The Siren Board

Thanks Bryan for the Bar Grille 1000 from Fort Worth!!! Here's what I have found so far...


The chopper looks really good! I guess the horn gasket was blown out so it leaked into the
chopper opening slot and magnesium oxidized the chopper right at the slot. It was only surface oxidation
and cleaned off with scotchbrite! The bearings are really smooth so I'll leave them in for now. The windings
and armature all look really good as well. Collector ring wires are ok at the rings. I should be able to
strip back enough at the tube seal to run the chopper. I had to cut the heads off of the screws to get the motor
out. One screw came out with vise grips and the other two are stuck so I am letting them soak.


Looking at the ancient gear reducer is interesting. There is still gear oil in it! The thing shifted over
in the truck when I made my first turn and oil started running out of the vent. You can sort of see the rotator motor/gear
reducer plate is also drilled and tapped for an Abart type reducer.


The horn support actually unbolted easily. I'll ask the old-timer at work his opinion on
fixing the cracks in the horn. Hopefully that won't be a big deal.


Looking at these bars close up I'm wondering if they are merely reinforcement that they
thought the horn needed originally. I can't think of any other reason for them.

Those are some interesting photos. In regards to the bar shaped grilles, they were basically reinforcements. Federal didn't want the horn to warp about as this would compromise sound output entirely - the horn has to be largely free of any warped spots to project sound effectively.
But then it became obvious the thicker metal panels used for the horn were already strong enough to avoid such severe warping, so they changed the grilles out for the debris-resistant mesh screen by 1955. I don't think the grilles were ever meant to keep out debris.

Well soaking the bolts didn't work. The chopper had stainless round head slotted head screws. One was missing and I was able to get one out after cutting the heads off of them with a Dremel with a little cut-off wheel. Out of all the old rotten Thunderbolts I have messed with I have never had a chopper bolt break until now. I soaked the remaining two and heated them with a propane (all I have) torch (not hot enough) and I did get one to move 3/4 of a turn but then it broke off after a half hour of manipulating it back and forth. Here's a pic of what I came up with to try to get the bolts out. A guy at work has a mag drill so I made a steel plate out of scrap and held it in place with two flat head 1/4-20 screws which were screwed into the good bolt holes.


Here it is before drilling the second bolt out. The hardest part of drilling out a bolt is getting it right on center. If you can do that you can drill with a small drill through the bolt then drill with a drill the same size as the minor diameter of the thread and you can peel the threads right out. You really have to have a mill to get it just right but I thought I would try this mag drill/plate deal because it would be such a pain to figure out how to hold the chopper tube in place on a mill. I hit the first bolt right on center and the threads of the bolt come out through the chopper bolt block wrapped around the drill bit.


Here's a closer view of the second bolt. I didn't have the same luck on this one because I didn't grind the bolt completely flush with the block. The drill walked over a little and there was some of the bolt thread left after I drilled it out. I still have my 1/4-20 helicoil set I used to fix a chopper upper bearing retainer on my first thunderbolt restoration so I drilled it with the helicoil drill and that drill followed the original hole and cleaned everything out. Now I just have to helicoil it and do a chopper test!!

Do you have the rest of the siren?

The birds nest packed three phase blower is still up on the platform in fort worth

Why is the blower 3 phase?

Will the blower and controls be removed soon?

Will the blower and controls be removed soon?

No.

Joshua_2002 wrote:Why is the blower 3 phase?

All series A1 Thunderbolts have three phase blowers from what i know. Single phase blowers with repulsion-start motors started being offered in the A2 series.