<html> Hi Joe,             The Hamilton was spec'ed for Darnell castors, but you never know when some Purchasing agent switched to save a nickel. I agree with you, a force fit for the socket is most important. Sloppy fit of sockets, due to either bad drilling or humidity shrinkage, is the #1 cause of castor failure. We have lined many of the holes with Veneer to tighten the sockets, also add 1 1/4" screws for better security. Regards Roger At 10:38 AM 10/6/02 -0700, Joseph Garrett wrote: <blockquote type=cite class=cite cite>All, I've been using the Darnell double wheel casters with Cast Aluminum Sockets, for many years. Alas, these were available from APSCO! I truly hope that Schaff, (now to be known as SchaffAPSCO <G>), will continue the many items that they got from APSCO! These Casters are definately Industrial Strength! They come in Hardwood or Carpet, so the application is variable. Once I have installed these casters, the basic problems of heavy use is no longer a problem. As a matter of fact, the efficiency of these casters can be a bit too much, some times, as they roll so easy, that sometimes you have to chase the piano as you play it! <G> In order to install these casters, I use an 15/16" spade bit to make the wood socket match the cast aluminum socket, (most wood sockets are smaller). This will make the socket a "press fit", that is desireable. The snugger the fit, the better, as it doesn't allow the socket to move around, even when the screws are somewhat loose! Once you get the sockets installed, it is necessary to "drive" the caster stems into the sockets. I have a designated screwdriver that has a large steel screw inserted through the handle, (from the top of the handle, down to the buried end of the screwdriver blade). I place the screwdriver blade into the "swaged" stem base, center the caster stem in the socket and drive the stem into the socket with my "BFH"! <G> As an aside, I have had very poor luck with the "cheaper" sets of casters, that are readily available. Although the Darnell Casters are expensive, they are very sturdy, safe and work the best. Hope this helps. Best Regards, Joe Garrett, RPT, (Oregon) Been There, Didn't Like It, So I'm Here To Stay! [G} _______________________________________________ pianotech list info: <a href="https://www.moypiano.com/resources/#archives" eudora="autourl">https://www.moypiano.com/resources/#archives</a> </blockquote> </html>