Recording Engineering & Production: Making records better, not just louder and cheaper. The brightest minds from the creative and scientific world of audio discuss the elements of audio production that interest you most.
Need help removing Capstan from 3M M79-24 [message #149009]
Tue, 18 April 2006 20:50
siberiaguy Messages: 28 Registered: May 2005 Location: Las Vegas, NV
Member
I'm trying to swap capstans (just the rubber part, not the whole assembly) from my parts machine.
There is a single Allen screw on the top of the Capstan (under the plastic cap). It is too tight to remove. The problem is that the shaft and pulley want to turn while trying to wrench on the Allen screw. I don't want to put a pipe wrench or channel locks on the shaft to hold it in place while I try to remove the screw. Anyone here know how to get the job done?
I can tell you what NOT to do! Don't use a pipe wrench or pliers on the capstan shaft !!!
I did this and totally screwed up my M79 capstan and bearings, sliding them over the scratched up shaft! Use a special wrench that has a leather strap for holding the shaft tightly.
Anyway, after getting everything back together it never worked right again until I had it fixed by a pro. There was a real bad wow effect like the shaft wasn't straight in the bearings or something. It cost me more to get it all fixed than just to have a pro do the work. And I think that my M79 repair tech had to use a machine shop to do the work anyway.
I think the tech guy that did my machine was Bart Gass or Bart Gauss somewhere in California. Not exactly sure, but he's probably retired now. I remember trying his number a few years ago and his son (i think) said he had been ill and was retiring from business.
So try to find an old timer that works on these machines properly and have them work on your capstan. That's my best advice. trust me, I have owned a few M79's over the past 25 years.
siberiaguy Messages: 28 Registered: May 2005 Location: Las Vegas, NV
Member
Well, after trying everything I could think of and posting my question to a few places to no avail, the screw had to be drilled out after the allen head became stripped from wrenching too hard. Someone must've applied too much Loctite at some point.
Once the screw head was removed the capstan rubber roller lifted right off. The spare shaft from my parts machine will need to be drilled and rethreaded.
The good news is that removing the old capstan roller from my working machine was much easier. The allen screw turns out to be normally threaded (not reverse).
The good news is that removing the old capstan roller from my working machine was much easier. The allen screw turns out to be normally threaded (not reverse).
That's good news! Glad you got it out. From my experience, you should have your capstan bearings cleaned out and relubricated with the proper lubricant.
I put my capstan on my M79 back together and it had this wow, wobble effect going on. I had a tech look at it and he took the bearings out and had a shop clean them and relub them and everything was fine after that. I guess the bearing get gunked up after all those years or the lube gets hard. My bearings were hard to spin. When I got them back they were like new and felt fine when spun.
Oh yea, be sure to check the capstan to puck rollers alignment when yer done. I had to add shims to my pucks to get the alignment right! I had tape being pulled downwards by the time it got to the reversing idler until I got everything shimmed up!
siberiaguy Messages: 28 Registered: May 2005 Location: Las Vegas, NV
Member
Good point regarding lubricant! Does anyone here have a brand preference when it comes to lubricant for the capstan bearings?
It's odd that those bearings are not sealed. Oxide particles from shedding tape could easily find their way under the capstan roller.
No idea what lubricant was used on my bearings. The guys at GRS did the work. I know that the shaft was sent out for machining, but I don't know if they did the bearing cleaning & lube or the machinist did.
I do remember Ted at GRS saying that there are different lubricants for specific bearings and the type of conditions and machines they are used in have a lot to do with the selection of the lube. Sorry I don't know more about it.
You would think that 3M woulda used a sealed bearing, like you said. Those bearings on the capstan shaft are WAY expensive! Over $100 each! Ouch !
Members
Search
FAQ
Register
Login
Home
