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Hi, John:
I've found some excellent buffing wheels and compounds from Bayland Products. Try www.baylandproducts.com. Use a cotton or flannel wheel, not sewn. You can call and ask them about which compounds they recommend for buffing plastic. Some are more aggressive, some less so. Using a sewn buffing wheel will burn the plastic. Keep the speed low, and keep the piece moving so it doesn't heat up. Good luck.
Paul McCloud
San Diego, CA
----- Original Message -----
From: John Ross
To: Pianotech
Sent: 03/06/2005 10:16:58 AM
Subject: Re: buffing keytops
Thank you Michael.
Where are those Canton flannel buffers available from?
John M. Ross
Windsor, Nova Scotia, Canada
jrpiano@win.eastlink.ca
----- Original Message -----
From: MICHAEL MORVAN
To: Pianotech
Sent: Sunday, March 06, 2005 1:50 PM
Subject: buffing keytops
John,
I have found buffing to be more of an art than a science. When your buffing ivory and bone you are doing two things, one is smoothing the surface and removing fine scratches, the other is sealing the pores. When your buffing plastic you are smoothing and removing fine scratches and not necessarily sealing it because plastic is not porous. I have found that a sewn canton flannel buff followed by an loose canton flannel buff works well for me. Take into consideration that when you are buffing you are simply putting the icing on the cake. What do I mean? Buffing is to shine and seal (in the case of ivory and bone.) The surface preparation should already be done. Buffing removes fine scratches well, and will leave a perfectly flat surface. If one relies on buffing to remove deep pits and scratches, this is where problems arise. The surface will not be perfectly flat, and heat will be generated. Heat will crack and burn ivory and bone, heat will melt and deform plastic. The trick is surface preparation, keep the key moving, and apply the proper pressure. Compound or rouge plays a role also. Compound can contain abrasives, you want to be sure that you are using a buffing compound and not a cutting compound. A cutting compound will leave as many scratches and lines in the top as you are trying to remove. I look at buffing keys as I look at refinishing a piano case. Your surface preparation and repairs must be done first, spraying lacquer on a piano sanded and left in 80 grit will not be as smooth and look as good as a case sanded to 600 grit, grain-filled and sprayed.
----- Original Message -----
From: John Ross
To: Pianotech
Sent: Sunday, March 06, 2005 12:06 PM
Subject: Re: Moulded Keytops, problems buffing
Hi,
Joe had mentioned problems buffing.
I also have problems in this area.
I had thought on a softer buffing wheel, but have been unable to find a source. The selections available at my suppliers, are limited.
Any ideas?
I had thought on slowing the wheel down. Would that help?
John M. Ross
jrpiano@win.eastlink.ca
From: MICHAEL MORVAN
To: Pianotech
Sent: Sunday, March 06, 2005 11:50 AM
Subject: Re: Moulded Keytops
Joe,
I agree with you 100%, thank you, it is wonderful that you know these things and are willing to share them. Molded keytops are all the same dimension within one set. Keysticks unfortunately are not (except for several sets of Yamaha keys I've covered that were within 0.004 of each other). I've found that most sets of keys differ in length, width and height. I have one set of keys I'm recovering now where the keysticks vary in width up to 0.065. This makes recovering them tricky. If you have a keystick wider than the top you will have to trim the stick, if the top is wider you will have to trim the top. Molded tops being the same width have the contours and radiuses "molded" into them, so if you trim this you will, as you said then have to reshape them, the radiuses and contour to match and yes, the dreaded buffing. I prefer to apply what I call custom tops. This is similar to factory procedures in which you apply a separate top and front. If done this way one can trim the excess and shape the keys regardless of the inconsistencies in width and yield good visual results. I've found that buffing plastic and ivory both have there areas of concern, but I use different wheels and techniques for both with good results. On the topic of keytop materials, I'm pretty sure I have all of the material available within the states and offer them. I have also acquired material from Aug. Laukhuff and Otto Heuss from Germany as well as P&S organ supply from England. These materials are of very high quality and texture but expense prevents their wide use. I've noticed that piano manufacturers are trending towards thicker and thicker tops, this means replacement tops will need to be thicker. I actually have a stash of keytop material that is 0.105 thick, but very rarely use them. I am not adverse to machining down the keystick to accommodate a new top because I am doing it on milling machines with tolerances to within a few thousandths of an inch, and it must be done. If one measures a keystick at 0.970 and is putting on a top that is 0.075 than you machine the key to 0.895 and you have retained the original dimension. The original dimension must be maintained or there will be a regulation nightmare. In some cases I find that a keystick has been machined with little regard for tolerances, and then a corrective measure must be applied. Three choices exist, have a new keyboard made, use a thicker or thinner top (depending on which direction the error is made), or build up the keys. Two of these choices are very expensive. Keytop replacement is tricky and is a decision that should be well thought out. The keyboard is a major focal point of the piano, it is the interaction point with the piano and is the foundation of all regulation. It is a challenge to balance appearance, playability and economy. Joe, what do you mean by "stink in my shop?" are you referring to a particular glue or the smell of machining off old plastic and ivory? Mike
----- Original Message -----
From: Joe Garrett
To: pianotech
Sent: Sunday, March 06, 2005 1:03 AM
Subject: Re: Moulded Keytops
Michael Morvan said: "The quality of the keytop, quality of the =
piano, quality of the rebuild, preference of the customer, knowledge and =
preference of the technician and budget. Crappy "molded" keytops are =
nice if applied properly, and three thousand dollars worth of new ivory =
is "crappy" if not applied properly. Molded keytops have the advantage =
of being inexpensive, uniform in shape and appearance, and relatively =
easy to apply with minimal skill, tooling and yields fair results. A =
disadvantage is that many people feel that they are a cheap top and as a =
result do not use them."
Michael,
What you've said, I agree with. However, it's what you didn't say about moulded keytops that concerns me.
1. Moulded keytops assumes that all key sets are the same dimension, which they are not. Therefore, trimming is necessary. Here lies the rub, as trimming of moulded keytop material is far more difficult than other materials. Especially in making the key set look consistant and have a smooth feel under the players hands. Secondly, if you've ever had to (try) to buff out scratches of moulded key top material, (and I'm sure you have, if you do keytops for a living.), it's next to impossible, as the material is too soft and will "burn/gaul" when even light pressure on a buffing wheel is applied. I'm not saying it can't be done, but it's a royal pain in the patoot to do!<G> Lastly, my aversion to moulded keytops is that it is too thick, especially for many older pianos with tight tolerances of the piano furniture. This requires milling the keystick down. I am totally averse to this practice for many reasons. Some of the "moulded keytop material" from Europe is better as some of it is what we call "Plexiglass". This material can be sanded and buffed. It's still too thick for my eye.<G> I too do keytops, but as only part of my overall service to my clients. I used to have someone else do it, as I really don't like the stink in my shop. Out of frustration with others I've taken to doing it....stink or not.<G>
Regards,
Joe Garrett, R.P.T.
Captain, Tool Police
Squares R I
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