Vintage Safe Restoration

[Tom O]

The only person I knew that was familiar with safes was a guy named Ron Pruin back in the early 90's. The Calgary Herald ran a full page article calling him Canada's #1 safecracker after his release he was deported back to the Netherlands. In the article he stated that he could have designed safes but who would have believed him!

 

[RobinHood]

The purpose of the threads is to not allow the dial/spindle assembly to simply fall out if you pull the dial towards yourself while opening the lid.

i think they are also used the control/adjust the disc spacing in the stack-up: with three key positions at 120* apart and an assumed 24 TPI (as observed by @YYCHobbyMachinist; 3/8”-24 is a standard UNF thread), each 1/3 of rotation of the disc equals 0.0139” of axial travel along the spindle.

you mentioned that the newer safes have 4 key slots in the spindle: that would give you even finer adjustment (0.0104” per 1/4 of rotation) to set the disc spacing.

clever design actually.

 

[YYCHM]

@Cap'n Kelly How thick is the web section of the cam and how proud does the boss extend from the web? Also, how much material would have to be bored out of the cam web in order to install a replacement boss?

Craig

 

[Johnwa]

It looks like at least one other disk rotates on the outside of the boss. From the pictures the ID of that disk is 0.429” so the OD of the boss must be just under that. With a threaded ID of ⅜” there isn’t a lot of meat left for the key way.

It looks like it would be a fun project.

 

[YYCHM]

With a threaded ID of ⅜” there isn’t a lot of meat left for the key way.

One image shows he mic'd the spindle thread at 0.295" so it's more in the realm of 5/16" X 24. I mocked up a prototype in aluminum, It's pretty tight alright. If the boss can be threaded with a tap, I think I can make a replacement boss out of brass. The 1/16" key kind of boggles my mind. That means 1/32" is engaging the boss and 1/32" is engaging the spindle. How to make a 1/16" square key is a whole different problem and I'm thinking a piece of drill rod might suffice.

Craig

 

[Johnwa]

Fastenal shows 1/16 key stock in their catalog, but I suspect it would be special order.

 

[RobinHood]

do we have the key way dimensions somewhere?

I could rough mill something down and then surface grind it to size if appropriate key is not available. Have done it in the past to adapt metric shaft to imperial pulley.

the key way on the shaft might have been cut using a slitting saw of appropriate size. Note the ramp out at the end of the key as it comes into the threads... I probably have a saw of correct size.

 

[YYCHM]

do we have the key way dimensions somewhere?

I could rough mill something down and then surface grind it to size if appropriate key is not available. Have done it in the past to adapt metric shaft to imperial pulley.

the key way on the shaft might have been cut using a slitting saw of appropriate size. Note the ramp out at the end of the key as it comes into the threads... I probably have a saw of correct size.

1/16" as far as we know and from my proto type I would tend to believe that as there ain't room for anything bigger.

As for the shaft/spindle, that's something I can't attempt to do as I don't have mill indexer. I'm assuming that the original spindle is serviceable for now.

For scale, this is what we are dealing with here.

Kelly needs to weight in before we go much further with this.

Craig

 

[Cap'n Kelly]

At this point I think some eyes on would be best. I am mobile so can bring parts and assembly anywhere in Calgary for a viewing session. I have a bit of a hiking commitment late this morning (May 7) but could be available in the afternoon or any following day. I am open to repair of the existing pieces.

 

[YYCHM]

At this point I think some eyes on would be best. I am mobile so can bring parts and assembly anywhere in Calgary for a viewing session. I have a bit of a hiking commitment late this morning (May 7) but could be available in the afternoon or any following day. I am open to repair of the existing pieces.

PM sent.

 

[YYCHM]

Who stepped up to the plate to help Kelly out? All's Kelly would say was that a member visited him today to take a look at the problem and they have a plan of action in place.

 

[Cap'n Kelly]

Who stepped up to the plate to help Kelly out? All's Kelly would say was that a member visited him today to take a look on the problem and they have a plan of action in place.

PM sent.

 

[Cap'n Kelly]

do we have the key way dimensions somewhere?

I could rough mill something down and then surface grind it to size if appropriate key is not available. Have done it in the past to adapt metric shaft to imperial pulley.

the key way on the shaft might have been cut using a slitting saw of appropriate size. Note the ramp out at the end of the key as it comes into the threads... I probably have a saw of correct size.

See attached sample picture of the top of a spline key. This is a later model lid as you may notice how the safe bolts are kept align by the bisection of each bolt instead of using grooves in the back plate. The attached drawing shows a different manufacturers detail but the key would be similar (references RH-right hand, LH-left hand, VU-vertical up, VG=vertical down are not applicable to my drive cam).

