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Searching for the perfect standoff or quickie fastener, or stud

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Artemetra

Artemetra

Mechanical
Jun 6, 2011
3
Hello folks, I'm trying to save on some weldments in a structure. In fact, the structure has 38 elements X 5 units X 6 welds per element = 1140 welds! A steel disk is welded 3/8" away from a plate with a port hole, on 3 nuts used as spacers. Welder must tack the nut in place then the disk. 190 disks makes for welders going postal.

What we need is a pop-in stand-off or something. Since the plate and disks are CNC plasma cut, no problem to make extra holes. Holes are 7/16" so 3/8" to 1/2" would work. Plates are all 1/4". Solution is mild cyanide (1%), mostly water - but maybe a thin metal clip would work. I'd love to find a plastic stud with mushroom head that would pop into the holes, then accept the disk.


 
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There is a company - Stud Welding Products out of LA 800-252-1919 that sells a nifty threaded stud welder. Not cheap - like $10,000 and might not be what you need. But we bought two of them and love them!!

At least you can look??!!
 
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Since the disks are plasma cut, one could slit in from the edge (6) places to create (3) tabs which could be formed down providing the correct standoff height. A tool that would form all (3) tabs at once in a press would not be too difficult to make.

Only artemetrA knows the function to know if it works...
 
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I like the idea of a pre-formed part - although it only cuts the welding in half. Same idea with the stud welder - you might still have to put nuts on to assemble after stud welding. There are some nice vids on YouTube for stud welding. Thanks for suggestions.
 
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I could really have fun with the title to this thread, but I will restrain myself...

Mike McCann
MMC Engineering

 
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You mentioned plastic standoffs as a possibility. Might one of these PCB fasteners do the trick?


There are some that meet the 3/8" standoff height, for example:


I'm not sure about the 7/16 hole, but it sounds like you have some flexibility in that regard.

The other problem is the panel thickness, since they are meant for circuit boards. You would need to counterbore, so probably not acceptable if all you're doing is cutting the plates.

Rob Campbell, PE
Imagitec: Imagination - Expertise - Execution
imagitec.net
 
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What about a blind rivet through the two plates with a spacer in between? Could be assembled from one side if that is a requirement.

Rob Campbell, PE
Imagitec: Imagination - Expertise - Execution
imagitec.net
 
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If you make the mounting holes square-ish, then you could cut double-barbed standoffs from say 3/8" plate and assemble everything with big hammers. Probably has a better chance of success with laser or waterjet cutting.

For the standoffs, think something shaped sort of like the letter 'H', or better the letter 'N', i.e. with grooves extending past each other to allow the barbs to spring in.



Mike Halloran
Pembroke Pines, FL, USA
 
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Mike, I am generally lacking in such civilized restraint . . . would that be a one-night standoff or a noon quickie fastener, perchance? Not exactly catalog items but they can be procured on a special case-by-case basis :>) Sorry.

In all seriousness, I also like the idea of a formed standoff or a pop-in circuit board spacer. But really, welders shouldn't complain too loudly, after all, that is what they do, weld!

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
 
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UPDATE: It looks like things may be changing on this - (as they often do!) But this plate is meant to keep solids in powder form from going back down the drain, and the search is on for a no-clog filter fitting. Made of unobtanium, probably.

THANKS for the Richco links - those look like the right thing, and illustrate well what I was thinking, although all too small. All the standoffs and spacer sites I could find weren't as good. My favorite idea is the blind rivet but it's difficult to find one long enough and of correct size/material.
 
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You might consider a blind threaded stud like this one:


You could instal these in holes in your base plate, and then, using spacers around the stud to get the right offset, secure the disk with some nuts.

A quick look around the Penn website didn't turn up any standoffs that would offset from the surface of the base plate in the direction you are looking for but you might be able to find something like that and avoid the spacers.

Doug
 
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My mind is struggling with the 1/4" steel disk being held in place by plastic snaptop fasteners. If you can use plastic, why not just make the entire thing a molded part and snap it into some holes in your base part?

Visit and become a bonafide cybersleuth. Thanks, XSleuth (formerly telecomguy)
 
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