Oxy/Ac weld aluminum for a horse stand

I need to make a stand for my wife's horse to stand on with her front legs for a trick show, something similar to the stands you see in a circus that the animals get up on. So it needs to be strong, but weight's an issue since we have to move it around. Been using something made out of wood, but it weighs more than the horse.

I'm a pretty good gas welder but have only welded steel, and have brazed a bit. What's involved butt welding square aluminum tube, probably 1-1/2" square, maybe 1/8" wall or so? The stand is 3' feet square, 2' off the ground. I assume the aluminum alloy will determine the rod to use? I'm not sure where to buy this material. I buy steel from a local supplier, they don't carry aluminum. My friend's an engineer, he'll check the structural design once I figure out if I can do this and what material to use.
thanks

Oxy-acetylene welding aluminum is very challenging. You will need at minimum, the proper aluminum welding flux. I would say even if you budget a lot of practice, chances are very high you will not achieve a satisfactory result. I don't mean to dissuade you from trying it or anything; by all means give it a go if you are up for a "learning experience." The fact you already know O/A steel well is actually a very good start. Be sure to have plenty of practice metal because you will blow holes through it and get it all oxidized and generally a big mess, in the process of learning this process. Also plan on removing all the old flux from your final pieces, if not removed it will corrode your aluminum work and make a big mess. I don't know how you'd remove it from inside of tubing, except from perform perfect, complete welds and fully enclose it so the atmosphere can not get inside. 1/8" wall thickness is probably about the easiest thickness in terms of ease of welding however, so you have that going for you. Eventually when you feel you are at a point where you can reliably perform a satisfactory weld, do it on your real pieces.

If you have any questions, give me a holler. I had limited success with the process before I moved up to my TIG setup.

There are also zinc-aluminum brazing rods that can join aluminum with oxy-fuel torch heat, and are a lot more user friendly than O/A welding, because no flux is required. They may not be as durable long term as a welded joint however. It certainly is not a ductile material as your average aluminum alloy, but can have high strength (and high hardness too.)

If getting this particular job done well is important, I would hire a professional with an aluminum TIG welding setup to do it. You could save some $ by purchasing the material yourself, and getting it all cut to size, and prepared. And perhaps draw up a clean plan, (say on graphing paper at a reduced scale) to deliver to whomever will do the work, so there is little chance of confusion or miscommunication. Label the pieces "A", "B", with a sharpie (and corresponding labels on your plans. Then you could have someone with an AC TIG setup go to town on it for you.

Generally where to look for materials depend on where you are. It may not make sense to order materials to pay an arm and a leg to have them shipped to you. There are however some sources online (such as http://www.mcmaster.com and http://www.onlinemetals.com) You might check out local craigslist for a material source. Sometimes people are selling material second hand for good deals on craigslist, I hear.

One thing to use caution with when attempting to gas weld aluminum is the typical need for special lenses in the welding goggles, depending on the type of flux used.

Poke around this site for awhile...you too jakeru: https://www.tinmantech.com/index.php

Aluminum gas welding )althout the tig welds shown don't look so great...
https://www.tinmantech.com/html/alum...ng_article.php

Aluminum welding flux can be hard to find. For kicks, try asking for it at your local welding supply! ;)

In addition to the tinman flux product, there is a much more "mainstream" alternative, manufactured by ESAB. It is called "ALL STATE BRAZALOY 35". Link to purchase 8oz container for $7.60 + shipping:
https://weldingsupply.securesites.co...8:AND:69080211
Link to product info:
http://products.esabna.com/EN/home/f...tegory_id.1115
Link to MSDS:
http://www.wescoweld.com/MSDS/ESAB-CD/MSDS/31.PDF

Although I have only tried the tinman flux, if I needed to buy more I'd try the more mainstream ESAB product (above); I am sure it does a good job for the use it is intended.

