Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum JB weld to fix a pedal?

Hi folks,

I have a Schubert piano from the the 1890s. Unfortunately, we snapped one of the cast iron pedals while moving it. No welder in town wants to touch cast iron, and I can't find anyone to braze it.

I was thinking about doing a redneck repair: JB Weld!

The backside (bottom side actually) of the pedal is hollow, so I was thinking about JB welding the pedal back together and then putting a piece of steel rod inside the hollow part held in with JB weld, of course, for extra rigidity.

Has anyone attempted this before? Is this even worth my time?

I can't find any replacement pedals online, so I feel like this is my only option for an inexpensive repair.

I did a little internet research, and people use jb weld to glue cast iron together. Heck, one guy did it to his Winnebago's engine block. Also, glue a steel rod to the underside of all of the pedals, just as a preventive measure. I sure hope I'm not steering you wrong!

Dudes engine block
http://www.youtube.com/watch?v=zb-kXty8bTY

PS. Take a wire brush to the points to where you are gluing, and get them clean.

JB "Weld" is an example of triumph of misleading marketing. A properly descriptive term would be JB "Expoy." It has a small fraction of the strength of cast iron. As with any overly hyped and skillfully marketed product there are lots of (dubious) testimonials.

The advertised tensile strength of JB Expoy (likely overstated by the same folks who successfully mislead the public to associate this glue with "welding") is about 20% that of cast iron.

http://chemistry.stackexchange.com/...imum-pressure-that-jb-weld-can-withstand

http://www.anvilfire.com/article.php?bodyName=/FAQs/cast_iron.htm

I am only a DIYer when it comes to pianos and overwhelmed by detailed discussions about temperaments etc., but I am in my element here as a several decades vehicle repair shop owner and a dirt track stock car builder/racer/maintainer for 13 years.

All the above said, if you don't anticipate the pedal ever again being stressed in any way approaching the event that broke it, and if you add reinforcement it might work. A skilled properly equipped welder can weld cast iron. There are those who do it regularly.

Don

It may be cheaper and easier to replace all of the pedals than to repair one of them.

JB Weld will last about 10 minutes on this job

I would agree with the others here in regards to welding vs epoxy vs strength of cast iron, with one exception....

Some pedals were designed incredibly poorly with the original casting. Sharp corners, weak transitions to stress points and excessively large holes in them for the trap linkages (this last one is a common place problem in some pedals and they tend to crack on the thin remaining sides aroune the holes).

That said, I have fixed a few pedals without issue using Devcon 10110 because of time/travel constraints. It has an adhesive tensile shear of 2800 lbs, compressive strenght of 8260 psi, and 5600 psi flexural strength and is the ideal choice IMHO.

The important thing is that reinforcing steel needs to be used (threaded rod) and the epoxy needs to be keyed into the surface with a dremel and carbide burr. The keying needs to be done in a way that you further don't weaken the original metal in new places.

It can be done, but this is not a job where you simply lay in some steel and gop epoxy all over the place...you have to be fairly clever about it.

Cast iron pedal failures can be mig or tig welded. I find it hard to believe welders out there are still scared to perform this task. Cast iron has issues with temperature shock so tiny tack welds are used then back filled and ground smooth. About a 30 dollar repair.

Google muggy weld and watch the numerous videos on welding cast iron parts deemed junk by the " world is still flat club"

I've done some redneck repairs with JBWeld very successfully.

You need to take care with surface preparation and alignment. Clean it very well, degrease with mineral spirits and alcohol, build a jig of some sort that would hold it while it sets, don't move it too early, etc.

In a case like this I'd pay to weld it. But, if JBWeld is really 20% as strong, and you have a hollow back, you can probably make the strength up by making it 5 times as thick.

I would do it in steps. First glue the repair, then stitch across with several rods (nails might work), then a thicker layer across that.

If it doesn't hold, use the old one to make a mold and cast a new one out of aluminum or whatever the local shop likes.

Or, use one of the old ones as a plug, do wet layup fiberglas over it to make a female mold, then layup fiberglas inside the mold for a perfect replica. Lots of ways to solve this one.

Or,
carve one out of wood.

Get some quality plywood, Baltic birch would work; clamp it in a vice, use a coping saw to get close, a four way rasp to shape, some sandpaper.

I have torn down many dozens of old pianos. If the pedals are salvageable I usually save them for just such an occasion. Why don't you post a picture, maybe a pac-rat like me or someone else may have just what you need.

Here are some pics:

If you look closely at the bottom pic, you will see the crack right next to the spot where the gold paint ends.

So far, after an hour and a half of calling, I've found two people who are willing to weld it. One is not cheap, and the other will not quote me a price till I bring it to his shop which is 1.5 hours round trip. I'm already looking at selling this piano at a loss, so this stings even more!

Any suggestions on where I could find a replacement would be much appreciated.

Schaff 1576 for brass, 1578 for nickel. You may need to adjust the mounts, but they should be a reasonable match. Replace all three pedals.