Metal NAB tape reels are quite a bit thinner than plastic ones, and sometimes require spacer shims placed between the reel table and tape reel to properly align the tape path and prevent rubbing against the edge of the reel. On Tandbergs and older Akais as well as some Revoxes and Studers, the spindle lock doesn't tighten up enough to hold metal tape reels snugly against the reel table unless shims are used. This looseness can cause the reel to rattle against the hub when fast-winding. Placing a shim between the reel table and the metal reel increases the overall reel thickness, and dramatically improves the clamping force so that the reel will not move within the hub adaptor. We do not supply shims with our hubs or separately. The image above shows manufactured Technics shims, but you can easily make your own. UPDATE; we've recently discovered a VERY simple source of shims; old useless CDs. You can add paper stick-on CD-R labels to increase thickness incrementally if needed, but two standard audio CDs stacked on each reel table are the perfect thickness to center the tape path with metal TDK 10.5" reels. This also snugs the reels up perfectly on our Revox A77 (which has really wimpy spring-loaded reel retainers) and eliminates movement and rattle while fast-winding. For best results, glue two CDs together with the label sides facing out; we use garden variety household cement spread very thinly. Doing this keeps them paired and also provides better friction against the reels. Mini (3") data CDs can be used, but only catch the very edge of the reel holes; we prefer the standard CDs for the larger surface area and greater friction they provide.

Our hubs FAQ page at has lots more on how to use our hubs and what types of reel-to reel-machines they do and do not fit.