If budget is tight, I would try welding with just a standard green filter first, just to get up and running. You can still make satisfactory welds and it will not "hurt" your eyes. I found I was able to achieve improved puddle vision by placing a blue shaded piece of thin plastic (find easily for < $10 by amazon or ebay searching "blue filter gel", cut to size,) in between the clear protective plate and green filter plate. If the reason you are selecting oxy-fuel welding aluminum instead of AC TIG is primarily because of economics, then before spending serious cash on "souping up" your aluminum oxy-fuel welding outfit, you really should weigh putting that money into an "AC-TIG welding outfit" fund (with probably a much higher eventual "return on investment")

Be aware the tinman source of information may be biased, in that its author profits by selling your their products. A good example of this bias is pointed out by John, of their comparison of an inconsistently performed, improperly prepared TIG aluminum weld joint versus probably the best possible O/A welding joint. Talk about misleading comparison. There are severe drawbacks of oxy-fuel aluminum welding that are kind of glossed over by this author/vendor. Namely, poor heat control, and requirement to clean up otherwise highly corrosive flux after welding is performed, (which is impractical or impossible for a lot of typically welded joints.) The heat control further limits the range of joints able to to oxy-fuel welded, in terms of being able to weld "thick to thin", or near any delicate edges or surfaces, which you really don't want "melted away." TIG is much more versatile in almost every way, IMHO. :) I really hope I am not sounding like a "wealthy TIG snob" when I say that. I am just speaking from my own experience, trying and putting many hours "welding time" into both... Trying to convey an "accurate" comparison.

You can still learn a lot about aluminum itself by playing with oxy-fuel welding, which will prove useful even if you later switch to learning to TIG aluminum, so by all means if that's the welding outfit you have access to and can currently justify trying, get some flux, rod, practice metal, and dive in. You can learn about behavior of aluminum at different temperatures, pre-heating techniques, stress relief/annealing of aluminum, "hot shortness" (weakness when hot) of aluminum, all about aluminum oxides (and methods to clean), "torch hand" heat control techniques, probably a bit about aluminum metallurgy, etc.

Sounds like a substantial learning curve involved in oxy-fuel aluminum welding. Since Beezfun, the OP, is already proficient at oxy-fuel steel welding I'm wondering if a steel solution is appropriate.

The current platform is 3' x 3' wood, very heavy, and supports a horse. A round platform would need to be about 3.4' in diameter to yield the same square footage and would have the advantage of rolling into place at a performance. A tour of local scrapyards might offer a steel tank of the right size (a 55-gallon drum is too narrow by about 18" of diameter), and from there Beezfun could cut it down to height and weld in a ledge and other internal supports to attach a wood landing surface. I'm guessing a wood surface is necessary in any new build, aluminum or steel, to give the horse shoes something to bite into- seems like horse shoes would slide too easily on a metal surface. Plus it would be easier to replace if it got dinged up from the impact of horse shoes.

I can't get away from the round platform idea to make the load-in and load-out easier... and a round wood platform 2 feet high is making me think of a cable spool from the power or phone company. Would that support a horse? It could be prettied up for performances.

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Originally Posted by DaveO

Sounds like a substantial learning curve involved in oxy-fuel aluminum welding. Since Beezfun, the OP, is already proficient at oxy-fuel steel welding I'm wondering if a steel solution is appropriate.

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Thanks for all suggestions and advice. I tried brazing some aluminum, the only thing I was modestly successful with was some stuff I got from Harbor Freight called Alumiweld. I wouldn't have confidence in the strength given I have no experience. I have decided to use 4130 steel tubing, I've welded that a fair bit and feel confident. My friend is an engineer and has drawn up a preliminary design. It weighs about 60# which is heavier than I'd like. I'm going to mockup a wood version for my wife to stand next to the horse just to see if it passes the sanity check for size. Maybe I can cut it down a little. I like your suggestion of making it round, making it easier to roll. However I have no way to fab tubing into round shape, that would also require fancier coping of the ends of the pipe, harder to make a jig, and most importantly the wife says after trial and error that things with straight edges work better. Horses apparantly don't see very well down by their feet (how do they run?) so it's easier for them to handle edges that are straight.

I'll post some pictures after I get a final design. I plan to load test by pushing down with tractor bucket on a piece of shoring about the size of the horses foot. Thanks for the help.

chrome-moly steel sounds like a great material choice, for ease of fabrication with the tools available (oxy-acetylene welding), and good strength to weight ratio. It will also give you a graceful failure if you do exceed the material's capacity, IE: it will bend/deform and give you some warning (rather than suddenly fracture).

The design / shape of the structure will be very important for getting the most rigidity out of the least amount of weight.

The alumiweld is an example of a zinc/aluminum brazing rod, by the way.

I think you made the right choice with 4130. 4130 was originally designed to be welded with O/A and is really easy to weld and get good looking welds with gas.