# Soldering/Welding Techniques

#### shortbus

Joined Sep 30, 2009
7,461
Yes, of course I try to design everything I make based on available commercial material stock sizes. I could easily build a machine that automatically cuts stock SS rods to length with a high degree of accuracy. It's the slight rounding (or at least chamfering) of both edges that has me a little worried though.
That's the great thing, there are places out there looking for work for their machines. Make a print and send out for quote, then you're left with assembly, no machine investment at all.

Not knowing what this is going to be or where it is used, just make sure you don't make the clearances to close if it is going in a wet or adverse environment. That was the beauty of the thought behind the AK-47, Kalashnikov kept the clearances loose so it worked in any or most any condition, but still got the job done. And looser dimensions cost less to machine. You will find a big difference in price between a part made to 0.0005" than one made to 0.001" and even more when you are able to use 0.002" or more.

#### Model-a

Joined Jun 16, 2009
18
I've silver soldered a lot of stainless tubing and fitting for vacuum systems and the trick is get the parts hot fast, if you heat slowly the SST oxidized and then you're screwed, the solder just balls up.

#### Janis59

Joined Aug 21, 2017
1,057
Model-A
We are often playing with a 10^-9-10^-11 Torr vacuum too, bet silver... its so damn expensive for so heavy-weight details of tonn or at least a part of tonn. I am using Argon and TIG instead - its cheaper, faster, cleaner and (pardon) less micro-pores. Thus the less inquisitive work with helium leak detector is needed (pardon one more time for arrogant mention of most painful shade-side of vacuum-aimed welding). Silver is non-shiftable material for wolfram welding on the hard drills blades and turner-bench instrument blades. There the small droplet is needed only, and no other methods give a good result, except the "poor-man" constructions welded with the missing, but it melts too fast at instrument work.

#### Janis59

Joined Aug 21, 2017
1,057
Shortbus: Did You have been kept a AK at the hands? My school age that was obligatorium lessons of "military training" for all school pupils boys except the girls. We shoot a hundreds in not thousands a times to get a satisfactory marks for accuracy test. We undergone the normative: distract in 10 seconds and compose it in 20 seconds. No any other lessons whilst a military lesson shows "academic shortness" (oh those communists!). Thus I know well, the "grand secret" was that simply there was no other details as only certain pipe and plenty of thin steel-platelets bent in all possible angles. Platelet never may get stuck nowhere even if gravel between the details. However the nightmare of bullets and guns are now 30 years as behind, but todays army grade weapon are far more precise. Why to spend 1000 bullets to kill one running enemy if more accurate gun may spend a 1 bullet with the same result (however I rather believe even enemy have never deserve the death, better a prison for whole life sentence).

#### Janis59

Joined Aug 21, 2017
1,057
used 304L for chemical piping and never treated it. For marine use, 316.
Generally yes, however Ive been read about rust time of naked metals in oceanic saline water when minded over materials for own-build yacht, the steel gives around the 1 to few mm/yr, aisi-306 gives about 0,1 mm/yr and 316 gives many decades long expected life span, but sure not a century. Thus, paint is welcome even over 316, and 304/306 is only order of magnitude weaker as 316.
However, for chem piping nothing is so wealthy as PP (polypropylene) and some cases polyethylene and king of the kings the teflon in the extreme cases. Remember year ago I calculated and built a two heat exchangers for company using a 4 kW of heat into etching maximum concentration of H2SO4, H3PO3 and similar deathmaker combinations to avoid boiling. The PP long-piping in the two-layer coil was really fine solution for problem and cost them laughingly small money. In aisi steel it probably may happen few-fold smaller in size, but at least hundred-fold expensive, and who knows what construction may have more resource for long-playing.

