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Short-term bridge repair before replacement


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I recently got myself a double bass but I've been tinkering around with things since I've had it.

I've changed the strings from nylon weed-whackers to Thomasik light gauges, which in turn meant I needed to lower the action as the WW's were almost twice the thickness of the Thomasik's. 

In doing so I noticed the bridge was, let's say, on the p*** (I'm no expert by any means but I thought the bridge needed to be at a right angle on the tailpiece side) so the hunt for a new bridge came about...

In the meantime I had lowered the action too much on the G string to the point where if I played higher than the fifth 'fret' it buzzed, I have a gig tomorrow so I needed to adjust this quickly so a short-term plan came about to put shims beneath the 'G' side foot in the hope that it raised the string height.

 

 

 

bridge2.jpg

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Here are some pics of what I did.

 

I put some tape onto the body so I could replace it in the same position.

I then slackened the strings so I could remove the bridge and carefully drew around it - the plan is to cut the drawing out so I have a rough idea of the foot contour for the new bridge.

We have some plastic sheets of varying thickness at work so I selected 2 x 0.7mm and 1 x 0.5mm to build up a spacer/shim. The plastic is very strong but also flexible so *should* adjust to the contour. I did think about using cork but I didn't know how it would respond to being under compression. Maybe others have experience in this but this is meant as a short-term thing to get me through tomorrow's gig.

I added a thin line of double-sided tape to the top of the spacer so it would stay in place beneath the foot before repositioning the bridge and running the string back over it.

 

It doesn't look brilliant but I can live with it for a few days before I'm let loose on shaping the new bridge (wish me luck). I'm expecting it to be a very long job of measuring, shaving, positioning, testing and repeating until it's correct but I hope it will be worth it.

 

A note on the sound of the bass itself with the new addition, it's actually very nice. I thought it would lose some warmth of the tone, what with something as harsh as smooth plastic between the bridge and body, but it's surprisingly nice.

 

I'll add pictures of the new bridge and the adjusting too in case anyone is interested.... 

bridge.jpg

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bridge5.jpg

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bridge7.jpg

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2 hours ago, DaveFry said:

Maybe raise just the G for the gig by means of a silver foil / thin copper packer between the G and the bridge ?

I thought about raising the string but I didn't know if the groove in the bridge would support such a lift.

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Good practical fix. 

 

I guess you tried moving the bridge around a bit and are sure that's the ideal location.  If not it's worth moving it up and down the strings till you find the best sound, then shape the bridge to fit that bit of the belly.

 

Something I realised recently is how bridge height affects sound as well as action.  Low action = easy to play and lots of mwah but a high bridge = more tone and volume. Ideally you want to raise the bridge to get the best sound then have the fingerboard raised up to the strings to get the action right!

 

My bass had the board raised when I bought it, but maybe still too low.  Now have an adjustable bridge ( down for jazz up for classical ).  Trouble is, I'm now hankering after the sound and response of high strings AND the mwah of low strings!  There is no end to this 🙂  .

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That bridge is a bit of a horror show! It will probably steam flat again, but you should really take a LOT of thickness out of the top of the bridge and scrape/plane the sides nice and smooth - otherwise all those dings and gouges will attract and absorb dirt, grime, rosin etc. As far as placement goes, the bridge should be EXACTLY centred on the inner notches of the f holes. That is the way the geometry of the bassbar, soundpost, top graduation etc is designed to work. For the money a decent luthier will charge for a bridge, I wouldn't faff about trying to do it myself. Sandpaper on the top doesn't work. I've never seen anyone get a bridge properly fitted like that. Roughly, yes, but it's the last little details that really make the difference

Edited by neilp
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22 hours ago, neilp said:

the bridge should be EXACTLY centred on the inner notches of the f holes.

Depends on how accurately your bass was made and what's been done to it since. 

