Repairing and extending the bit on an old key

[andrewa]

Newby.

Done plenty of searching, both on here and Google, but not found what I'm after.

I've decided to make new keys for the locks on our varied 18c furniture, and for other restoration projects I have.

I recently found a selection of old keys on eBay, which are ideally suited to my purpose, and much cheaper than buying newly produced "blanks" of old keys, however , many have been cut already, and need to be returned to "blank" condition.

I've managed to successfully make the bit larger on a few keys, using solder, filing it back, and then recutting the key but the finished product is silver. Is there another way that this can be done which is easier, and/or does anyone know how to change the colour of solder to a darker shade?

As as an aside, I'm really enjoying pulling old furniture locks apart, and making new keys to suit. I've successfully made keys for 4 items to date.

Andrew Allan

[Pschiffe]

Newby.

Done plenty of searching, both on here and Google, but not found what I'm after.

I've decided to make new keys for the locks on our varied 18c furniture, and for other restoration projects I have.

I recently found a selection of old keys on eBay, which are ideally suited to my purpose, and much cheaper than buying newly produced "blanks" of old keys, however , many have been cut already, and need to be returned to "blank" condition.

I've managed to successfully make the bit larger on a few keys, using solder, filing it back, and then recutting the key but the finished product is silver. Is there another way that this can be done which is easier, and/or does anyone know how to change the colour of solder to a darker shade?

As as an aside, I'm really enjoying pulling old furniture locks apart, and making new keys to suit. I've successfully made keys for 4 items to date.

Andrew Allan

I think that solder is too soft to make a lasting key. Perhaps you could build the bits up by "brazing" with brass rod but this requires considerable heat. There is a product called Brass Ager which is used to darken brass, steel or zinc but I doubt it will work on solder:
http://www.kennedyhardware.com/brass...ution-m-3.html

Pete Schifferli

[Mickthepick]

Hi Andrew,

Firstly, welcome to the forum!
Secondly, you could cut the flag off completely, trench a groove in the key shank, then braze or silver solder a new flag of the correct dimensions into the shank. This way there would be a minimal silver line to deal with.
Please post your keys, as one of the members may have, or know where you could find blanks for your furniture.

Kind regards,
Mickthepick.

[andrewa]

Thanks for the ideas. I need to better understand soldering, and how and when to use flux, before I start thinking about brazing!

it's all fun.

[daveham]

Better still, if it's a steel key, weld on a new flag. Then the repair will be invisible.

[Donnie]

Hello, copper sulfate will change 50/50 solder color to the color of copper. if you need to darken the solder, mix a little flux in with the copper sulfate. experiment to achieve the blend that you desire.
Brazing, or brass welding a brass key is a rather futile effort as the brass rod & the key tend to melt at the same , or near the same temp.
there may be an alloy in the key that you are not able to discover until you try it.. practice on a key of no value.

[Doug MacQueen]

There are low temp soft solders which melt way below 1000 F and high temp hard solders which melt above 1000 F. Tix is good low temp brand. However for serious strength use a hi temp hard silver solder. Hard solder works best when the gap is a very close fit, .001-002". Attaching small pieces of metal to larger is always more difficult than soldering objects of similar mass, until you learn how to control the heat, and even then sometimes it is preferable to add a big piece and cut it down to size. It is hard to see the temp rise on brass so turn the lighting down in the room but not so much that you can't see when the flux has burned the water out and then melts and looks like water on the metal. Don't even try to add the solder until after that point is reached. Using it to fill cuts on keys is not a great idea, better to add a new bit. Properly done, a hard silver solder joint can be as strong as a weld on mild steel. And don't quench brass after soldering as it will soften the metal. Pictured are the basics needed for high temp silver soldering. Fire brick, solder , flux and torch. And practice!

[daveham]

Doug has summed it up ! Soft solder is fine for non load bearing applications such as electrical joints or copper tubes but totally unsuitable for fastening an new flag to a key.

If you look at a new off-the - shelf 3-lever mortise lock key the flag is electrically welded to the shaft an thus stays put.

In order to silver one needs to get the parent materials (flag and shaft) to say 370 degrees F. Soft solder melts at under 200 degrees F

[Doug MacQueen]

Let me throw a little water on this fire. Here are pics of 2 flat steel keys silver soldered together. The whole process was maybe 5 minutes or so. It was done with Mapp gas.

[BBE]

Newby.


I've managed to successfully make the bit larger on a few keys, using solder, filing it back, and then recutting the key but the finished product is silver. Is there another way that this can be done which is easier, and/or does anyone know how to change the colour of solder to a darker shade?

Try a stained glass supply store They have a solution used to make the silver color of solder look darker and more antique if you keep using solder.
BBE.