Here is the soundboard, with the bridge attached, resting in the case.
Closeup of the treble end of the bridge along with the molding that will eventually be glued to the edge of the soundboard. Things are really tight here and there is only 2 or 3 mm of clearance between the end of the bridge and the molding.
Closeups of the bridge after inserting the bridge pins.
There are four "ribs" glued to the underside of the soundboard to stiffen it - here is the second one being glued in place.
I also started the work of trimming the lid and flap to their final size. The flap needs to be big enough for a large cat to stretch out and go to sleep on it.
I trimmed the curved part of the lid by clamping it to the case and using a 1/2" router bit with an oversized end bearing to leave a slight overhang. Fortunately this is an easy cut to make from above because you are cutting with the grain of the wood. There were, however, a few places that needed to have almost 3/8" of wood removed so I made three passes over it using progressively smaller bearings and finishing up with a 7/8" bearing which left an overhang of about 3/16".
Here is the lid with the flap resting on top of it in the open position. I went to a lot of trouble to get both the flap and the end of the lid perfectly square so that when it is folded back like this the edges line up perfectly.
After reading the manual, are the bridge pin holes really drilled only 2 mm deep?(!) That's where it said to put the masking tape 'flap' on the bit. It also said the pins must bottom out in the hole and go a little further, like a nail. But only 2 mm deep holes? My marking awl will go deeper than that.
ReplyDeleteI think that the instructions here are just wrong - possibly because that section was edited at some point and left in an inconsistent state.
DeleteThe only context in which the words "about 2 mm above the top of the bridge" make sense to me is in describing where the top of the bridge pins should end up once they are in place.
I calculated it like this:
The bridge pins are about 12 mm long, the last 1 mm of which is sharpened to a point.
I wanted the pins to be about 2.5 mm above the top of the bridge when fitted.
Because of the approximately 1 mm step at the top of the bridge that means that about 3.5 mm of the pin will be protruding and about 8.5 mm will be embedded in the bridge. That suggests that a hole about 5 or 6 mm deep will be about right since it will allow us to push the pin another 2 or 3 mm into the wood at the bottom of the hole.
At this point experimentation takes over. Get a piece of scrap walnut, drill some 5 mm deep holes in it and try pushing a few pins into it and figure out how far in they go, how hard you have to push them and how secure they appear to be. Then adjust the depth of the hole if necessary. After doing the first 50 or so you will find that tape flaps on the drill bit are pretty much unnecessary and you are just doing it entirely based on the amount of hand movement needed.
You will probably find that you have at least 15 or 20 spare bridge pins that you can use for this. Let me know if you need some more - I have quite a lot of spare ones of that size.