How to file a saddle in a slope?

[Gil80]

Hi.

I need to file the bottom of a saddle so the high E is lower than the low E.
I’ve measured how much is needed to sand off and I marked the line. Imagine a diagonal line which means gradually taking off more material from the low E to the high E. Where the high E requires more material to be removed from the saddle to create this slope.

The problem I’m facing is that when I try to sand the saddle I get this curvature and then I end up sanding more than I need in order to remove that curvature.

Is there a smart way to sand it to the slope I need?

[redir]

Adjust pressure to follow your line. After so many you get the hang of it.

[charles Tauber]

It comes down to tools and/or technique.

There are a dozen or more ways to accomplish the task. At one extreme is to buy or make a dedicated tool that largely eliminates the need for skill and technique. At the other extreme is to use a common, simple, multi-purpose tool, but use it well, which requires skill and technique.

One dedicated tool is this one, a specialty tool at nearly $200:



One common, simple tool is this one, available at any hardware store for $10:




The first requires relatively little skill or technique to achieve repeatable results: the second requires considerably more skill and technique to achieve repeatable results. There is lots of ground in-between.

One simple, relatively common method is to use a "shooting board" with a sandpapered straight edge. Lee Valley makes all of the components for a formal shooting board, including a track for the sander (or plane), but it is easy to scale that down to make one for just a few dollars, suitable for just nuts and saddle sanding.

Here is Lee Valley's version of their "shooting sander", from which you'll get the idea:



To make your own inexpensive version, apply 80 grit sandpaper to any straight edge - a short level, a block of wood, the edge of a piece of MDF/plywood, etc. You can make a simple bench hook (https://en.wikipedia.org/wiki/Bench_hook), similar to that shown in the video, from a few scraps of MDF and a few screws. Technique-wise, don't "scrub" the sandpapered straight edge back and forth as doing so will tend to curve the bottom of the saddle/nut. Instead, sand on the push, only.

There are numerous other ways to accomplish the same task, used individually or in combination. After trying many of them, I find this to be simple, effective and repeatable, particularly since I already had the shooting board, track and sander for other woodworking purposes. Thought I'd share the idea/application, though it isn't unique to me or even my invention.

[Quickstep192]

I would leave the bottom flat and make the height adjustments at the top of the saddle.

[HeyMikey]

Right, I’ve always thought the bottom should stay flat to make 100% contact with the bridge.

[charles Tauber]

If the top of the saddle has been contoured for compensation, removing material from the top of the saddle required one to redo the compensation. For that reason it is customary to remove material from the bottom when possible. Doing so takes less time and effort.

[redir]

The OP is talking about adjusting the action so that the Low E goes down but the High E stays the same. So he needs to taper the saddle from X height at the Low E to zero at the high E. It's normal to round off a piece when you are sanding it. Switching directions and rotating the piece help with that but in this case you have to be careful. Technically it's probably impossible to not take any off the high E end but you can make it so minimal that it doesn't matter.

What I have found works for me is to hold the piece on the end you want to remove, the low E in this case, and push on the sanding board from that end only. Watch the line constantly and also make sure you are not putting an angle into the bottom of the saddle from front to back. Once you get close move towards holding the saddle more in the middle and keep a mental image of NOT removing material on the High E end.

[Brucebubs]

I removed the saddle and lowered just the 6E from the top on my Huss & Dalton, then re-shaped the compensation gave it a quick polish and re-fitted it - perfect.

[Gil80]

Thanks for your comments.
I'd prefer to remove material from the bottom, since the top is already compensated and it's my first go at fixing action and intonation and I wouldn't want to change the compensated saddle at this stage.

I first want to get the action set according to my measurements (truss rod already adjusted).
after I get the action correctly, I'd deal with intonation compensation.
So bottom part of the saddle is where I'd like to fix the issue.

I'll try applying more pressure where the high E is located and use only one forward motion when sanding.