Over the years i have heard about ''sweating '' sights on, but never gone into what it actually is ! or how it works and how its done thanks for any explanations on it !

You place the barrel under a bright light and threaten it within an inch of it's life...

Actually, the term "sweating" with regards to installing sights means "to join", usually by solder. The common way to do this is to prep, or, tin the barrel and sights with solder, clamp the two together, apply heat and let the solder liquify and flow to join the two together.

Well, I'm not sure how this applies to sights exactly, but in the industry we used to refer to "sweating 'something' in" as freezing one part, heating the other, and then pressing/slipping one part inside another. This was usually done with "press fit" parts that may/would gaul or be ruined by just trying to press one into the other by pure force alone. For example, installing a bushing into a housing or something like that.
The "sweating" term would come from the moisture drops formed after the frozen part heated up; condensation.
By freezing a part on dry ice, liquid nitrogen, or in a good freezer lets say, it shrinks. By heating the mating part in an oven the hole gets bigger, and thus the two parts will fit together easily. After they both come to room tempreature, they are fitted very tightly together with no damage if the tolerances on the parts are good/right. Often a regular press fit part may be a thou (.001") or so oversize to the hole, but by "sweating" a part in it can be say up to 4 thou or so oversize making it very secure/tight after the temps normalize.
Did this help? Take care.

Sweating is a tight press fit, usualy by freezing/heating as Unit5A described, sometimes called cold welding. It is semi-permanant, the wheel bearing retainers on older American rear wheel drive cars and trucks where often sweated to the axle if the did not have circlips at the axle tips.

Tinning is soldering and will not change the properties of the base metal. With proper technique, it will not alter the base metals and can be fully undone.

Brassing is joining with brazing rod, the base metal is heated normaly high enough to alter its properties, virtualy any metal can be joined to any metal with this technique, including aluminum to stainless. It is also the only reliable way to join cast iron outside a controlled environment. Depending on the metals joined, and alloy will form in the base metals at the joint and it is permanant.

Welding is melting and fusing the base metals together with an alloy filler. It is permanant and the whole can be treated as a single piece of material.

Sometimes Cold Welding is also used to describe a technique of gas welding where the filler was melted into the base while only heating the base enough to cause it to stick. It is used for temporary welds. This technique is pretty much dead with the advent of arc welding allowing tack welds that don't affect the base metal for a significant distance.

All trades have their own nomenclature and its possible that in gunsmithing "sweating" always refers to soldering. This stuff is purely from my non-gunsmithing professional life experience.

Sweating is, from what I learned years ago, is soldering, usually sights like he refers to. Plumbers do sweating all the time.

The press fit you others are referring to is called the "temperature differentional method"

quote:

Sweating is a tight press fit, usualy by freezing/heating as Unit5A described,

This may be correct but the term "sweating on a sight" (especially sights with no band) typically means soldering them.

Westpac has it right ! As far as sights go.

IMHO;WAH!- Having been into guns most of my life and in industry all my working carrier I have this take on it.

The heating cooling technique is correct. However, in the gun world there was a carry over from banded front sights to include the soldering and if I may be so bold it is an accepted misnomer. roger

quote:

'Sweating'' what is it ?

It's what I have been doing for the past 5 years waiting for a gunsmith to finish a rather difficult project for me.

well we've been sweating things in our shop for a bit over 100 years now. sweating is a term used to describe a method of soldering. Solder flows to heat. two types of soldering are skim and sweat. in skim soldering you heat the edges of the material and the solder flows over to top and bonds to the edges of the material. in sweating you heat back from the edges onto the main portions. then when the solder is applied it flows far inbetween the 2 parts forming a much larger and stronger bonding surface. incidentally soldering is not a metalurgical bond as such, but is most applicably described and gluing with metal. Depending on what you are doing with solder depends on the flux you would use. Different metals and applications require different fluxes. hope this answers your question

I figured it had something to do with solder.

quote:

Sweating is a tight press fit, usualy by freezing/heating as Unit5A described,

Most gunsmiths aren't equipped for this sort of fitting. When a gunsmith talks about somehing being "sweated on", he means it was soldered in place, such as was done with the rear sight band on the M1903 Springfield, for example.....

I always refer to the other thing mentioned as an interference fit.
To me sweating is doing the solder job.

The term interference fit can also be used to describe a simple press fit.
When different temperatures are used some refer to it as a shrink fit. This works much better on larger items. As in leave the flywheel out on the snow over night. Heat the new starter ring and drop it on.

quote:

Originally posted by ireload2:
The term interference fit can also be used to describe a simple press fit.
When different temperatures are used some refer to it as a shrink fit. This works much better on larger items. As in leave the flywheel out on the snow over night. Heat the new starter ring and drop it on.

My father, the great engineer, used the words "interference" and "shrink" that way to talk about engineering. He only used "sweat" when talking about soldering plumbing fittings.

I've heard the term used for joining copper pipe with solder in house plumbing too.

There are slang terms like this with several different meanings I'm sure, depending on the industry or locations.

I "sweat" fit copper pipe for work regularly. Since the solder moves to the heat you heat the far side of the work, when the near side gets hot enough to melt the solder it will flow to the far (hotter) side, thereby insuring the entire joint is soldered.