[pianotech] Plate screw problem

[David Renaud]

Hello

     Thank you for the response thus far......

     My tool shop says the $6 titanium bit is only titanium coated and it should not be 
A problem to drill out with a good quality carbide bit. The sales person says they would
Be very surprised if a carbide bit could not handle this, for they drill through steel ibeams
With such. 

      I like Don's suggestion of drilling out the entire mess with a big bit and plugging the hole
With pin block material to start over.  I will try a good quality carbide bit unless someone on
The list knows something is amiss with this plan.

      The requested picture will need to wait until I am next in the shop.....but I will describe the corner. Typical of a boesendorfer, open face, the pin block has layers with a lower thin shelf 
Forward of the bass section. There are plate screws forward of the bass agraffes into that lower shelf, the closest of these shelf screws I  think is about 6 inches from the corner. The corner itself is where tall thin
Plate struts meet, so yes; a thin tall deep plate hole. In fact it was a thinner smaller screw in this
Corner as the strut width could accommodate. I the broken off in the wood....plus now a shreded titanium coated bit occupying a little bit of the plate hole.  

      I terms of function, I don't see that courner taking much stress.......then block is firmly
Married to the shelf and stretcher and not going to move. The bass strings are pulling up at the 
Agrafff, but with those shelf screws directly in front of them......that screw is not doing much, 
I admit to being temptet to fill the hole with west system epoxy with as much screw as I can fit
Cut to size to put in the hole. That glue -screw head would never come apart, and the next person to ever remove the block would be swearing at me, drilling it out, cutting from under the strut, and would be very unhappy. With a new block, that may be never in the life of the piano.

      All that said, the proper thing to do at this point is to drill out that mess and plug that hole.

Regarding beeswax......yes.  I often use it when it feels so tight I have a gut feeling it is needed.
I never felt I was forcing so much. A very old screw, and in this corner a thinner weaker screw.
Perhaps already weakened from previous installation, tightening or removal.

    So I learn I should always use a little beeswax, and not depend on my gut feeling about it.
Also I recall someone in a class suggesting they like to go with new screws.......perhaps someone that had this experience before and determined not to go there again.

    Any warnings regarding a carbide bit attempt? I don't have experience drilling metal.
    Sound right to you.

   Let this be a warning to others..........Use the beeswax.
   This lesson will cost me some time and money.....

                                                                      Thank You
                                                                       Dave Renaud




Sent from my iPad

On 2011-07-15, at 8:13 AM, "Don Mannino" <donmannino at ca.rr.com> wrote:

> David,
> 
> Don't you just hate it when that happens?  
> A few options, depending on the particulars of this plate hole and location:
> - The hollow tube type screw extractor drills would work if the plate hole
> is large enough.  It would have to be a tight fit in the plate, then would
> just barely go around the broken screw.  So maybe not going to work.
> - Is it possible to drill up from the bottom?  Sounds like it isn't because
> of the location.
> - Best possibility I can think of is to use a LARGE drill, about the same
> size as the plate hole, to drill down on top of the broken screw.  I'm not
> completely sure from your description if a long section of drill bit is also
> stuck in there, or just little pieces.  Little pieces shouldn't be a
> problem, but a jammed drill bit section might be.  In any case, going gently
> with a large drill but, spinning at a good speed  bit with light pressure,
> should at least allow you to create a flat top on the screw.  If the screw
> is large enough, that will then create a good surface to drill with a small
> bit, then try an easy-out on an extension.  If this is the original screw,
> it should not be that tight in the wood.
> 
> If the screw is too small for an easy-out, a patient drilling all the way
> through with the large bit is the best option.  Then make a plug of pinblock
> material, glue that in, and when dry drill a new hole and put in a new
> screw.
> 
> I am sure that others have also had this happen, so hopefully someone will
> have other ideas.
> 
> Good luck!
> 
> Don Mannino
> 
> 
> -----Original Message-----
> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
> Of David Renaud
> Sent: Thursday, July 14, 2011 7:46 PM
> To: pianotech at ptg.org
> Subject: [pianotech] Plate screw problem
> 
> Plate screw snapped putting it back in.....old screw.....
> 
>