Capstan shaft reconditioning service - Revox Studer Otari Teac Tascam

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. The Japanese soon copied this good idea. 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 below. 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.

Japanese machines  for each type of shaft a special jig has to be made up. We have 2 jigs for two shaft systems Japanese shafts.  Otari - where the shaft cannot be separated from the special magnetic rotor - see picture in gallery.  Teac / Tascam where the shaft is part of  a separate flywheel assembly eg 32, 34 etc - see picture in gallery

Studer A80, A80VU and A800 1 and 2".  Most large format A80/A800 models you are unable to take the shaft out. You MUST send the complete motor to us. DO NOT force!  You cannot do this diy!  Be prepared.

Pricing We can do all Revox and Studer 1/4 - 2" as well as the two Japanese types. Usually for Studer and Revox, we wait until we have 5 shafts or more so as to keep costs down as there is a setup fee we are charged. This means the waiting period may be 3 - 6 weeks.  If you require an express service (usually <2 weeks) we will need to charge the setup fee.

At this stage we cant do others unless you can give us a batch of at least 10 and then its justified for us to build a jig . 

For electronically commutated motors C270, A807, A820  fitted to later machines - these are a little more complicated in that a number of different bearing and lubrication systems / types were used.  Some have two roller bearings and these should be replaced at the same time. The basic kit+ lubricant is applicable to sintered bearing types using PDP65 or GLY2100 whilst the '+ roller bearings is applicable to A807 with roller bearings (specific red sticker) with one of two possible lubricants. 

Explanation of offering types.

Basic.  only reconditioning of bare shaft - no lubricant

Basic Kit.  Capstan shaft reconditioning + appropriate lubricant sufficient for multiple applications / services .

Basic + roller bearing/s. Applicable to Studer A807 with roller bearings. replacement roller bearings included.  

Are you unsure or nervous or for A80VU 1" & 2"?   We suggest you send your complete motor to us and then we can overhaul accordingly. We offer the use of our DHL account so you can send your precious motor to us safely. Please contact us for details.

DOWNLOAD THE INSTRUCTIONS FOR CAPSTAN SHAFT RECONDITIONING

Capstan Shaft Reconditioning V5.pdf   Jan-24