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Double Bass Broken Tuning Machine

B

Benton

Jun 5, 2002
151
3
57
Waterbury Connecticut
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#1
I'm bummed, I got back from the gig sunday and heard a rattle in my case. The paddle of the D tuning key had broken off. OOps. The machines have worked well for years and I think are original with the instrument. It looks like I need to replace them. I would like to repair it but don't think I can without exact parts. I saw the earlier post on the machines but I they look epensive. I thought I would like to find replacments similar to the originals but an worried about the fit. The post are 3 15/16" apart on both plates. Any ideas and suggestions would be appreciated thanks.

Benton
 
#2
Trying to attach a pic.

pic1.jpg
 
#3
Have you considered having it welded? (bronze-welding, as I am pretty sure the "paddle" is brass, and the fracture was caused by fatigue...) Just looking at the picture, I think any good GTAW welder could put that back together.

Ask around at some specialty welding shops. You have nothing to lose.... It is also possible that it could be brazed, using what is commonly called silver-solder, but which is actually a form of brazing. Without knowing the exact composition of the brass, I can't recommend one over the other, but my intuition would lean toward the Gas Tungsten Arc Welding (Sometimes called TIG or even Heliarc...ask around.)

I guess the other (possibly even better) possibility would be to remove the broken brass stub from the shaft, and install a completely new paddle. Unless the old machines are worn out, I would not replace the machine for an eminently repairable part.

Good luck,

Chet
 
#5
I do like to fix stuff. I thought it was a weak spot to braze but was thinking about it. I do know a pro welder but he is an iron worker I'll have to ask. I'm shure it could be done but it will probably look rough.
Thanks
 
#6
Brazing is a bit like soldering- you really need some area to flow into to get a good bond. Best bet is to remove the broken stub from the shaft, make a new petal, and braze it into the slot. Trying to simply braze the broken pieces back together probably won't hold for long.
 
#8
You can braze these back together if you put a big 'monkey fist' of filler rod around the whole broken bit. It's strong but ugly. Silver Solder needs a tighter and more substantial fit to be a permanent repair. Making a new 'key' from plate brass - what was mentioned just earlier is a better bet. It's possible to make it look like new if you do it this way and take the time to make a new rivet and get the brass plated.

I bought a little dividing head for my milling machine so I could make the Kay gears. It's way more trouble than it's worth but the worm is really difficult to make without an NC or CNC lathe. This part might be commercially available if it's a common size and pitch. If someone had a machine shop make some of the gears and worms they'd probably make their investment back. I've never seen these advertised for sale.
 
#9
to my eye, it is a forged connection, the paddle weakened by fatigue and then sheared off flush, with a remnant still held fast within the 'bulb' of the shaft. Possibly the paddle could get flipped around, filed smooth, & reinserted into the cleaned out slot for a 'farmer fix'.
Might buy some time until you come up with something you're happy with.
 
#12
I decided to try and braze the paddle back into place. I used a brass brush to clean the area, silver solder and my burnzomatic. I clamped the pieces together added flux and heated till the solder flowed flipped and repeated. It was messy but tight. After filing the excess solder drips (I was a little to agressive) and polising it looked mint. the only problem was it was the only shiny part so I polished and lubed the whole set.
P7210193.jpg



I had seached for the best oil to lube it but didn't have shoe polish that was recomended. Instead I used T9 bike Lubeit "cleans, lubes, protects, repels dirt, dust and mud totally waterproof." It has wax and smells good.

I also shortened one of the pegs that was too long and was pushing the plate on the opposite side of the pegbox out with my grinder.

It now looks and tunes better than before.

Thanks for all the help,
Benton
 
#14
I checked with a pro. The only problem is he is a luthier and doesn't work with metal, only wood. His recomondation was replacement. I waited for the parts but once I saw the problem with the fit I had nothing to loose. My mechanic buddy was the one that said it needed to be brazed.

It was too strong for me to break with my fingers but if it gets whacked it will probably fail at the braze. It has been tuning for a week and a half now and is smoother than before.
 
#15
I recently had the same type of problem with an old Kay. I took the whole plate off and brought it to a jewelry "doctor" nearby. They did a nice job fixing it and it cost $20. I figured by the time I bought all the needed supplies and the brass pieces it would cost me at least that. I'm sure they did a better job than I would have.

I think sometimes " I could do that" but there is a learning curve and I don't really have time to be an expert at everything.
 
#16
Benton said:
I decided to try and braze the paddle back into place. I used a brass brush to clean the area, silver solder and my burnzomatic. I clamped the pieces together added flux and heated till the solder flowed flipped and repeated. It was messy but tight. After filing the excess solder drips (I was a little to agressive) and polising it looked mint. the only problem was it was the only shiny part so I polished and lubed the whole set.
P7210193.jpg



I had seached for the best oil to lube it but didn't have shoe polish that was recomended. Instead I used T9 bike Lubeit "cleans, lubes, protects, repels dirt, dust and mud totally waterproof." It has wax and smells good.

I also shortened one of the pegs that was too long and was pushing the plate on the opposite side of the pegbox out with my grinder.

It now looks and tunes better than before.

Thanks for all the help,
Benton
Click to expand...

A little Vaseline works fine almost all of the time as a lubricant. Sometimes the screw in the gear has been over tightened and needs to be loosened a quarter of a turn.
 
#17
Go to a hobby shop or hardware store, and get a piece of brass the same thickness as the paddle, trace the pattern, and cut it out a new part with a jig saw, and then fine shape it, with files. This is not too hard to do, brass is a very soft metal. You may have to drill out a small pin to remove the remnants of the old paddle.

I did this once for a friend who had been carrying around a set of pliers, to tune up his D string for years! He was very happy with the new key.
 
#18
Benton, you are totally my hero. Thanks for posting, the same thing has happened to me. D paddle. Argh! Fortunately, I have a friend who is a jeweler. I've shown him your post. He's worried about brazing with the machine head in place.

Should we remove the machine head, or can it be welded in place? Has anyone welded one while it was on the neck?
 
#20
Hi.

I_plod said:
Should we remove the machine head, or can it be welded in place? Has anyone welded one while it was on the neck?
Click to expand...

Haven't needed to weld/braze them while on a bass and I probaly would in this kind of a case, but I sure wouldn't recommend that approach to anyone who has to outsource the work.

If I was to do a repair like that for someone else, I'd insist that they bring the tuner plate only.

Easy enough to remove the tuner plate and much, much easier to transport to the jeweller frind of Yours than the whole instrument.
The jewellers workspaces aren't usually designed for items as large as a DB either ;).

OTOH, if he/she comes to Your place to do the repair, the call is his/hers.

Regards
Sam
 

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