felt as loop first lever

To replace the keybed bushings, one must micrometrically measure the pins (which must not be worn) and use the corresponding calibrated cauls. This is to ensure the correct clearance and avoid loose keys. The thickness of the felt is also important in the selection. It is a job for experts. The removal of the old bushings must occur without damaging the wood. Therefore, I advise against performing this work yourself. However, you must ensure that the "good" technician performing the work evaluates all of this. Sometimes simple clips or a poor quality cloth of inadequate thickness are used. This is not acceptable. If the pins are oxidized, they must be replaced, both the front oval ones and the central ones. All of the same length and diameter!!!!! Failure to replace them could lead to rapid wear of the new felt. Cauls are better if metallic (brass); in that case, heat can be applied during gluing, as is done in the factory. This promotes perfect sliding even with minimal lateral play.

Naturally, once the work is finished, every key must be checked and precisely calibrated with a special tool. The perpendicularity of the keys must also be checked after replacing the pins and central bushings.

If the work and the choice of cauls, pins, and felt thickness have been carried out competently, it should not be necessary to calibrate the keys by turning the oval pins to eliminate excessive front play (a procedure that would shorten the life of the cloth).

P.S. Technically speaking from a piano perspective, poor key action can turn a small inconvenience into a major pianistic problem. When the bushings are dirty or worn, or the pins are oxidized, and the pianist strikes the keys with an oblique direction, they feel a sudden sticking of the keys under their fingers due to the sudden and discontinuous increase in friction. In this situation, the keys could suddenly jam during descent. Avoid, on the advice of some "joker," LUBRICATING the pins. This will shortly lead to a greater problem by dirtying the bushings... which will no longer slide!!!!!!!! If necessary, use only TEFLON spray..... without overdoing it.

Thank you very much!

I understand that it is a complex job.

However, I would like to try to solve the same problem first on a few keys of an old upright piano of very little value, so that if it turns out to be good work, I can replicate it on all the keys of the piano I currently use.

I found felts on FTP, is it a good supplier? Or are there better ones online?

I see that the felt thickness measurements vary by 0.1 mm; must the thickness correspond exactly to the difference between the width of the wooden slot and the diameter of the pins?

Another thing, I cannot find cauls online, do you know where I can purchase them?

And must the size of the cauls be identical to the diameter of the pin?

Thank you very much!

supplier ok. regarding diameters, it cannot be said from a distance. The ideal thing is to do a test. Generally, a felt of 1.2-1.3 mm is appropriate. The caul must be a tiny bit larger than the pin. You will understand experimentally how much, depending on the cloth and the glue used. Good luck with your work

thank you very much !

have a good day