 

My bass and cello were knocked up in factories in the late 19th century and much messed with since.  Cello sounds better with the bridge nearer the tailpece, bass sounds better with it a few mm closer to the fingerboard. Tim Batchelar set it up for me... and I don't doubt he got it right.

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5 hours ago, NickA said:

Depends on how accurately your bass was made and what's been done to it since. 

 

My bass and cello were knocked up in factories in the late 19th century and much messed with since.  Cello sounds better with the bridge nearer the tailpece, bass sounds better with it a few mm closer to the fingerboard. Tim Batchelar set it up for me... and I don't doubt he got it right.

But we aren't talking about a much messed with 19th century instrument, are we?

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Ok... Step Two; shaping the new bridge.

I'm going with the old 'sandpaper on the soundboard' method.

I found the masking tape I have doesn't stick well to the sandpaper, but with some fiddling around and securing the top and bottom with extra tape, it holds in place with only minor running repairs needed.

Then it was a case of running the bridge back and forwards whilst trying to keep the bridge upright.

bridgeshape.jpg

bridgeshape2.jpg

bridgeshape3.jpg

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I'm fitting a Realist Copperhead (bought from this site from @BartleyDaviesBass) at the same time so I knew I needed to adjust the contour of the foot to allow for this addition, so I added a spacer the same width as the Copperhead and repeated the back and forwards motion until I had shavings the full length of the foot.

 

You can see the black ink lines of where the bridge should be positioned and the blue pencil lines that gave me a guide for the position. There is only a small area where I can smoothen the feet but the sandpaper was good and with a regular visit from the vacuum cleaner, it went better than I had hoped.

Obviously there is still work to do, but overall I'm chuffed with how it has turned out, the feet sit nice and flat with no spacings.

The next step is to work on the top of the bridge... 

 

bridgeshape4.jpg

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On 30/04/2022 at 15:13, neilp said:

But we aren't talking about a much messed with 19th century instrument, are we?

No, this is a Thomann bass, about five years old. I wouldn't trust myself with something worth thousands.

Then again, I probably will never own a double bass worth thousands.

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Now to trim down the bridge...

I traced over the shape of the arc from the bridge I'm replacing but I've added an extra 3mm or so to give me a little safety when trimming.

I'll be fitting this - along with the new pickup today/tomorrow - and then it's the slow job of adjusting the string height to what I want before removing it again to slim down the width of the bridge to (I've been told 6mm) for the strings to sit nicely.

bridgeshape5.jpg

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And it's on!

New bridge in place - I need to shape the top of the bridge - and Copperhead pickup fitted.

I've moved the A closer to the E by 2mm, personal choice after the previous bridge seemed a little too spaced. 

Chuffed.

bridgeshape6.jpg

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Nice work @dazza14and very brave of you, I must say.

When I read the first post in this thread, I was going to suggest paying just a little more and buying yourself an adjustable bridge -  that way, you can change strings and / or experiment with different string heights.....
But obviously, I was too late to the thread! lol

When fitting the strings, did you grate some pencil "lead" into the slots? This helps reduce friction when tuning the strings.
Hope you find your ideal strings - I've been through a few sets myself ;) 

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23 hours ago, Marc S said:

Nice work @dazza14and very brave of you, I must say.

When I read the first post in this thread, I was going to suggest paying just a little more and buying yourself an adjustable bridge -  that way, you can change strings and / or experiment with different string heights.....
But obviously, I was too late to the thread! lol

When fitting the strings, did you grate some pencil "lead" into the slots? This helps reduce friction when tuning the strings.
Hope you find your ideal strings - I've been through a few sets myself ;) 

Hi, thank you, I used pencil lead on the bridge grooves, not sure if it worked/helped but if it doesn't hinder, I do it.

I did think about an adjustable bridge because it gives me a few options and a margin of error if things go wrong but I opted for a set bridge. The strings are Thomosik light gauges and I like them. I'll be gigging it in a few weeks... (gulp)

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