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-   -   Poor Riveting (https://vansairforce.net/community/showthread.php?t=146684)

rv9builder 02-19-2017 08:20 PM

Quote:

Originally Posted by RV74ME (Post 1151506)
On the subject of acceptable rivets, I'm wondering is it ok if you have a properly formed shop head that is "overdriven" (won't fit in the rivet gauge), but still meets the minimum head height? Hope that makes sense.

As long as it meets the minimum head height, it's OK if the diameter is too large to fit in the rivet gauge. (That's assuming it isn't so large in diameter that the head is starting to crack.)

RV7A Flyer 02-19-2017 10:31 PM

Quote:

Originally Posted by rv9builder (Post 1151509)
As long as it meets the minimum head height, it's OK if the diameter is too large to fit in the rivet gauge. (That's assuming it isn't so large in diameter that the head is starting to crack.)

In fact, it's not *supposed* to fit in the rivet gauge. It's a go-nogo gauge...if the rivet head can fit inside the hole, it's *not* driven enough.

ETA: Yes, I know that the hole is supposed to be *EXACTLY* the ideal (minimum) diameter, and an absolutely perfectly set rivet will "pop" into the hole with no slop at all...but really...how many times does that actually happen? Better to be slightly overdriven, and the gauge will usually just kind of "wobble" on the head, but the head won't go all the way through, than to have one that is underdriven and doesn't "fill the hole".

az_gila 02-20-2017 01:29 AM

Look the same, but -
 
Quote:

Originally Posted by RV7A Flyer (Post 1151524)
In fact, it's not *supposed* to fit in the rivet gauge. It's a go-nogo gauge...if the rivet head can fit inside the hole, it's *not* driven enough.

ETA: Yes, I know that the hole is supposed to be *EXACTLY* the ideal (minimum) diameter, and an absolutely perfectly set rivet will "pop" into the hole with no slop at all...but really...how many times does that actually happen? Better to be slightly overdriven, and the gauge will usually just kind of "wobble" on the head, but the head won't go all the way through, than to have one that is underdriven and doesn't "fill the hole".

Check your gauges first.

This one from Spruce is a No-Go one as mentioned above -

https://www.aircraftspruce.com/pages...rivetgauge.php

But some of the older ones, or ones from other sources, look identical but are set up to measure an exact 1.5D/0.5D rivet head.

Make sure you know which version you are using...:confused:

vic syracuse 02-20-2017 05:30 AM

Overdriven rivets actually have more tensile strength but you need to be careful around thin materials. They can be cause of cracks developing in the material, and if you look closely you can sometimes see the two materials begin to separate.

That being said, I would rather see a few overdriven rivets in a project than underdriven ones, as long as they all aren't concentrated on 1 piece.

There may be a perfect airplane out there, but I haven't seen it yet, including mine. Everyone once in a while there is a rivet that is just a bugger to get to, and it comes out less than perfect. You can have up to 10% of your rivets being bad and it still be acceptable, again as long as they aren't concentrated on one piece.

So, for the newbies, don't fret too much. Ask for help if you are unsure. The pictures that have been shown here are the worst of the worst. They didn't need a gauge to tell the builder they weren't right.

Vic

Oliver 02-23-2017 01:51 PM

Quote:

Originally Posted by RV7A Flyer (Post 1151524)
In fact, it's not *supposed* to fit in the rivet gauge. It's a go-nogo gauge...if the rivet head can fit inside the hole, it's *not* driven enough. [...]

We have two gauges, from ATS and from Cleaveland. Both are set for 1.5 x rivet diameter. Many of the 3/32? rivets will however end up not high enough, if driven to a width of 1.5x.

1.3x rivet diameter is technically sufficient. I therefore made a 1.3x no-go gauge, to measure the absolute minimum diameter. With shorter rivets, I usually end up at a width of around 1.4x, what still leaves an acceptable height.

I also feel that a width of 1.3x - 1.4x can be achieved with only a short burst. A width of over 1.5x, so that the rivet doesn?t pass the gauge anymore, however requires quite a bit more hammering with the rivet gun, what increases the risk to slip with either the gun or the bucking bar.

I drive longer rivets to a diameter of 1.5x, though.

Oliver

David Paule 02-23-2017 02:24 PM

I follow the riveting spec on Van's site. The acceptable dimensions it lists are not exactly the rule of thumb, worth noting, and the commercial rivet gauges I've seen do not meet the spec.

I made a -3 gauge and a -4 gauge for myself.

Dave

rvbuilder2002 02-23-2017 03:04 PM

Quote:

Originally Posted by Oliver (Post 1152627)
We have two gauges, from ATS and from Cleaveland. Both are set for 1.5 x rivet diameter. Many of the 3/32” rivets will however end up not high enough, if driven to a width of 1.5x.

1.3x rivet diameter is technically sufficient. I therefore made a 1.3x no-go gauge, to measure the absolute minimum diameter. With shorter rivets, I usually end up at a width of around 1.4x, what still leaves an acceptable height.

I also feel that a width of 1.3x - 1.4x can be achieved with only a short burst. A width of over 1.5x, so that the rivet doesn’t pass the gauge anymore, however requires quite a bit more hammering with the rivet gun, what increases the risk to slip with either the gun or the bucking bar.

I drive longer rivets to a diameter of 1.5x, though.

Oliver

To ex[and a bit more on the info in your post.....

The 1.5 rule of thumb (and all of the rivet gauges that have been made using it), is not a specification. It is a genral us guide line / rule of thumb that is much easier to follow that the actual specification.
The specification allows quite a bit of latitude/tolerance one side or the other of teh 1.5X guide line, for shop head diam. and height.

LettersFromFlyoverCountry 02-26-2017 08:36 AM

I've been doing a LOT of riveting -- the aft bulkhead on the RV-12 for example -- and it came out great.

You know why?

Because just as I start to squeeze the rivet, I say to myself, "Stay out of Vic's threads. Stay out of Vic's threads. Stay out of Vic's threads."


az_gila 02-26-2017 08:50 AM

Quote:

Originally Posted by rvbuilder2002 (Post 1152647)
To ex[and a bit more on the info in your post.....

The 1.5 rule of thumb (and all of the rivet gauges that have been made using it), is not a specification. It is a genral us guide line / rule of thumb that is much easier to follow that the actual specification.
The specification allows quite a bit of latitude/tolerance one side or the other of teh 1.5X guide line, for shop head diam. and height.

This is the original - html spec version created in 1997 by Brian Yablon and myself - page that lists the spec Vans 'borrowed' that Scott mentions.

http://web.archive.org/web/200008161...ash.net/~gila/

Note the picture on the main page, many builders use the height portion of the rivet gauge incorrectly when measuring the shop height on dimpled material.

vic syracuse 02-26-2017 09:23 AM

Quote:

Originally Posted by LettersFromFlyoverCountry (Post 1153341)
I've been doing a LOT of riveting -- the aft bulkhead on the RV-12 for example -- and it came out great.

You know why?

Because just as I start to squeeze the rivet, I say to myself, "Stay out of Vic's threads. Stay out of Vic's threads. Stay out of Vic's threads."


Too funny. But glad I am helping to make a difference. :)

Vic


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