I bought a $20 riveter to rivet two pieces of plastic together. I’ve tried it about 20 times but the big center part is still there and I can’t snap it off without breaking the plastic. What am I doing wrong, or do I need to just cut it off with pliers, but that doesn’t look like what they did with the rest of the rivets on the plastic, it looks like the center piece was totally gone.
I assume it’s some kind of pop rivet. Sounds like the hole isn’t large enough. You need room for the rivet to expand in the hole.
I figured out I have to squeeze the handle twice to break the center off, but it doesn’t work right (the rivet just slides right out) and it looks different, the existing rivets are hollow in the center and are flush with both sides of the plastic, while the ones I’m using extend about a quarter of an inch below the service
I hate it how some people can build a house by themselves, while I cause a complete disaster and need help here every time I touch a screw or bolt.
I can’t just use screws and nuts because it’s attaching tabs that have to rotate to a plastic backing, and screws would loosen up, and I want it to look as original as possible.
The riveter works like a jack, push it flat to the bottom of the rivet and squeeze as many times as you need to get it to snap off. With each squeeze you need to push the riveter back to the bottom of the rivet.
It often helps to put a washer on the back-side of the rivet. This will help with it splitting the plastic, and will make it easier to pop the rivet shank off.
Yes to all of the above. Washer, then squeeze twice, at least.
Or you can squeeze it to where you feel it is tight enough and then you can tap the aluminum nail out of the center hole, or cut it off.
Its a stupid tool, you have the brain. 
and I 3rd the washer suggestion.
Hmmm are you placing the pin in the right end? The body of the rivet goes into the hole which you are mending and then the rivet pin goes through from the other side. The pin sticks out and that is what the riveter grasps.
Here is a video http://www.youtube.com/watch?v=0bGAiC0_i_k
For plastic something like a Klamptite rivet is ideal although an rivet with a aluminium head and stem should work, if your using a steel stem rivet its not going to break without the plastic failing.
I did get it to work on rigid material like an old circuit board, the washer trick didn’t work for plastic but I’m pretty sure I have the wrong fastener anyway, the existing rivets have a clear hole in the middle, not a broken off skinny piece, and they’re flush on both sides, while the ones I have extend down about a 1/3 inch.
Sounds like you might need shorter rivets.
Bingo!
Give the rivet something to keep it from expanding far enough to split the plastic, plus keep the edgre from curling up into the plastic.
And it sounds like the ones you are replacing are “hollow rivets” - the so-called “pop” rivets are “blind” or “pulled” rivets.
Make sure the hole you drill = the size the rivet box calls for (this is NOT the same as the rivet diameter!) and the inside of the washer is the same as the HOLE.
p.s. - I could possibly build a house, but don’t expect me to pop-rivet it together 
when I rivet plastic I use a thin metal washer. So add me to the list of those suggesting it. If you don’t have a washer just use scrap aluminum and drill a whole.
Make sure the dimensions are align - the length of the rivet (thickness of the material + thickness of washer(s) + whatever is indicated on the rivet package as pull-through. The diameter of the rivet, hole in plastic and inside diameter of the washer(s).
Excess material will allow the rivet to expand inside the hole and the knob on the end will embed inside the work before snapping off.
Whatever is holding the pieces together, a rivet should be able to work. If not, a grommet is also a cheap and easy bit of work - at least if you have a machinist’s vise sturdy enough to hold the mandrel.
I don’t know if they still make this stuff, or where to get it, but there was a kind of plastic rivet that simply needed to be heated to form the rivet head. You cut a piece of this plastic rod to the right size, and heat applied to either end would cause it to expand. I used some of this at least 20 years ago on plastic parts, my local hardware store carried the stuff back then.
Here’s the Popular Science articlewhere I first heard of this stuff back in the dark ages. Searching for the company Radfast didn’t find me anything. Another simple way to do it is to use a nylon nut and bolt and a drop of glue on the nut once you’ve got it in position.
I guess it’s time for pictures
http://s699.photobucket.com/user/Mdcastleman/media/IMG_2355.jpg.html
http://s699.photobucket.com/user/Mdcastleman/media/IMG_2356.jpg.html
So what kind of fastener do I have, and what tool do I need to put new ones in.
(in case anyone is wondering what it is, it’s a plastic tray to support neon tubing)
Can the top piece be unscrewed from the bottom? Do the tabs pivot about the fasteners?
Is there some reason you can’t just use a machine screw, 2 flat washers (1 each side) and a lock nut to do the job?
I’m guessing that plastic loves to shatter, so a hollow rivet, which requires hammering (for the DIY version) is out.
Back to pop rivet - any rivet must be held in place while being smashed - otherwise the rivet body will bulge between the pieces being riveted.
There’s only one piece of plastic backing and the tabs, the two views are the top and bottom of the same piece. The tabs to swing around to either lock the glass tubing in place or enable it to be removed.
I figured machine screws would loosen up when the tabs were rotated around, and aesthetically it would be preferable to replicate what’s there. The plastic is extremely fragile, since it’s 40 years old and been exposed to heat and thin. I’ve already spent hours trying to patch up cracks and missing spots with JB weld.
Assemble them with Loctite on the threads and they won’t work loose. You can adjust to get the right tension.
My guess is that what’s there is not something readily available (if available at all) as a repair item.