Upset flush rivets 1

[Rob130]

Is there a standard practice when installing protruding head upset flush, or flush both sides rivets, to determine the amount of material removed to allow the buck tail to be flush?

I would assume the dimension would be a specific width for the csk relative to the rivet diameter or a % of the material thickness to be csk.

Mil Specs and NAS523 have not addressed this.

Thanks in advance.

Rob

 

[Sparweb]

Better to simply shave the tail afterward. There's a tool for doing this. Ask around on the shop floor.

Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[Rob130]

Thanks Sparweb, I usually shave the rivet but I am more concerned with how deep the csk should be. Would it be safe to assume the csk should be the same size as a NAS 1097 head for the same rivet diameter?

I would think some standard exists to determine the proper size/depth to double flush.

Any further info would be appreciated.

 

[Sparweb]

Never seen a standard for double flush-ing a rivet. Someone ought to write one, lest some poor AME be unable to find it in the binder they all wear around their necks.

Fascetious comments aside, try Mil-R-47196 from the ASSIST website.

Is any tension going to be applied to these rivets?

Copying the head height for a NAS 1097 rivet sounds good, as it will allow you to use thinner sheets, as the case may be. Specify a flush bucked head size for the installer on the drawing, and if he has any experience at all, he'll know what to do.

Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[koopas]

Rob,

Are you talking about shooting a protruding head rivet "NACA" style? That's where you upset the tail into a 82 deg. csk.

If so, the Douglas SRM's have guidelines for countersink diameter and min. sheet thickness as a function of rivet diameter.

Hope this helps,
Alex

 

[Stache]

I have had the experience of installing thousands of double flush rivets as technician while attending college.

Each manufacture has their own specification for double flush rivets. As an example the F-106 Delta Dart built by Convair used “DD” rivets in the intakes which were double flushed. The countersinks for their installation was the same. However the shop head was larger then micro shaved off flush on the outside skins.

If the countersinks holes are not the same during installation one cks will crack and break off. I haven’t seen the practice of double flushing rivets since the late 50’s as the installation takes an experienced technician or two in some cases.

Most of the double flush installation will use a “DD” rivet so it will expand and fill the cks properly before work harding. If a “AD” rivet is used it will crack most of the time during installation.

Stache