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Dimpling challenge

claycookiemonster

Well Known Member
A beyond-QB stage fuselage, but now I need to put doublers in the belly for beacons and antennas. Of course, I want those flush riveted, so I have to dimple the lower belly skin, but how?

I do that that small kit of pull-rivet dimplers, haven't tried them yet. Maybe drive a dimple die from the outside with a rivet gun and get a friend to buck the other die from inside?

Advice, oh wise ones?
 
I've got a brass drift with a hole drilled in the end to receive a female dimple die. Also have a junk brass tipped rivet gun set drilled to take the corresponding male die. Works good, but you obviously have to get access to both sides.

I have one of those pop rivet dimple sets and I hate that thing. Maybe it's just my less than stellar technique, but I always stretch or bend the mandril before eI get a good crisp dimple. I've used it for a couple of places I couldn't reach when I didn't have a helper, but I would MUCH rather use my hillbilly engineered dies in a rivet gun. You do have to make sure you have them square to teh work though, or you ca end up with smilies.

In a pinch, I've also used a female die nested in a heavy chunk of whatever, and the male die in a small socket on the end of a nut-driver, then just tap it with a hammer.
 
Maybe drive a dimple die from the outside with a rivet gun and get a friend to buck the other die from inside?

Yes this works but proceed carefully as it forms very quick. In lieu of a helper I have used a very heavy piece of steel drilled and recessed for the die.

Russell
 
Home made tools

I've got a brass drift with a hole drilled in the end to receive a female dimple die. Also have a junk brass tipped rivet gun set drilled to take the corresponding male die. Works good, but you obviously have to get access to both sides.
...<snip>...

Same here. Works very well.
Cold rolled steel home brew bars. They all have a 3/16" hole for dies. You can buy the gun set with a hole as well. Practice with a partner and dial down pressure to bare minimum.
 
I used the pop-rivet dimple dies with good success.

Another technique would be to do draw dimpling. You take a hunk of steel maybe 1" X 1" X 3". Drill #40 and #30 holes in each end. Use your countersink cage to cut a 100 degree countersink to hold a rivet flush. Insert the rivet on the belly through the skin and any doubler. Have someone hold the steel draw dimple die on the inside and gently tap on the rivet with a ball peen hammer to draw down the skin into a dimple. It doesn't take much hammering and you don't want to stretch the skin too much. Remove the dimple die and shoot the rivet with the rivet gun and mushroom set. Use the same rivet you hammered into place to fill the hole, since it has been shaped to fit just that hole.
 
I use pop-rivet dimpler and used pop-rivets for the doubler since I didn't have a helper
 
I used the pop rivet dimple dies too. No problem. The dimple is not as crisp as one done with a squeezer or DRDT, but it's acceptable. For riveting flush rivets solo where my arms can't reach, I put a tungsten bucking bar on a floor jack securely up against the skin and back-riveted from the inside:

 
I’ve used my pop rivet dimple dies many many times. I have two sets of dies. The first ones were not very “crisp”. The newer set (now several years old) are as crisp as any dimple I’ve set with my squeezers or C-frame. I think I got them at Avery, but not sure. It’s been a while.

The way I do this solo, which is all the time, is - I tape the male die with nail in to the hole on the outside of the airplane. Then I crawl inside with my rivet puller and female die, and complete the dimple…… then crawl back out and move the male die, nail, and tape to the next hole and repeat. I can get at least three dimples with one nail and piece of tape. Other than working my senior citizen body into the proper position inside the fuselage to accomplish this, it is quite easy, and for a typical antenna doubler, only takes about 5 minutes or so. I need help to set the rivets, but that only takes a few minutes with an experienced riveter/bucker.

I’ve also used a variation of this procedure to torque nuts on fasteners on my firewall, or fuselage, such as bolts or AN bulkhead fittings. I tape an open end wrench on the bolt head or AN fitting with the wrench end bearing against something near it in the tightening direction, like a bracket or some part of the airplane. The tape is only used to hold the wrench in place so it doesn’t fall off the bolt/fitting. Gorilla tape is awesome for this and can be used over and over. Then I crawl inside with my torque wrench and tighten the nut. Hit it with a little torque seal so I know it’s been torqued.
 
Another option

Fab your doubler to fit the fuse skin to your liking.

Glue the doubler in place with 3M 2216.

Mark and drill mounting holes from inside or outside.

Enjoy a beer while thinking how easy that was 😊
 
Tool

I made this simplemtool to hold the inner die and then used a light touch on the rivet gun. I tried the pop rivet dimpler but they werent crisp enough.
 

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Maybe drive a dimple die from the outside with a rivet gun and get a friend to buck the other die from inside?

Advice, oh wise ones?

This is what I do for most of them. You can make die holders from 1/2" bolt shanks. Just make them long enough that you can get your fingers on them. I took an old pnuematic chisel bit (same shank as rivet guns) and flattened the end and drilled to hold the dies.

the other tool works fine for 025, but struggles with 032.
 
FYI - If you're using a Comant antenna (CI-122), no dimpling is required. The four screws line up perfectly with the holes in the fuse.
 
An after action report from the pull-dimpler operation. No Problemo. I had a partner and an average Ace Hardware sort of rivet puller. Didn't even go through that many nails. Simple.
 
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