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Topic: Blind Rivets
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Posted by Chris Ray on August 14, 1997 at 15:30:24:
Ever run into a situation when you have to join two or more pieces of sheet metal, plate or flats together or in combination? The ovbvious way to do this is to either use rivets or bolts. What do you do when you can't have any surface protrusions or bosses left by such fasteners? Well you could plug weld pieces together but sometimes that's a messy way to do things and maybe there is the possibility of warping.
Okay, then try blind riveting your parts together. This is a way to have a very sound mechanical join without leaving surface blemishes or protusions. I use this method in a variety of situations, most notably when stacking plates for a stepped effect. I join each layer so the surface is flush for the following layer if it is a case where I may not be step stacking and using single rivets for the whole group. I can rivet one group of plates, then add another plate or bar stock on top of that and continue, etc. There are other conditions where this technique is useful too.
Start by clamping your parts together then drilling the appropriate holes straight through. When done, then take the two most outer parts and go back to the drill press and chamfer the outside hole on the side facing outward, of course. Needless to say we use a chamfering bit for this, you know, the kind used to match screw heads for a flush fit. Don't over drill the chamfer though, you don't need a whole lot of it, just enough to give your work the strength it needs.
Okay, so we've done that now what next? Well, you can use regular rivets and cut off the heads unless they are flush rivets. Here's what I do normally though. I have a roll of soft iron baling wire which is about 7/32" dia.which is pretty light for heavy duty stuff but fine for a lot of plate/sheet work that I do. Otherwise I use common nails....yes, the kind you build your house with. These come in a variety of sizes up to and beyond 1/4" dia. and are usually made of soft iron, did you know that? It's an excellent material for rivets, not quite as good as regular rivets or baling wire but very usable nevertheless. You can even use soft iron spikes which may be as thick as 3/8" if you don't have any small rounds lying around.
Alright, you then cut your rivet oversize and you have to determine either by eye or experience how much to leave in order to fill out the chamfered holes in your material. Start peening the rivet on one side, just enough not to let it slip out of the hole, turn the piece over and LIFT slightly and peen that side. I say lift because you want to still leave enough of a protrusion on the other side, which you can't see, so when you flip your work over there is enough material to finish the job. We realize of course, that we are hammering against some backup material, right? Sometimes a heavy object or dolly is used when hammering in the "air".
When you are done, you should have rounded lumps which is the excess material of the peened rivets. Next take a sharp cold chisel and chisel off the excess, flush with your work. That's it. Some folks like to grind off the excess material but for me that's an ugly way to do things. It's faster in fact to use the chisel. If you have forged surfaces, you can match the unevenness with your chisel so there is no indication that rivets were ever used.
Like magic, those plates are stuck together somehow. "I wonder how s/he did that", someone may ask.
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