I'm not a piano tech but thought I'd post this both here and in the Piano Forum.

I recently had keytops replaced with plastic. Now I notice whenever my thumb touches the underside edge of one of the adjacent keytops (such as when playing an octave) it feels sharp and pointy. It's almost like there is a rough seam running along the front edge of each keytop.

As a professional pianist, I regularly play many pianos during the course of a week, but have not encountered this before. This particular keyboard now feels less than "friendly" and needless to say, I am disappointed with the result.

Is this a known problem with a specific brand (or grade) of plastic keytops? Is the only solution to remove these and sand them, or should I consider replacing these with a different set?

Thanks!

It happens. This is flash, plastic that exudes out between the sections of the mold. If it is severe enough to be troublesome, I scrape it off with a file or scraper, which takes some technique. I generally do it during the final trimming of the keytops. Talk to the person who did the work.

It can be one or two notes per octave, always the same notes. The difference is apparent visually.

This may not be just flash, but the gate for the mold instead. The gate is where the plastic enters the mold during the injecting molding process. When the parts are ejected from the machine, they are either automatically cut off the sprue, or manually trimmed.

Flash is the thin flat stuff you see on the edges of parts. This is caused by a number of reasons including not enough pressure during the molding process, and contamination of the material its self.

I learned this while working on interactive training programs for the plastics industry.

John

The gate is at the back of the key.

I have had good luck trimming plastic pieces down to be flush to another surface by using a single-edged razor blade almost edge on to the surface being trimmed, and dragging it along. It's not unlike how a razor is used to shave. The keys would have to be removed to do this, but the person who did the recovering should be willing to do so.

Roy,

Key tops will always require some finishing after fitting. The covers will have raised edges (they come out of the moulds with this shape), throats will require trimming to get them in line with the sharp fronts, the front corners will need to be rounded and the edges fitted to the wood without removing key-stick wood or rounding the bottom of key fronts, before the set is finally buffed.

If all these matters are addressed before the final buffing of the key set, you'll end up with a nice job. Unfortunately, out there in repair-land, things don't always turn out as some would like.

Of course, the technician who attends to every detail will have to charge more or he/she won't eat. On the other hand, some clients don't mind a few corners being cut as long as the job is cheap, while others will be prepared to pay a premium to get a nice result.

The real tragedies occur when a perfectionist client contracts the knock-em-out cheap tech, or when the bargain hunter client is served by the perfectionist technician.

There is room for all sorts of clients and techncians in the market. However, have a talk to your tech. and see if he would be prepared to round off the corners and rebuff.

All the best.
Ron O.

Then this is definitely flash then.

I've removed flash in the same fashion as Roy does. A simple trim with an Xacto knife works wonders.

John