Metal NAB reels are quite a bit thinner than plastic ones, and sometimes require spacer shims. These when placed between the reel table and reel, raise the reel height slightly so as to properly align the tape path and prevent the tape 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 move and 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 shift within the hub adaptor. We do not supply shims with our hubs or separately. Shown above is a pair of Otari-manufactured rubber shims; virtually every reel machine maker had a version of these, but only Tascam and Otari still sell them. Fortunately, you can easily make your own; see at right.	We've recently discovered a great way to create shims by utilizing round paper or cork disposable drink coasters. Party goods stores sell these, and so do some package stores (usually printed with beer logos). Bars and restaurants use these and throw them away after one use; simply take yours home with you. Coasters right around 1mm thick and 3.5" to 4" in diameter work great. Find and mark the center point; then punch a hole with an awl or icepick. Carefully enlarge the hole to about 15mm diameter using a ream, scissors blade or other pointy  implement until it just fits snugly down over your reel table spindle and flush against the reel table. Neaten up the hole edge and you're done. The hole may fray and enlarge with time if removed and remounted routinely (unneeded unless you switch reel sizes a lot) but given that these are virtually free and quick to make, this aging issue does not pose a significant downside.