Dial turn resistance of combination locks

[MartinHewitt]

So far I have bought two used combination locks. Both had additional spacer washers to what the lock would have had, when it was new. In both cases I removed these additional washers because the lock worked for me better without them. On both locks the dial is turning very smoothly now. With the washers the locks turned for me uncomfortably hard.

I would like to know why people put washers into them. Do people want higher turn resistance? Is there an advantage? Or an advantage for certain users? Is it maybe easier to turn the correct combinations for untrained users? Or did the lock change so that it does not need the washers now, but did need it decades ago? Maybe the lock had a problem and a clueless locksmith put the washers into the lock just in case it might help?

Any ideas?

Martin Hewitt

[Jaakko Fagerlund]

Depends on the lock, but most usually have the torque adjustment and unfortunately, most "locksmiths" know nothing about these locks. Offtopic, but just talked to a guy whose safe a locksmith couldn't open in 2 hours despite having the correct numbers on a piece of paper...

[Fritz the Cat]

Hi Martin, Does either of your locks get eassier to turn afteryou dror park a wheel ? My lock seems to turn hard but gets asier after I park the 1st wheel then the 2cd . I was wondering about that but since I only have experience with two different locks I thought perhaps it was normal .

Maybe the extra washer just gives yoan option to adjust as the spindle thread to the drive cam is what sets the clerances by rotation and key . So perhaps the washer gives you the ability to adjust between what the spacing the spindle to can thread offers ?

What thread sizeis is the spindle .Compare to the thickness of the washer ?

[DIY Dave]

In a SAVTA course I attended, the teacher instructed us to leave the dial somewhat snug. People usually tend to spin the dial as fast as they can (which can wear down internal parts) and a tight dial can prevent that.

[MartinHewitt]

Depends on the lock, but most usually have the torque adjustment

Both locks don't have a torque adjustment mechanism. So adding washers is the only way.

:ugeek: Hi Martin, Does either of your locks get eassier to turn afteryou dror park a wheel ?

Parked a wheel 1 is wheel 1 at the right gate position? So you have wheel 1 at the gate and turn wheel 2 and 3 together? You compare the turning resistance of this to "wheel 1 not at gate and wheel 2 and 3 turning together" or to "wheel 1, 2 and 3 turning together"? If it is the later, it does make sense that three wheels turning have a higher rotational resistance than two wheels turning. From my two locks I can't say much about turning resistance because I don't really feel the difference between one, two or three turning wheels.

Maybe the extra washer just gives yoan option to adjust as the spindle thread to the drive cam is what sets the clerances by rotation and key . So perhaps the washer gives you the ability to adjust between what the spacing the spindle to can thread offers ?

I don't think so. The limit is the wheel pack retainer. Probably the only way to restrict the cam movement is by putting something between the dial ring and the safe door.

What thread sizeis is the spindle .Compare to the thickness of the washer ?

The spindle of the 6730 is 5/16" and that of the Kromer is 9mm. The washers are much larger, because there is this tube where the wheels sit on and an air gap between this tube and the spindle.

In a SAVTA course I attended, the teacher instructed us to leave the dial somewhat snug. People usually tend to spin the dial as fast as they can (which can wear down internal parts) and a tight dial can prevent that.

Maybe they somebody should tell Oldfast, that his dialing is not healthy for a lock? Did the tell what and how it is wearing down? Is it because the quick dialing itself or because untrained people need more tries to dial the correct combination as they overdial in smooth locks? My guess would have been, that a lock with too many washers has more wear on the contact of the wheels to the spacer washers and the speed of the turning has no influence on wear.

Martin Hewitt

[MartinHewitt]

Btw. the dial on the 6730 was a bit crooked due to a bent spindle. Probably because of this somebody did fill the slightly hollow backside of the dial with grease. I am sure this didn't help because the dial does not have any contact there with the dial ring. But somebody must have seen a problem and tried to fix it without understanding of the problem. I don't know if the same person inserted the additional spacer washers, but probably not as somebody who has access to spacer washers probably don't put a pound of grease into the dial.

The 3011 came to me without dial. So I don't know if there was a problem. The dial I later got for it had a bent back plate on the dial which also led to a crooked dial. To fix this also somebody put grease there, but less and at a location where the dial has contact with the dial ring. With a straightened back plate the dial turns now smoothly without grease.

[tumbl3r]

It've tended to loosen my dials up a bit from where they are when I get them. Actually, there seems to be no rhyme or reason to the torque settings on these locks. I've gotten some that are tight as could be and others that hardly have any drag at all. As far as I can tell I prefer low to moderate drag, but I think it's probably a good idea to get used to a variety. I've always understood that you want some torque on the wheel pack to prevent vibratory attacks, but I might be way off on that.

[MartinHewitt]

It've tended to loosen my dials up a bit from where they are when I get them.

What do you have to do for this normally? Is it just adjusting the torque adjuster? Are there also additional washers? Do they need cleaning? In case of safes a problem with the mounting?

I've gotten some that are tight as could be and others that hardly have any drag at all. As far as I can tell I prefer low to moderate drag, but I think it's probably a good idea to get used to a variety.

Yup, maybe I will reinsert the washers to see how the feeling is. I assume that with a higher turn resistance the resistance increases much more with the number of wheels turning?

I've always understood that you want some torque on the wheel pack to prevent vibratory attacks, but I might be way off on that.

As far as I know the official way to solve this problem is to make the weight in the wheels balanced so that they don't have an incentive to turn. But a higher resistance certainly slows down attacks.

