Shock mount differences

[Jordan Baker]

Hi all

I have noticed some slight differences in the wireless set shock mounts. Particularly for the centre metal portion. The two sandblasted parts have threaded holes. One hole had a partial counter sunk. Then the all black mount is only counter sunk. The centre section is also made a slightly thinner piece of metal.

Has anyone else noticed differences like these?

[David Dunlop]

Hello Jordan.

My suspicion is the countersinking work was done by someone who was using the bridge for a purpose other than its original intent. It makes no sense at all in any wireless applications I have ever seen. The bridge is designed as an intermediary component in a wireless installation, not an end component where a nice hidden bit of hardware is required.

I have seen variations in metal thicknesses over the years, as well as subtle variations in the angles/shape of the metal bits which are probably manufacturer variations. When placed side by side, these various bridges all showed the same height and spread between the mounting holes in the feet. These, it would seem, were the two critical measurements.

What I have seen over time, is that a small number of these bridges turn up with no BA threading at all in the top holes. Drilled smooth. I think this is a post war mod when supplies of BA hardware where dropping out of the supply system.
The reason the bridges were threaded in the first place was because some wireless installations have precious little room to get a spanner down underneath the bridge to access a nut. The process of installation would have been to mount the bridges with easy access to the required hardware. Then the wireless carrier would be mounted to the bridges. Since the bridges are threaded, and can no longer move when bolted down, the cheesehead BA screw has a round, internal thread lock washer placed between the head of the screw and the carrier face to prevent it from loosening when run home.

Once the top threads of the bridge are drilled out, you have no choice but place a lock washer and nut down under the bridge, the lock washer between the nut and the underside of the bridge to prevent the nut from loosening. This won't work with limited access in some installations.

Hope this makes sense. I haven't had my morning cup of tea yet.

David

[Jordan Baker]

Hi David

It makes perfect sense to me after being up all night from night shift. Lol.

I had not thought of the idea of my having enough room to get a spanner in there for securing the tray.

I've made a mold of the black one. My intent is to recast new rubber with the broken ones with new made metal ends.

[David Dunlop]

Sounds like an interesting project, Jordan. If you want to drill and tap the tops for the correct BA hardware, there is a company just outside of Boston that sells it. If memory serves me today, the cheesehead screw required has a 3/4 inch thread length and one inch is the common size today. I found they trim down just fine and the company in question is great to deal with.

Also, I recall about a year ago, somewhere on the forum, somebody in Australia posting that the stock these bridges are made from is still in production and available in certain lengths from somewhere. It is basically a long slab of the three steel and two rubber sections already bonded together. Cannot find the thread right now, but if still available all you would need is a shop style electric hacksaw to set the stock into to slice off the right sized pieces for drilling and tapping the three appropriate holes.

Now go get some sleep. I'm finally into the tea now.

David

[Ron Pier]

We had this thread a few years back. Rob Love indicates a supplier of a modern equivalent.

http://www.mapleleafup.net/forums/sh...ad.php?t=22650

Ron

[Jordan Baker]

Thanks for the links guys. I've been reading these old ones all week.

I was more interested in learning about the differences between the different styles I had pictured.