Screen door lock

[ErrolFlynn]

There’s a broken spring in my fly screen door.

The main bolt extends a certain way out of the lock, as you know. Then when that tiny little latch contacts the striker plate the main bolt is released further by maybe another 5 mm. When in that position the door can be locked.

Well, the spring that pushes the main bolt out that extra 5 mm is broken on mine. There’s enough of the spring to shove the main bolt out some of the time (or maybe it’s just when I bang the door closed). It’s a tiny coil spring, maybe 4 mm in dia and probably was about 10 or 15 mm in length in its relaxed/extended state.

Just wondering if anyone has experienced this before and scrounged a spring from somewhere.

I know some of you might be thinking go and buy a new lock. Well, I’ve just been to a locksmith and bought a new barrel for it and had it set to match other keys. Anyway, I’d rather not toss the thing when all it needs is a 50 cent spring.

[419]

I’d rather not toss the thing when all it needs is a 50 cent spring.

You might be allowing about 44 cents too much.

Fair chance you can find the spring you need or adapt one from this assortment of 200 for $12.
Just a moment...
If so, you'll still have $11.94 worth of 199 springs to cover the rest of your lifetime needs.

[ErrolFlynn]

Could be. I spotted that. Though, they all, in so far as I can guess, look on the large side. Unfortunately, I'm not within cooee of a Bunnings store. There's a little Mitre 10 nearby that I might check. I had been thinking of calling into some trade places (eg. auto repair workshop, plumber store). Short of pulling apart the plunger pump on a bottle of hair shampoo in the hope the spring on the innards of the pump might fit.

And it wasn't all that long ago I replaced the door lock in one of the bedrooms. The innards had fouled up. I replaced the bolt and threw out the old. There was a spring inside that. See. It doesn't pay to throw out anything. Damn it. I keep thinking about that spring.

Thanks for your suggestion.

[droog]

4mm diameter ?
Try pulling apart a few ball point pens they are about that diameter, just trim to required length with a pair of side cutters.

[ErrolFlynn]

Actually, Ms EF suggested a pen too, and it's a good idea, but I thought they were rather thin. Big enough to get around the plastic ink sleeve. Just measured my spring - 6 mm.

[Skew ChiDAMN!!]

6mm? What gauge wire? Sounds like a brush spring might do, if you have any old brushed motors lying around.

[ErrolFlynn]

a brush spring might do

The thought occurred to me too, but alas I don't have any power tools that I want to pillage. I reckon that would be ideal.

Droog suggested a spring from a ballpoint pen. I had nothing better to do yesterday afternoon. So, I took one apart and popped the pen spring into the lock. There was good and bad to that: It worked! There was a spring locating lug in the lock. Alas, the spring dia was too small. So I twisted it and forced it on. I put the lock back into the door and it worked perfectly. The bad is that I'm concerned that if the spring pops off it might stuff the lock if it lodges somewhere it shouldn't. Perhaps I could put it inside the original (broken) spring. Most of it's still there.

I've yet to visit my local Mitre 10 and other spots that might sell springs.

[ErrolFlynn]

My local auto spares shop had a box of springs, and $1.90 later I had a couple of possibles; the smaller of which fitted and worked perfectly.

Should anyone else be considering having a go at their screen door lock I’ll pass along my experience.

Firstly, I never had a key for this lock. You generally need the key to be able to remove the cylinder. A web video described pushing a tiny blade between the cylinder wall and the lock assembly and using that flick the lever/cam into the unlocked position, then the cylinder can be removed. It looked very easy on the video. I couldn’t do it. Actually, I mentioned my experience to my locksmith who agreed that it’s difficult. Locksmiths probably use their lockpicking tools. (Must get a set of them.)

Another method is to break the cylinder assembly. A couple of shifting spanners on each end and with surprisingly light pressure it broke, which allows easy removal of both ends from either side of the lock. These things must have been designed to be broken easily.

A new cylinder was purchased from the locksmith and keyed to the same combination as my front door, which will be convenient. Cost $46, which was better than the $105 from Mitre 10 for a whole new lock assembly and with the inconvenience of having to carry around another key.

I initially had trouble fitting the cylinder. It slipped into place without trouble, but it wouldn’t work. I couldn't figure it out. It didn’t do anything. It wouldn’t lock or unlock. I slid the cylinder into position (and it was oriented correctly) and secured it using the locating screw. Wrong procedure!

