than flush ? The next open hole looks like the hole is on a slight angle too. Do you have a picture of the other side of the skins dimple ? It should be symmetrical and straight/even all the way around. Again, it could be the angle of the photo.
What was used to dimple with ? A hand squeezer ? I've heard of some "Matco" squeezers that don't work very well. Avery's has a good quality one. |
Yes the picture is tricky sorry... the camera dind't want to focus correctly on shiny aluminium! I will try to take another one today...
As for the slight angle, I saw it too when I downloaded the picture on the computer so I went in the shop to check...it's only a optical illusion because on the skin it's perfectly straight, weird!! As for the dimple, the rivets does seem to sit a little slightly deeper than flush, but really nothing u could ever notice if you don't really zoom on the head and pass your hand over it... over dimpling with a hand squeezer is possible!? As for what I used, I have an ATS Super Duty Stainless Squeezer... http://www.aircraft-tool.com/shop/de...T_ID=ATSRS-1SD Thanks |
The real question is whether you want to save $38 on a $70K project on something that you will use around 10,000 times. I don't think this is marketing hype, the springback dimples will produce a better dimple, and a better looking airplane at the end of the day. It will not be any stronger, but when you see it parked in a line of RVs no-one will be asking why your rivets aren't quite so flush as the others.
There are places to save money, but (in my opinion) having the right tool for a task to be done 10,000 is probably not one of them. It's your airplane, so make your own decision, but I used the spring back dimples. Pete |
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Hey Pete, I know what you mean, but for right now I am on a really tight budget being still a student not always fun.... As soon as I finish school I will be able to buy all the tools I want... :P As for the spring back dimple, I still believe too it's a marketing hype because I worked for a small aircraft structure company for a while before and I am at school for A&P on my last year now and never heard of spring back dimples before starting the RV.... Still my perfectionist mind wanted me to make sure those I had were good.... Anyway, here's a couple new pictures I tried... ![]() ![]() ![]() Thanks! |
Spring back dimple dies
Most of the major tool companies sell spring back dimple dies. Aircraft Spruce typically doesn't make their own tools, they purchase them from the other tool companies. You can call Aircraft Spruce and ask them who manufactures their dies. It wouldn't surprise me if they are actually spring back dies.
I used an old set of regular dies (1980's) on some of my early R-7A skins then switched to spring back dies further in the project. Sure wished I had the spring back dies when I started the project. Set a few rivets and see if the head sits flush. That is really the best test of the dies. |
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If you use a flat/flush rivet set when bucking, there's a possibility that when bucking the rivet it may buck slightly raised up and away from the dimpled hole leaving a gap between it and the skin, but it will be flush with the surface. It really looks like your using a "fuel tank" dimple die set in the picture. I too highly recommend a set of spring back dimple dies from Avery along with their squeezer. I prefer their hand squeezer as the yokes are interchangeable with their pneumatic squeezers. I started out with the Avery Hand Squeezer, and after borrowing a friends pneumatic squeezer I quickly found there was going to be a huge time savings using a pneumatic squeezer to squeeze the rivets over the hand version. So by the time I had the tail done, I had saved up enough to by a pneumatic squeezer for the rest of the plane and I'm soooo glad I did. I kept a no-hole yoke in the hand squeezer and C-yoke and 4" yoke in the pneumatic. Not to mention having the adjustable shaft is also a huge time saver over having to put shims in every time you want to set something of different thickness, or switch from dimpling to squeezing. I know the feeling of being on a tight budget, but what others have said about saving $30 on a tool for an $80,000+ airplane is not a good idea. The completed airplane may lose it's value by thousands based on the sub-par quality of the workmanship. |
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Thanks for the reply... I tried squeezing a couple of rivets on a different skin with the same dies and the set rivet looks perfect! I'll try to grab a picture... anyway, I decided to buy a set of spring back dimple dies from ATS at the same time as I will pass my order for my rivet gun just to be sure and compare! Is the quality of the spring back dies from ATS good? As for the squeezer, I wish I had bough the squeezer from Avery but now I have an ATS Super Duty Stainless Steel Squeezer, it works perfectly... the only downside is that they have their own set of yoke! |
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