Repinning and rebushing is an essential skill all piano technicians should be familiar with. A little practice with some old hammer flanges will go a long way to improve your work.
There are several center pin locations on the piano. The hammer flange, jack, repetition lever, wippen flange, damper underlever, and underlever flange. Initial practice with hammer flanges is the easiest and is also the most repinned part of the piano. The principles and procedures are the same regardless of which part you are repinning.
Center pin extractor / insertion tool
Micrometer or Calipers
Sharp razor knife
Bushing cloth (Renner shoelace style cloth pictured here)
Bushing cloth sizer (Renner)
Flush cutting nippers
Drill bit in pin vise (#37 or .104” drill bit)
Tension gram gauge
To have a center pin and bushing with:
Tight pin in the birdseye
No wobble between the two parts
Cloth seam at 11 to 1 o’clock positions
Clean flush edges
Remove the center pin using the extraction tool.
Measure the current center pin using the micrometer or caliper and prepare to use 1 size larger. Check the handy conversion chart here.
Remove the bushing using the drill bit*
Test the bushing cloth in the center pin hole if the cloth does not pull through the hole size it using the Renner bushing cloth sizing tool. *
Pull the bushing cloth through the holes leaving a small amount of cloth on the ends for glue. While pulling the cloth through you should have the cloth seam at about the 1 or 11 o’clock position. *
Place a small amount of wood glue on the cloth*
Pull the rest of the cloth through to flush up the one end*.
Insert the new center pin to act as a caul for gluing. *
Let it sit for 20 minutes or so.*
After drying remove the center pin*
Flush cut the cloth ends with the razor knife, ensure clean cuts, and side.*
Test the new center pin size in the birdseye. If the new size pin can be inserted by hand it is too loose and you will need to go a size larger. You should not be able to insert centerpins by hand.
Use the Manino broaches to friction iron and ream the cloth, going no further than the size of the new center pin. Use progressive sizes and work your way up to the appropriate size. Working your way up with help prevent pushing out your new bushing
Using your smaller center pin size, insert this size by hand to line up all the new bushed part around the flange. This will hold the part together and act as a leader pin that will easily be pushed out while the new pin is inserted.
Partially insert the new centerpin.
Use the centerpin insertion tool to completely insert the new centerpin, flushing up the one side.
Test the fit by swinging the flange, checking with the tension gauge, and checking for wobble.
Use the flush cutting nippers to provide a clean flush edge.
*Only to be done if you need to replace the bushing along with the centerpin.
Additional practice with jacks and rep levers are a good way to improve this skill and ensure that you are not running into this in the field for the first time without having done it.
Watch the full video demonstration: