drill bit for cast iron

[Allan Gilreath, RPT]

Ed, et al,

I find it far better to drill through the plate, if necessary so I can get a
bolt through the post rather than just a filler block on this type of
repair. I then use a long enough bolt so I can use a fender washer, if
there's room, a lock washer and the nut.  One reason for this is that I'm
depending on the bolt to hold the tension rather than glue since any glue
inserted would just be on top of a failed glue joint rather than to fresh
wood. The really creative part can show up in the lower tenor or bass when
the tuning pin plane doesn't allow for easy access to drill and bolt
directly through a post.

Btw, standard metal bits do fine as long as they're sharp and plenty of
pressure is used so that they cut rather than trying to burn a hole through
(as I imagine the masonry bit would.)  

Allan
Allan L. Gilreath, RPT

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of ed440 at mindspring.com
Sent: Thursday, August 24, 2006 3:23 AM
To: Pianotech List
Subject: Re: drill bit for cast iron

Why are you drilling through the plate?
This repair is usually done using the holes which already exist.
Ed Sutton

-----Original Message-----
>From: Bob Hull <hullfam5 at yahoo.com>
>Sent: Aug 24, 2006 12:32 AM
>To: pianotech at ptg.org
>Subject: drill bit for cast iron
>
>Drill Bit Question:
>
>Background: Yesterday I was trying to repair an
>Everett console that had a separation crack between
>the last lamination of the pinblock and the back beam.
> I guess it's glue joint failure and a downward
>warping of the wood from the downward pull of the
>tuning pins.  
>
>I made plans to install 3 bolts 3/8" x 5"L  after
>applying CA down in the crack.  However, drilling
>through the plate took about 45 minutes to do 1 hole. 
>I used a carbide tipped masonry bit per the suggestion
>of a industrial machine tool and  supply co.  I also
>tried using a 1/4" bit first and then progressing to a
>3/8" bit.  So, I wound up just installing 1 bolt due
>to time restraints.  
>
>I have done this repair a few times before but it's
>been awhile and I don't remember it taking this long
>to drill thru the plate.  I used a good low rpm
>electric drill vsr 0-600 rpms.
>
>Any drill bit recommendations?
>
>Thanks,
>
>Bob Hull
>
>  
>
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