1444's First Fully TIG-Welded Frame

[catacon]

Hey all,

Team 1444 acquired a Diversion 165 for our shop this year and immediately assigned it to main welding duty. We've had a larger Miller MIG that has been holding it down for years, but we decided to step up our game and fully TIG the robot this year. We've had sub-assemblies TIG welded before, but never the entire robot. So far, we are very pleased with how things are turning out. The 165 isn't quite up to some of the thicker plate used in the gearboxes, but that's nothing multiple passes can't solve. Students and mentors alike are still learning, but it has been a lot of fun so far and we are looking forward to more TIG'd goodness in the future.

Frame sub-assembly:





Frame tacked and ready for seam welding:



Fully welded (for now):



Several dimes have been stacked...

[D_Price]

Very nice and clean looking weld lines. Just wondering if you will have any weight issues when the robot is fuly assembled?

[DarkRune]

Don't know why, but I'm getting a 2014 robot vibe from this haha. Anyway, can't wait to see it when its complete, I bet it will be gorgeous.
Good luck!

[catacon]

Originally Posted by D_Price

Very nice and clean looking weld lines. Just wondering if you will have any weight issues when the robot is fuly assembled?

Eh...it's hard to say. That frame only weighs 14lbs. But we are a little worried about weight, so we are taking some lightening measures now.

Originally Posted by DarkRune

Don't know why, but I'm getting a 2014 robot vibe from this haha. Anyway, can't wait to see it when its complete, I bet it will be gorgeous.
Good luck!

Haha. Well so far it looks quite a bit different than our 2014 robot. Black paint might happen again, though. ;-)

[Tristan Lall]

Do you have details on the alloys of the extrusions, plates and filler metal, and the heat treatment (if any)? I'm curious if there was explicit consideration of the reduction in temper of the alloy due to welding (heat-affected zone).

Also, let us know if there's any trouble fitting bearings into the machined holes, due to distortion in the welding process. Did you use jigs to ensure the gearboxes remain square? Or are you planning post-weld/post-heat-treatment finish machining?

[catacon]

Originally Posted by Tristan Lall

Do you have details on the alloys of the extrusions, plates and filler metal, and the heat treatment (if any)? I'm curious if there was explicit consideration of the reduction in temper of the alloy due to welding (heat-affected zone).

Also, let us know if there's any trouble fitting bearings into the machined holes, due to distortion in the welding process. Did you use jigs to ensure the gearboxes remain square? Or are you planning post-weld/post-heat-treatment finish machining?

Everything is 6061 T6 with 4043 filler done with 100% Argon. With the thicker plates, we did do some preheating to aid in getting decent penetration and we make some attempt to slowly cool the pieces. Early on, we had some students quenching parts which is a big no-no.

On this particular assembly, we did use a jig to keep the bearing holes centered. On some of our smaller assemblies (i.e. those that will fit on our mill), we will machine them after welding.

Thanks for the comments!

[Ryan Dognaux]

Looking great guys, 1444 always makes some of the coolest stuff all in-house.

[Shrub]

It's so beautiful the frame looks like it's going to be very interesting!

[catacon]

Originally Posted by Ryan Dognaux

Looking great guys, 1444 always makes some of the coolest stuff all in-house.

Originally Posted by Shrub

It's so beautiful the frame looks like it's going to be very interesting!

Thanks guys!

[JamesCH95]

Lookin' pretty good!

Who is doing the welding and what sort of parameters/consumables are they using?

[catacon]

Originally Posted by JamesCH95

Lookin' pretty good!

Who is doing the welding and what sort of parameters/consumables are they using?

It has been a mixture of students and mentors. Despite being an EE, I've become our main welding mentor; I think I'm the only one crazy enough to do it.

We've been using Hobart MaxalTIG 3/32" and 1/16" 4043 filler, green (pure) tungsten electrodes, and 100% Argon. (All generously donated by a sponsor, Delta Gas and Welding Supplies!) We just got some ChemSharp for sharpening electrodes and I swear that stuff is magic...SO much better than grinding. We use the Miller footpedal and a Weldcraft A-150 flex valve torch.

Our Diversion 165 is pretty light for some of the stuff that we do, so it has been maxed out most of the season. A few of our weldments required multiple passes with preheating. It does great for 1/8 and 1/16 wall tubing, though. We've gotten some X-Ray-quality welds on that material.

[JamesCH95]

Originally Posted by catacon

It has been a mixture of students and mentors. Despite being an EE, I've become our main welding mentor; I think I'm the only one crazy enough to do it.

We've been using Hobart MaxalTIG 3/32" and 1/16" 4043 filler, green (pure) tungsten electrodes, and 100% Argon. (All generously donated by a sponsor, Delta Gas and Welding Supplies!) We just got some ChemSharp for sharpening electrodes and I swear that stuff is magic...SO much better than grinding. We use the Miller footpedal and a Weldcraft A-150 flex valve torch.

Our Diversion 165 is pretty light for some of the stuff that we do, so it has been maxed out most of the season. A few of our weldments required multiple passes with preheating. It does great for 1/8 and 1/16 wall tubing, though. We've gotten some X-Ray-quality welds on that material.

Very nice!

I would suggest two things (as someone who has earned certs in aluminum and steel TIG):

1) 50/50 Ar/He gas is wonderful, especially for welding thicker aluminum sections. The added heat transfer from helium allows you to weld thicker material at lower currents as well as run higher currents on smaller electrodes. Welding thin sections also benefits from 50/50 as well.

2) Toss the pure tungsten, it is pure garbage. I know it's 'old school' to use pure tungsten, but it's simply not as good as alloyed tungsten in current capacity or arc stability. A zirconated (yellow) or E3 (purple) tungsten will hold a point under load, resulting in better arc control, and the end will never melt and fall into the weld pool.

Otherwise, keep up the good work!

[catacon]

Originally Posted by JamesCH95

Very nice!

I would suggest two things (as someone who has earned certs in aluminum and steel TIG):

1) 50/50 Ar/He gas is wonderful, especially for welding thicker aluminum sections. The added heat transfer from helium allows you to weld thicker material at lower currents as well as run higher currents on smaller electrodes. Welding thin sections also benefits from 50/50 as well.

2) Toss the pure tungsten, it is pure garbage. I know it's 'old school' to use pure tungsten, but it's simply not as good as alloyed tungsten in current capacity or arc stability. A zirconated (yellow) or E3 (purple) tungsten will hold a point under load, resulting in better arc control, and the end will never melt and fall into the weld pool.

Otherwise, keep up the good work!

Thanks for the advice! I'd love to give Ar/He mix a try. We have a bunch of pure electrodes, so I figured I would use those up before getting something nicer.

[Tristan Lall]

Originally Posted by catacon

We have a bunch of pure electrodes, so I figured I would use those up before getting something nicer.

Given how much better the doped electrodes work, this is probably a false economy. Better to spend a little more on electrodes, and significantly reduce the risk of a bad weld in a critical assembly.