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View Full Version : How do I take the top off of an upright bass?



Eric Schatz
12-05-2014, 12:41 PM
I need to fix a crack in one of my lower bouts. It's split from the corner almost to the endpin. I've never taken the top off an instrument and am a little worried about getting things proper. I'm not afraid to do it but I won't go at without a handle on the process first.

Does anyone have any tutorials on this. I have the Chuck Traeger book and am pouring over it. His explanations seem viable but I'm looking for more/other info. Anybody have any advise?

Thanks

george wilson
12-05-2014, 7:30 PM
An old,VERY THIN bacon turner is the tool that is used by violin makers to remove tops and backs. You used to could easily find them in flea markets., They taper down in thickness to extremely thin (.010" or less) at the front end. They are made of good spring steel,too. New bacon turners are not tapered,and are too thick every where.

Hot water on the bacon turners,and careful wedging along the sides will remove the top. It should have been glued on with hide glue.

I made a steamer for such jobs. It is a strong can with a lid that is clamped on(actually a powder container for tank ammunition). You're not likely to find one,so get a small pressure cooker. I drilled and tapped a hole in the top of my can,screwed in a brass fitting,and hose clamped on a thickish neoprene hose. The kind with fabric imbedded in it. Thick so as to not burn your fingers. I made a tapered mini nozzle on the front end and flattened it so the steam would come out in a narrow jet right into the joint. Set upon a hot plate and it's ready to steam all loose. Minimal damage to the varnish is desired. Thus the squeezed down nozzle. This and the bacon turner will do good work.

Mel Fulks
12-05-2014, 7:59 PM
I've used springs from broken tape rules for similar but smaller projects. They are real thin and can be filed a little thinner
on the ends.

Kevin L. Waldron
12-06-2014, 9:45 AM
A commercial heat gun ( hair dryer style.... but with variable heat settings $100-250).... set for about 210-225 ( could possibly take more to get the process started... but it will kinda flow once you get started and you can back off the heat ) you will need to use a tool similar to recommended above....If you want to steam it off use a Shark Steamer (Walmart or similar.... about $65) Should be hide glue as mentioned above...... you can re-install by coating the outer lip of the top with hide glue let it setup/dry.... replace top and use the heat gun to again apply heat and clamp as you go.

Blessings,

Kevin

Eric Schatz
12-06-2014, 12:25 PM
I've checked it out and I can get the top off pretty easily I think (with patience). How do I make sure it goes back on lined up correctly? I'm more worried about the putting it all back together part than the fixing part. Do I need jigs to aline things or do I just make sure there's enough lip around the outside, glue, clamp like a mad man and let it sit?

Kevin L. Waldron
12-06-2014, 2:21 PM
If I were doing this... mark top/outer rim with something that could be removed.... pencil/marker etc. Proceed to remove top..... drill head block and tail block with small index hole.... place small sharp/index pin in holes...... replace top prior to work and align with outside markers.... gently press and you now have index locator pins...... repair top and replace/re-glue using index pins as locators.

We often do this with a fret board..... we will shoot two staple into the neck..... cut the staples placed in the neck with pliers etc. leaving a barb ever so tall/small in the neck.....place fret board on neck and press gently .....you now have index pins for line-up and gluing. Small barb/pin has minimal impact on the instrument. If you don't like metal barb you could use wooden dowel sharpened.

Blessings,

Kevin

george wilson
12-07-2014, 6:08 PM
I have long used a heat gun for heating up the celluloid bindings on guitars. They bend like wet noodles when hot,and hold their shapes when they cool.

However I would really caution the use of heat guns AT ALL for removing tops and backs. The heat guns can very easily get things too hot. They can instantly fry celluloid bindings,and can melt and destroy varnish,and crack and warp wood. Even in experienced hands celluloid can be gotten too hot. That is not of much consequence when the celluloid is not yet attached to an instrument. But,irreversible damage can definitely result when you're playing the heat on wood.

My very best advice is to not try using one if you value your instrument. Stick to what I have advised.

Kevin L. Waldron
12-07-2014, 7:28 PM
Don't totally agree with George.... one reason there are 256 Crayon Colors in the large box of Crayons...... there is someone who likes one of them or all of the colors somewhere..... everyone has an opinion and we are all entitled to ours! We respect George for his.. and his experience.

