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EASY, QUICK and ACCURATE way for filing bump key shoulder/tip

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#1 PhreeX



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Posted 12 April 2007 - 04:30 PM

I made my first set of keys from blanks and now I am waiting to get my order from bumpkey.us (highly recomended btw) .. I ordred the set of 11 keys ... now, as like everyoneelse that either makes their own set, or ordered them, you need to file the shoulder down (or else you can't, well, BUMP the key) ... using something as simple as a pair of vice-grips and a $2 file will work but for speed, accuracy and easy I found using a Dremel Motor Tool with a round, flexible filing wheel can make for a perfect, quick and acurate reasult ...

I mention this for filing the shoulder only, as for making your own set, that is up to you for how you wisdh to do it, I used a vice and metal triangle file on a key blank, and it works, but still, i'd rather just wait for my new set of 11 keys to arrive ...

Just throwing out that advice for anyone that needs to file down their shoulder (and tip but you don't always have to) and has a Dremel Tool ....

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#2 theopratr


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Posted 12 April 2007 - 10:23 PM

Using a Dremel tool as you suggest is certainly easier than filing by hand!

For the amateur bumper, however, I would reserve this as an advanced move.

First, to everyone buying your keys from bumpkey.us - don't file your originals! It is repeated time and again, but seriously... don't do it. When you end up bumping your heart out, or filing your keys incorrectly, you'll be buying them again.

The price of bump keys from bumpkey.us is very reasonable, but having a shiny new lock sitting in front of you and having to wait a few days to have your key shipped is horrible. Get a set of copies (or two, or three, or four...) and use those for all your bumping practice.

I would recommend becoming proficient using the pull out method first. If you have a decent copy of an original key, you'll know that your key is not suspect in your failure. Practice, practice, practice. Get pull out down to an art, and only then should you attempt to file your tips and shoulders for minimal movement. This way, you can file manually - and gradually - until the key works. If you don't know exactly how far the key needs to be filed down, using a Dremel tool will result in your absolutely wrecking your key.

The “minimal movement method” gets the name from the fact that the key really is almost not moving at all… using pull out, you can move the key the distance from one groove to another… minimal movement displaces the key less than a third of that distance. See the diagram for what I hope to be a helpful visual:

Posted Image

Filing too much causes the key to stop in a position where the bottom pins are on top of the groove, causing some bottom pins to end up crossing the shear line. Thus, the key need only be filed the distance between the normal resting point of the pin and about half way up the face of the peak.

And yes, I realize that in the diagram all the pins are the same length... varying the pin size in MSPAINT is a pain.

#3 Chucklz


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Posted 01 May 2007 - 11:30 PM

A very good rule of thumb is to file so that the resulting key is the equivalent of a code cut key with the cuts advanced one half space on the machine.

#4 ChicagoLocks


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Posted 12 May 2011 - 09:06 AM

Nice suggestion and it will help a lot who want to file a shoulder and tip for smooth bumping.