 

[RobinHood]

Thanks for the picture/info regarding the key.

the spindle-bezel-knob assembly was successfully separated yesterday. Turns out that the spindle is threaded into the knob with a 5/16”-24 thread. The bezel is held captive between the bottom of the knob and a shoulder on the spindle. It is prevented from rotating by the “thread locking pin” which is at a 45* angle to the axis and driven into a blind hole.



the pin is 1/8” OD so I used a 7/64” end mill to start the removing process. I held the assembly by the knob in a 1” 5C collet in a square block set at 45* in the milling vise. I eyeball centred the cutter. I drilled down about 1/4” and then ran out of room because the mill spindle was starting to interfere with the part. So I switched to a 7/64” twist drill. I figured it would just follow the path of the EM, but give me more reach. It worked fine. Kept pecking away until I got some rust on the drill bit - figured I must be through, so stopped. Used my picks to get the pin pieces out. Then realized that there was a thread and unthreaded the spindle from the knob. Here are the parts.



oh, the thread on the other end of the spindle is 40 TPI. I will remake the spindle next. Stay tuned for that.

when the factory made the lid, they machined the casting in two operations: one from the face (outside) and one from the back (inside). There is a boss that extends from the back through which the spindle passes. The drive cam boss (bronze disc with the holes that needs a remaking because of the failed repair this part), fits inside the cast boss and provides bearing support for the rear of the spindle. The front support is by the shoulder on the spindle below the bezel as it passes through a register in the face of the lid. The two bores are not concentric as seen here.


I put a close fitting gauge pin (the silver object) in the face bore extending into the cast boss on the back side of the lid. You can clearly see how off center it is. I will need to rebore the face hole to make it concentric with the rear boss bore as that is the only place where there is extra material available for removal. I will make the spindle shoulder oversize to match the new oversized hole.

i am actually thinking that this may have contributed to the failure of the drive cam boss in the first place. The wall section where the three key ways are is so thin to begin with, that any excess wear quickly chafes through the wall.

more to come as progress is made...

 

[RobinHood]

Here are some more progress pictures.

The threaded bore inside the knob is off axis by 19 thousands (measured at 1/2” from the face)



Bored out the lid face bore so it is concentric with the inside boss bore. It will need a 3/8” brass bushing on the spindle shaft to make up the difference.



Here I am setting up the new brass drive disc in the dividing head for the 11 divisions - ten 8-32 threaded holes and one 1/4” notch.



The spindle still needs the key way cut, the center section turned down to match the recess on the lid face and the 3/8” brass sleeve.
The drive disc needs the bore threaded, the key ways cut and the boss OD turned to match the ID of the lid boss.

 

[Cap'n Kelly]

FANTASTIC! I have pictured the last photo in my head for years but was incapable myself of doing it. I also had no idea the additional corrections that needed attention. The visuals and the detailed descriptions really tell an additional story.

 

[RobinHood]

A little more work done today. Threaded the drive disc 5/16-40. Turned down its boss to fit into the lid bore. I used a trepanning tool I had on hand to machine out the 70 thou recess.



this is the lid boss the drive disc has to fit into


then it was time to deal with the misalignment of the face recess with the through bore. Again, a picture of the problem: there is a gage pin in the bore. the off-center is clearly visible.


since the face recess needs to be co-centric with the rear boss, I used a 5/8” collet to hold the lid in the lathe to bore the face recess.



and the result


next I turned down the shoulder of the spindle for a nice sliding fit. I finished off today by milling the key way using a 50 thou slitting saw.


here are the new parts as of today. The drive disc needs the three key ways and a key needs to be made. The misaligned knob threads do not affect operation and I would keep it original as a “feature”

 

[PeterT]

Lots of delicate setups & operations. Way to go!

 

[kevin.decelles]

Good photos and descriptions. I learned much. Thx!


Sent from my iPad using Tapatalk

 

[RobinHood]

Thanks Gents. I am learning a lot too.

Today it was time to make a little broach: 50thou wide (to match the key way in the spindle). I was considering using part of a 1/16” (0.0625”) parting blade as it already has two of the relief angles from factory. I did not have a good way to set up the angles on the surface grinder (no sine bar) to grind off 12.5thou to make it the required 50thou. Plus I have no way of holding it in the mill spindle without welding some sort of shank onto it. So the next best candidate was this:
a busted HSS end mill. It has a 3/8” shank. I rough ground it on the bench grinder before I switched to holding it in the spin indexer and grinding on the Clarkson T&C grinder. The spindexer allowed me to grind in the relief angles while getting the cutting face to 50thou.


the flat on the shank will be used to indicate the cutter in the bore. It was ground at the same time as the front face (both faces are visible in above picture). The edges were honed to remove the grinding burrs.

here I am setting up for broaching. I used a well fitting gage pin to center the part in the mill vice. The drive disc is held in a hex collet block so I can get the 120* angular spacing required. (One could also use a dividing head or a rapid indexer for this operation). Since the gage pin is in a through hole, I used an O-ring to prevent it from falling through.


the broach is held in an ER chuck with a short piece of bolt behind it to prevent it from being pushed into the collet (probably overkill, as we are only going into brass)


next will be the actual broaching...