breaking blanks in impressioning is not a fail, its a common part of the process, you just start another one
as alta shot said
nickel silver is very hard to impression, look in your keyway toward the top, is the bottom point of the pin centered in that keyway? or is it to the left or right,
determine where the center of the pin collums runs and then file a forty five degree angle from both sides of the blank so that the center line directly under the pins rests on the edge.
this will put a weak edge under the pins and you can look for impressions on that. Its important that you try to file this edge without changing the angle of the file stroke as you push it across the blank, so that the work is one flat plane, not several, you need the clean surface to see the impressions on.The impressions for this edge are best made by bumping up while binding then bumping down while binding and doing it both left binding and right binding. pulling would only confuse the pin location on the blank
if you do file a knife edge, remember that there is room in the plug for top of keyway tension because the pins are a little further in the keyway than the shoulder of the key, file the knife edge where the pins are, do not carry that knife edge to the shoulder because everyone breaks blanks right at the shoulder where the forces shear the blank just as you have done in the photo, this area where the blanks break should never be filed in any way
I used to impression by eye in daylight, but now I use a ten power loupe. if working indoors, a direct strong light from a point source may be better than diffuse light from long fluorescent tubes.
you can also enhance the search for useable marks by putting black marker on the edge, but you must distinguish between bumps and the effects or
pushing the blank in and pulling it out, these marks should be ignored.
once you get the first marks, learn to push the file through one time in a very even manner so that at no time in the stroke of the file does the angle of the file change,
this will leave a flat that is easy to read marks on, if you change the angle during the file stroke, it will leave a multi faceted surface that makes distinguishing marks difficult.
you have to think of the mechanics of the shoulder/upper arm push and the elbow and wrist mechanics as the file is pushed through
arrange for the right height above whatever bench you work on so that doing it well does not require much adjustment during the file stroke
large vise grips make it difficult to avoid breaking blanks, use the two smaller ones they will just work better, when I use them, I also try to bite the wire cutter in the vice grip into the edge of the bow of the key, usually I notch it with a triangle file to help make it bite
this will prevent the blank from slipping on the keybow.
If you are impressioning a lock that has a loose cylinder rattling in it, such as an american lock or master padlock, I used to reccommend that the shoulder itself be filed where it touches the cap lamination or the drillbreaker on an american lock, because in the past it could be that the attempt to bump is causing the the shoulder to take the bump on the drillbreaker leaving the blank in the cylinder unmarked, but more recently
I have seen that this is not a problem any more, its probably a matter of what blank you are using
brass is heavy aluminum is light, you drop these blanks on a hard surface to listen to the ring they make, this usually tells something about how hard a metal is with hardness making a higher pitched sound. an allen wrench is very hard steel, drop one and listen, then drop a piece of other metal of similiar size and you can compare probable hardness, its not scientific but its pretty good SWAG (Scientific Wild Ass Guess)
brass is yellow, aluminum is white, steel is greyish, stainless is silvery,Nickle silver is the color of a nickle, greyishsilver eventually you will just
know what metal you are working with. metal color is affected by oxidation and other staining, copper is redishbrown, brown or even red if its been in heat. you can see this in pennies especially the ones before 1982
Do not trust an impression that is not consistant with the known pin spacing, if an impression is out of spacing, this could be from not holding the shoulder of the key against the plug face as you bump, or it could be lateral drift of the file stroke.
Impressions can drift off center as you continue to make progress, if you do not see an impression, look to the top edges of your cut, and if you think an impression is actualy hiding on this point or the very tip of the key where the forty five degree angle meets the top edge of the blank, some blanks actually have to be filed on this place
most of this is already here in the very good posts from altashot and Gweins, and others.
Statistics: Posted by rai — Tue Apr 01, 2014 9:27 am