Hello to all:
I'm having a mechanical problem I think someone in this forum may be able to help me with because it's just like a stuck lifter. I'm attempting to clean and restore a 1920's sewing machine and the reciprocating needle rod that moves up and down through a cast iron bushing has seized. I have bathed the top and bottom of the opening with "Break Away", a penetrating oil, with no luck so far. This piece is really stuck in there. I've tapped it as hard as I dare with a brass mallet with no luck (the part is delecate). Does anyone have any good tricks for unseizing a moving part of this kind? I can't use heat because it will destroy the adjacent decorative paint and devalue the machine. Muriatic acid? Thanks for your input! CT

 

sounds like youve done about all you can do by using penetrating oil and letting it set to see if it frees up, if heating isnt an option.
depending if you can get a new needle rod for this machine you could drill out the old one I suppose if you have clearance to do so.

 

Would heating the needle rod with a soldering iron be out of the question?

 

It might be possible to use a puller to press it out.

With some creative thinking it may be possible to make an puller adapter to fit the housing to grip it without damaging anything.

Also, a machinist may be able to make a cap to put on the end to protect it so you can be a bit more agressive with a hammer.

 

Hi to all and thanks for responses so far. Still the penetrating oil isn't working. The cap idea sounds like a possibility and I will look into it. I also have a small puller and I'll see if it looks possible. I'm still curious about the muriatic acid- has anyone used this with success? If I put a few drops where the rod goes through the borings and hope the capillary action draws it in, do you think it will make things worse? Would I have to degrease somehow before trying this? Thanks, keep sending ideas. CT

 

The muriatic acid won't work.

You would need to have a fair volume pass through the space because as it dissolves the rust, its potency diminishes and would need to be replenished.
I use muriatic and phosphoric acid on steel and have to keep the surface wet for a time for it to be able to do its job.
Also, muriatic will not only dissolve rust but attacks steel as well.
The acid type to use is phosphoric as it only eats rust and actually leaves a protective coating behind.
This is what's in naval jelly and automotive metel prep.

The cap idea will allow you to apply force without damaging the piece you are trying to remove.