Welding Tips and Tricks

Hello all. My first post and I'm hoping for some help on a situation I've surprisingly never run into before. I'm replacing some damaged motorcycle frame sections on a restoration project that are somewhat structural in nature. The existing metal is .120 25mm steel, and I'm planning on welding in some .085 chromoly. I'd like to finish the butt joint so it isn't visible, but it needs to be strong, too. Should I chamfer the butt joint or should they mate up tight with flat ends? I'd use a plug, but I'm having a hard time finding a matching piece of material - all the .120 I find is 1", not 25mm. Maybe I should match the wall thickness for a plug and try and blend the mismatched OD's? Thoughts?

If the tubing is 25mm, then the frame must be Japanese? If so, all the frames I’ve welded from there have been 0.063 wall.

But to answer your question... match the OD even if you have to order the tubing. You can use some 0.024 MIG wire and open root the weld. It will be far stronger than the antique tubing If you can’t find tubing, PM me. I’ve got some or can spin you up a plug to join the halves if you prefer.

cj737 wrote:If the tubing is 25mm, then the frame must be Japanese? If so, all the frames I’ve welded from there have been 0.063 wall.

But to answer your question... match the OD even if you have to order the tubing. You can use some 0.024 MIG wire and open root the weld. It will be far stronger than the antique tubing If you can’t find tubing, PM me. I’ve got some or can spin you up a plug to join the halves if you prefer.

Awesome, thanks for the tip! The frame is a 1975 Yamaha RD250, and the wall thickness seems thicker than 063 but I'll clean it up and remeasure with an anvil mic instead of a calipers. I might have been picking up a bur or rolled edge. As a hobbyist I've never done an open root TIG weld, but this is a good reason to practice. Dumb question, but do I set the amperage for the thickness of the rod on the root? And after the root pass is in do I up the amperage? I'm pretty new to this as I'm sure is painfully obvious to you guys!

Sconnie - If you're new to that type of welding, definitely consider making many many practice runs on scrap tubing first. Even consider buying quite a bit more tubing than you may need for the job so it is the same. Open roots (and even beveled butt joints) on relatively thin tubing are some of the most challenging TIG welds of all, IMO. Especially for people that don't do it regularly.

Spartan wrote:Sconnie - If you're new to that type of welding, definitely consider making many many practice runs on scrap tubing first. Even consider buying quite a bit more tubing than you may need for the job so it is the same. Open roots (and even beveled butt joints) on relatively thin tubing are some of the most challenging TIG welds of all, IMO. Especially for people that don't do it regularly.

Got it. Our local instructor at the tech school in Madison has his own shop, I may need to enlist his services. I can make a few things look pretty, but I might be over my head on this one.

Sconnie wrote: Awesome, thanks for the tip! The frame is a 1975 Yamaha RD250, and the wall thickness seems thicker than 063 but I'll clean it up and remeasure with an anvil mic instead of a calipers. I might have been picking up a bur or rolled edge. As a hobbyist I've never done an open root TIG weld, but this is a good reason to practice. Dumb question, but do I set the amperage for the thickness of the rod on the root? And after the root pass is in do I up the amperage? I'm pretty new to this as I'm sure is painfully obvious to you guys!

Thought I recognized that frame

So when you "gap" the tubes, you use just about enough amperage for the tubing thickness (expect 55-60 amps). You need to clean the inside of the tube with a flap disc (you can get these in 1"x.25 to fit in your die grinder or Dremel). Take a 6" piece of MIG wire, bend it into a V, pinch it between the butted tubes, tack in 2 places. Pull the MIG wire out. Tack in 2 more places.

Now when you weld, just do 1/6 - 1/4 of the tube at a time. Stop and reposition yourself to be comfortable. Use a 1/16 filler wire (ER70-S2 or S6 is fine). Light up where you left off, move the torch and when the puddle "keyholes" add filler. Keyhole, dip, keyhole, dip, repeat until you get all the way around.

This is not rocket science. You are perfectly safe making this repair. Keep a tight arc, take your time, reposition often. You can do this.

When you're done, you can use a sanding belt and flatten the filler to flush to the surface without fear as you have 100% penetration due to the open gap. Just clean everything really well before you start.

Pictures when you're done please!