Search for #10-32 Cage Nuts to fit Ampeg SVT-CL Preamp mtg flanges

[nevetslab]

After placing the order for the #10-24 Clip-On Nuts with MSC Direct, I went back to McMaster-Carr to place the push-in nylon part into my next parts order with them, and, after looking further with their clip-on nuts, I found basically the same part as I just ordered from MSC Direct for way less. So, I ordered those....McMaster-Carr P/N 94850A120 for $10.29/25 pcs. So, I ordered those, along with that nylon part to inspect. Went back to MSC Direct to see if I could cancel that order. I was told they have a 10 minute window to cancel or change an order, but they checked with the warehouse in Neveda, and were able to cancel the order. Whew! I've attached the part drawing of the McMaster-Carr part below;

#10-24 Clip-On Nut McMaster-Carr.pdf

[nevetslab]

The McMaster-Carr parts arrived yesterday, while I played hooky. The Black metal Clip-Nut looks like it will drop right into place, though substantially larger than the cage nut. Between the spring metal 'clamp' wings, there is a smaller spring punched out that does the clamping function, with the width of that part fitting into the 0.281" square hole, so it will register in the hole. I've yet to open an SVT-CL to confirm this.

The Nylon square molded part looks to drop right into place, with the 'wings' that serve to lock the part into place expand when the mating screw is threaded into place. The thru-hole is 0.136" ID, passing thru the 1/16" thick mounting flange (the part is called out to work for both # 8 and #10 screws). So, I fetched my small machinist vise to hold the part, clamping the wings so the #10-24 tap would also cut thread into both sides of the wings. After removing the tap, I rotated it in the vise, ran the tap thru again allowing the wings to expand, driving the tap thru further, to see if anything broke in the process. Nothing did. Then, threaded a #10-24 socket cap screw into it to see the part with the wings expanded. At the base, with the screw threaded in, the wings expanded from the nominal 0.278" width to 0.286", while the wings expanded out to 0.375" with the screw threaded all the way thru. I didn't see any hint of cracking at the base, so threading the mounting screw into it further locks the part into the chassis flange square holes. The big question in my mind, of course, is.....will the part break at some point? From a breakage stand-point, the Clip Nut wins hands-down. Cost difference between the two parts: $0.27 ea on the Nylon part ($13.30/50 pcs min qty) vs $0.43 ea on the Clip Nut ($10.79/25 pcs min qty).

I haven't yet opened up an SVT-CL to check both parts out. I did just get an SVT-VR into the shop, so I'll at least get a chance to see how it's mechanics are for either part. It too uses the same #10-24 x 1-1/4" Oval Head screw as the SVT-CL to mount the preamp into the cabinet.

[nevetslab]

I have an SVT-VR in the shop now, one that hasn't ever been set up, so loose hardware everywhere, no protection sleeving on the hold-down clamps, overheated crimp on the heater wire terminals on the back side of the power tube PCB assy. So, good opportunity to try the cage nut replacements. The rear pair are mounted into the preamp chassis flange, while the front pair are mounted into the removable cover. Those cage nuts will have to be replaced by similar cage nuts or those Nylon parts I had to tap, while the rear pair I can fit the #10-24 clip nuts. I removed those cage nuts and tucked them away as replacements, and installed the clip nuts. They fit just fine, with the internal stamped spring from the formed metal clip registered into the chassis opening. I thought for a moment, with the cage nuts installed, that the openings were rectangular, but it was just the cage nuts masking the square opening.

I then prepared one more Nylon part, cut threads into the part, then removed the two front cage nuts from the Preamp cover, and pressed in the Nylon parts. As the center of the part no longer 'floats' as the cage nuts do, I did have to slip a scribe thru the cabinet screw holes to register the Nylon nuts on the front of the Preamp. They did thread in just fine, as do the rear clip nuts. I'll leave these installed, once I'm thru with the Set-Up process on the new SVT-VR, adding four Asian #10-24 cage nuts to my Ampeg Parts supply.