Vise jaws for spreading work apart?

[rohare]

Is there such a thing as vise jaws for spreading work apart rather than clamping it together? I know this isn't the primary purpose of a bench vise, but it seems like someone would have made such a product regardless. So far I haven't been able to find any. Thanks much!

 

[kd4gij]

Most bench vises wont take much force opening up as thay just have a clip on the screw.

 

[Tozguy]

Do you have a specific job to do that requires spreading?

 

[epanzella]

Port-o-Power makes a hydraulic ram kit that has spreader jaws. I don't use mine that often but when I need it nothing else will do.

 

[RandyM]

Port-o-Power makes a hydraulic ram kit that has spreader jaws. I don't use mine that often but when I need it nothing else will do.

Yup, me too.

 

[rohare]

Do you have a specific job to do that requires spreading?

Yes, I am spreading a padlock. I started a project last year to reverse engineer an old high security padlock. I've tried various attempts at making very accurate measurements of the distance that the shackle can be withdrawn from the lock body and have evolved my method over time. Currently I'm using a magnetic base and a dial test indicator to take the measurements, but i'm still having difficulty with spreading the lock and shackel in a very repeatable manner without variation. I don't want my measurements skewed by variation in the spreading of the shackel rather than changes in the internal state of the lock.

This requires very little pressure on the vise so I don't think that would cause any problem, but if there is a better tool for the job I'm open to suggestions. I posted here last year about measurement techniques and the sugesstions were spot on even though I resisted them at first because of the expense involved. Thanks for the help!

 

[epanzella]

I don't completely understand your project but if you don't need much force to spread the lock you could make a v-shaped or slotted plate to hold the lock body and hang
weights off the shackle for repeatable results.

 

[francist]

There are bar clamps made to spread things apart -- kind of like a pipe clamp -- that are used by furniture makers/restorers to spread joints on chairs and such. Lee Valley is one source that comes to mind but am sure there are others. They can be clamped down to your bench thus creating a vise-like fixture.

-frank

 

[Mark in Indiana]

Yes, I am spreading a padlock. I started a project last year to reverse engineer an old high security padlock. I've tried various attempts at making very accurate measurements of the distance that the shackle can be withdrawn from the lock body and have evolved my method over time. Currently I'm using a magnetic base and a dial test indicator to take the measurements, but i'm still having difficulty with spreading the lock and shackel in a very repeatable manner without variation. I don't want my measurements skewed by variation in the spreading of the shackel rather than changes in the internal state of the lock.

This requires very little pressure on the vise so I don't think that would cause any problem, but if there is a better tool for the job I'm open to suggestions. I posted here last year about measurement techniques and the sugesstions were spot on even though I resisted them at first because of the expense involved. Thanks for the help!

I will try to describe this as well as I can: If you take 2 combination wrenches (say a 7/8" & 15/16") and place the open ends together so they resemble a couple of horse shoes side to side. Place the 2 wrench tips inside your shackle and push the sides out by moving the wrench handles together. If I didn't do a good job with my description, I will post a picture later today.

Very Important: NEVER USE A VISE FOR SPREADING. YOU WILL BREAK IT.

Happy Trails.

 

[Tozguy]

Thanks for the details. As I understand it you are measuring the padlock open and closed and want repeatability. There is the possibility of some flex to factor in. As already mentioned hanging a weight to spread it open might be a way to get repeatability.
The padlock body could be sitting on a steel bar and facing downwards. The weight hanging on the shackle. Or vice-versa.


If that setup is difficult to indicate then maybe a horizontal set up with the weight on a string that goes around a pulley would work.