Corbin Mortise Lock Cylinder Removal

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  #1  
Old 05-31-12, 02:27 PM
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Corbin Mortise Lock Cylinder Removal

Greetings,

I am trying to remove the lock cylinder to facilitate the replacement of same
as the key has to be wiggled to allow the cylinder to turn. i am hoping the
tumblers are worn as my local locksmith advises he can likely provide a
replacement lock cylinder or hopefully re-key this one.

I have tried to research as best as possible and my take is that if I loosen
the set screw on the side of the door that is closest to the the lock cylinder
(left side in photo) then the lock cylinder will be released and should unscrew.

When I tried loosening the front (left) set screw , the cylinder does loosen,
along with the ring that surrounds it, but it will only turn (ccw) approx 90
degrees easily (so the lock cylinder is basically upside down) before it
meets resistance. I don't want to force it as all functions are currently
working. I also did try to loosen the rear screw at the same time as front
screw and no change. Also removed the front screw and no change.

I was contemplating removing the front set screw and inserting WD40
hose to see if I could provide some lubrication to the internals in case it is
corrosion on threads (assuming it is threaded) but decided to look for
experienced advice first before cautiously proceding.

Anyone dismantled this particular lock ?

Thanks in advance for any assistance.

Syd
 
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  #2  
Old 05-31-12, 03:07 PM
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I remember that the cylinder has a fairly fine thread so it wouldn't take much in the way of dirt or corrosion to make it difficult to turn. I would advise against the WD-40 but maybe if you could use a padded pliers (to prevent damage to the cylinder) it would allow you to unscrew.
 
  #3  
Old 06-03-12, 10:41 AM
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A little persuasion can be helpful, but first try loosening the top and bottom fixing screws. Often the cylinder is tightened up before the fixing screws are tightened, thus twisting the lock body slightly in the mortise.
 
  #4  
Old 06-04-12, 06:44 PM
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Thanks GlobalLocky !! Loosening those two screws on the side of the door that hold in what I think you call the cassette (or latch mechanism) allowed the cylinder to move freely and unsrew as expected. I will take it to a locksmith to either get a new cylinder or have the tumbler pins replaced ... depending on what is available and what they offer. Will advise if any hiccup to the plan. Syd
 
  #5  
Old 06-07-12, 07:16 AM
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Thanks for the follow up Syd. Glad to be of service.
 
  #6  
Old 11-20-12, 01:35 PM
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I am trying to fix a Russwin lock that is exactly like this one that is pictured except it is right handed. Original problem was a frozen lock. That is fixed but, when I put it back in the door it seem I have not put things together properly. The key only works part time......and sometimes it requires moving the lock handle inside. Acts like a piece of machinery that is out of time. Does the lock have to be in a certain position when the cylinder is put back in? Thanks!
 
  #7  
Old 11-21-12, 06:16 PM
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Things to check:
1) Sometimes the key cylinder is screwed back in too tight. Generally, when the cylinder starts to snug up on the collar, back it up to the correct position (keyhole down, name reading correctly above). Try the key. You may need to back it up one more full turn, just not so much that the collar flops around loose.

2) Make sure the set screw engages the cylinder slot...rotate the cylinder back & forth slightly while tightening the set screw to "feel" for the slot.

3) On real old locks, the parts may have worn to the extent that a properly positioned cylinder has stopped working. A cheap (& improper) fix is sometimes done by rotating the cylinder slightly left or right before tightening the set screw to hold it a bit off-center, which can buy you a little more time before replacement. You can tell if this was done to your lock by examining the cylinder for thread damage near the groove. Also, the cylinder will be hard to thread in & out.

4) Did you grease or oil the friction points within the lock before re-assembly?

5) Occasionally, over-tightening the inner knob and/or outer handle can put the lock in a bind. Loosen, re-position, check operation, re-tighten.

6) Erratic operation could be related to why it was frozen in the first place.
 
  #8  
Old 11-21-12, 06:26 PM
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Oops. On the lubrication point, don't put oil or grease in the key cylinder. Powdered graphite (or some of the newer non-petroleum based lubes recommended for key cylinders) is best.
 
  #9  
Old 11-21-12, 09:39 PM
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Thank you for the detailed response! This is my first lock project and I truly appreciate the help. I used graphite to lubricate the lock cyl. but I did not lube the contact points. One thing I have noticed based on your post is that the inside handle that operates the lock is very loose. I suspect this could be the problem as the contact points are moving around too much to interact every time. How do I tighten this? I will also back off one turn to see if that helps. Thanks again.
 
  #10  
Old 11-23-12, 08:53 PM
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First, to clarify "contact points" I simply mean the lock's internal moving parts where they would be subject to wear. The key cylinder is treated separately by shooting a few puffs of graphite into the keyhole.

Does this lock have a grip handle with thumb-press outside & turn knob inside?

Since you've had it apart, do you remember if the inside spindle is of the "split-hook" type, ie., threaded, but split along it's length, with one half having a sort of hook on the un-threaded end where it is secured behind the lock's hub?
This was a very common design 50+ years ago, & was one of the first components to wear out over time, due to the constant loosening of the spindle set screw.

(cont.)
 
  #11  
Old 11-23-12, 09:07 PM
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Properly re-greasing the hub & other internal parts (NOT the spindle/knob/set-screw assy), can extend the life of these old locks for many years. But at some point the threads between spindle & knob become stripped, and/or the hub wears beyond repair. Aftermarket parts are rare.

So, regardless of the design, you're still looking at taking it all back apart, (unscrew, but do not disassemble the key cylinder, which if, as it's own separate component, doesn't work smoothly, take to a locksmith for repair), clean the grunge off the parts, re-lube & re-assemble the lock body & secure the cylinder. Check for smooth operation before placing back in door. By this process of elimination, you should discover where the problem occurs, as you re-assemble the parts back on the door.
 
  #12  
Old 11-28-12, 12:08 PM
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Sorry it has taken so long to get back to you. This is the first day with decent weather that I have been off work and I did not mind having the door open. LOL Thank you so much for your knowledge. I am no longer intimidated by these locks and that is good because my house was built in '48 and I have more work to do. The problem was simple.......I only needed to tighten the cyl one more turn and now everything works as it should. I am very happy and very grateful. The additional information you provided is fantastic. I will use it as well. I have had a couple of people look at this lock through the years and all they could say was replace it. Now I am well armed for the next adjustment. Thanks again!
 
  #13  
Old 11-28-12, 06:22 PM
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Glad it works now, & as they say, if it ain't broke, don't fix it... but if you initially installed the cylinder "snugly", but had to "tighten" it one more turn, it indicates you may have a shorter-than-original (aftermarket) cylinder or thicker-than-normal door, or too many spacers. Ideally, a mortise cylinder should be threaded into a lock body 5 to 7 turns, as this ensures good thread/set screw engagement, & centers the cylinder cam over the boltwork which can result in smoother operation/longer life.

But, as I said, if it now works smooth, leave it be!
 
  #14  
Old 11-29-12, 07:59 AM
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Since the lock has been "worked on" through the years I have no way to know the amount of turns on the original installation so I tried to put it back where it was. I actually made nearly one half of the final turn with my hand and then completed it with channel locks. When spring comes I plan to remove the lock and handles to clean up years of tarnish and old paint. What would be the best way to do this, and then protect the polished finish? I have a buffer on a bench grinder.
 
  #15  
Old 11-29-12, 06:59 PM
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Don't know much about metal finishing beyond using a little Brasso to buff up cast brass or bronze, but if there's any plated parts, don't know what you do with those. I think there's a forum here on metalworking that would help with that.
 
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