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Bridge modification - angles and bodges   You are logged in as Guest
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mrstwinkle

 

Posts: 444
Joined: May 14 2017
 

Bridge modification - angles and bodges 

So - ongoing old guitar with neck angle problem. Have shaved down bridge and saddle massively, but still need to lower saddle even more (2mm-ish). Guitar is playable at the mo at settings in pic but really could do with going even lower on action.

I can probably drop a little lower by cutting into the wood of the bridge by a fraction, but concerned my break angle will disappear. So was wondering is there any reason I can't get a strip of rosewood and glue it between the holes of the bridge and the saddle to move the point at which strings meet holes is closer to saddle? i.e. are the holes purely an anchor point or do they affect the acoustics somehow?

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  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 2 2017 14:32:20
 
Morante

 

Posts: 1774
Joined: Nov. 21 2010
 

RE: Bridge modification - angles and... (in reply to mrstwinkle

Remove the frets and plane the fretboard towards the nut. Replace frets, problem solved. Alternatively, you could remove the back and reset the neck
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 2 2017 15:19:07
 
keith

Posts: 1108
Joined: Sep. 29 2009
From: Land of Daniel Boone

RE: Bridge modification - angles and... (in reply to mrstwinkle

first of all, what is the current action with the set up? second, what is going on with the saddle? it looks to be not seated and coming out of the slot. a new saddle is definitely in order. I am not sure there is 2mm saddle that can be removed. it appears major surgery is needed.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 9 2017 10:22:39
 
mrstwinkle

 

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RE: Bridge modification - angles and... (in reply to keith

Action is just under 5mm at 12th fret.

Saddle groove is down to about 2mm deep so saddle is more sitting -on- rather than -in-. it actually sounds okay and looks worse in photo than in reality since sandpapering it down led to unevenness at the ends. A problem with a saddle this thin is it flexes while sandpapering down.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 9 2017 13:40:46
 
Echi

 

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RE: Bridge modification - angles and... (in reply to mrstwinkle

If I was in you I would first make an estimation on how much is the guitar worth.
If it’s worthy to fix it, then I’d ask a luthier to do it properly as these kind of works is often complicated.
IMHO a guitar should have at least 6.5 mm distance between the top and the bottom of the string at the bridge. Less than this can make it difficult to play for your right hand. In other words, be careful not to shave the bridge too much.
In your case the action is so high you probably need to have your guitar properly assessed before trying to fix it.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 9 2017 14:38:48
 
Flamingrae

 

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Joined: May 19 2009
 

RE: Bridge modification - angles and... (in reply to mrstwinkle

Someone needs to start a thread "Polishing a Turd". That aside, a few suggestions - up to you how far you take them.
1/ Plenty of wood on the bridge - you can cut the saddle slot deeper
2/ Make new saddle to fit.
3/ Break angle - plug holes and re-drill lower down nearer the soundboard using drills mounted into a length of 2 or 2.5 steel. You can do a 12 hole system that will mean you get a better break angle.
4/ You might have to cut the middle channel of the bridge a bit deeper if you do No.3 to expose the redrilled holes. I've used a router to do this before.
5/ Keith's suggestion of a new bridge is also quite valid if any of the above appears to be beyond you. Whilst you get a good chance to make everything function, it relies on you positioning everything as is, to get it to play in tune.
6/ You could take the bridge off, make amends and the put back on??

I have my own "turd" on the table at the mo. However, I took everything off from the main frame, replaced the soundboard with one that was redundant from an earlier job. It's almost the same as building from new now, so I don't have the "repair" factor to deal with.
Hope this helps.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 9 2017 14:58:00
 
RobF

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Joined: Aug. 24 2017
 

RE: Bridge modification - angles and... (in reply to mrstwinkle

Without seeing the rest of the guitar it’s difficult to recommend a solution but I think any further bridge work should only be carried out with a mind towards stabilizing the structure. The solution lies at the neck end, as Morente has suggested.

For the bridge, I would deepen the saddle slot by about a half millimetre, just to the point where the bottom of the slot meets the wing and fit a saddle the same width as the slot having about 1mm protrusion above the wood of the bridge. I’d also clean up the flat spot made by lowering the wood, but that’s just cosmetic, unless the strings are hitting the wood after exiting the tie block hole, in which case it should be done.

