drill bit for cast iron

[John Ross]

Make sure to clamp the separation closed, before drilling. This stops 
sawdust from falling in the crack. The sawdust, might be vacuumed out, 
but then again, the stuff in the bottom of the hole might be there to 
stay, and hinder the closing of the gap.
I have had no problem in drilling with normal metal bits.
I use carriage bolts, with the head in the back, and use acorn nuts on 
the front for neatness.
Bolt every lagbolt hole (or large screw) across the top, to prevent 
further separation, even although, they look good now. Usually about 5.
John M. Ross
Windsor, Nova Scotia, Canada.
jrpiano at win.eastlink.ca
----- Original Message ----- 
From: "Bob Hull" <hullfam5 at yahoo.com>
To: <pianotech at ptg.org>
Sent: Thursday, August 24, 2006 1:32 AM
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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