Putting a Positive on Negative Pressure

Posted: October 26, 2011 in Anodizing projects, Machining projects, Welding projects
Tags: , , , , , ,

I’ve been trying to get some hood time with my aluminum welding so as to try and improve my skills. I had a request to build a couple of small vacuum canisters that are going to be used for the installation of an aftermarket cruise control system on a couple of Yamaha FJR 1300 motorcycles. It wasn’t a huge job, at first, and I was able to stumble my way through to moderate success.

The only criteria was size. The canister needed to maintain an external dimension of 2 inches diameter by 4.5 inches long. I started with 2” 6061 aluminum round with .125” wall thickness (I know it was a bit heavy however I didn’t have .065”) and chopped off a 4” section. Then I shaved a couple of .75” pieces off of 2” solid 6061. Using the lathe I machined a couple of steps into the end caps to allow for a perfect canister fit.

I fired up the Miller TIG and laid down a couple of beads no problem…so I thought. Once I machined down the welds I installed a 1/8” NPT 1/8” barb brass fitting into the canister, dunked it in a bucket of water and fed 120 psi of air to it. Lots of bubbles, oops. I figured no problem, this is a learning experience. I ran some more beads, machined and performed another leak test. Still bubbles. So I did it 2 more times trying hard not to get frustrated. Performed a 4th leak test, still bubbles, I couldn’t decide if it was time to cry yet.

Obviously the system I was using was not working, I needed to change something. I decided to machine a couple of huge grooves in welds to allow for wider penetration. I had already machined grooves previously however not to an extreme. However it was to a point were the project was garbage if I couldn’t get it sealed. So with a massive valley to lay some aluminum rod into I welded the canister up for a 5th time. Machined it for the 5th time and leak tested it for the 5th time. Perfect! No leaks. Note to self…do not fear the large groove. The aluminum has no problem flowing, penetrating, and filling the gap.

So the canister kind of took on an odd shape due to all the machining however the functionality was not compromised. As an added learning step I decided to anodize the unit to see how the welds would anodize. After polishing the unit and putting it through a cleaning stage I dunked the unit into my anodizing tank for a couple of hours. Upon post anodize inspection it was fairly obvious that the 6061 canister and the aluminum filler wire anodized 2 different colors. I soaked the canister in the orange dye for 15 minutes curious to see if the to aluminum colors would be hidden with dye color. Apparently not, lesson learned. No big deal to fix. I set the canister back up on the lathe and sanded down the poorly colored ends and then polished them up on the buffing wheel.

I can’t say that this is the prettiest thing I have ever made however its main purpose was to try and teach me something and that it did. The best part is that I have to make a second one so I’ll see if I can take my new found knowledge and apply it in hopes of better success.

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Comments
  1. Jason says:

    There is something about anodizing aluminum, the welds always show up different. I have been told there is some kind of paint pen you can use to paint the welds before you anodize, that will blend them in. Haven’t tried it myself yet, but will have to shortly. -_-

    • gordsgarage says:

      Hey Jason, I had no idea that the welds would anodize so drastically different. I’ve never heard of how to deal with the situation, the paint pen you mention sounds interesting. I tried to internet search it but came up empty (I didn’t try too hard) Any chance you have a link or anymore info you can pass my way?
      Thanks!
      Gord

  2. Jason says:

    Sorry I didn’t get back to you sooner… I’ve got a call into the anodizer that we used last, but we don’t do too much of it, mostly powdercoat.

    I did find this (towards the bottom): http://www.anodizing.org/FAQ/faq_cont2.html

    They talk about using as little heat as possible & making sure that you use 5356 wire, as it’s alloy makeup is closest to that of what you’re typically working with.

    Hope this helps. When I hear anything about the paint, I will let you know.

    • gordsgarage says:

      Hi Jason, fantastic information! The link you sent has some great information. I had used a 4043 filler rod for the canister which appears to have been the totally wrong choice. I researched the 5356 a little more it it appears to be the rod that suits my anodizing application. The heat information is good too however that is a bit more difficult to control, I’ll work on it. Thanks a billion for this one, next time I am at the welding supplier I’m picking up some 5356. Stay tuned for more testing.

      Gord

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