If there is enough wood on the fingerboard then Morente’s suggestion is probably the first line of defence. Basically, you remove wood from the nut end to reset the neck angle to give you the desired action at the 12th. But, if the fingerboard is thin, say much less than 3.5 - 4mm, then this might not be possible or desirable from a structural point of view. At that point replacing the fingerboard with a deeper one could get you where you want to be. A 6mm thick fingerboard is pretty standard and will effectively lower the action by ...*edit - sorry about this, it should say... ‘half of’ whatever the difference in thickness is from the old fingerboard.

If the fingerboard dimensions are already good then slipping the back could be considered, but this is major surgery. At that point you have to ask yourself if the guitar is worth the trouble.

All IMO, of course. Best,
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 9 2017 16:21:05
 
mrstwinkle

 

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RE: Bridge modification - angles and... (in reply to RobF

I think I'll try deepening the saddle next as suggested. I don't have a router but I reckon half a dozen mini hacksaw blades side-by-side would do it, albeit crudely. Yeah the surface of the bridge will get scruffed up but i'm not too fussed. if I an get 2mm from that it might just be enough.

Fretboard -could- be shaved down a bit at the nut, maybe to the depth of the fret wire grooves. But we're talking here-be-dragons point of no return stuff with my limited skillset.

Tricky one to judge value. On one hand it is theoretically a junk a guitar that cost very very little. But I like it as it sounds good..
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 9 2017 18:49:43
 
RobF

Posts: 1116
Joined: Aug. 24 2017
 

RE: Bridge modification - angles and... (in reply to mrstwinkle

Hi, I think deepening the saddle slot to give the saddle more support than it has now is a good thing. But I personally wouldn’t shave the bridge any more. At this point, looking at what can be done at the neck is a strategy worth considering, IMO.

Bringing it to a local luthier for their opinion can’t hurt. If you like the sound of the guitar then having the fingerboard planed and refretted might be worthwhile.

But if the guitar has little value and you are enjoying doing the modifications as a do-it-yourself project, then anything goes, I guess, and you can try to get what you want through altering the bridge. It makes sense to want to stay within your limits rather than pushing it to the point that you end up with something that’s no longer playable.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 9 2017 20:22:36
 
RobF

Posts: 1116
Joined: Aug. 24 2017
 

RE: Bridge modification - angles and... (in reply to mrstwinkle

If you want to clean out or lower the saddle slot an easy way to do it is to take a piece of hardwood slightly narrower at the edge than the slot’s width and shorter than the slot’s length, square up the edge and glue some 80 grit sandpaper to the edge. Trim the sandpaper flush and you’ll have a sanding stick you can then use to sand the bottom of the slot. No need for routers or saw blades and you should be able to do it without harming the wings. Cheers,
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 9 2017 21:26:18
 
constructordeguitarras

Posts: 1488
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Bridge modification - angles and... (in reply to mrstwinkle

Remember that to lower the action at the 12th fret one millimeter, you would need to lower the saddle two millimeters--because the 12th fret is the mid-point of the strings. At 5-mm action, you would want to lower the saddle a minimum of 4 mm, to get 3-mm action, which is playable for flamenco. It does not look like you have room to do this on your bridge.

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www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 10 2017 4:25:52
 
estebanana

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RE: Bridge modification - angles and... (in reply to mrstwinkle

If you have a neck angle problem, measure the thickness of the fingerboard at the nut too see if you can gain less angle by planing the board. You're fussing with the wrong end of the thing.


If you have it take out the frets. The bridge work is easy, you need to cold forge a slot scraper out if an old iron nail. Make a new saddle, carefully.

You'll have the refret regrets if you plow the bridge down.

Not enough board to replane? Go get a 4" wide drywall knife or a cake frosting knife and sharpen one edge. Then find an entry point and get the board off the neck. Clean it all up, push the neck where it should be and glue the board back on. Or glue in a new one.

