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 Post subject: Re: 360 Casualty
 Post Posted: Thu Dec 24, 2009 2:15 am 
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I have also added a picture of my neck pick-up which looks a little crumbly on one side. Is this an issue? Also, I know someone mentioned that the neck length should be fine as long as the neck slotted into place correctly but I am concerned that given that the neck was obviously subject to a fairly forceful blow, there could be slight compression of the wood on the body. How serious is a deviation on the norm and does anyone have the specs i.e. the length / angle etc..

Merry Christmas everyone...


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 Post subject: Re: 360 Casualty
 Post Posted: Thu Dec 24, 2009 3:09 am 
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Quote:
I have also added a picture of my neck pick-up which looks a little crumbly on one side. Is this an issue?
No, but the rewind might be. I don't have any evidence, but I would be concerned that a pickup maker such as Kent Armstrong may rewind pickups with 'standard' #42 gauge pickup wire instead of the correct Rickenbacker #44 gauge - simply because they will have large supplies of it anyway.

Quote:
Also, I know someone mentioned that the neck length should be fine as long as the neck slotted into place correctly but I am concerned that given that the neck was obviously subject to a fairly forceful blow, there could be slight compression of the wood on the body. How serious is a deviation on the norm and does anyone have the specs i.e. the length / angle etc...
With a tenon that short it's essential that it's a perfect tight fit into the body socket, or the glue will be acting as filler on one side or the other, which will weaken the joint - this may be the reason it failed before. If it's anything less than an absolutely perfect fit, it's definitely better to make it so by laminating on a thin veneer to the back, then sanding it down to the right size if necessary. I doubt there's any benefit in trying to extend the tenon even if the socket is deeper though - it's just another glue joint.


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 Post subject: Re: 360 Casualty
 Post Posted: Thu Dec 24, 2009 3:58 am 
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Thanks Blue Angel.
Well, the neck fits very snugly into the socket and there is almost no side to side movement.
Thank you for the note on the pick-up. When I've finished the restoration, I'll fit new pick-ups from Rosetti who are just down the road from me in Essex as I have just discovered! In fact I will eventually replace all the electrics as they are all really tired and scratchy and the stereo mixer does not work at all!


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 Post subject: Re: 360 Casualty
 Post Posted: Thu Dec 24, 2009 4:26 am 
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Quote:
Thanks Blue Angel.
Well, the neck fits very snugly into the socket and there is almost no side to side movement.


Turn the almost nothing to NOTHING using a shim(s) both side to side and front to back.

iiiPopes was saying you need a little channel available for the excess glue to escape from.

The neck length should be fine because you can adjust the intonation at the bridge, if you would like to check, the distance from the nut to the 12th fret should be equal to the distance between the 12th fret and the bridge give or take.

Nice going so far!!


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 Post subject: Re: 360 Casualty
 Post Posted: Thu Dec 24, 2009 6:01 pm 
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Turn the almost nothing to NOTHING using a shim(s) both side to side and front to back.
Exactly. Remember that wood glue is only 'stronger than the wood itself' (as many modern glues are) when the glue is locking the wood fibers directly together by penetrating into the wood on both sides of a firm contact. The glue material itself is quite weak, and becomes just filler if there is any gap between the two pieces of wood.

Even epoxy (which is probably the strongest 'material' glue) is much weaker than hard wood when used as filler - it's the composite created by saturating the structure of the wood with the glue that creates the strength, even if the depth of penetration is small.

To make a really strong joint here the tenon needs to be a tight push fit into the socket, with no detectable movement in either direction. In this case the glue at the sides of the tenon is just as important as that at the back - if it's a perfect fit, the glue there is under a pure shear stress, which is how it's strongest. The glue between the back of the tenon and the back of the body is under a peel stress, which is how it's weakest.

Traditional woodwork joints are all designed so that the glue simply locks tight-fitting pieces of wood together and stops them moving - the strength is provided by the fit, not the glue, which is then almost always in shear stress anyway. Even pre-industrial glues are stronger than the wood, used like this.

My high school woodwork course was useful!


