[pianotech] Plate screw problem

[David Renaud]

Ron said.....

> Or you can cut out the inner rim underneath the block and attack it from the bottom.

Nice, yes, of course......
This plate screw is located just shy of the shelf....and far enough from any tuning pin holes I could actually drill up from the bottom.
Flexible shaft........drill up.....plug/fill, start over from the top.

It's rather deep and narrow through a plate strut to tap....

                                                            Dave Renaud

Sent from my iPad

On 2011-07-15, at 10:55 AM, Ron Nossaman <rnossaman at cox.net> wrote:

> On 7/15/2011 9:00 AM, David Renaud wrote:
>> 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.
> 
> New screws are my first choice, for reasons you're discovering.
> 
> 
>> Any warnings regarding a carbide bit attempt? I don't have experience
>> drilling metal. Sound right to you.
> 
> Sounds like near certain disaster to me. A decent quality bit wouldn't have broken drilling a mild steel bolt, unless it was a small diameter bit and you forced it badly. The cheap bits I've come across tend to either be too soft to use, or more likely too hard and brittle. A bit that was improperly tempered (optimistically assuming it's made of an appropriate steel in the first place) isn't going to do you any favors when you try to drill out embedded pieces with a carbide bit, assuming you can find one long enough. The whole thing being deeply buried under the plate doesn't help at all either.
> 
> I think I'd try Pianotek's 3/8" extractor first. I'd get the biggest soldering iron I could find with a tip that would just fit through the plate hole and long enough to reach the screw stub, unless it's broken below the block surface, which is most likely. I'd pick out whatever I could get by any means I could devise , any broken drill bit pieces. Then use the extractor to bore down to the top of the screw stub. I'd then chuck a 3/8" maple dowel into the drill, and spin it on the top of the screw until the smoke poured out in a dense cloud. That'll heat the screw. I'd give it a few minutes for the heat to travel the length of the screw then do it again, and maybe a third time. When you've got a screw that's too hot to touch bare handed embedded in maple, it's going to dry that maple out and it will shrink away from the screw slightly. Then, slowly and cautiously, use the extractor to try to either surround the screw and core it out, or engage the top and carefully back it out.
> 
> Or you can cut out the inner rim underneath the block and attack it from the bottom.
> 
> And just say no to cheap TiN coated drill bits.
> 
> Ron N