The bridge will be toast if you plow into

Thanks for the neck is whippy and bendy, slot it and glue in a carbon fiber spar before you put the board back on.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 10 2017 5:23:44
 
estebanana

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Joined: Oct. 16 2009
 

RE: Bridge modification - angles and... (in reply to mrstwinkle

You can also cut the neck off and bolt it back on. Sometimes a better option for a cheap guitar.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 10 2017 5:29:02
 
keith

Posts: 1108
Joined: Sep. 29 2009
From: Land of Daniel Boone

RE: Bridge modification - angles and... (in reply to mrstwinkle

question for the luthiers. if the action is currently 5mm would the existing fretboard need to be planed down and then a new fretboard glued ontop of the existing ebony? I am trying to envision how planning the fretboard would lower the action or is that the first step and gluing a new fretboard is the second step. thanks.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 10 2017 21:14:03
 
Echi

 

Posts: 939
Joined: Jan. 11 2013
 

RE: Bridge modification - angles and... (in reply to mrstwinkle

1 mm less at the bridge (or at the nut) would make it for 0,5 mm less at the 12th fret.
In this case, to reach the action of 3 mm at the 12th fret you would need to lower down one of the 2 extremities of 4 mm.
As you can’t do anything more on the bridge you must shave down the fretboard towards the headstock and lower the nut of 4 mm, without changing the actual fretboard settings at the 12th fret.
Probably you may use taller frets and shave just 3 mm at nut.
At the end the fretboard would look with an odd avenue.
The fact is that a freatboard too thin at the nut saddle would allow the neck to bend.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 10 2017 21:58:29
 
RobF

Posts: 1116
Joined: Aug. 24 2017
 

RE: Bridge modification - angles and... (in reply to keith

Hi Keith,
As far as the guitar in this thread is concerned, we’ve only seen a picture of the bridge so it’s difficult to say too much more about it beyond agreeing that the problem lies at the neck end and messing with the bridge any further isn’t the preferred solution. Although I still think the stability of the saddle in its slot could be addressed.

Planing a fingerboard is done during a refret job to adjust the plane of the fingerboard so that the nut end is lowered while leaving the 12th fret end of the FB close to its original thickness. Just like lowering the saddle this will decrease the string height above the 12th fret by about half the amount the nut end was lowered. I’m saying “about” because the planing procedure can result in some fingerboard material being removed at the 12th fret area, although not necessarily, and that amount will have to be deducted from the 1/2. The fingerboard doesn’t get replaced.

In the case of trying to go from 5mm to 3mm, it’s doubtful it can be achieved by planing. If the current fingerboard is thin, then a thicker fingerboard can be the solution. If the neck has pulled up and is bowed then what Estabanana suggested to reglue the existing fingerboard after pulling the neck straight is a solution. Addressing any whippiness by inserting a reinforcing rod is a pretty good idea, too. If the neck is strong and there’s lots of fingerboard then the guitar was likely built with a bad neck angle or the body has settled to raise the angle and major work will have to be done.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 10 2017 22:06:28
 
Echi

 

Posts: 939
Joined: Jan. 11 2013
 

RE: Bridge modification - angles and... (in reply to mrstwinkle

Exactly. As you cannot go too low by shaving the actual fretboard you can add a new layer of ebony 2 mm thick on top of the existing fretboard and shave down gradually to 0 at the nut.
Alternatively you can replace the fretboard but this may involve in having to touch up the varnish of the top and neck.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 10 2017 22:25:58
 
RobF

Posts: 1116
Joined: Aug. 24 2017
 

RE: Bridge modification - angles and... (in reply to Echi

I guess I should have said that the solution lies at the neck end as without seeing the guitar we really don’t know where the problem lies...
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 10 2017 22:48:19
 
jshelton5040

Posts: 1500
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RE: Bridge modification - angles and... (in reply to Echi

quote:

ORIGINAL: Echi

Exactly. As you cannot go too low by shaving the actual fretboard you can add a new layer of ebony 2 mm thick on top of the existing fretboard and shave down gradually to 0 at the nut.
Alternatively you can replace the fretboard but this may involve in having to touch up the varnish of the top and neck.

This is a procedure that I have done many times but in reality it is better to pull the back and reset the neck since it results in a much better cosmetic solution.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 11 2017 0:49:19
 
mrstwinkle

 

Posts: 444
Joined: May 14 2017
 

RE: Bridge modification - angles and... (in reply to Echi

If a new fingerboard on top of the other is only 2mm thick, presumably the grooves for the metal of the frets actually cuts through it? Does this cause issues?
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 13 2017 10:58:53
 
constructordeguitarras

Posts: 1488
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Bridge modification - angles and... (in reply to mrstwinkle

It should not cause any issue if you glue it on properly. But let us know....

_____________________________

Ethan Deutsch
www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.
  REPORT THIS POST AS INAPPROPRIATE |  Date Dec. 14 2017 18:01:57
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