The Siren Board

I have recently acquired a Federal Electric model A. It is in good condition, but there are a few problems. The chopper rubs against the stator twice every revolution. The wire insulation is also coming apart, but I plan on fixing that later. I have already tried to take the chopper out to see if there was any rust, but the chopper wouldn't come out. I did spin the chopper but the only thing out of the ordinary was the areas of contact. Does anyone have some tips on how I could potentially fix this?

Can you post any pictures of the siren by chance? The best way to get the rotor out is to lightly sand the exposed bit of shaft that sticks out from the rotor (if there is any) and spray some penetrating oil around the shaft and rotor. Let it soak for a while, reapply a few times, then GENTLY tap on the shaft while tugging on the rotor. If this doesn’t work, a small gear/bearing puller can also do the job.

The rubbing is more than likely due to either the rotor being knocked out of alignment somehow, be it something due to the motor mount or it ate some debris that put the rotor askew. Before disassembly I recommend marking the problem areas on the rotor and stator and gently grinding down the stator first. Then do a test fit to see if the rubbing is still present. I hope this helps!

Chicagosiren-hunters wrote: ↑

Thu Aug 18, 2022 12:28 pm

Can you post any pictures of the siren by chance?

I currently don't have any but I will add pictures and a video to show the contact points when I get the chance.
Thank you for the help!

Here are the pics

One problem could be that those are not factory-set screws holding the chopper on the shaft. The set screws should have allen screw cutouts, not screw driver cutouts.

_________________
Owner of a Federal Sign and Signal Model 5, Model D, L, RX, Simplex 624-181

.....Also note how the spindle (small round piece) inside the hub (Piece that the set screws are screwed into) is not centered,...that is what is causing the contact w/ the chopper.....the spindle is more than likely correctly centered and the hub , for what ever reason, is not centered correctly.

Unit of Civil Defense wrote: ↑

Fri Aug 19, 2022 1:25 am

.....Also note how the spindle (small round piece) inside the hub (Piece that the set screws are screwed into) is not centered,...that is what is causing the contact w/ the chopper.....the spindle is more than likely correctly centered and the hub , for what ever reason, is not centered correctly.

Do you have any idea on how it could be re-centered? Or should I just go with Chicagosiren-hunters's advice?

thun_derbolt1000t wrote: ↑

Fri Aug 19, 2022 12:58 am

One problem could be that those are not factory-set screws holding the chopper on the shaft. The set screws should have allen screw cutouts, not screw driver cutouts.

Those are indeed factory screws. I don't have pictures handy but my early A, as well as all others I've seen, also has these button-head screws securing the rotor to the shaft. I believe they did this up to the early Enterprises units.

I'd advise taking the whole thing apart before tackling the rotor. Remember there's a motor back there too, so there's a chance that something got caught or the brushes got corroded to the commutator. Send pictures of the motor when you do, then we can try and diagnose from there.

aluminum rotor on a steel shaft. that is a nightmare. as a machinist, i can clearly say, that you might as well break the easiest to fix part. on really badly corroded alluminum engines, i just break the head bolts, and take em out, piece by piece,and helicoil, or drill to a new size, and tap, and go. if that rotor is truly coroded on, you might want to try kroil. it sometimes works. otherwise, you may wanna cut out the center, and make/have made a new one. than the rotor could be centered and balanced again

StormanCharlie wrote: ↑

Fri Aug 19, 2022 3:16 pm

Unit of Civil Defense wrote: ↑

Fri Aug 19, 2022 1:25 am

.....Also note how the spindle (small round piece) inside the hub (Piece that the set screws are screwed into) is not centered,...that is what is causing the contact w/ the chopper.....the spindle is more than likely correctly centered and the hub , for what ever reason, is not centered correctly.

Do you have any idea on how it could be re-centered? Or should I just go with Chicagosiren-hunters's advice?

Do you have any idea on how it could be re-centered?
Yes, probably will cost you more than what you are willing to pay(machine shop) as carolinasignalco alluded to.....

Or should I just go with Chicagosiren-hunters's advice?
No, grinding on the stator wont solve this issue.