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  #1  
Old 02-20-2017, 02:18 AM
JurgenRoeland JurgenRoeland is offline
 
Join Date: Oct 2010
Location: Belgium, Geraardsbergen
Posts: 102
Default Dimple double layered material.

Maybe a stupid question but I'll ask it anyhow.

On the rear bottom fuselage - in a moment of excess motivation - I already rivetted the F728 B bellcrank channel and F729A bellcrank rib to the F778 bottom tail skin.
So now, my F706-B fuselage bulkhead can't move anymore and it sits thight with the F778 bottom skin. For match drilling,that was of couse not a problem but now i'm faced with dimpling issues.

I still have to dimple these F729A bottom flange holes and thinking of using the pneumatic squeezer to squeeze both holes at the same time in order to dimple #40.
Looking at the result of that I wonder if that's really the way to do it and if the quality of the dimples will be ok.

any remarks welcome.

greetings

J. Roeland
Belgium
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  #2  
Old 02-20-2017, 07:00 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 3,870
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Quote:
Originally Posted by JurgenRoeland View Post
I still have to dimple these F729A bottom flange holes and thinking of using the pneumatic squeezer to squeeze both holes at the same time in order to dimple #40.
Looking at the result of that I wonder if that's really the way to do it and if the quality of the dimples will be ok.
Hopefully Scott will weigh in here, but I have done this where the skins were thin and it was unavoidable. YMMV, though, so use some small pieces and verify for yourself. I am not shy about using the deburring tool for a final fit adjustment of the dimple.
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Last edited by BillL : 02-20-2017 at 07:03 AM.
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  #3  
Old 02-20-2017, 11:54 AM
nilberg nilberg is offline
 
Join Date: Dec 2012
Location: Katy, TX
Posts: 108
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Hmmm how many rivets, how much dimpling and have you started the center section yet.

The reason for asking is that the center section skin will actually overlap both the bulkhead and the F-778 skin, you will later match drill a new row of holes in the F-778 and you have to tuck the F-770 in between the two bottom skin (F-778 and F-776.

Having the bulkhead riveted could make thinks even more difficult later in the building.

I did not dimple the F-778 interface with F-776 and F-706 before the final joining of center section and aft fuselage (just before riveting).
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  #4  
Old 02-20-2017, 01:34 PM
nilberg nilberg is offline
 
Join Date: Dec 2012
Location: Katy, TX
Posts: 108
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Never mind my previous post. I checked your build log and you have already excellently worked around all the challenges I mentioned (including the dimpling in the 2nd rivet row).

Last edited by nilberg : 02-20-2017 at 01:35 PM. Reason: Grammar
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  #5  
Old 02-21-2017, 12:50 AM
JurgenRoeland JurgenRoeland is offline
 
Join Date: Oct 2010
Location: Belgium, Geraardsbergen
Posts: 102
Default

Thanks all for the replies.

I have indeed meanwhile managed to dimple the second row using a c-frame style setup without c-frame and whacking them with the mallet. That worked quite fine.
On the forward side, the only way was to dimple through both layers of the bottom skin with the flange of the bulkhead together.
If I would have to remove the full row of rivets, that would potentially leave a much worse situation then to double dimple those couple of holes in the center.

However, my question was more in general if it is a good idea after all to double dimple and what might be the risks involved.

greetings and already thanks for the answers.
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  #6  
Old 02-21-2017, 06:23 AM
bill v bill v is offline
 
Join Date: Mar 2011
Location: zeeland michigan
Posts: 108
Default firewall and side skins

I had the same question concerning the firewall side skin and cowling hinge I asked vans if I should countersink these holes. they preferred I dimple the side skin and firewall together and countersink the shim and hinge for the dimple to fit into. they said the skin .032 and stainless firewall could be dimpled together.
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  #7  
Old 02-22-2017, 05:39 AM
JurgenRoeland JurgenRoeland is offline
 
Join Date: Oct 2010
Location: Belgium, Geraardsbergen
Posts: 102
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If I remind well, the bottom skin of the tail cone and the flange of F706 are both .032 so if it's ok to dimple steelplate of the firewall and .032 together, then two pieces of .032 of alumnium should also be ok.

Thanks for the helps guys.
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  #8  
Old 02-22-2017, 10:50 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 3,870
Default

The front of the fuse/firewall is where I power dimpled the stack. Pre dimpled. but still re-dimpled the 032 skin/016 SS firewall/.025 spacer/ 050 skyloc all together.

It made them nest properly and a touch of the deburring on the external yielded a nice factory head and tight material stack. No other way I could think of doing it.
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