Double Bass Bridge Setup/Shaping Instruction

[Michael Drost]

Folks,

I plan to shape a new bridge for my back up bass.

I have the Traeger book and everything makes sense except the section on how he uses a compass to trace the exact curvature of the top.

I wonder if anyone can offer advice as to how to most effectively carve the bridge feet to the shape of the top?

Any and all advice is much appreciated!

 

[s0707]

Folks,

...
I have the Traeger book and everything makes sense except the section on how he uses a compass to trace the exact curvature of the top.
...

Could it be the same method as they use to transfer profiles of moldings when they meet at 90 degrees, or profiles of logs in log construction... For the idea, see the 3rd and 4th pictures of the transfer scribe in Veritas Transfer/Log Scribe - Lee Valley Tools

 

[Michael Drost]

Could it be the same method as they use to transfer profiles of moldings when they meet at 90 degrees, or profiles of logs in log construction... For the idea, see the 3rd and 4th pictures of the transfer scribe in Veritas Transfer/Log Scribe - Lee Valley Tools

I believe that is correct sir! Thanks!

 

[Michael Drost]

All done!

 

[unbrokenchain]

Nice job!

I've fit a number of bridge feet and didn't find a need for a compass (or at least didn't know how to use one even if it would have been useful ), just knife and sandpaper. Did you use one in this case?

 

[Michael Drost]

Nice job!

I've fit a number of bridge feet and didn't find a need for a compass (or at least didn't know how to use one even if it would have been useful ), just knife and sandpaper. Did you use one in this case?

Thanks!

I used one of those bridge feet jigs from Gollihur. It worked pretty well. I spent a lot of time prepping. I didn’t use the compass. I just used a thick pencil. It did the trick. Hogged off the wood on my belt sander and did the fine work with the jig, sand paper, and a cabinet scraper.

 

[neilG]

If you're talking about scribing the curvature of the top onto the bridge feet, here's a really simple, nearly free jig you can use. Put some felt on the bottom so you don't scratch the varnish.

 

[Michael Drost]

If you're talking about scribing the curvature of the top onto the bridge feet, here's a really simple, nearly free jig you can use. Put some felt on the bottom so you don't scratch the varnish.

That’s great! I’m going to make one soon.

I appreciate the advice and picture.

 

[Michael Drost]

Folks,

Here are a few more pictures from my adventure yesterday. The jig did have one issue. Perhaps someone else may be able to enlighten me. It wouldn't allow for the bridge with adjusters to be inserted at the proper angle with the adjusters installed. I masked the bridge together without the adjusters and used the jig as normal. It seemed to work fine. I used a lot of blue painters tape to protect the top from damage.

I secured the bass with a ratchet strap(lightly) to my work table and cloths over the edges and a larger cloth rolled up right over the sound post. This held the sound post in position while I did my work. It seemed to work well.

String spacing 1". The bridge arch was tapered to 6mm.

I did make the bridge perpendicular to the top, whereas Chuck T. suggested a slight lean toward the tailpiece.

I fit the bridge with the adjusters provided and after I finished the bridge I installed the Full Circle pickup.

BTW - This is a Thompson RM-200 hybrid. They ship the bass with bridges that have adjusters too large to accept the Full Circle pickup. I am a fan of the FC and have it on my main bass. It just works. This was my incentive for fitting a new bridge.

Anyway, I am happy to have this bass as a backup now.

All said, it was a fun project.

 

[bherman]

You did a really nice job! I did a bridge for my Eminence EUB (the one that came with it had been pretty badly hacked) and it didn't come out nearly as good as yours. I scribed it and used various methods to fit it to the body. Looks like the jig is the ticket, although it;s an expensive tool for one-off use.

 

[Michael Drost]

If you're talking about scribing the curvature of the top onto the bridge feet, here's a really simple, nearly free jig you can use. Put some felt on the bottom so you don't scratch the varnish.

neilG,

Here is the version I came up with today. A piece of walnut about 1 1/2" by 2". Drilled a hole at an angle through the wood. I used a drill bit stop to adjust the height of the pencil. I also added mole skin on both sides to prevent scratching. It can be reversed for different heights as well. Thanks for the idea!

 

[Fredrik E. Nilsen]

String spacing 1". The bridge arch was tapered to 6mm.

I did make the bridge perpendicular to the top, whereas Chuck T. suggested a slight lean toward the tailpiece.

I fit the bridge with the adjusters provided and after I finished the bridge I installed the Full Circle pickup.

BTW - This is a Thompson RM-200 hybrid. They ship the bass with bridges that have adjusters too large to accept the Full Circle pickup. I am a fan of the FC and have it on my main bass. It just works. This was my incentive for fitting a new bridge.

I would probably make the top a bit thinner (from the upper side). The Full Circle comes in different models, for different sized adjusters.

 

[Michael Drost]

I would probably make the top a bit thinner (from the upper side). The Full Circle comes in different models, for different sized adjusters.

Thanks for the advice!

When I spoke with Steve at the String Emporium he said that this bridge would not accept an FC. The threaded size of the old, original adjusters measure 7/16”. Huge! I believe FC only offers 1/4”, 5/16” and 6mm. Don’t quote me on that. Haha.

 

[Fredrik E. Nilsen]

Thanks for the advice!

When I spoke with Steve at the String Emporium he said that this bridge would not accept an FC. The threaded size of the old, original adjusters measure 7/16”. Huge! I believe FC only offers 1/4”, 5/16” and 6mm. Don’t quote me on that. Haha.

Ah, I see. I believe you are right about the FC.

 

[Greg Clinkingbeard]

You guys with your fancy jigs. I’ve done a few hundred by simply holding the pencil flat against the top and scribing a line. Maybe I’m missing something.

Michael, you got your bridge done and that’s the important thing. Be sure the string slots, notches, dents, paths or whatever people are calling them are slightly rounded so the strings make easy bends. The string should make perfect contact on each side of the bridge but the slot should be angled slightly to match the angle of the string. Does that make sense?

Depth should be no more than half of the string diameter and 1/3 is probably enough.

 

[Michael Drost]

You guys with your fancy jigs. I’ve done a few hundred by simply holding the pencil flat against the top and scribing a line. Maybe I’m missing something.

Michael, you got your bridge done and that’s the important thing. Be sure the string slots, notches, dents, paths or whatever people are calling them are slightly rounded so the strings make easy bends. The string should make perfect contact on each side of the bridge but the slot should be angled slightly to match the angle of the string. Does that make sense?

Depth should be no more than half of the string diameter and 1/3 is probably enough.

Greg,

Thanks for the advice! I did use a pencil for this bridge. Haha.

I appreciate the string groove advice. It is noted!

Quite honestly, this stuff(bass repair etc.) is so much fun. I look forward to the next project. Thanks for your help, and thank to everyone for the input!

Mike

 

[powerbass]

If you are doing a brand new bridge you need to make a stick of wood that gently spreads the feet a tiny amount which simulates string tension (downward string tension spreads the feet apart). This one is fancy metal.

 

[BucketOfFish]

This accommodates adjusters. No roller though. InternationalViolin in tool section #T737, $60

 

[KUNGfuSHERIFF]

You fit the bridge to the instrument, then the adjusters to the bridge.

 

[gerry grable]

Nice job!

I've fit a number of bridge feet and didn't find a need for a compass (or at least didn't know how to use one even if it would have been useful ), just knife and sandpaper. Did you use one in this case?

And painter's tape?