We've done a lot of instrument building, repair and woodworking ...... ( still sell musical instrument parts, pieces, kits, instruments, etc. ) probably been around almost as long as George.....

Thus the reason I recommend a commercial dryer preferably one with digital readout or at least a cooking thermometer. Shellac will begin to melt between 176-212 degrees. Shellac is technically a
a bioadhesive polymer.... natural plastic..... it is fairly consistent in its melting point. Hide glue will begin to melt at or around 140 degrees. The heat gun temperature needs to be somewhat higher to transfer the heat to the joint and the removing tool...... it's fairly easy and straight forward to remove part's, piece's using this method.... although I'd admit it is not for a novice... but if your removing a top of a double bass I'd assume you have some experience or you would not be attempting this.

Further disagree that All instruments should be made with hide glue.......there are always exceptions/limitations on any glue...... hide glue limitations for the most part include it's thermal limitations, micro-organism destruction of the joint, and low shock absorption...brittle joints ....... Use the best glue for the intended purpose and needs, destination/environment, whether that be Hide Glue, Fish Glue, PVC glue, Polyurethane Adhesives, Resorcinol Glue, Cyanoacrylate Glue and others. Violin's for the most part are well suited for hide glue but if an instrument were going to be used in a hot arid area, desert, or tropical location or for that matter an extreme cold environment hide glue would not be my first choice.

Blessings,

Kevin

Some of the kits we now make
301773301774

John Coloccia
12-07-2014, 9:35 PM
My first thought is why are you taking the instrument apart? Can you post a picture of the damage? Unless it's splintered and you need to rebuild the area, you can probably repair it pretty easily without removing anything. I could try to explain various methods to do it, but there has already been so much written and explained online that I could never possibly do as good a job as has already been done. Suffice it to say that there are numerous ways to align the crack if necessary, perform the repair, clamp reinforcement cleats to the inside, and all without any invasive disassembly of the instrument.

Jim Creech
12-08-2014, 11:37 AM
I agree with John. I have repaired many a bass and cello without removing the top (or back). If there is no possible way of effecting repairs without removal I would remove the back rather than the top. To soften glue I use hot vinegar. You may need to score the finish to allow the vinegar to seep into the joint. It takes time and patience but no worry about possibly damaging the finish with a heat gun. Post some pics and maybe we can better help.

george wilson
12-08-2014, 11:46 AM
Admitting a heat gun is not for a novice is an important statement. If this is admitted,why recommend it to a person who's experience we don't know? He has said he never has taken the top off an instrument. That should be a clue.

As mentioned above,vinegar is a good way to get glue to soften. It is even used by the furniture conservation department in Williamsburg,a World class furniture restoration group.

Instruments glued with hide glue have managed to last hundreds of years. That is a pretty good track record. They may have been repaired,but they WERE able to be repaired. Not all have been repaired at all,though. Egyptian artifacts have been found glued with hide glue also,lasting thousands of years.

How do you know the bass is finished with shellac?

There are many things I do that I would not recommend to a beginner.

It is just way too easy to overheat,causing damage as I have noted.

Eric Schatz
12-08-2014, 9:24 PM
Let me say that I have no experience with instrument building or repair. My bass is carved and I paid around 10K for it. However, I have a pretty decent wood shop and do most of my work by hand (other than breaking down large sheets and resawing, and routing profiles). I'm pretty sure I have all of the equipment that I need for this (other than a fancy heat gun). I also have a friend that has done the same operation.
Having said this, I'm a middle school orchestra teacher and a first time dad. I have no budget for the $1400 that has been priced to repair my instrument. So I'm off to do this myself. I could post a pic of the crack if I could figure out a way to do that.

george wilson
12-08-2014, 9:37 PM
Eric,where are you located?

Eric Schatz
12-09-2014, 7:55 AM
Terre Haute, Indiana

george wilson
12-09-2014, 10:22 AM
What brand of computer do you have? I PM'ed instructions for using a Mac to load pictures. Someone else could chime in if you have a different computer. You have to have a camera with a USB cable to get started.