#### SamR

Joined Mar 19, 2019
1,825
piping nothing is so wealthy as PP (polypropylene) and some cases polyethylene
Except that most of our product was molten esterified wood resin and our piping was either 250 psi steam jacketed or 50 psi steam traced and insulated to keep the product liquid for pumping. Also because of fire hazard we used SS tubing instead of plastic. The only plastic lines were some large diameter buried waste lines. Fire hazard precludes a lot of plastic in chemical plants. There is no beating plastic for acids and caustic and much better than the old lead piping.

#### shortbus

Joined Sep 30, 2009
7,461
Shortbus: Did You have been kept a AK at the hands?
Not as a soldier, but I do have 2 of them and a SKS.

#### cmartinez

Joined Jan 17, 2007
6,785
What have I gotten myself into???? ... I'm trying to solder a part cut from a 1/16" stainless sheet with a 3/32" stainless rod ... and so far I've only made an unspeakable mess ... I'm going to start looking into jewelry making techniques ... YouTube, here I go...

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,900
Again, possibly resistance soldering. The tweezers will hold the parts together and you would pass a current through the two materials and solder. I don't know what temperatures can be achieved.

#### cmartinez

Joined Jan 17, 2007
6,785
Again, possibly resistance soldering. The tweezers will hold the parts together and you would pass a current through the two materials and solder. I don't know what temperatures can be achieved.
I'm considering all options at this point. Problem is, I don't have any resistance soldering equipment.

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,900
Got a high current transformer and a variac?
Add a push button rather than a foot switch.
Rig up two electrodes.

e.g. https://www.mtixtl.com/FA-TS-2.5KW-20V-UL.aspx

I searched for "transformers for thermal evaporators". A bit overkill.

#### cmartinez

Joined Jan 17, 2007
6,785

#### Wolframore

Joined Jan 21, 2019
1,627
Doesn’t it need to be strong?

#### Wolframore

Joined Jan 21, 2019
1,627
Just becareful if you heat it up too much you will lose the ability to fight corrosion by bonding the chromium to carbides. I would suggest TIG welding. When you say stainless what grade are you using? Austenitic, ferritic,.. what grade?

#### shortbus

Joined Sep 30, 2009
7,461
What seems to be the problem? I for myself don't see it. And you are close to what I would do when you say jewelry making techniques. Can you get fire brick there? Many small jewelry things are silver soldered on fire brick. Put your SS rod on the brick and then use a piece of square stock to hold the sheet metal square to the top of the brick. All of this will keep things in arrangement while you solder. How I know this is from an elective fine arts course in junior high school.

Or when this goes to production instead of making the sheet piece like you show just make the hole where the pin/rod goes a complete hole with a rim around it.

#### Wolframore

Joined Jan 21, 2019
1,627
Actually a machined round with interference fit of .003 might work if you don’t have to cam the flat piece. Or it can be keyed

#### cmartinez

Joined Jan 17, 2007
6,785
What seems to be the problem? I for myself don't see it. And you are close to what I would do when you say jewelry making techniques. Can you get fire brick there? Many small jewelry things are silver soldered on fire brick. Put your SS rod on the brick and then use a piece of square stock to hold the sheet metal square to the top of the brick. All of this will keep things in arrangement while you solder. How I know this is from an elective fine arts course in junior high school.

Or when this goes to production instead of making the sheet piece like you show just make the hole where the pin/rod goes a complete hole with a rim around it.
Currently looking at jewelry spot welders...

#### cmartinez

Joined Jan 17, 2007
6,785
Just becareful if you heat it up too much you will lose the ability to fight corrosion by bonding the chromium to carbides. I would suggest TIG welding. When you say stainless what grade are you using? Austenitic, ferritic,.. what grade?
I'm using 302 ss commercial grade sheet. It's completely non-magnetic, if that tells you something about its composition.

#### Wolframore

Joined Jan 21, 2019
1,627
302 is an austenitic grade very similar to 304 (generically known as 18/8). Hopefully you have 302L (for low carbon) this allows for more heating and welding without creating chromium carbides which could have a negative effect on corrosion resistance. Doe this come into contact with water and that's why it was chosen? It's not a particularly hard material in case you need wear resistance as well.