[pianotech] Cosmetic aspects of filed hammers

[David Boyce]

Thanks for your responses folks.

Alan, you say
>
> *David, *
> *Did you remove the hammers and place them in groups in a vise to 
> dress the hammers, or do them in situ?*
> *On this 1883 Bechstein I used French chalk to whiten the hammer 
> surfaces and then vigorous brushing with a nailbrush.*
I did them in situ. I've never removed a sert of hammers just for filing.
In what form was the french chalk you used? One of the little 
rectangular-profile sticks?

I think your screwdriver idea is great! It exactly solves what I 
observed to be the problems with the mini-drill tool. That is, lack of 
torque means that 1) it's hard to keep a constant speed and 2) you can 
only use a wheel of small diameter.  The power screwdriver/sandbobbin 
approach solves both problems! A power screwdriver is bound to have MUCH 
more torque than the mini drill.  Can I ask what glue you use to stick 
the sandpaper to the bobbin?

Also, you mention interestingly that you use the same setup but with 
steel wool on the bobbin, to revive strings.  How do you attach the 
steel wool?

Joe, thanks for your comments
> In the hand-filed photo, I was taught to start the filing further 
> towards the tail than you did;  I start at least before the widest 
> point, and often before or at the staple.  The reason for this is that 
> if you start after the widest point (if you start closer to the 
> crown), you are effectively  increasing the hammer radius at the 
> crown, thus flattening the hammer crown.  This is illustrated by the 
> exaggerated photo below. 
I appreciate exactly what you mean. I do try to keep a proper profile, 
though I've never started as far back as the staple.  The idea of taking 
off a layer or "skin" of felt all the way round would certainly solve 
the problem of the grubbiness on the upper surface.  Mind you, there is 
the aspect of time and cost, related to the quality of the piano.  In 
the particular example I sent, and for that particular section of 
hammers, the filing does start nearer the nose the I usually would, but 
for those hammers it kept the profile OK.  I love the idea of 
frantically trying to glue back on excess removed felt!  I can't guess 
the brand of piano, by the way!

John Ross, I do like the idea of using the sand blaster with glass 
beads. I've been thinking for a while about a compressor.  What else do 
you use the setup for, in addition to cleaning actions?

Jack, you say
>
> I have a special paddle I use, it is a piece of dragon skin I glued 
> onto a paddle. It takes the felt off very quickly. I then go on to 
> finer grits with various paddles
>
> and sandpaper strips finishing off with 600 grit.
Do you start right back at the staple, and take off a layer of felt all 
the way round, as Joe recommends? It's really the "cleaning" aspect that 
I was asking about.  I wasn't familiar with dragon skin, so looked it 
up. Interesting. Where do you obtain it?

Thanks again folks.

Best regards,

David Boyce

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