Shimming AR XII and XII with "custom" size

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akpasta
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Shimming AR XII and XII with "custom" size

Post by akpasta » Mon Jul 13, 2020 10:01 am

Hey all,

I found out via instagram that the Fender builder who helped design the alternate reality xii and who has done some custom vintage spec xii guitars, that shimming the fender xii, both vintage and reissue, makes a huge difference on the playability! Which is great!

However, stew mac does not make a shim that drops in because these necks are different from both guitar and bass necks (as far as I know).

So I'm required to make a custom shim from one of their stamps.

Their guitar stamps are too small, so I've got to use a bass stamp. But the bass stamps are too large!

My question is, if the shim is too long, how does cutting the shim affect its angle? It seems like if you're not using the full length of the shim, you're not getting the full break, is that correct?

What should I do?

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Re: Shimming AR XII and XII with "custom" size

Post by SignoftheDragon » Mon Jul 13, 2020 1:34 pm

I'm pretty picky about my 12-strings- love low action and hate fret buzz, etc.

So far my ARXII's (I have 2- LPB and Oly White) both have decently low action, intonate properly (the blue one at least- I haven't had the white one in for a setup) and feel great in the hand. I wouldn't have even thought of a need to shim them.

I did hand-make a shim for my Venus XII- just traced the wierd-shaped heel on some .030 polystyrene and cut it square at 1.25" long, I THINK it made a difference- i've never had reason to readjust it.

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Re: Shimming AR XII and XII with "custom" size

Post by akpasta » Mon Jul 13, 2020 2:01 pm

I have my vintage xii in great playing shape, but based on the advice from a Fender builder (look him up on instagram calopez_fender) - https://www.instagram.com/p/B7wBALtHHyp ... _copy_link , who literally makes vintage xii spec custom guitars, I wanted to try a shim on my vintage one.

Regarding the AR XII, I am fairly happy with the setup, but the action past the 5th fret is a bit too high for my liking, yet the bridge saddles are mostly adjusted as low as they will go. However, action closer to the nut is just about right on. Therefore, to me, the guitar would probably benefit from a steeper break angle.

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Re: Shimming AR XII and XII with "custom" size

Post by timtam » Mon Jul 13, 2020 8:50 pm

akpasta wrote:
Mon Jul 13, 2020 10:01 am
My question is, if the shim is too long, how does cutting the shim affect its angle? It seems like if you're not using the full length of the shim, you're not getting the full break, is that correct?
No - the taper is constant, so the angling of the shim is unaffected by where you cut the shim. The only consideration is that any constant/offset thickness of the shim can be affected by where you cut it, which can change the final position of the strings (although not by much).

TL;DR .. don't sweat it.

A tapered shim theoretically should go from zero thickness at one end to full thickness at the other end. That way its only effect is to angle the neck. But it's basically impossible to build a shim with zero thickness at one end. If you look at the Stewmac shim specs, they also have a small offset, ie a small constant thickness at the thin end, that is added to the effect of the angulation, raising the neck slightly. eg approx 0.48mm for the 0.25 degree bass shim ...
Taper specs (approximate)
0.25-degree shim tapers from 0.030" to 0.019" (0.76mm to 0.48mm)
0.5-degree shim tapers from 0.028" to 0.008" (0.71mm to 0.20mm)
1-degree shim tapers from 0.060" to 0.010" (1.52mm to 0.25mm)

So if you cut some of the 0.25deg shim off near the thick end, the thin end will still have the same 0.48mm offset (and of course the same taper angle). But if you instead cut it near the thin end, you will be adding to the offset by whatever the additional thickness is at the point where you cut it. That would raise the neck by a little extra.

So if you want the shim to function in the same way as if it was not cut, cut it near the thick end.

But shimming is obviously a bit of a trial and error process anyway. So unless you do the trigonometry you don't know what effect a given shim is going to have on the bridge height until you try it. And even then the shims are not exactly what the specs say, as they gave some manufacturing tolerance.

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Re: Shimming AR XII and XII with "custom" size

Post by akpasta » Tue Jul 14, 2020 6:23 am

This is incredibly helpful Information! Thank you!

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Re: Shimming AR XII and XII with "custom" size

Post by Sonichris » Tue Jul 14, 2020 9:52 am

Aren't vintage EXII necks just wider at the heal? how much wider? why not just use a cut in half Stew Mac shim? Or, even use it complete with the edges not quite showing the shim.

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Re: Shimming AR XII and XII with "custom" size

Post by akpasta » Tue Jul 14, 2020 11:31 am

The vintage XII heels are wider and longer than a guitar shim. You have to use a bass shim and cut it down both length and width and drill holes.

I haven't measured the AR XII heel.

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Re: Shimming AR XII and XII with "custom" size

Post by akpasta » Mon Jul 27, 2020 12:41 pm

In case anyone else wants to try shimming theirs, the AR XII has the same heel pretty much as any other Fender neck, so a fender shim from Stewmac fit perfectly with no modification. I used a 0.25 degree shim (as recommended by a Fender builder) which allowed for more even action along the whole neck, but not a super drastic change. I like to use a 0.5 degree on 6 string offsets, but I'm not sure it would work on this guitar because the Gotoh bridge saddles don't seem to have a lot of height in them, as opposed to a Jazzmaster or Jaguar, in which you can REALLY raise the bridge up high and benefit from the extra tilt to get the action nice and low throughout.

At some point I'll get around to shimming my vintage Electric XII, and on that one I think I will use a 0.5 degree shim, because those bridge blocks have a lot of height adjustment. But I'll definitely have to custom cut that one because those heels are somewhere between the size of a guitar and bass.

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Re: Shimming AR XII and XII with "custom" size

Post by Soniqfreq » Mon Oct 19, 2020 8:50 pm

I just setup my new AR EXII yesterday and everything was fine without a shim. However, I read this thread so I decided to take off the neck when I put on new strings. I noticed that there were two strips of cardboard stacked in the back of the neck pocket. I guess that is the factory shim. I compared the depth to some StewMac wood shims I had and they were a near match to the 0.5 degree wood shim. The 0.5 worked perfectly so I used that instead of the cardboard so I have a solid shim in the pocket.

For reference my neck relief is set to 0.10” at 8th fret (capo on 1st and pressing 17th.).0.25 was not enough and 0.75 degrees was way too much.

Another thing I noticed is that when I popped the neck up to set the truss, the original
cardboard shims shifted since they are loose in the pocket. So if you notice the break point changed after loosening the neck screws, the factory cardboard probably shifted.

Action is great at 4/64ths from E to E and it plays super easy now up and down the fingerboard.

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