Adventures in Welding…

7 11 2010

Well, maybe not quite “Adventures”…more like “sitting around thinking about how the hell i’m going to get this welding done”.

In any case, the majority of the time on the project has been learning how to weld, and thinking about how to weld.  I ended up TIG welding aluminum angle together into frames that would hold each of the 9 battery packs in various orientations.

Here are some pics of the starting of the welding process.  Keep in mind that this is from freaking MARCH! And i’m still not done yet…AIEEEEE!

32 feet of 1" angle aluminum ready to be chopped up for battery trays

Post chopping battery tray material

A couple of days later...Battery Trays!

At this point, things were looking good, the types of welds used for these were butt and outside corner welds.  These were quite simple and didn’t require much time to get looking OK.  Some of them had some burn through, but it wasn’t too bad:

One of my first test TIG welds on a corner of aluminum angle. Some contamination, but not too bad...

Not too bad on this side too.

OOP! a bit of burn-through here. This is tough!

At this point, i had to start on the subframe, and attaching the trays to the subframe.  This is where things started to go south.  Unlike the trays, this required a lot of fillet welding, which gave me fits…for MONTHS!  For a long time,  something like 20-25% of the welds were passable, and the rest were complete crap…  For example:

Fillet Weld...egads this doesn't look so good (May 2010)

So, i worked on this for a couple of months off and on.  I have piles and piles of scrap material.  Now i’m at the point where probably 95% of them are pretty good.  Fillet welding aluminum can be tricky, but the things that I was doing wrong that caused lots off issues were (in no particular order):

  • Torch placement: Because it’s difficult to see the weld puddle when doing an inside corner, i’d move the torch too far away or angle it so i could see.  Moving the torch too far away would make the gas not reach the weld puddle, and lots of contamination would happen.
  • Torch angle: for the same reason (seeing the puddle), i would tilt the torch so it started pointing towards me.  This means that the heat is directed towards the filler rod, so when i tried to dip the rod into the puddle, the filler rod would melt before it got to the puddle.  Also, it would melt outside the argon gas, and become horribly contaminated.
  • Wind: Seriously, this took a while to figure out.  In the place where I weld (the TechShop in Menlo Park, CA), there’s a decent amount of ventilation in the room (this is a good thing).  However, there was so much that the shielding gas was getting blown away from the weld puddle and everything was getting contaminated.  The reason this took so long to figure out was that it was inconsistent depending on the day and how the room was laid out.

So, the major lessons learned are that aluminum really is susceptible to contamination outside of the shielding gas bubble.

More recently, my fillets have been looking decent.  They’re still inconsistent looking, but they’re solid:

Fillet weld...looking better!

So, here’s what i think is the final battery frame:

the finished (for now) battery frame, including all four mount points.

Another view of the battery frame.

This includes the mounting points, which took me a good amount of time to figure out.

That’s it for now, i’ve got some pics to show of the mount points and moto frame, but i need to get some better pictures first.  That’s it for now.  Thanks for reading!

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