Capstan shaft reconditioning service
Reconditioning Capstan Shaft
Why and what is it? Revox and Studer used to 'dull' the ends of their capstan shafts to provide better grip on the tape. Over time most capstan shafts become very shiny with this surface less able to provide the correct grip on the tape thus increasing wow and flutter.
When Revox Studer introduced the dulled shafts they indicated in a service bulletin that this allows lower pinch roller pressure with improvements in tape wander and thus wow and flutter but also less tape wear. To give you an idea of the significance of this, early machines had pinch roller pressure of 1.2 - 1.5 KgF whilst later machines this was reduced this to 0.8 KgF. Early machines you are able to adjust this but on later machines like the A810 it is essentially not adjustable or within a very narrow range. Thus, it is really important on later machines to restore the capstan surface. In the factory tech bulletin they also suggest that all early shafts would benefit from the same reconditioning process.
We have teamed up with a retired ex Studer engineer who has the machinery and know-how to recondition shafts. At one time in his apprenticeship he actually worked in the capstan shaft conditioning shop. I now insist all machines that come through our workshop have their shafts reconditioned.
Can your shaft be reconditioned? As long as there is no obvious mechanical degradation like grooves or ridges, most capstan shafts can be reconditioned. We can recondition any capstan shaft fitted to Studer and Revox machines including the old 36 series (G36 etc). The process does not involve grinding, or abrasion but more akin to fine controlled bead blasting which does not 'remove' metal per say but rather 'melds' the metal surface without significantly altering its dimensions. This can be done between 5 - 10 times. You simply send us your capstan shaft and when we have collected 5 or more they are done as a batch to keep setup costs down. An instruction sheet how to dismantle, prepare and send includes a self-assessment of whether the shaft can be reconditioned can be downloaded here. When we send the shaft back it includes a small amount of appropriate lubricant sufficient for 1 motor plus 2 or 3 service application in the future and of course another instruction sheet.
Listings shown are for 1/4" machines. For Studer 1/2" - 2" multi-track machines please ask for a quote.
For electronically commutated motors (multi wire >4) fitted to C270, A807 and other later machines - these are a lot more complicated as a number of different bearing and lubrication systems / types were used. The basic kit is applicable with one of two possible lubricants. The deluxe kit offered however does not contain extra parts but rather that you send the complete motor to us and we will recondition it complete - hence why it is a little more expensive. It will have the correct lubricant replenished and the motor assembled and tested.
Basic Kit. Capstan shaft reconditioning and vial of appropriate lubricant.
Deluxe Kit. As above + new plastic end cap with lube hole, new felt and bellville thrust washers. For earlier motors with a roller bearing, it will also include a new low noise bearing. For A-G36 motors it will include a full overhaul and lube kit for the flywheel assembly and motor. For C270 and A807 motors this includes you sending the motor to us and we recondition it in toto for you.