Thu Jun 24, 2010 2:32 pm by Magic1
Earlier I advised newbies to make a transparent training lock and today I got around to taking my own advice and the end result is below. This was not without it's problems so I thought if anyone was thinking of doing it, there are some things that need to be remembered. Basically the plan is to remove the top steel cover of the lock and replace it with a transparent window, made of 'Perspex'. Perspex is a UK brand name for transparent acrylic sheet material.
The first point is that all brands of lever locks are different, so we can only deal with generalities here. An obvious problem is that if the new 'window' is thicker than the old steel case, the key will never be able to fully engage into the lock and cause it to open. It will still open from the rear. This particular lock uses a warded key, so I can drill out the keyhole to shoulder diameter and the key will works from the front as well . The ward actually stops the key from falling out the back hole in the case.
Although the lock I have was dirt cheap, it really is a clever piece of work as far as tolerances go and is designed to work and carry on working for decades, providing an idiot like myself does not come along and gut it every five minutes. From a dimensional point of view, one has to be careful to note where dimensions are referenced from. For example in my lock references are not taken from the actual outside or inside of the case, but from indentations stamped into the case. When we replace the top of the case with perspex these indentations do not exist and therefore the gap between the rear steel case and the perspex is larger than before. At the lever pack this dimension is critical and the end result is that the lever pack is not as compressed as much as before and small gaps appear between levers, spacers and the bolt. I have no idea what the experts call this, but I call it lever 'spread'. I will try and find a photo that illustrates this and attach it. If you now apply a picking tool to the pack the levers tend to move apart and in the worst case to picking finger can actually slide between components of the lever pack. So whatever you do to your lock when fitting the window, you have to check that the lever pack is still compressed and not flopping about. I will try and get a photo of that too. After you have looked at what is happening in your lock, you end up with one of two choices, you can pack out the slack ..... or make the whole lock thinner !. I chose the latter course. This is done by reducing the height of all spacing components.
If you are making tools using training lock, you can use the outside or inner surface of the rear steel case half, but need to think three times before using the replacement surfaces as reference, or a key shoulder if making tools.
A sash lever lock also contains a latch bolt. If you are thinking of making video's using your training lock it may be an idea to remove the latch components as they only complicate and confuse .... and do nothing in the lock picking sense.
OK having said all that, a transparent training lever lock is the quickest and best way of understanding how they do and do not work and it is well worth the effort of making one. If you don't then you will never be able to see what happens when you turn the key the wrong way !. Have fun ....
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