RE: [bostonburns] question for metal heads
All of what Doug says is true and at this point you’re probably noticing that it’s no picnic to weld aluminum. You might consider the following
- Use steel instead. Is it really necessary to use Aluminum? Done properly, the difference in weight won’t be much. Esp. considering that you’re probably going to have to err on the beefy side since the AL welds are going to be suspect.
- Consider brazing (a.k.a. silver solder, etc) this is reasonably easy to do and makes a pretty strong joint if done right. You might have to change your planned joint geometry to make brazing effective. Brazing likes a lot of surface are to join parts.
- Use bolts and other mechanical joints to do the job. Perhaps in conjunction with brazing.
Also, draw what you want to do in detail no matter how simple it seems and then show / explain it to a lot of people. Another set of eyes will see things you missed and just the process of explaining things may lead to a break-through to a better way.
From: Douglas Ruuska [mailto:d_ruuska@...]
Sent: Friday, January 30, 2004 5:31 PM
Subject: RE: [bostonburns] question for metal heads
As far as welding aluminum is concerned I do not have much experience, but I do have some knowledge to impart, imagine that.
Aluminum can be welded by a number of processes, laser, MIG, TIG & HeliArc. Most likely you will be able to borrow a MIG (Metal Inert Gas wire-feed welder) like the ones that John & I own. If that is the case there are a number of considerations to take into account. If you are familiar with MIG welding of steel, then aluminum should not be so very difficult. The differences are summarized as follows:
100% Argon gas must be used, where for steel Argon/CO2 or pure CO2 is used. If you already have the gages etc for Argon/CO2, then they can be used with Argon. There are 2 common alloys of Aluminum that are used 4043 & 5356. For 115V MIG welders, 4043 should be used. It is softer than 5356 so there can be problems feeding it and setting the drive wheel tension correctly is something that should be done. Another consideration is that of utilizing an aluminum welding adaptor kit which provides drive wheels that are less likely to cause the Al wire to bunch up off the spool and a non-metallic lined feed tube to reduce friction on the wire. with this kind of setup you can easily weld 22-12Ga aluminum. tips for Al wire are slightly wider in inside diameter as the Aluminum expands more upon heating and will tend to bind in a tip designed for the same diameter steel wire. You can get away with welding up to 1/8" this way, but you need to preheat the parts first, but not to mo! re than 230-250F. Cleaning the surface is even more important here than with steel for 2 reasons, chemical contamination, such as with oils make for a poor weld and surface oxides of aluminum melt at 3700F whereas unoxidized Al melts at 1200F. The surface should be cleaned with a stainless steel wire brush that is only used on Aluminum and should be used in one direction only for best results. Also positive electrode polarity must be used. A welder used for steel may be set up this way, but if it has been used with flux core wire it may be reversed. You also need to work faster with Aluminum as it heats up more readily and tends to blow through quicker. Push the weld pool in front of you and do not pull it towards you as you might do in steel.
Whew, hope that that gives you some good info.
As far as machining goes, let me know what you need to do, perhaps post pics of the part on your site with basic dimensions and I will tell you if it is within the capabilities of my shop or not.
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- Oh and I can probably make your parts for you.
From: Dan Mascenik [mailto:dtm@...]
Sent: Friday, January 30, 2004 1:23 PM
Subject: [bostonburns] question for metal heads
I'd like to survey any welders or machinists on this list for advice on my
next motorized piece of furniture. My goal this year is to make the vehicle
stronger, lighter and more reliable. I'd like to make the thing out of
aluminum tube stock, but I've never welded aluminum before.
Is it possible to weld aluminum (so it won't crack) with a regular wire
welder? If not, what kind of welder should I use?
Does anyone have an aluminum-capable welder I could borrow for a couple
months? :-) In Philadelphia...?
Finally, there are a couple specialized steel parts that would need to be
replicated in aluminum. They're pretty simple, but I don't have access to a
milling machine. Could I give a couple of steel parts to someone to make
aluminum replicas? I'd be happy to pay for any materials.
Thanks in advance to anyone who can help!
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