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prkaye

Well Known Member
I still haven't figured out how to dimple holes in tight spots between two flanges where the web gets very narrow (e.g. rudder ribs). When the web gets so narrow that the dimple die itself won't even fit between the flanges...
any suggestions?
 
The solution is pop-rivet dimple dies. You can get them from Cleaveland, Avery, and other tools shops. I purchased a set in both 3/32" and 1/8"; haven't used them much, but when I have nothing else would accomplish the task. I've ground them to fit in tight places as well; just have to make sure the face is polished to prevent scratches. It was perhaps the only time I've ever used a die grinder for it's intended purpose :)
 
I use a vice-grip dimpler from Avery Tools in this situation. It's hard to feed the mandrel for a pop-rivet dimple die through the hole in the trailing edge of control surface ribs.

Guy
 
On some parts like the top rudder rib and the inboard elevator ribs, there is not even enough room to get the "pop rivet" dimpler in there. What I (and others) have done is to get a piece of steel angle and machine countersink the appropriate size "female" dimple into the angle. It helps to make it near the end and edge of the steel angle. Clamp the angle in the vice. Slide the rib over the hole and use the male dimple die and the ram from your c-frame dimpler to dimple the last hole or two on these ribs.
angledimpler.jpg

Aren't these RV-9(A) rudders fun? :D
 
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The only problem with that approach (which is quite clever) is that I don't have the c-frame dimpler... I have the DDRT-2 thing with the big handle. So I don't have anything to hold the male dimple die so that I can ram it down. I suppose I could drill a hole in a block of wood and put the die in that...

If i get a spot where the avery vice grip dimpler doesn't fit, I'll try that... for $35 I figured it was worth getting the vice grip tool.

Thanks!
 
You will use the vise-grip dimpler a lot! You may have to grind a little bit where the jaws are welded to the dimple dies in order to really get into tight places. Don't overdo it, though.
 
I just realised I already have a pop-rivet dimple die. Looking at it, I don't understand when this tool would be useful. The female die is attached to a "nail" (I call it a nail because that's what it looks like) that goes up into the pop riveter. The male die slides down over the shank of the nail and the pop riveter squeezes the dies together by pulling up on the nail.

From what I can see, to dimple anything you have to have enough clearance on the opposite side to be able to poke that nail through the hole to be dimpled. This is quite impossible in a narrow flange. If I had enough clearance to get that nail in there, I would certainly have enough clearance to fit the yoke in there to use a squeezer for dimpling.

Also, there is an extra "nail" included with the dimple die, this one not attached to anything (no female die attached). What is this extra nail for?

Am I misunderstanding the functioning of this tool?
 
there are those who have and those who will...

The extra nail is there so when you pull too hard and break the first one, you have another. I think mine came with 6 or so extra nails -- already broke one. The local hardware store's aviation department carries more. -Jim
 
The pop rivet dimple die is useful when you need to dimple a hole too far from an edge to use a squeezer, but there is some reason why you can't use the C-frame. I don't recall the details, but I know I ran into several places like that.

The nails get chewed up a bit by the jaws on the pop riveter, so you can only get a certain number of uses before you'll need to replace them with new ones.

There are some things you can do to help get the pop riveter in some places where it wouldn't normally fit. I don't think it will help you here, but it may be useful in other places - example

For the flanges near the ends of the ribs - I bent the flanges a bit to open them up and improve the clearance, did the dimpling with a Vise Grips dimpler (I think - that was a long time ago), then bent the flanges back to their original angle.
 
prkaye said:
I just realised I already have a pop-rivet dimple die. Looking at it, I don't understand when this tool would be useful. The female die is attached to a "nail"
Click to expand...

But it doesnt have to be, just flip them around. I did all of the holes closest to the bend on the elevators and rudder on my 8 with the pop rivet dies. The only holes I have not been able to dimple with either the vice grip squeezer or the pop rivet dies is the two aft most holes that hold the fiberglass caps on because you dont do them till after it is all riveted together (and the fiberglass tips ready to mount) and they are -4's for the pop rivets so my -3 vice grip wont work. I'll have to make that countersunk plate like rjsflyer posted.
 
Phil,
I spread the rib tip a little, dimpled with the Avery Vice Grip dimpler, then bent the flange back http://www.mykitlog.com/users/display_log.php?user=cnpeters&project=214&category=0&log=21544&row=8 . To rivet later on, I was able to use the 4 inch no hole yoke down to the 2nd to last rivet, but used a blind rivet on the last hole (MS-319 something - on the Van's plans as an option. See third pic in link http://www.mykitlog.com/users/display_log.php?user=cnpeters&project=214&category=0&log=21761&row=3 . Also, since you are close to this stage, I found the longeron yoke worked well getting the skin to spar to horn brace rivets http://www.mykitlog.com/users/display_log.php?user=cnpeters&project=214&category=0&log=21592&row=5 . Van's give a blind rivet option, but the longeron yoke reached all four holes each side.
 
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