hi all,
the last days i am trying to get some info about welding metal parts together.i have found many techniks and i am a bit confused.in these forums i see that many of you guys made excelent things with metals so i thought it would be a good idea to ask for help from the profesionals here in rcu.i am interesting for custom making landing gears for my future planes ,with working shock absorbers and scalelike.
i see that there are 3 posible teckniks : soldering brazing and welding.i am not familiar with any of them and i dont know witch is best suitable for this task.i searched the site but i didnt find a forum about those marvelus landing gears you have made . please help me about the equipment i will need and how to do it.
i am searching for a good technick for making or repairing landing gears or engine muflers and piping.
please help
thanks very much
achilles

Try this

http://www.rcuniverse.com/magazine/a...article_id=172

Axilleas, That is a great article on Soldering that is linked above.
Here are the basic differances between soldering, brazing, & welding.

-Soldering requires lowest temperature, and produces the weakest joint of the 3 processes. Its like glueing a joint with molten metal.
Usually a led/tin aloy. Silver-solder is stronger but not much.
-Brazing requires much higher temperatures, and produces a very strong joint, but is still just glueing the joint. This is done with a brass rod and torch usually. It requires oxy/acet to reach thease temperatures. A Map-Gas torch may get hot enough but I have not tried one.
* Both soldering & brazing will join most disimilar metals like copper,brass,steel, etc, but don't melt the metals togeather.*
-Welding is the strongest of all by far! Welding actually melts and mechanically joins the pieces togeather. Almost any aloy can be welded using differant processes, but not many disimillar metals can be welded as they have to mix togeather in molten form to make the joint. The filler metal (rod) also has to be simillar to the weldment. (2 base metals)This is why aluminum can not be welded,brazed, or soldered to steel, brass, copper, etc, but steel brass, & copper can be soldered or brazed togeather. They typically can not be welded togeather though. (steel to brass for example)

In my professional opinion, forget about "welding". It requires at least an oxy/acet torch set (only good on some metals) that costs a few hundred dollars, or an electric arc-welder that costs much more. Even though I have over $16,000 invested in my welding equipment, I could NOT "weld" thease tiny parts that thease guys use on thease landing gears and pipes! For all practical purposes, SOLDERING in some form or other is about all a modeler can really do without some very expensive equipment, and high level of skill.

Hope this helps you understand the differances better! Q.

hi m,
many thanks for the help. i am thinking of silver soldering. you are right about the welding. but there are many types of silver soldering. do you suggest one?
thanks again.
achilles

Axilleas, I can not. The guys that build those beautiful pieces would be able to educate you on what "process" they use. I too am intrested.

Hi!
Silver soldering with an electrical soldering iron is quit simple.
But remember that all soldering done when it comes to practical landing gears are mostly done by winding thin copper wire around the piano wire prior to soldering and then heating the wire and applying solder.
If your'e going to sweet solder (The best metode) use Great Planes silver solder. This is the best sweet soldering material available. I have used it for 32 years and are very satisfied with it.
You should not use brazing (using a propane or acetylene /oxigen torch) as the heat softens the piano wire and is impossible to restore its flexibility (at least for us mortals).

i am not talking about piano wires. i mean landing gears for large airplanes . my mistake. i didn t explaine exactly what i whant to do.
these are pieces of tubing and steel blocks soldered or welded or what else.. together to finaly form a working mechanism. these peices are made parhaps to a lathe machine from simle blocks of metal. the problem is how to solder them together.all of you guys saw these working landing gears . parhaps to big warbirds.i purchased some from robarts for my sbd and i saw that it is a simple structure and simple pieces together.but how tho solder them??
achilles

I don't know how involved you want to get but it sounds like TIG (tungsen inert gas) welding is what you want to do. A good welding/fabricating shop would have a TIG welder. TIG is great on a variety of thin metals including stainless steel. This is the type of welding used to fabricate exhaust systems used on race cars and on many full scale aircraft parts. But, it requires a relativly expensive machine and a very skilled welder.

Soldering with low temp silver solder is different from silver soldering. The low temp stuff, like from Great Planes, has a low silver content and using soldering iron temps. As the metal is heated and the pores expand, solder flows into the pores to great a bond. All the low temp solders do not allow for enough expansion to be as strong as brazing. And, the solder itself does not have much tensile strength. In other words, a lap joint would be much stronger than an edge joint. Or a joint like copper pipe in an elbow would be very strong because the pipe fits inside and the solder flows in by means of capillary action.

