Drilling Vintage Tremolo mounting holes

Sambostar

So, I git a cheap drill stand and a 500W Silverline drill from Ebay.  Rational was that it was cheap (Around £30 all in) and I can offset it and use the whole thing mounted on a guitar body, stand and all.  Also a cheap pillar drill would probably have the same amount of chuck play and wouldn't have the throat anyway to do V Trem holes.

The play in the drill chuck is really something to behold, as I was kind of expecting, but if you don't mount your work tight and just hold it in place after marking a centre point, it seems to work. The good thing is that the adjustable speed goes really low.

So after finding some drill bits (Between 3/32" and 7/64" I believe is 2.5mm) I made a start on a drill jig using oak.  Used a 3mm Brad point on it.

I tested the jig using a 3mm HSS on some old Spruce 2" x 3" CLS and double sided taped them together, drilling down 10mm or so and then finishing off with a smaller 2.5mm HSS bit, again holding the whole thing loosely, rather than clamping it. 

Mounted up the trem on the test Spruce and it's rattling around, which I guess is a good sign.  About just under 1mm play forwards and back and nothing really side to side, so I guess that was less accurate.

Question is, if it is rattling about on the test piece, does that mean the holes are centred adequately?  I mean surely it would bind if it they were out of alignment?

Now obviously the Spruce is soft, so I'II need to try it on something harder, but this whole contraption is for a Basswood body, which is almost as soft as Spruce, so hoping it will work.

Nomad

Sambostar said:

Mounted up the trem on the test Spruce and it's rattling around, which I guess is a good sign.  About just under 1mm play forwards and back and nothing really side to side, so I guess that was less accurate.

Question is, if it is rattling about on the test piece, does that mean the holes are centred adequately?  I mean surely it would bind if it they were out of alignment?

It depends on how big the holes are in the plate and the diameter of the shanks on the screws. Truth is, there will always be some amount of misalignment in the row of screws unless perfection comes in to land. Same with the plate - there will be inaccuracies in the positions of the holes (fore and aft as well as left and right). It's a question of how big the positional errors are in each case.

If the trem plate moves fore and aft convincingly and has a believable amount of tilt, then it's probably okay (for certain precision-dependent values of 'okay').

Sambostar

It's a USA Trem plate with round holes and it rocks OK and still rattles a bit until it locks, beyond the angle of the baseplate chamfer. 

Suppose I could always fit a Wilkinson or something with more tolerance if I cock it up, which will probably be the case as I'm partially drilling into end grain plugs.

I'II shape the oak block the same as the Trem from the front, align it and try and lock it down tight on the body and pray.

Actually just occurred to me that I could use the Makita Combi with the hole jig, as the run out is far more accurate.

ICBM

Nomad said:

Truth is, there will always be some amount of misalignment in the row of screws unless perfection comes in to land.

*Always*. It only depends on how precisely you measure - no three holes can ever be *perfectly* in a straight line, let alone six. (Sorry, my dad was a metrologist so stuff like this was drummed into me .)

In general a Fender 6-screw trem will work OK unless the screws are badly out of alignment. The wood is soft enough and the screws slightly flexible that they will self-adjust under load from the strings to some extent. Front-to-back error is actually less of an issue than side-to-side, which is one of the reasons the Wilkinson bridge with the oval holes is a clever design even if you don't need it to compensate for a properly different screw spacing.

Sambostar

This is what I'm thinking.  Basswood will be fairly obliging on that front.  Oak maybe not, but who builds a guitar out of oak anyway?

The holes measure up OK side to side, they veer off by maybe 1/3 of a mm on the other face, although I flipped it to use it as a jig anyhow.  Maybe I'II have a go at making a third jig.

Nomad

ICBM said:

Nomad said:

Truth is, there will always be some amount of misalignment in the row of screws unless perfection comes in to land.

*Always*. It only depends on how precisely you measure - no three holes can ever be *perfectly* in a straight line, let alone six. (Sorry, my dad was a metrologist so stuff like this was drummed into me .)

Perfection never comes in to land.

Speaking as someone who does precision mechanical design day in, day out, tolerances and their effects are ever present.

ICBM

Nomad said:

Speaking as someone who does precision mechanical design day in, day out, tolerances and their effects are ever present. 

Aha! You'd probably get on well with my dad then .

You can never say anything to him involving words like "exactly" or "precisely" without the old bugger insisting on a tolerance spec…

Sassafras

ICBM said:

Nomad said:

Speaking as someone who does precision mechanical design day in, day out, tolerances and their effects are ever present. 

Aha! You'd probably get on well with my dad then .

You can never say anything to him involving words like "exactly" or "precisely" without the old bugger insisting on a tolerance spec…

You're obviously a chip off the old block.