Does anyone remember what those mushroom-type nuts were that were used with threaded rods when putting pay phones on cinder block walls? We have an installation of large flat-screen TVs on block walls in classrooms. The customer insists on threaded rods through the wall to the classroom on the other side. We nicknamed them 'mushrooms', where the rod threaded into a hub on them and the view on the other side was just a domed dimple, similar to the head of a carriage bolt. Any idea of what they were called?

Might have been a weld nut?

They looked like this, but instead of an attached rod, there was a threaded socket to accept the rod coming through the wall so that only the dimple showed:

PICTURE

John, I think you're onto it. I found this using the term 'weld nut' in a search and came up with this, which is very close. The ones I'm seeking are larger and have more of a smooth domed finish, like the head of a carriage bolt. Thanks for the information.

WELD NUT PICTURE

Ed try flat cap nut or blind nut.

Take a look on the McMaster-Carr website.

Binding Posts

Steel Round-Base Weld Nuts

If your talking about 8" CMU, just use a carriage bolt, you can easily find 12" lengths at home depot. Make sure you drill from the opposite side of the TV mount, just in case you blast a hole the size of a barn door, upon exit; the mount will cover this up. Once you thread your nut, you'll also have to plan to cut any excess bolt length off with a 4" cut-off wheel..

would acorn nuts work ?

https://en.wikipedia.org/wiki/Acorn_nut

Sex bolts, like we use on door closers?
https://en.wikipedia.org/wiki/Sex_bolt

Ed,

We always called them Cap Nuts, and they looked like Skip's picture.

Sam

Like Sam and Skip say, cap or acorn nuts and I would definitely use a washer too.

-Hal

What I'm looking for has a 2-1/8" round mushroom that only protrudes from the wall's surface about 1/4" total. It looks like the head of a carriage bolt, only much larger in diameter in order to spread the holding power over a larger area. There are pictures of them in the BSP for coin phone installation, but I can't get a picture on here.

Acorn nuts, etc. protrude too far out and there is an issue with appearance once a nut and washer are used. If all else fails, we may just have to go the route of long carriage bolts.

Ed, if you have to, get a die set and cut threads onto long, unthreaded rod. I've done that before.

Sam

Are the heads on these still too small for you?

Elavator Bolts

Or are you looking for a nut with rounded (mushroom) head?

These are closer, but still not it. The rod part needs to be 12" long, and yes, the head needs to be rounded. The ideal solution is for the nut to have a female threaded entry so that variable length threaded rod can be used.

I think this is what Ed is talking about. I found it at the bar I work at. It was through a brick wall but is otherwise unused.

This particular one looks to be 5/16 thread, the cap is 2-1/2" across and it only sits 1/4 to 3/8 inch proud of the wall.

Ya know, something like that would be a simple thing for a welding shop to make up. Threaded rod welded to a disc. Krylon rattle can paint to match the wall. Easy peasy.

Don't forget that there are double-female threaded rod couplers. You could cut the "stem" of our mushroom back inside the wall, screw on a coupler with perhaps a jam nut then use a regular bolt on the TV mount side. But if looks on that side aren't important just hang the mount on the threaded rod protruding from the wall, sock it up with a nut and washer then cut the excess length.

-Hal

What does it look like where the threads meet the cap?

Welded I'm sure. Definitely two pieces.

-Hal

I guess you could call it a weld. They don't strike me as being made of the same material. The threaded stud shows some rust, while the mushroom cap seems more like stainless. I could take some more photos when I go to work tonight. It's definitely not removable, the thread and cap are permanently joined by what looks like a weld.

Chris, you're spot-on. That is exactly what I'm looking for. I just remember the actual head having about a 1" long female threaded hub on the back side to receive the 5/16" threaded rod. That's why we nicknamed them "mushrooms", because this hub looked like the stem of a mushroom with the obvious mushroom head.

I installed hundreds of pay phones back in the 90s. I can't believe that I don't have any of these things left or at least a name/manufacturer for them!

And they make fun of people for hoarding. If I had only kept those invoices or catalogs. Wait! I do still have my full set of Sprint/North Supply catalogs in storage and I purchased them through SNS. The end may be in sight.

Ed -

If we'd kept all the stuff (material, catalogs, reference guides etc.) that we ever had, we'd be featured on that show "hoarders".

Don't second guess yourself.

The Board is here to help you find all those things.

And it works!

Sam

Glad I could help. Ed, if you find a manufacturer and/or part number, be sure to post back here. I'm not likely to be installing any payphones, but those things could be really handy for mounting all kinds of other things through cement and especially crumbly old brick.

Just wondering would a supplier like Fastenal or Granger have a fitting like that?

I checked and unless they are special order they don't show up on their sites.