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 Post subject: Re: 360 Casualty
 Post Posted: Thu Jan 07, 2010 8:35 pm 
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Hello Everyone! All the best for 2010 - I'm looking forward to a Rick-filled year!!! Sorry about the delay but I have been waiting for my glue to arrive. A quick question for the future - I was cleaning up my rusty truss rods and noticed that one is longer than the other!! Is this normal? It might seem dumb but I want to make sure I put these things back correctly as there seems to be very little to illustrate this. Also, how do they create tension as at the body-end there is nothing stopping the truss rod from being pulled through the body - stop me if I'm wrong as I have not actually tried to pull a truss rod through the body like this and wont try either but I would like to understand the physics behind this particular truss rod style...

here's a pic of the truss rods - sorry not a great one but you can see the difference...

http://i93.photobucket.com/albums/l49/A ... srod-1.jpg

Thanks Dudes

... I start gluing the neck and the body cracks tomorrow, busy cooking some glue...


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 Post subject: Re: 360 Casualty
 Post Posted: Thu Jan 07, 2010 8:54 pm 
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here is a link to some pictures i found. they may be of some help. I like the idea of firming up the wood at each end with superglue.

http://media.photobucket.com/image/rick ... acker4.jpg


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 Post subject: Re: 360 Casualty
 Post Posted: Fri Jan 08, 2010 2:35 am 
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Quote:
A quick question for the future - I was cleaning up my rusty truss rods and noticed that one is longer than the other!! Is this normal? It might seem dumb but I want to make sure I put these things back correctly as there seems to be very little to illustrate this. Also, how do they create tension as at the body-end there is nothing stopping the truss rod from being pulled through the body - stop me if I'm wrong as I have not actually tried to pull a truss rod through the body like this and wont try either but I would like to understand the physics behind this particular truss rod style...
These older rods (pre-1985) work by generating their force 'internally', so they don't need to be attached to the neck, and don't put any end-to-end tension on it. The threaded end of the rod is shortened relative to the unthreaded end which is held by the small bar on which the nut presses, so they try to take up a 'bow' shape - but because they are trapped together by the channel, what happens is that both curve backwards instead, applying a force to the neck.

The advantages of this system are that the neck wood is not compressed against the tension of the rod, so there is no gradual squashing of the wood over time. Also, because the metal rod can slide up and down in its channel, it's not only easy to replace but is almost immune from temperature and humidty-related changes - the rod is affected by temperature but not at all by humidity, and the wood by humidity but almost not by temperature, so the two simply move independently without affecting the internal tension of the rod - unlike the new-style rods, where the tension of the rod relative to the wood and hence the neck curvature is affected by both. The old rods can remain stable and need no adjustment even for decades in many cases, once set right.

The disadvantage is that the 'bow' shape created by tightening the rod against itself is extremely powerful, almost more than the backwards curve it generates, so there is a tendency for it to try to expand inside the channel in the neck instead, and can even pop the fingerboard off, if adjusted by someone that doesn't know how to adjust it the right way - which is to bend the neck to the right position first (releasing the tension on the nut), then tighten up the nut to hold that position. Even if it doesn't pop off the board, tightening it the wrong way tends to bend the threaded end of the rod downwards, which is quite common to find on old Ricks and makes getting the nut tool on quite difficult... often the first sign of trouble.

I don't know why the rods are different lengths - it might be that one has been bent in the past, and someone has fixed it by cutting off the damaged section and the equivalent length from the other half, and re-threading it further to make it work again. This can be done without affecting the operation, in fact. (As long as the amount taken off is small, like this.)


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 Post subject: Re: 360 Casualty
 Post Posted: Fri Jan 08, 2010 10:46 pm 
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Thank you BA, I had no idea and am still somewhat baffled by the idea. I get the part about pressure on the fingerboard, but can't envision what part the 2nd bar plays or how tightening the nut "clamps it down". I haven't found any clear illustrations of the system in operation. Do you know of any other instruments using this type of truss rod? It's very interesting.


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 Post subject: Re: 360 Casualty
 Post Posted: Sat Jan 09, 2010 12:08 am 
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Warwick use them - or did, I haven't worked on one for a while, and it may be only the genuine German ones anyway.

The second bar is what the first is tightened against. The short cross-bar under the nut presses on the end of it, so as you tighten the nut, the thread pulls through the hole in the cross-bar and shortens the lower rod relative to the upper one which can't move because it's stopped by the bar. It's almost how a heat-sensitive 'bi-metallic strip' works, like you would find in a thermostat - except that there the two pieces of metal are welded along their whole length because it's thermal expansion that causes them to bend, not physical tensioning.


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