Real silver soldering (not to be confused with the low temp mentioned previously) is similar to brazing in that it used much higher temps than regular soldering. The metal is heated to a cherry red color for brazing and to just under that for silver soldering. Because silver solder is thinner (less viscous) when melted, it flows into joints and pores at a lower temp than the brass alloy rod used for brazing. But the silver solder is the strongest of these types of processes when a lap joint or similar joint is used. When brazing with brass alloy brazing rod, the metal can lose it's temper because the temp reached is in the 1500 degree F range. Silver soldering reaches approx 1100-1200 degrees F.

TIG welding, if done properly, is great for lap joints, T joints, etc. You can use a very fine tungsten electrode and fine welding rod to join very thin metals. The metal can then be heated and quenched to restore the original hardness (depends on the metal and the exact properties it had before). Small parts can probably be done at home. Or a tool room (business that make tools and dies) can likely help with that.

If you have any questions, let me know. I used to be a welder and a tool and die maker.

Good luck,
Jim

Hi Jim,
many thanks for the help.
i made a small research in the google and i found out that for making tig weldings i need:
1)electronic equipment
2)gas tank
3)elektrodes
i dont know if i am right. there are many types of them that i am confused. i canot estimate the total value of the above.for example :
what size of tanks and what valves?
what size of electronics and electrodes type and value?
can you estimate a vaue for what i need to weld small parts with a few centimeters long??

the other alternative , silver soldering , is interesting also. if we forget the low temp solderings and talk abou silver soldering at about 600-650 celsius do you think that is enouth?
the only equipment will be a propane torch.
are you experienced with that types of soldering?

thanks again,
achilles

Silver soldering (high temp type) can produce very strong joints suitable to almost any application. There is a caveat, tho, that the joints must be properly designed. Many racing bicycle frames have been silver soldered or brased, that is a testiment to the strenght available in the processes.

You've not given us a very good idea of the sorts of joints you will be making, so it's hard to answer your question in that regard. You say landing gear for large planes, I assume you mean 20 poundish giant scale aircraft. With properly designed joints, silver solder could be adequate.

That said, brazing and silver soldering are techniques that require some finesse and experience. You would need to make an investment in time and materials to practice with, and in fact, an experienced instructor would help. At a minimum, you'd need:

Various grades of silver solder (it comes in different melting temperatures. You use the highest temp stuff first, then go to the lower and lower temps as your assembly progresses, thereby not melting the previous joints).
appropriate fluxes
An oxy/acetylene torch, or at least an acetylene/air torch with appropriate nozzles and tank (s), hoses and regulators.
some things to solder together
lots of time to practice.
A suitably ventilated area to work in
fire extinguisher!

Silver Soldering and Brazing require pretty much the same skill level as welding, this isn't lead/tin soldering. You'll need to invest a couple hundred dollars to get going.

A simple tig setup would run you a little shy of $1000, and then you'd need much practice. If all your work is aluminum or steel, a small mig setup (about 5-600 with gas) might be adequate, but tig does finer work.

Have you considered the machine tools you'll likely need to make gear struts and such? Their costs will likely outstrip your welding equipment costs by a large margin, unless you're building very simple tube-to-tube-to-bar assemblies.

Might be cheaper to just buy Robarts or something. There's a good reason why they cost what they do!

Good luck!

J

What Jburry said is very true. Thats also why I said what I did where even with a substantial investment in machines, I could not weld thease tiny parts! As good as I am with my TIG machine on aluminum and stainless, I could not weld those little parts. Maybe others could with speciaized equipment, but not me. (I also didn't used to be a weldor. I am one. I have my own shop, and run 2 portable rigs.) The chance of anyone here reading this,...that is NOT specifically in the business of welding that thin of material, is dreaming if they think that they can. Buying a TIG machine will relieve you of a thousand dollars + , and ya still won't be able to accomplish what you want any time soon. I would pay close attention to the guys that are doing what you want to do! In my PROFESSIONAL opinion ,,, soldering in some form or another is about the best a modeler can do.,,,,,damn....I said that already didn't I? [X(]

