[pianotech] bridge pin drill speeds

[William Monroe]

Hi Will,

I've drilled with a foredom tool for a while now, and like it a lot.  I
don't use a jig to set the angle, but drill by hand instead.  Once I get a
few unisons in, it's been relatively easy for me to maintain a consistent
angle.  If you had to pick one RPM setting, 2500 is about right, IMO.  With
the foredom, I have always connected it to the variable speed accessory so I
can adjust the RPM to a workable speed.  I suppose in theory I should be
using a slightly slower speed with the larger size drills, but I haven't
found it necessary.  I adjust the speed of the drill at the treble end, and
keep it there for the whole of both bridges.  I have a pneumatic drill that
operates at 2600 RPM, and based upon observation I'd say that's about where
I have the foredom tool set (the foredom tool is adjustable on a dial scale
1-10 which is relatively informative, but precisely useless.  ;-]   )

I've have burned a few holes (and bits) in the past while trying to find the
optimal speed, and if memory serves, it doesn't take much above 3500 RPM to
be problematic.

I'm surprised that the pneumatic hose seems unwieldy to you.  If you go
pneumatic, the small diameter, lightweight polyurethane coil hoses work well
if you suspend them above the piano (or in your case, workbench since you'll
be out of the piano).  Combine that with a small high speed pneumatic drill
and you're golden.  Like this one:
http://www.amazon.com/Chicago-Pneumatic-CP7300R-4-Inch-Reversible/dp/B000NP0RC8

William R. Monroe


On Fri, Sep 30, 2011 at 12:33 PM, Encore Pianos
<encorepianos at metrocast.net>wrote:

> To those of you on the forum who do bridge recapping and such, I pose the
> following question:  what do you consider to be an optimal RPM speed for the
> bridge pin drill bit to be turning at?****
>
> ** **
>
> I have a reason for this question.  In the past I have drilled my bridges
> in the piano with the bridge glued on the board, and the board glued into
> the rim,using a hand electric drill.  But I am in the process of changing my
> bridge capping methodology whereby I am capping the bridge with horizontally
> laminated veneers, and this means I will be planning the root to establish
> down bearing, and then gluing on the laminated cap of established thickness
> to it.  After I plane the bridge root, I will remove the bridge from the
> panel (which is held in place by a multitude of screws) to readily glue on
> the cap.  I want to take advantage of this access to drill and notch my
> bridges as well, and then glue the bridge to the panel, and finally glue the
> whole board into the rim.  Given that I will have the bridge off the panel
> and attached to a work table, I am planning on making a drilling jig with
> the desired drilling angle built in, along with an adjustable depth stop.
> The jig would need to use some kind of small inline drill like a pneumatic
> inline drill (about 2500 RPM) or and electric inline drilling tool (Dremel
> tools 5,000 to 35,000 RPM)****
>
> ** **
>
> Testing on my drill press at 2500 RPM, the pneumatic seems doable.  But the
> hose attached to the tool can be unwieldy, so I am leaning towards an
> electric tool.  But I am concerned that the speeds of 5,000 RPM up will be
> too fast, and burn and expand the hole.  Does anyone have experience using a
> Dremel type tool for bridge drilling?  ****
>
> ** **
>
> I will happily entertain other suggestions for tools.  Thanks for your
> input.****
>
> ** **
>
> Will****
>
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