[CAUT] Grinding plate counter-bearing

[Ron Nossaman]

On 7/26/2011 11:11 AM, Don Mannino wrote:
> I have a little project I need to work on, and thought I would ask for
> some advice. I need to grind the treble counter-bearings off of the
> plate of a piano in a customer’s home.

Wow, Don,
Little project? And people think I'm crazy! How big a debris field is 
involved in a medium size project? Oh, and that's desecrating a feature 
too, you realize. Contrary to the intent of the manufacturer, whatever 
that may have been.


>I am hoping someone here has a
> good suggestion for which tool works best to give a clean removal that
> stays relatively flat. I would like to avoid screwing up the plate
> finish nearby, and leave a flat surface that I can put a half-round on.

In the shop, with no tuning pins, I use a small angle grinder with the 
coarsest wheel I can get, followed by a carbide burr in an electric die 
grinder, followed by filling the cast in low areas with an 
epoxy/grinding dust mix, followed by right angle pneumatic die grinding 
with a coarse sanding disc. Coats everything in the shop with graphite, 
and still takes most of a day total, and requires extensive plate 
painting and shop cleaning afterward. There's a considerable amount of 
iron in some of those counter bearings. If someone knows of an 
elliptical 1/4" shank burr that'll eat cast iron like 40 grit through 
spruce and make chips instead of dust, I'd love to know about it. What's 
the brand of piano, and why the project?


> Keeping in mind the need to do it in the home, any suggestions? Dremel
> with a specific tip, maybe?

Not much power available, and I don't know if Dremel makes a wheel or 
disc suitably coarse and tough. You could grow old sitting there buffing 
molecular layers

I don't think I'd consider this little project for outpatient surgery 
unless they're willing to pay for a whole bunch of hours (days) making 
both minimal mess, and progress.

Ron N