Edit; BTW, Any machine that you choose will come equipped with the regulators and lines required. The GAS bottle is a seperate investment on your part as is re-filling it. The "consumables" gas, wire, rod, tips , whatever, are NOT included. Thease you will have to buy before you strike an arc! Aluminum for example requires a differant INERT gas than does steel. This gets EXPENSIVE real quick.
Do yourself a favor and call a local welding supply house and ask some questions. I love it when some guy heads to Home-Depot, buys a machine, and after running some wire or burning some rod, actually thinks hes a weldor! Just blows me away!

hi guys ,
thanks again for the info.
both of you are wright adout the skills and equipment. as you stated it is simpliest to buy some robarts at the end.as i had no idea of what i need and how dificult it is, i thought that i might be able to construct these parts.at first glance it seems it is easy but NOT if you exanine futher.i totaly abandon this idea of landing gears.
in my research and our discusion i found and learned very interesting thinks.i am thinking only of purchasing a silver soldering equipment as i can use it in many parts, for example for solderind wires ,pushrods,rods...
am i whong again?
i solder these parts with lead and i think i could it better with a silver soldering.but it is necesary to use oxy? propane is not enouth?

also what is the diference in tig and mig? i see that there are machines both types on ebay about 300-500$. do you think it is worth it? as i said i totaly abandom the idea of the small parts. i already have a simple welding machine .the simple one with only electrodes with no gas(i dont know exactly how to name it) and i always wanted to upgrade to a beter one.
but i am confused again with tig and mig. i used this machine for making the tables and selfs in my workshop.os soldering fenses. what do you think i might need for these kind of jobs?the gas is the same on mig and tig?both mig and tig can weld alouminium and steel?
is it worth it the machines of 30-500$ on ebay ??

many thanks
achilles

I use this Silver Solder using a 200W soldering iron. Works great on pushrods&clevis :

http://www3.towerhobbies.com/cgi-bin...&I=LXFS75&P=ML

Low temp silver solder is perfectly adequate for pushrods, cabane struts and just about anything else in a model. While a solder gun will work for it, I find it best to use a propane torch for the job, as good even heat is key to a good joint (as is thorough cleaning and good flux). High temp silver solder isn't necessary for most of what we do. But if you want to learn a new skill, go for it!

You currently have (I think) what we refer to as a stick welder, where you put a flux coated electrode, about a foot long, in an electrode holder, strike an arc, and manage feed rate, arc length, etc manually. Every couple minutes, you install a new electrode and continue on. This process is good for mostly heavier steels, though some fine work can be done, it's tricky.

Mig I believe stands for Metal Inert Gas (could be wrong here, but it's close). The welder contains a spool of welding wire, usually dozens of feet. The wire is fine, about 0.030", and is mechanically fed by a motor at a predetermined rate thru the cable (it's hollow), and out a gun. The welder is trigger operated, pulling the trigger turns on the welding transformer and starts the feed motor. Striking the arc is effortless, all you gotta do is hold the gun steady and keep a consistant lenght of exposed wire. In true mig welding, there's no flux, shielding is provided by an inert gas (co2, argon, etc. are used, different ones for different metals). There's a variant of Mig used mostly by hobby welders (like myself) called flux core. This is good for mild steels (most of what you or I use for shelves and the like). You use the same mig welding machine, but change the wire inside to this flux cored wire (it's hollow and full of flux), and you don't need the shielding gas. Works very well, but there's more spatter and there's slag left to be cleaned. Tru mig welding leaves no slag. Mig is great for working with sheet metals, as well as structural metals, down to about 20ga, and depending on the machine, up to as thick as you like. My small unit is good to 1/4" thick plate, plenty for my needs. It operates on 120v wall current, a bonus for me.

Tig I believe is Tungsten Inert Gas, and is actually closer to oxy-acetylene welding, in my mind. The welding machine provides only an arc, not the filler material (the rod, if you will). The welder strikes the arc with the electric torch, and then feeds a separate electrode into the arc with his other hand. Shielding gas is used, like with Mig, and is provided by the electric torch. This process gives an experienced welder amazing control and the ability to produce perfect welds with no slag and little heat damage to the surrounding metal. I've seen experienced TIG operators weld a pop can back together, water tight!

That's a quick answer. Lots more than that to know....

