[pianotech] Glue Strength for Pedal Lyre Repair

Terry Farrell mfarrel2 at tampabay.rr.com
Fri Apr 30 14:06:27 MDT 2010


Paul - Thanks for posting the pics - worth a zillion words. I have  
found that it is not common to get a perfectly clean break in a piece  
of wood like this. Typically there will be enough irregularities and  
splinters that make a perfect fit impossible. In all honesty, from  
looking at your pics, the break does appear fairly clean - maybe the  
pieces did mate up just about perfectly. In that case, wood glue  
should work. However, I would always use epoxy on a break such as  
this. Wood glue is not strong at all when it has to bridge any gaps.  
Appropriate epoxy is very strong that way. I just chisel off the  
irregularities and splinters and then epoxy together - that way you're  
guaranteed a super-strong repair - and with the lyre, you certainly  
want that.

Regarding the loose dowels. If you hand drilled, that is likely a good  
part of the reason. Another is maybe the dowel is slightly undersized.  
What kind of wood was the dowel? Yes, you do want a tight fit for wood  
glue. Here again, I would drill the hole oversize, use a RED OAK dowel  
(super strong and porous for epoxy to grip) and epoxy it in place  
using the West System two step bonding method (same for the block).  
That will give you the strongest possible repair.

Wood glue (Titebond) has it's place, and it could work well here, but  
it wouldn't be my first choice.

Terry Farrell

On Apr 30, 2010, at 11:38 AM, Paul Milesi, RPT wrote:

> Many thanks to all who contributed to my education the past couple  
> of days!
> I ended up gluing the two original top block pieces together,  
> clamped for 24
> hours, then drilled and inserted three 1/2" hardwood dowels.   
> Finally, I put
> a little stain on the dowel ends to blend them with the lyre finish
> (refinished years ago by somebody else).
>
> While aware of Steinway lyre construction using posts and wedges, I  
> thought
> it best not to remove remaining top block piece from posts or remove  
> the
> wedges.  I felt re-inserting wedges after gluing the top block might  
> split
> my glue joint open again.  I just tried to take advantage of the wide
> surface area between the two pieces to achieve a good glue joint.
>
> Question about the doweling:  When I drilled the 1/2" holes, my  
> dowels were
> a little lose, not a tight fit that needed to be pounded or squeezed  
> in.  I
> assume with enough glue, this is OK?  When I use hammer shanks for  
> wood
> filler, the shanks are generally tight in the hole I've drilled.   
> Not sure
> why these turned out differently.  If anybody reads this paragraph,  
> I'd sure
> appreciate insight into whether tight fit is necessary, and how to  
> best
> achieve it.  Thinking about this because I know clamping a glue  
> joint is so
> important.
>
> Pix attached.
>
> Paul Milesi, RPT
> Washington, DC
> (202) 667-3136
> E-mail:  paul at pmpiano.com
> Website:  http://www.pmpiano.com
>
> < 
> P4280230 
> .jpg 
> > 
> <P4280232.jpg><P4300235.jpg><P4300238.jpg><P4300237.jpg><P4300243.jpg>



More information about the pianotech mailing list

This PTG archive page provided courtesy of Moy Piano Service, LLC