Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Demonstration of "The Zapper"

I was taking some time this morning to even out the friction on my "new" 1912 Steinway O. Amazingly this action has pretty free action centers, but there were a few tight hammer flanges here and there. I took this opportunity to try out the "Zapper" that Del loaned me a while back (Thanks Del!).

Sorry about the poor quality. My 15-year-old daughter recorded this on her cell phone. However, this video will go down in history as my debut on Youtube!

http://www.youtube.com/watch?v=9YKcPOWVjcw

Very nice Ryan. Thanks for the demo. Wonder how you make one of those things? Or, if they are for sale somewhere?

That's amazing! I though surely it was snake oil when I first saw the vid. Obviously not, and with Del in the picture I ought to have known better. But I am curious, how exactly does it work?

Thanks for posting the video, Ryan.

I guess it's a voltage converter attached to a couple electrodes, with a breaker in the middle (it seems it has a knob, perhaps a potentiometer to control the applied voltage?).

It applies a low electric current to the center pin. By doing that, the pin slightly increases its temperature, and dilates (easing the bushing). After it cools down (rather fast), the pin is back to its normal size.

Looks like a simple, but quite effective device.

Ryan:

Do you have a multimeter? Are there any numbers in the device that could give us an idea about the applied current?

I believe it has a pretty good sized transformer that steps the current down so it doesn't "Zap" you!. The end you touch to the centerpin is a pair of tweezers that's been separated by a wood block. The circuit is closed by connecting to the centerpin which heats up due to resistance.

I had been reading some old Journals from the 70's and occasionally would come across a mention of the Zapper. I was down at Del's shop some time ago and asked if he'd ever seen a "Zapper". I was pleased when he replied "I've got one around here somewhere...". (I think Del has just about everything piano related "around here somewhere...".

I've read that the transformers in doorbells works pretty well. It would be fun to make a few of them for a chapter project. It's supposed to work well for freeing up other parts like stiff let-off button eye screws.

A multimeter? I know I have one of those around here somewhere...

Let me see what I can come up with.

I don't think the pin could expand to such a degree as to have an easing effect. I think it acts by scorching the felt a little bit. If you leave it on too long it will be too loose.

I have a spring loaded micrometer with a plastic anvil. I'll see if there is a measurable size increase in a centerpin when running the current through it.

I think you could be very right about scorching, that might affect the bushing more than the dilation.

Thanks! That's an amazing piece of equipment. So it basically heats the centerpin (metal, I'm assuming) by electrical resistance. I wonder if the expansion if the metal as it heats up is what frees the bushing.

I just measured the pin while zapping it and found no measurable increase in size. It did get pretty hot though! Its actually a good thing the pin doesn't get significantly bigger or it would just enlarge the birds eye making it loose in the wrong place!

I see; So what are you loosening? I'm not terribly knowledgeable in this realm, but I am curious.

I guess it's like holding a strip of foil across the electrodes of a battery. Boy does that ever get hot!

I think the reason the Zapper was around in the 70's but disappeared is because it does loosen the centre pin in the birds eye as well as the bushings. I think that I recall seeing scorched wood from the use of this devise but it was a long time ago, as you said they disappeared. I don't think this is the same as the conspiracy theories about car companies sitting on patents for fuel efficient engine designs. I think this one died because of the downside of burning the wood components. When we repin we make sure the pin is tight in the wood and works freely in the felt bushing. The Zapper doesn't make that distinction.

Interesting point, Thomson. I'll have to do some more experiments and see what effect zapping has on the birdseye.

Yep, completely insignificant variation in size...

Note to self: don't talk about physics right after taking a nap

I tried some more zapping and after letting the part sit and cool down I cut the shank away from the flange leaving just the pin in the flange. The pin was still snug in the birdseye. I did this on 5 samples and they all stayed snug. I then zapped one for 20 seconds. It did get a little bit looser but was still tight enough that it wouldn't wander. My conclusion is that the Zapper doesn't really affect the tightness of the pin in the birdseye significantly.

I easy key bushing by ironing the bushings with a heated brass caul of a convenient size. What it does is to heat the felt (and the glue) and removes any humidity from the felt.

I think the zapper does not scorch the felt but dryes it, the same way the heated caul dryes the bushings.

When repairing shank flanges I always put a pin the same size it had and I ream and burnish the bushing felt until I have 4 to 6 cycles. Only if the center pin of that size is loose in the bird's eye I go one size up.

I think the zapper can avoid a lot of repinning work.

I wonder how it would work on my wife when she makes those 25 mile long lists of chores that she wants me to do? Hehehe.

What's interesting, Jerry is that you hold onto the tweezers while you do the zapping so the current is running through YOU as well as the centerpin. But I think it's like putting your finger across a 9-volt battery - you don't really feel it. Yet as Horwitzian observed, put tin foil across the battery and you'll get some heat!

I bet if you put the Zapper on your (or your wife's!) tongue...Now THAT would probably be quite effective! That's an experiment I'm not planning on trying!

Made my own and use it for certain applications. The time that it actually applies current to the center pin is about 2 to 3 seconds - rarely more. This is usually not enough to heat the wood in the birdseye enough to cause damage.
The downside in my opinion is that many times the flange bushing is tighter on one side more than the other - the zapper cannot make that distinction.
Just now assembling new flanges to new Tokiwa whips and the majority of the flange bushings are tighter on one side than the other. Glad they did not come assembled. Won't be zapping them.

Hey Ryan. I just noticed that all the "Related videos" attached to yours relate to fishing and not piano tech work.

It's an interesting idea. I could see where it would have its uses. Does verdigris come back after being zapped? Ryan, give us a 50,000 mile update later this year

In most instances, reaming and repinning is a more effective fix (I think). As Gene points out, reaming the bushings to the correct size on both sides is important. And I can dip the pins in teflon powder before insertion.