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Welding cast magnesium?

Hi All,

I have a bicycle frame made from AZ61 magnesium. One of the rear drop- outs (the part where the rear wheel attaches) broke. It appears that this part is made from cast magnesium (the rest of the bike is TIG welded tubing). Right where it broke, there is a hole for a bolt which is used to align the wheel. This bolt is not strictly necessary, and it undoubtely weakens the area.

Here are some photos:

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How difficult would it be to repair this? Would a repair be significantly weaker than the original? I figure that if the bolt hole is eliminated, a weld might even be stronger than the original.

Any suggestions on how to find a welder capable (and willing) to fix this?

Joseph

Reply to
joseph.santaniello
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The trick will be finding a suitable filler rod for that alloy of magnesium.

Reply to
Ernie Leimkuhler

Any god tig welder should be able to do this. Check your local bike or boat shops. Liberty Alloys has fillers for this alloy.

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Looks like that part was designed to fail. Eliminating the cross hole would make a big difference. Radiusing and polishing the inside of that slot will make a difference.

Reply to
starbolins

The holes are a design legacy from steel frames. The newer models do not have them. I was quite surprised when I saw how thin it actually was once I could see inside!

Joseph

Reply to
joseph.santaniello

Or get a frame that's not designed and built like shit in the first place. I'm sure the other side wants to break next.

Reply to
Cydrome Leader

Too late! In defense of the frame, it was -10C and I dropped it on a concrete floor. Not exactly what it was designed to do.

Joseph

Reply to
joseph.santaniello

ha, not designed to have any strength?

Reply to
Cydrome Leader

It doesn't need much strength in that part when assembled, with the axle in place.

Dave

Reply to
spamTHISbrp

If you had to pick, I would rather have the rear wheel fall off than the front one.

Reply to
Cydrome Leader

About 40 years ago I was shown how to weld magnesium chain saw parts by a welding salesman. The first thing he said was "get a shovel". You placed the part on the shovel before you started working on it. If it got away you could carry the whole thing outside.

Reply to
NewsGroups

A few years ago, I was cruising at 70 mph on the interstate south of Shelbyville Indiana coming home from training at Mazak in Kentucky. My driver side wheel on my Ranger 4x4 departed my company suddenly. Outside of the drop, the event was uneventful. I should have waited a bit longer before applying brakes since the rotor didn't have much traction and grew a flat spot.

Loosing the Warn hub was the most expensive part of the deal. You buy them in pairs. The guy with the tow truck gave me a deal on the tow. He was a fellow member of the Siemper Fie fraternity

Wes

Reply to
Wes

Reply to
MK1

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