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when to apply tension

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#1 noparking3


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Posted 29 January 2008 - 10:46 AM

i've read up about all the techniques and one small detail has been consistantly missing. do you need to apply tension on the key before and while you tap it? or do you apply it just as the key is going in?

it seems to me that the pins would have resistance to popping up if tension was applied before the bump, but that's what it seems is happening in the videos, etc.

#2 theopratr


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Posted 31 January 2008 - 07:15 PM

Very light tension is applied during the entire process, as this is what will turn the key when the bump is successful. To not apply constant tension and try to "catch" the bump is rather impossible, because the shear line is clear for only a few hundredths of a second.

You are correct, however, in thinking that tension can foul up an attempt at bumping. This is why the tension applied must be as light as possible - just about the same amount of tension that would be necessary to make the correct key for the lock turn. Excess tension will cause pins to bind at the shearline, causing the bump to fail.

#3 anarchymicro


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Posted 05 February 2008 - 11:56 PM

Yep, very light tension is the go for sure. I used to not have a very good success rate with bumping untill I realised just how little tension you need. The amount of tension I put on the key is probably the same or a little less then it would take to move the cylinder the slightest bit with the real key. If you sort of hit it with a slight angle toward the way the key turns I also found that helps. I got a few lockwood padlocks here and I can consistently bump them over 10 times in a row using my glasses case :P.
I apply more tension after i've hit the key (already bumped) just to make the key turn in one motion so it opens up :)