[MartinHewitt]

Another thought: If you can clearly feel the pickup of the wheels you do not need to count turns. Turn left until you feel the third wheel or a certain resistance which you are accustomed to. Then continue turning until you get the right number. Turn right until the second wheel turns and continue until the right number and so on. Counting pickups might be easier than counting on a scale flying by.

[DIY Dave]

In a SAVTA course I attended, the teacher instructed us to leave the dial somewhat snug. People usually tend to spin the dial as fast as they can (which can wear down internal parts) and a tight dial can prevent that.

Maybe they somebody should tell Oldfast, that his dialing is not healthy for a lock? Did the tell what and how it is wearing down? Is it because the quick dialing itself or because untrained people need more tries to dial the correct combination as they overdial in smooth locks? My guess would have been, that a lock with too many washers has more wear on the contact of the wheels to the spacer washers and the speed of the turning has no influence on wear.

Martin Hewitt[/quote]

I believe it's to keep the flys from bumping into each other so hard as the combination is dialed

[tumbl3r]

What do you have to do for this normally? Is it just adjusting the torque adjuster? Are there also additional washers? Do they need cleaning? In case of safes a problem with the mounting?

For the locks I've had, it's just the little allen screw that adjusts the torque, but I know all of them don't have that. I guess additional shims/washers is probably the only way to do those, but I honestly don't have any experience with them.

Yup, maybe I will reinsert the washers to see how the feeling is. I assume that with a higher turn resistance the resistance increases much more with the number of wheels turning?

Very much so! It seems to be pretty linear with the increase in turning force required proportional to the number of wheels being turned.

As far as I know the official way to solve this problem is to make the weight in the wheels balanced so that they don't have an incentive to turn. But a higher resistance certainly slows down attacks.

interesting... I didn't know that. I makes sense though. One thing I love about this stuff is that there's something new to learn every day

[Oldfast]

.....Maybe they somebody should tell Oldfast, that his dialing is not healthy for a lock?

My first plan of attack always, is to spin the livin' shit out of it in hopes that the lock will melt off
and the safe can be opened. If I see molten lava spewing out the base of the door within a few
minutes, I know I'm getting close. Sometimes this doesn't work... then I'll attempt to manipulate.

Of the used locks I've purchased, some came with additional washers, some were missing washers, and others had the correct number of washers but were in the wrong places. I've also found washers placed at the base of the dial. Why or what the reasons were at the time is a guessing game. Some locksmiths are quite apt with safe work. Others have limited knowledge, but they responsibly work within their limits. Then, unfortunately, there are those that really know very little about safes but cannot bring themselves to turn down the job/money. Someone may have simply added washers when servicing the lock, thinking it was missing some. Or, they may have been attempting to correct a problem. In your case, removing the additional washer created no symptoms, and in fact, seemed to make for a smoother running lock. I'd say you're good to go. Save the washer - maybe your next lock will be missing one. lol

Wheel pack tension; as mentioned, some locks have a torque adjuster operated by an allen wrench. Others will have a tension washer at the base of the wheel post - pressure on the wheel pack can be varied by bending or flattening this washer. Too much torque coupled with a missing or very thinly worn washer between wheels could create 'drag'. Enough friction exists between them that one wheel will drag the previously set wheel with it for a brief time. e.g. You position w2 at its' gate. But moving w3 drags w2 ever so slightly out of alignment. To the other extreme - too much slop and the wheels may not always pick each other up. A drive pin will actually bounce right over the fly of the adjacent wheel. 'Overrun' can be another result - wheels continue moving after the dial has stopped. Just as Tumbl3r said, it's good to get accustom to both. Some spin seamlessly with one finger. Others will force ya into damn near ham-fistin' the son-of-bitch. lol

Some companies have surprisingly high torque recommendations for their locks. I dunno for sure, but I believe it's for a number of reasons. I think one of the main reasons though is what DIY Dave eluded to. Users do tend to spin/whirl the dial. Even in such a small space an enormous amount of force can be generated. When drive pins and flies collide at these rates, premature wear and deformation will occur. 'Wheel slippage' is another issue from high impact. Normally w3 is affected since it catches most of the abuse. Basically, the relationship between the outer ring and inner hub is changed slightly when it's slammed into motion, resulting in number shift. Older wheel designs are prone to this. But modern wheel construction now locks the two portions of the wheel together more securely & reliably. At any rate, the added turning resistance certainly helps to at least dampen the impact from overly-excited users.

Proper torque settings can also aid in diagnosing/overcoming some lockouts. A botched combo change, for example, that leaves one or more wheels unlocked. If you haven't read it, S&G has a great pdf online; "Sargent and Greenleaf Mechanical Combination Lock Guide". There are a couple mistakes (I believe) within it that can be confusing. But the section on troubleshooting/dialing diagnostics is a fantastic read. No other company that I'm aware of has such an extensive piece of writing about their locks available for the common user.

[MartinHewitt]

My first plan of attack always, is to spin the livin' shit out of it in hopes that the lock will melt off

Yeah, thought so. Especially with the whole lot of Zamac parts.

Save the washer - maybe your next lock will be missing one. lol

A bit like Playmobil. The original packages have often some extra small parts and sometimes a small part is missing. But with Playmobil you can just ask to send a part for free if it is missing or defect unlike with used locks.

Thanks, for the great information!

"Sargent and Greenleaf Mechanical Combination Lock Guide"

Thanks for reminding me. I should more often have a look. With the description therein I finally managed to count wheels.

[MartinHewitt]

Got today my new 6642 and 6630. I did just open the 6642 and it does have a higher turn resistance. So that must be the way it should be.