It took me a while to figure out (mostly by trial and error) that I had to position the cylinder in the lock, push on the auxiliary bolt (tiny button thingy) to release the main bolt, and then use either the key or the latch set the lock, and only then insert the locating screw. There may have been some other procedure, but that’s what worked for me.

[419]

Another method is to break the cylinder assembly. A couple of shifting spanners on each end and with surprisingly light pressure it broke, which allows easy removal of both ends from either side of the lock.

That's what I and plenty of others have been doing for years, except I prefer vise grips as they allow a bit more control and wriggle to help break the lock.

These things must have been designed to be broken easily.

No, it's just an unintended consequence of the design of these locks, which are held together at their strongest point on the spine above the cam at the top of the picture below of probably the most common type of screen door lock in Australia. It's necessarily a pretty slim bit of metal to allow the cam to rotate, and the screw hole weakens it even further and that's about the point it'll usually break.

[419]

I initially had trouble fitting the cylinder. It slipped into place without trouble, but it wouldn’t work. I couldn't figure it out. It didn’t do anything. It wouldn’t lock or unlock. I slid the cylinder into position (and it was oriented correctly) and secured it using the locating screw. Wrong procedure!

It took me a while to figure out (mostly by trial and error) that I had to position the cylinder in the lock, push on the auxiliary bolt (tiny button thingy) to release the main bolt, and then use either the key or the latch set the lock, and only then insert the locating screw. There may have been some other procedure, but that’s what worked for me.

I hate to say this as it offends every aspect of manhood, but when installing locks it can save a lot of time and frustration to do the unthinkable: Read the instructions!

Similar but different locks can require different bits to be in different positions to install correctly.

I once spent a fair part of an [and I am being uncommonly restrained and polite in this description] increasingly frustrating afternoon installing a screen door lock that looked like plenty of others I'd installed previously. When in desperation I finally read the instructions it turned out there were several variables, such as key position, snib position, handle position and so on that had to be in specific positions to install it correctly. I worked out that these variables allowed something like 33 possible combinations, most or all of the other 32 of which I had probably tried several time each, but the only one that worked was the one clearly shown in the instructions which I had carefully avoided reading.

[ErrolFlynn]

do the unthinkable: Read the instructions!

Hmm! I know the feeling.

In my case, I had no instructions. It was an old door and lock. I bought the new cylinder from the locksmith who kindly pointed out the correct orientation of the cam. Though, I now realise that would have been obvious, really. Before hitting on the right one of those 33 possible combinations, I wondered if I'd been sold the wrong cylinder or if the lock had something else wrong with it, as I'd never experienced it working correctly since I bought the place. Perhaps it wasn't fixable.

I had to laugh at your comment. I used to work at an auto garage and had a lot of experience in fitting car accessories. There was an ongoing joke about that amongst the lads... and the first procedure in fitting accessories: Throw away the instructions! Though, I take your point. They can be essential.

[Handyjack]

First time I replaced the screen door lock, I went back to the locksmith twice!
Having done it countless times since, it is fairly easy. Make sure you have the key, set the bolt in the closed position, insert the cylinder with the cam at the front and when in the correct position (normally middle) insert the screw. Attach handles and test. Now just hope there is not too much adjustment to do to the striker.

I have a collection of cylinders and keys as very often I just buy a whole kit but reuse the existing cylinder as often it might be keyed to other locks, or there are multiple key holders.

[419]

... insert the screw. Attach handles and test.

Something I've never been able to work out is why some door and screen door locks can be sensitive to overtightening the screws, causing the locks to be stiff or sometimes impossible to operate until the sweet spot is found between being firmly attached and allowing the lock to operate.

With timber doors I suspect that sometimes it's because the latch is bored slightly off perpendicular to the lock stile so that tightening causes the cylinders and spindles or tangs to be out of line. With screen and security doors with welded attachment points and not much distance between the front and back faces I have no idea.

[ErrolFlynn]

Probably much the same reason as your experience with wooden doors.

I can only surmise, with the locating screw being at the centre of the cylinder, which is also the cylinder’s weakest point, that tightening the screw could tend to bend the cylinder. The cam is located at the centre. I imagine that if both barrels and the cam are out of alignment any rotation would become difficult if the thing is bent.


This wouldn’t be the intention in the design, but if the various cutouts in the door that were made to accommodate the lock were not quite in the correct locations (exactly) tightening the screw might bend the cylinder and so make it difficult to operate.