Galled Stainless Steel machinist jack??

[Janderso]

I whipped up a machinist jack the other day. I used a piece of stainless steel that I had laying around, it machines beautifully.
It came out great except it felt like there was some grit in the bore.
I placed both pieces in my ultra sonic cleaner.
When it was finished I screwed the pieces together. It got tighter and tighter. Maybe because the pieces expanded in the heat?
Now it’s ruined. I can’t budge it. It’s completely stuck. Scrap pile!!
I used a commercial tap and die to produce the threads.

What the heck happened??
Have you ever experienced this??

Don’t laugh at my knurling

 

[tjb]

I've never tried this before, but I think I remember reading somewhere you might be to loosen it by freezing it.

 

[ddillman]

I have run into that on equipment fasteners. once they start galling you are doomed.

 

[tjb]

P.S.: Shame because that's a nice looking jack.

 

[Chipper5783]

Take your pick, sacrifice one to save the other (i.e. machine it apart). Remake that piece of a different material.

The threads in the other piece will probably clean up.

 

[RJSakowski]

You may be able to salvage it by running some lubricant into the threads. WD40 is my choice but use your favorite. If you heat the pieces and then add the lube, it will draw down into the threads as the cool. I didn't see any flats for a wrench so you might want to use a collet or wrap the parts with aluminum or copper to prevent marring in a bench vise. You could machine wrench flats too. Try some gentle back and forth twisting to try to break it free. Once you have some movement, continue working back and forth, increasing the travel. It doesn't work every time but it may work for you. Once the parts are separated, chase the threads to remove any galling and you should have a serviceable jack again.

 

[cathead]

It's probably best to set it aside and make one out of mild steel or stressproof. Some of the
stainless material is very prone to galling which looks to be the case here. Look at it as a
learning opportunity and move on with your new knowledge.

 

[mattthemuppet2]

from what I've read, once stainless on stainless has galled you're done. They're effectively welded together.

one way to salvage that would be to cut off the thread and face the bottom part flat. Then either remake the screw or loctite a set screw into the knurled head and tap the base for the new thread.

 

[Janderso]

It's probably best to set it aside and make one out of mild steel or stressproof. Some of the
stainless material is very prone to galling which looks to be the case here. Look at it as a
learning opportunity and move on with your new knowledge.

Somewhere along the way I read or heard it's a good idea to have different materials to avoid galling.
Is this true?
I have some stress proof.

 

[Janderso]

They're effectively welded together.

So it seems.
I'll try the freezer then heat-lubricant. Couldn't hurt