Attack of the killer Grafonola

[Phono-Phan]

Well, After over 30 years of doing repairs on old phonographs, one of them finally got me. I was working on a tabletop Columbia Grafonola motor. I could tell there was spring tension on the mainsprings but nothing would turn. There was no tension getting to the governor because I could rock it back and forth a bit. As I was checking out the rest of the gearing all of a sudden the shaft that is driven by the mainspring blew out of the casting with a very loud band. The shaft and gear spun and hit the inside of my hand at the base of my index finger leaving a deep two inch long gash. After about 3 hours at the Urgent Care, I got patched up with a couple of stiches internally and four externally. Fortunately, the cut just missed tendons and nerves. I haven't returned to the scene of the crime yet to find out why the shaft blew out of the motor frame. I guess the moral of this story is that you can never assume how much tension is on the mainspring when working on a motor that is locked up.

[Mr Grumpy]

Glad to hear it wasn't more serious and please keep us posted as to what caused the blow-out.
I was cut deep enough to require inside stitches from a high-five*, and it's usually an indication
of a pretty serious laceration.

*

[Victrolacollector]

Was this that drive gear (bull gear)?

[VintageTechnologies]

Was this that drive gear (bull gear)?

The hospital ER staff probably figured it was really a bull dog. A rogue Graphonola ("what the heck is that?") seemed more implausible.

[Phono-Phan]

You are not far off. I had to explain what happened to at least 6 different people at the Urgent Care facility. All of them also asked what a Victrola motor was. I thought that they would be more familiar with the term Victrola rather than Grafonola but apparently not. I am hoping to get back out to the shop in a couple of days to figure out what caused the shaft to blow out of the casting. I'll post pictures of what I find.

[marcapra]

Once I was at the Stanton auction and was looking at a Columbia Grafonola upright. I pulled up on the turntable to see the motor board beneath and the turntable was stuck on the spindle. Then, I heard the most hell raising sound I have ever heard coming from a phonograph. Metal on metal gears were clashing and getting stripped and the sound was heard all over the auditorium. This was in the real big barn of a place, not the small building where they usually hold the auction. I called Uncle Vanya to see if I had done some serious damage, and he said "yes, the gears are stripped!"

[VintageTechnologies]

Well, that must have been embarrassing!

I think I will stick with the Edisons!

[Phono-Phan]

Well, it has been a week since the killer Grafonola got me. I took some pictures of the shaft that blew out of the motor frame. The pictures don't show it very well but the right pivot tip started gouging the brass gear from almost all the way inside. And then proceeded to put a deep gouge in the gear as the shaft blew out. I just don't know how it blew out so violently. It sounded like a gun going off. Is it possible that the cast iron frame flexed just enough to let the gear fly out? That doesn't seem possible to me but I can't think of anything else. The crank didn't seem to have that much tension on it when I tried to wind it up a little prior to starting to work on the motor. There is no way I can fit the shaft back in place without moving the pivots out. The end pivots for this shaft were securely in place when the shaft blew out. There is also a very similar and older looking gouge mark right next the new gouge that has the same arcing. Maybe this happened once before to this motor. It must be possessed. I am hoping that I can find another motor like this for parts. The mainsprings are now either broken or unhooked and a few of the brass gears are damaged. My hand is healing alright but I still don't have much strength in my index finger.

[CDBPDX]

OUCH! It looks like the adjustment screw for the pivot pin is bent & broken which would allow the pivot pin to move slightly if the tightening screw was even a tiny bit loose. Most likely, the tightening screw for that pivot pin was also just loose enough to allow the pivot pin to slip just a tiny bit. With a full spring winding, there is a tremendous amount of stress on that pivot point. If the pivot pin slips even a tiny bit, that would have caused this. That's probably one of the reasons these points have 2 screws to secure them. I think this was a rare case where both failed. Hope I never have to experience this!

Cliff

[Phono-Phan]

I did noticed the head of the adjustment screw for the pivot was broken but both set screws were tight and both pivots are tight with no signs of moving.