J

JBerry, I couldn't have said that better myself!
Just remember with a fluxcore wire you need to change the polarity from electrode posative as with MIG, to electrode negative for fluxcore wire. The "ground" clamp becomes posative. From how you speak I know you already knew that, but this was for Axilleas information.
I too run a small 110 vac Lincoln SP-135-T which would do about anything a home weldor would need. Hobart also has a very fine 110vac machine called a Handler-140. This is a better machine than the Lincoln IMO. I own both, and the Hobart can be had for less money than the Lincoln through outfits like www.northerntool.com for example. Both are MIG (GMAW) capable machines with regulator,guages, hose etc. included, but can be used as fluxcore (FCAW) welders by simply changing the polarity, and eliminating the gas bottle and related hardware.This process allows you to weld in the wind outside, where the MIG will not reliably.
Axilleas, Do NOT abandon your quest! "Welding" is just not the "process" you need to use for this application in my opinion.
If I wanted to join thease types of pieces, I'd be asking the guys like JBerry that are doing it.
My Dad was a jewelry fabricator and had a natural-gas torch to melt the silver. I don't know anything else about it other than it provided a very clean flame. I think that oxy./acet. would be too dirty and too hot for this but I may be wrong.
If you want a basic weldor, I would highly recommend a wire feeder. Just buy a good one from someone like Hobart,Lincoln, or Miller.
Prices for a commercial grade 110 vac machine will run between about $500 & $700.00. The ones you can buy at outlets like HD are NOT commercial grade machines no matter what name is on it. They typically run a couple hundred $ less. I would never buy a used machine that I couldn't try out, or from anyone that I didn't know. Good luck! Q.

edit; TIG is as JBerry said, is just like welding or brazing with a torch in one hand, and a rod in the other. The differance is that the "fire" is an electrical arc thats heat can be controaled by a foot pedal. The electric "torch" also delivers a shielding gas to the weld. Differant metals require differant shielding gasses and rods. Almost any aloy can be welded with TIG as long as the wind don't blow.
MIG feeds a solid wire (the rod) and shields the weld as the TIG does. TIG is the most accurate of the two.
FC is a wire feeder that is just like the MIG, but has the shielding gas (flux) inside a tubular electrode/wire, and can be used anywhere a standard welding rod could be used, but typically burns hotter than MIG due to the blanket of flux that lays on the weld, and a lack of cooling gas blowing on it. This is getting pretty complicated but I think you may have a better idea what the differances are.

quepasa,

Mom's bf is a silver/goldsmith, and uses an oxy-air torch for silverwork. Works very nicely for him, and is capable of very small flames (as small as a butane torch lighter) to flame sizes more typical of a blowtorch. A MPS gas brazing torch would be almost as good, but less handy with the bottle attached.

Mine Mig a Lincoln Mig Pak 10, not a commercial grade machine, but up to anything I am. Paid for itself in short order, making some custom stuff for work. I play as a blacksmith in my backyard too, having set up a small smithy behind my shed. Mostly do knife making and small wrought iron work. The welder complements this nicely.

Here's some of my work....

J

Very nice work! You Sir, are an artist! (that was a compliment)

hi guys,
you have described the proceses very clearly and everything was very helpfull. i will make a research on the market about the costs and i will let you know.what do you mean by commercial grade or NOT?
do you mean for profesianall equipment suply stores ?
many thanks
achilles

Commercial grade equipment is manufactured for the needs of industry. It's designed to be dependable enough for people to rely on it at their jobs, where folks make their money using the equipment. You'll find heavier steel cases, higher duty cycles, higher capacities and more rugged controls and equipment. You'll find this stuff at welding supply shops. These places are great, and often have a demo room where you can try the various models of equipment, at least our local Liquid Air dealer does.

Non-commercial grade equipment, which you'll find at home improvement and department stores, are designed for hobbyist or recreational/home use. Lighter cabinets, low duty cycles, lower capacities, and lower durability.

That said, even the home owner grade equipment sold by the larger manufacturers is quite useable. My Lincoln is such a beast, and it performs very well. A local farm supply store sells Deca welders, made in Italy, also mostly light duty stuff, that also works quite well.

I have used a Liquid Air branded Lincoln (I think it was a lincoln) of similar specs to the one I now own, but commercial grade. It was clearly more rugged, and would outlast mine in "unloving" hands, and had a higher duty cycle, but in my hands the results were indistinguishable.

I'm going to give advise contrary to what quepasa has given (variety is the spice!), and suggest a non-commercial welder if you're interested in a Mig unit. Few hobbiests need high duty cycles, and unless you're the type to abuse your equipment, it'll last plenty well. You can put the 200 bucks you save into metal and supplies with which to practice the art.

Have fun!

J

ok,
thanks Jim!!!!