Castle Castings Siren Techical Help: SHAFT NUTS

[Urban Disturber]

I'm currently cosmetically restoring one of two 3-phase Castle Castings sirens I have.

After spending hours heating/hitting/soaking the outside locking nuts on the motor shaft, we had to cut the outer nuts off in the end.

I have one of the original right-hand threaded nuts, which is back on the shaft, but I need another one to replace the cut-off lock nut.

Also, I need 2 of the left-hand threaded nuts as the surviving one has lost its thread after an attempt to clean up the thread on the shaft.
The thread on the shaft is still intact.

If anyone can provide any help, that would be grand, as little can be found on the technicalities of Castle Castings sirens...

In the meantime, here is a video of the siren BEFORE I started work on it:

http://www.youtube.com/watch?v=xL3qFr5eg3Y

[SirenMadness]

Do you have a set of threading dies? Maybe you can use the dies to figure out what spec of thread the shaft is and buy a new nut with the matching thread.

[holler]

For the nuts I would look at a specialty fastner outlet such as Fastenal or smallparts.com.

As for figuring out the thread pitch, get a little thread pitch gauge. They are in most tap and die sets.

[Urban Disturber]

I've been told my someone with a thread gauge that it's a 7/8 BSF (British Standard FINE) thread.

I think I've found some 7/8 BSF nuts on Amazon- including a L/H one!

Otherwise, this is an incredibly rare old-skool thread nowadays...
Som suppliers giggled when I mentioned "7/8 BSF"

[hobbeekid]

Whatever you do to fasten the rotors back in place,make sure they're securely fastened, it could get dangerous if a rotor fly's off on windup....

[Train Fan]

Whatever you do to fasten the rotors back in place,make sure they're securely fastened, it could get dangerous if a rotor fly's off on windup....

He said it's a cosmetic resto job.

[danwisbey85]

when i had my siren, the rotor nut threads were two types, one thread on one side was clockwise and the other side was anti-clockwise, not much help sorry but handy tip to note!

[SirenMadness]

Weird to see two different directions of thread on the same machine. Was this common practice in Europe back in the day?

[Jim Z]

Weird to see two different directions of thread on the same machine. Was this common practice in Europe back in the day?

I don't think it was limited to Europe; when you have rotating machinery where the elements have a good amount of mass, using reverse threading on something rotating in a particular direction is wise. You would want the thread handed-ness to encourage the fastener to "self tighten" in service.

In the '60s it wasn't uncommon for cars to have left-hand thread lug nuts/studs on the left side of the car.

[Siren_Dude]

If I recall correctly, I think my large CLM also has reversed nuts. Can't remember if it was both rotors or just one. I'll take a look later tonight and see.