Apologies for the delay to reply. Was busy yesterday.Most of the bolts on the LP12 are best done up to the correct tightness. By correct I mean the tightness that wouldq typically be right for a bolt or screw of that type.
It's quite easy to demonstrate how to judge bolt tightness by feel but it's harder to explain over the net. But feel is the best way to do it. Yes, you can use a torque wrench, if you have one that is accurate at low values, but with little bolts and screws you can feel when it's right more easily with your fingers.
Find something you can practice on. I used to show people on an old bike stem. It doesn't matter what it is, the principal is the same. Thread the bolt or screw in until it 'lands', until it gets to the point where any more rotation is tightening it. From that point the majority of bolts will want about a quarter of a turn but you can feel it. The amount of resistance you'll feel for that quarter of a turn will feel constant and then it will get to a point where the resistance will start to change. Depending on the type of screw and what it's going into either you'll feel that much more force is needed to turn the bolt or, strangely, that it's turning more easily. What is happening is that either you're now starting to try and deform the materials or they are weak enough that they are failing easily. Either way, you are going to far and if you continue you risk damaging something.
As long as you don't strip the thing you can tighten up and undo a bolt lots of times getting a good feel for it. Then just translate that onto the bolts on the LP12 and you're good. It might feel strange at first as you don't think you're doing the bolts up very tight but you are. The tool is multiplying your force.
I said almost all of the bolts on the LP12, there are exceptions. The hanger and plinth mounting bolts on the standard top plate, do those fechers up proper tight! Because if you don't, they can come lose when you're tightening the spring and plinth fastening nuts. Especially if you're using very tight locking nuts. Both the bolts and nuts are steel so will take a good old tighten. If you're using an alloy top-plate I'd thread lock the rods into the inserts for the same reason.
Thanks a lot for the detailed info. I don’t have a torque wrench that is accurate in smaller values. Only firm 2-25 Nm. So I’ll have to learn to do it by feel as you say, for each particular fasterner.
So the Arm collar bolts on the armboard are supposed to be much less tight than most of the other bolts? Certainly makes a big difference to the sound, but from listening I found the sound a bit too soft if they are too lose, although it’s very musical.
As I said before there are two different versions (and might be more) of the single layered double laminated MDF armboard. One is lighter and the other heavier. Any ideas why? Maybe the heavier one is less prone to deforming under pressure from those arm collar bolts.