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<DIV><FONT face=Arial size=2>Terry and Ron. O.</FONT></DIV>
<DIV><FONT face=Arial size=2>Thanks for the replies and information, especially
the formulas from Ron O. I'm planing to use machine screws on my next block.
Would you recommend a fine or coarse thread?</FONT></DIV>
<DIV><FONT face=Arial size=2>Fenton</FONT></DIV>
<DIV> </DIV>
<DIV>Fenton and Michael,</DIV>
<DIV><BR></DIV>
<DIV>We use machine screws to fix our pin block to the plate. We use 8 mm
countersunk machine screws and the pin block holes are threaded in the maple
before we fit the screws. The tapping drill size we use is the same as is used
for threading metal with the same thread size.</DIV>
<DIV><BR></DIV>
<DIV>Speaking of tapping drill sizes, I have a short formula which has been
kicking around in my head for couple decades which I use for calculating the
tapping size for a thread. The formula is handy because it is sometimes more
convenient than looking up tapping tables. The formula for the minor diameter of
a thread is;</DIV>
<DIV><BR></DIV>
<DIV><X-TAB> </X-TAB>(major diameter
in thou) - (1220/tpi)</DIV>
<DIV><BR></DIV>
<DIV>This is handy when tapping for agraffes for example, when we're dealing
with an unusual thread that we won't find on a tapping chart. For example, lets
take an agraffe with a 1/4" diameter and 36 threads per inch. The tapping drill
size for this thread can be found using the following;</DIV>
<DIV><BR></DIV>
<DIV><X-TAB> </X-TAB>Diameter of major
diameter in thou is 250</DIV>
<DIV><X-TAB> </X-TAB>Threads per inch
is 36</DIV>
<DIV><BR></DIV>
<DIV>Substituting the above into the formula we get;</DIV>
<DIV><BR></DIV>
<DIV><X-TAB> </X-TAB>250 -
(1220/36)</DIV>
<DIV><BR></DIV>
<DIV><X-TAB> </X-TAB>250 - 33.88</DIV>
<DIV><BR></DIV>
<DIV><X-TAB> </X-TAB>216.11</DIV>
<DIV><BR></DIV>
<DIV>So 216 thou is the minor diameter of this thread. The nearest nominal
tapping drill will be 7/32", which has a diameter of 218
thou.<X-TAB> </X-TAB>The tapping drill should always be
slightly larger than the actual minor diameter of the thread, to allow for
better clearance of the swarf.</DIV>
<DIV><BR></DIV>
<DIV>The same formula can be used for metric threads also, but the major
diameter in mm needs to be converted to thou by multiplying the diameter by
39.37, and the thread pitch in mm needs to be converted to threads per inch. To
do this divide the metric pitch into 25.4. For example, a 0.7 metric pitch,
expressed as threads per inch is;</DIV>
<DIV><BR></DIV>
<DIV><X-TAB> </X-TAB>25.4/0.7</DIV>
<DIV><BR></DIV>
<DIV><X-TAB> </X-TAB>36.285 threads
per inch</DIV>
<DIV><BR></DIV>
<DIV>For those of your who might be rebuilding grands, and sometimes need to use
replacement agraffes with a new thread size, when the original agraffes are no
longer available, these formulae can quite useful.</DIV>
<DIV><BR></DIV>
<DIV>Ron O.</DIV>
<DIV><BR></DIV>
<BLOCKQUOTE cite="" type="cite"><FONT face=Arial
size=-1>Micheal,</FONT></BLOCKQUOTE>
<BLOCKQUOTE cite="" type="cite"><FONT face=Arial size=-1>I know some of this
thread was meant as a joke, but I'm interested in your comment regarding
machine threads in the pin block, if you were serious. I've diffenately used
machine treads in maple, but nothing as critical as a pin block. Please
comment on thread size, drill size, ect. I assume you might use a smaller
drill than recomended for metal. Or maybe I missed the joke.</FONT></BLOCKQUOTE>
<BLOCKQUOTE cite="" type="cite"><FONT face=Arial
size=-1>Thanks,</FONT></BLOCKQUOTE>
<BLOCKQUOTE cite="" type="cite"><FONT face=Arial
size=-1>Fenton</FONT></BLOCKQUOTE>
<BLOCKQUOTE cite="" type="cite"><FONT face=Arial
size=2></FONT> </BLOCKQUOTE></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=mfarrel2@tampabay.rr.com
href="mailto:mfarrel2@tampabay.rr.com">Farrell</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">Pianotech List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, June 16, 2008 1:32 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Machine Threads in Pinblock,
was WD-40</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial>I hadn't followed the WD-40 thread, so I don't know who
(Michael) you are referring to Fenton, but I also routinely use machine screws
in pinblocks. I really can't tell you exactly what size/bit/etc. I use - just
whatever size machine screw fits and I use coarse thread and drill
as small a hole as I can screw a nicely buttered-up machine screw in
there.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Just seems to me that a machine screw is more secure
than a wood screw- you have full length of the machine screw with treads
locked into the wood. If I'm not mistaken, Ron Overs is doing this also -
probably others.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Terry Farrell</FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=fmurray@cruzio.com href="mailto:fmurray@cruzio.com">Fenton
Murray</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">Pianotech List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, June 16, 2008 1:10
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Machine Threads in Pinblock,
was WD-40</DIV>
<DIV><BR></DIV>
<DIV><FONT size=2>>to thread machine screws into the
pinblocks</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Micheal,</FONT></DIV>
<DIV><FONT face=Arial size=2>I know some of this thread was meant as a joke,
but I'm interested in your comment regarding machine threads in the pin
block, if you were serious. I've diffenately used machine treads in maple,
but nothing as critical as a pin block. Please comment on thread size, drill
size, ect. I assume you might use a smaller drill than recomended for metal.
Or maybe I missed the joke.</FONT></DIV>
<DIV><FONT face=Arial size=2>Thanks,</FONT></DIV>
<DIV><FONT face=Arial size=2>Fenton</FONT></DIV>
<DIV><FONT face=Arial
size=2></FONT> </DIV></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>