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 Post subject: I need a "shim" lesson
PostPosted: Tue May 21, 2019 9:03 pm 
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Walnut
Walnut

Joined: Sun May 15, 2016 11:35 am
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First name: Bill
State: Oklahoma
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I Just put together some stratocaster parts and have run into a problem. To get the strings up off of the fretboard I had to adjust my bridge saddles to the very top of the 3/8" set screws and that is still not quite high enough. I need to lower the bridge saddles 1/8" or a little more. I think that probably the best way to do that is to shim the neck pocket to change the neck angle a bit? What size of shim will likely get me where I need to be? I've only seen the shims at stewmac. Are those the ones to use? THX


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PostPosted: Tue May 21, 2019 9:49 pm 
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Koa
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Location: Cowichan Valley, BC, Canada
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Yup those stewmac shims are for that exact thing. In a pinch I've thrown a 1mm pick in there. I've never used the stemac shims though, they seem expensive, compared to maple veneer which is what I've been using. I cut it to fit the pocket exactly, and then I sand it on my bench sander into a taper, I stack those until the angle is right. Sometimes I'll glue them together before shimming, (the shims together, not the shims into the pocket.)


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PostPosted: Wed May 22, 2019 10:09 am 
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Koa
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I keep a small stash of the StewMac shims for Fenders where the neck angle just isn't right or I'm using a non standard bridge. Quick and dirty, but you can make your own. My goal is to have the neck angle such that the fret plane just hits the tops of the saddles at their lowest adjustment

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PostPosted: Wed May 22, 2019 9:58 pm 
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Walnut
Walnut

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State: Oklahoma
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Upon further working on this guitar I discovered that the neck pocket is just too tight. The first two necks I installed just never seated all the way to the back of the pocket. I installed a third neck and it did go all the way in so I was able to get my saddles back down in the normal range. I think I would like to reinstall the first neck I had on the guitar. Should I use a little sandpaper on the sides of the pocket or use some lubricant? What are you guys suggestions?


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PostPosted: Wed May 22, 2019 10:39 pm 
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Joined: Sun Mar 06, 2011 12:04 am
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First name: Chris
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Lubricant? Heck, no. Sandpaper, a file, or Scotchbrite - some kind of abrasive - but never a lube.

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PostPosted: Thu May 23, 2019 12:34 am 
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Old Growth Brazilian Rosewood
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Chris Pile wrote:
Lubricant? Heck, no. Sandpaper, a file, or Scotchbrite - some kind of abrasive - but never a lube.


What Chris said.

I wanted to add that not only is the neck angle something to get right with the shims the neck left to right or sideways angle is important too especially when you are needing to work the pocket for a decent fit. Many parts castors suffer from this which can leave the high e string too close to the overly beveled fret ends causing strings to slip off the neck when fretted. With this said be sure as well to not only shim and fit for the angle to the bridge but trial string her up and see where the strings are in terms of the sides of the neck too.

It's not unusual to have to shim a neck especially on aftermarket parts that never seem to fit as billed.... With a trusty micrometer and some business cards you can make temporary shims to determine what thicknesses and where get you where you want to go and then bang one out of real wood as the others have mentioned and call it a day.

Lastly before setting neck angle be sure to simulate the fret plane shape or more specifically how the truss rod will be adjusted under string tension because this impacts the neck angle greatly. To do this you need to understand relief and how in a perfect world we want a touch of relief on the treble side and more relief on the bass side. Not all necks will do this and it's a toss up but what ever you have to work with and what ever compromises you have to make with your neck it should be set with the truss rod to the same levels of relief as it will have with string tension to accurately shim the pocket and set the neck angle.

Although reality for commercial shops is always different from hobbyists many commercial shops are reluctant to work on parts guitars until all assembly hoops have been jumped through by someone else or estimating jobs is impossible with the lousy fit of the commercial necks to the commercial bodies. We reject working on parts casters unless it's been a fully strung up, playable instrument prior and we have the opportunity to evaluate it that way. FYI the major reason for this is the neck fit to the body on aftermarket stuff, it frequently sucks and requires a lot of rework and time which is exactly what you are experiencing.

But adjust the truss rod and get the neck shape right and check it all again and you may find that your shimming requirements lessen or even go away.

Good luck.

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PostPosted: Thu May 23, 2019 10:28 pm 
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Walnut
Walnut

Joined: Sun May 15, 2016 11:35 am
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First name: Bill
State: Oklahoma
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I used some sandpaper and smoothed out the neck pocket and it made all the difference. The neck still has a tight fit but went in all the way this time and seated properly without the need for a shim. I never thought to check the neck pocket when I started this project and thought the neck was properly seated when it was not. I have switched necks on guitars for many years and don't remember ever having this happen to me. This was a usacg neck and a mjtele body and both seem to be high quality pieces. I have used both before and never had any issues. This time was just user error. Anyway, I adjusted everything out and the guitar plays like it should. Thanks for the help guys....


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