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Bucking Rivets (Bucking Bar Guide from 3D printer)

marchudson

Well Known Member
I tend to work in the shop solo while building as I'm sure most of you do. When it comes time to buck rivets, it's tough to keep one eye on the rivet gun and the other on the bucking bar. I usually sight the placement and alignment of the tungsten bar then switch to watching the gun as the rivet is driven. The bar is mainly held by feel. This has worked for most of the rivets driven but every once in a while, the bar slips off or is held at an angle and the rivet has to be removed and corrected. In addition to all of this, I usually run a line of blue painters tape on the bucking bar side of the material to protect anything from an accidental touch from the bucking bar.

My son talked me into getting a low cost 3d printer, which it did. Well this little tool is really starting to pay for itself. I modeled and printed up a bucking bar guide. If you have done any 3d printing, you know it can take a while for a print to complete so instead of printing to the full 1.5" as planned, I printed a test guide to only 1/2 inch high. Even at this height, it works like magic.

The first photo is an overview shot. In the second picture, you can see I have made a .024 step for the flange to fit into. On other models I printed it has a flat bottom. The 3rd pictures shows a typical application.

I didn't have high expectations initially but was surprised at how well it holds the bar perpendicular to the material. It has the added benefit of providing clamping force to the two pieces being joined. I don't use any protective tape on the shop head side because the bar can't hit anything but the rivet and the bucking bar won't slide off of the rivet.

The last picture shows another tool that was printed, a rod end bearing tool.
 

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Great Idea

Great idea, thanks for sharing. I can't handle a printer myself and I wont be able learn 3D construction software in this life, but my sons are very helpfull.
 
The bucking bar tool is awesome. You make me want to go buy a 3D printer now.

I'm not sure how you use the rod end bearing tool you made. Can you explain?
 
You know, you will never finish the plane if you keep tinkering this well on other stuff. 8^)
 
This is really an excellent idea. First thing printed for the -14 project, I'm sure this will inspire many more uses for my CR10s
 
FYI - the design shown here is for a 1" x 5/8" bar, I've made a revised design that will accommodate the 1" x 1" mini tungsten bar from cleaveland but is the same in every way. Happy to send the STL files along as well.

For a few moments I was thinking "maybe I should buy the 1x5/8 bar" but I decided to be cheap and change the tool-helper instead of buy another tool for once :D
 
3D printing is cool

I reckon this is awesome. Forget international shipping - one email with a file that was - 19KB - (less than 20,000 characters) emailed on Friday. By Sunday arvo I’ve got the part in my hand. Could have done it even quicker but *life*.

Simply AWESOME!

Thank you Marc.
 

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Request for Copy of STL file

Hi Ryan,
I’m building an RV14a and this holder would be great. I have a granddaughter in high school learning to use one of the 3D printers and realize she could build one of these holders for me. I sent you my email address in a PM. Could you send me a Copy of the latest version of the STL file?
Thanks,
Ted Mifflin
 
File Request

Ryan,

I'm in major need of this. Will you please send the files? I've sent a PM with an e-mail address.

Thanks, and FABULOUS idea!
Mike
 
Great Idea

I got a 3D printer for Christmas, so figured I may as well start with something easy. Doesn't get any easier than a square! I made 3 different bucking bar "guides" for my tungsten bar - one for 3- rivets where the shop head is on a flat surfaces (no dimple), one for 3- rivets with a dimple in ribs (so same idea as the OP with a ledge to account for the rib flange height), and one for 4- rivets on a flat surface, like the spar. The reason they are different sizes is because the ledge that the bucking bar bottoms out against is made to have the thickness of a properly set rivet in those different scenarios. Overkill for sure, but fun to play with.

This was more about the learning experience than anything, but pretty awesome to be able to draw it up and have something in hand in such a short time!
 

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I used mine this weekend on my rudder! Thanks, Marc! It worked great, though I saw a few areas for potential improvement, so I did. First, the hex on it was bigger than any sockets I currently had, so I made the hex fit my largest socket (a 22mm socket). Next, when I was playing with my print I realized, I could have just put a 3/8 drive hole in it, so I did that too. Now I can turn it with a socket, a 3/8 drive racket, a box end wrench, or an adjustable wrench. Whatever I feel like using at the time. The STL can be downloaded at the link below for anyone who wants it.

https://drive.google.com/file/d/1Z1bkfYnKHXOwm1qB8OlVwbl0xqS7sZCH/view?usp=sharing
 

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That's a great idea, Brandon! Would you be willing to share the file?

I got a 3D printer for Christmas, so figured I may as well start with something easy. Doesn't get any easier than a square! I made 3 different bucking bar "guides" for my tungsten bar - one for 3- rivets where the shop head is on a flat surfaces (no dimple), one for 3- rivets with a dimple in ribs (so same idea as the OP with a ledge to account for the rib flange height), and one for 4- rivets on a flat surface, like the spar. The reason they are different sizes is because the ledge that the bucking bar bottoms out against is made to have the thickness of a properly set rivet in those different scenarios. Overkill for sure, but fun to play with.

