Looking for cleco functionality in a rivet size package - considering 3/32 temp rivets.

[booshambo]

Hello,

I'd like to use some temporary assembly technique on some Al aircraft control surface parts.

I'm planning on initially using 3/32 pulled all aluminum rivets in place of clecos in some places for
parts that will eventually have 1/8 CCP-42 (or similar) blind rivets.

This is to allow the parts to be test fit in the final structure without the cleco interference where that is an issue.

The temp rivets will eventually be drilled out and updrill and etc. will occur.

Some concerns are hogging out the holes during the drill out and the bother of removal. An adjustable depth drill
bearing (ats 1341s) is planned for the removal task.

Question: is there any other technique that would allow temp setup for verifying assembly fitup? I'm also looking at
Heyco "snap rivets" (a plastic body and push in expander mandrel that aren't available in the desired
diameter it appears...) that I've used with almost satisfactory results on 1/8 holes.

A plastic or AL sheet metal screw might work but perhaps a long shot due to potential for violence to
the rivet hole. Has to be blind attach/removal.

Thanks very much for any thoughts.
b

 

[WKTaylor]

Soooo... bs...

Al aircraft control surface parts.][/b]

... Please advise... what is '...some Al aircraft control surface parts.'???????

Let-me get this straight... Can we presume that this is for an intended modification to an existing 'high-value/unique assembly'? You want to make a test-fit prototype with small Dia, easily removed temp fasteners... then salvage the assembly by removing the small Dia temp fasteners... and drill-for/install the nominal fasteners... correct?

CHERRY Aerospace MAY have what you are looking for...

https://www.cherryaerospace.com/product/blindrivets#chobert

Cherry® Tacking Rivet
Tacking RivetThe Cherry® Tacking Rivet provides simple blind rivet installation and troublefree removal. The Cherry® CCR284 is designed to improve drill-out by using external splines on the rivet shank to prevent rotation. The Cherry® Tacking Rivet is available with a 5056 aluminum sleeve and a C-1018 steel stem. Sleeve finishes include clear, red, or black anodize.

Contact CHERRY tech-support to discuss...

CAUTIONS1. As with all great ideas, there could be some unintended consequences, such as...
a. Drilling-out blind installs removes ~80% of the rivet... but the tail and end-of-shank are trapped in the assy... unless You have a way for them to be removed. Unless, of course, leaving debris in the Assy is 'OK'...
b. And what happens if the 'test-fit' is off... and has to be adjusted... and 'added holes' are now miss-located????
... And do-on....

NOTE1. One method I've used in the past is thin double-stick tape. I've even used 3M double-stick-tape designed for wall-mounting small hangers/parts... with a 'pull-tab' that allows easy/clean removal. Short segments 'edge-to-edge or spaced' might also work for extensive installs... if not abused. If needed... simply pilot-drill thru everything in final/adjusted position... then pull-off the tape and proceed to install.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[rb1957]

I was thinking of two sided tape too ... cheap and nasty. Plastic rivets would work too.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[WKTaylor]

Rb... I'd thought about plastic rivets too... but couldn't find any with very small 3/32 [0.094, 2.38mm] diameter.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[booshambo]

Hey,

WKTaylor asked:
... Please advise... what is '...some Al aircraft control surface parts.'???????

It is pre-bent but not drilled skins that are about to become flap and aileron (for example).
Early on in this process it becomes "high value" due to time invested.

Regarding the presumption as to what I'm about, essentially yes, but
I think of the goal not so much as a modification of the part or design, but of the assembly
process, in order to accommodate inaccuracies in the quick build part of the
project (done by factory, or someone else, or even yourself )
relative to the plans.

I'm trying to avoid hanging a complete flap before discovering the
plans don't match the wing as built. Not tragically off, but enough to matter.
I'd like to do removable stuff to the extent
possible so I can get mid course correction without so much scrap.

Clecos prevent me from hanging the flap, so adhesive is used some in those cases.
I have bespoke trays to soak the things in acetone after proper position
has been achieved and some initial rivet holes have been drilled.
I'd like to use about 4 (vice 20) temp rivets to register the hinge before
the glue is removed.
The glue thing offers large scale relocation possibilities and the
rivets allow minor pulling of holes to fine tune things as needed.

In addition there are all the other degrees of freedom that have to work
out. For example the skin to ribs connection is pretty critical to
assess height of the top of a control surface relative to the
specific wing as built. I hate all this delay and fussing about but
I hate even more the results I've seen of just going only to plans.
Plans, like a Beethoven sonate score, are only a suggestion of what it
takes to achieve beauty.

The Cherry temp things look to be quite interesting whether they address my needs or not. Thanks very
much for that link.

I'm using double tape in other places but had not yet gotten any kind of suitable thin stuff. Thanks very
much for that reference as well.

Regards,
b

 

[SWComposites]

Is this for a home-built aircraft or a production aircraft?

 

[WKTaylor]

bs... I helped my dad build a Thorp T18 in the 1960s. It had matched-hole tooling for every metal parts with just a few exceptions... where 'a hard tool-fixture was made for precision alignment. All these were done using draftsman's vellum drawings and layout spreadsheet from John Thorp.

All the match-hole tooled templates and a very-few hard-fixtures were made by a tooling craftsman, Vaughn Parker, exactly per the designer's math. Parts made from these tools came together with surprising precision to the point it was easily assembled with #40 holes and clecos... then the holes were up-sized [mostly] to #30 and 1/8 rivets. The homebuilt T18 metal parts were so precisely made on these templates and tools... which I experienced as a teenager.... that it bothered me to work in the late 1970s and early 1980s at 'old fashioned aircraft Assy shops'... with holding fixtures for major parts and shop-made hole templates that were sketchy... when drilling and riveting began... as a degreed enginerd-in-training.

With 3D CAD I am astonished You have this level of anxiety with part precision. Vans proved this method can work well... except their 'execution' of the concept had technical issues that were indicators of unclear and unchallenged thinking... then vendor's ran-wild.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[verymadmac]

There is a not insignificant risk the blind rivets will spin when you go to drill them out.
Would it be possible to 3D print some custom strips with press pins on it that match the hole pitch (printed pins aren't going to be reliably strong but there no reason why you can't use lots of them).

 

[RoarkS]

Build a prototype. Then do it right.

//Also if anyone knows how to get the back of drilled out rivets (blind or conventional) out of flight controls after drilling out broken static wicks I'm all listening.

 

[MintJulep]

Tiny plastic push rivets.

https://www.essentracomponents.com/en-us/p/push-in-rivets-tough-rivet/trm-1

 

[Sparweb]

Also if anyone knows how to get the back of drilled out rivets (blind or conventional) out of flight controls after drilling out broken static wicks I'm all listening.

Sure RoarkS: You just dismantle the entire flight control surface assembly. I swear, the questions on Eng-Tips just keep gettin' easier all the time.


booshambo:

Plans, like a Beethoven sonate score, are only a suggestion of what it takes to achieve beauty.

It's still just a Van's RV. Once you get it in the air, you'll forget all about the tribulations of assembly.

using double tape in other places but had not yet gotten any kind of suitable thin stuff.

Pretty sure this is quickly found if you keep plugging away at the 3M website.