This was more about the learning experience than anything, but pretty awesome to be able to draw it up and have something in hand in suck a short time!
 
That's a great idea, Brandon! Would you be willing to share the file?

Happy to share the files. Let me play around with the different sizes first to make sure they’re accurate though. I haven’t had a chance to actually rivet with them yet. I’ll do that tomorrow and see what the verdict is.

I know most of the time these won’t be necessary to use because the timing method is plenty for riveting. Where I have struggled is in locations where it’s blind and you can’t get the same “standard” pressure on the bar, so the normal 3 seconds (or whatever it is for you) of the gun doesn’t equal the same shop head. That’s where I think having a backstop for the bar may come in handy for newbies like myself.
 
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love the idea, that's an awesome use for 3d-printing

@skelrad:
Did you put a lip on the inside in order to define the height of the shop-head of the rivet?
That's one thing I'd be concerned about because once the bucking bar bottoms out on the lip the rivit gun might proceed to denting the skin because of lack of rivet-bar backpressure.
That said, I'd still like to see a test on some scrap, if the "lip" is close enough to the rivet it might actually work.
 
Great idea. Take my money. :) Thanks in advance for the files. First time builder here so anything to help move things along is welcomed.
PD
 
love the idea, that's an awesome use for 3d-printing

@skelrad:
Did you put a lip on the inside in order to define the height of the shop-head of the rivet?
That's one thing I'd be concerned about because once the bucking bar bottoms out on the lip the rivit gun might proceed to denting the skin because of lack of rivet-bar backpressure.
That said, I'd still like to see a test on some scrap, if the "lip" is close enough to the rivet it might actually work.

Yeah, I've thought about that and don't know the answer yet until I try it out. The "lip" is actually the entire bottom of the holder that the bar sets on. My intention was to have the bar and holder move as one, versus having the holder set on the surface of the material and then have the bucking bar slide down and stop as the rivet is formed. I don't have a huge problem with keeping things vertical, so I wasn't wanting a way to guide the bar down vertically, only wanting a gauge to help rivet head size.

I'll post back with the outcome.
 
Gave it a shot

I ran out to the garage to drive a few rivets in scrap. Overall, the gauges, or whatever they are, worked pretty well. As with anything, there are some gotchas though. The ones for driving shop heads on flat surfaces (no dimple) are pretty dummy proof - the gauge/bar starts off at rivet shank height above the surface of the material and riveting goes normally, and then the sound of the riveting changes slightly once the gauge and bar hit the surface material, meaning the proper height of the rivet head has been reached. I honestly don't know how useful these really are for this type of material, since I have found that the areas without dimples have pretty decent access for riveting and aren't that problematic. I mostly wanted a guide for the -4 rivets on the wing spars, not because I couldn't see well, but because it would lower my blood pressure over worry of accidentally dinging the spar with the bucking bar. After trying it out on scrap, I think it will do that, so I'll give it a try on spar #2 when I am ready to build the second wing. For about $0.20 of plastic, why not?

For the dimpled material, there are some considerations because of the fact it's always on thinner material, mostly skins. Again, the gauge actually worked pretty well on the scrap and gave consistent and reliable rivet head sizes without having to do any guesswork. That being said, just like with any other riveting, you can't keep pounding on the skin after the rivet is set. Once the rivet is set, now the surface area that is resting on the shop head side is the bar plus the square of the gauge plastic. If you keep hitting it with the rivet gun, you will inevitably start to create a nice square of deformed skin as the rivet set hits the perimeter of the gauge. This part I expected, but I didn't actually see any problems until I purposefully kept pounding on the rivet with pressure on the bar/gauge after the rivet was formed. If you don't pay attention, you could definitely cause some skin deformation though, just like with any riveting. I think this concern can actually be designed out though. I'm going to mock up a rib gauge that doesn't actually have an offset for the height of the rib flange. Instead, I'll make the platform of the gauge that would rest on the rib flange a little wider, like the OP did. As long as you use the rib web as a guide for the bar and don't angle it way down towards the skin, I don't see any reason why any part of the gauge needs to rest on the skin. Without that portion, the likelihood of causing any skin deformation from the rivet gun pounding on the gauge is significantly limited (I don't see it being a problem on the rib flange portion - that's more material thickness, so you'd really have to go nuts with the gun to outline the gauge square on the skin side).

One other thing I noticed was a "well duh" design flaw in the -3 gauge used for ribs. The measurements are pretty spot on in terms of shop head height and offset for the rib flange material, but I need to make the width of the gauge material on the rib web side smaller. As-is, it doesn't have enough room to slide over the rivet shank because it hits the rib web. I'll probably do a complete design change anyway though, so probably won't bother fixing this one. I also found that for whatever reason, even though the dimensions are the same for the dimple gauge, it fits too snuggly on my bar and is hard to remove it. Chalk that up to the accuracy of melting plastic and expecting size tolerances down to hundredths/thousandths of an inch.
 

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