Fixing broken front handle

[woody paul]

May be tricky remove piece from case then fabricate similar piece out of steel with spigot on end to go in to handle you will probably need to cut handle high up to get spigot in.

[peatff]

Put a magnet on it, it looks like steel to me. It would weld or plate and rivet whether it's aluminium or steel and the weld will be stronger than the original metal.

[wyk]

That handle won't mend and work safely no matter how good the welder is. Be safe and replace it. There are better things to spend ones time on.

[Kev Stephenson]

It's bust, new bit required, simples

[H-A]

New one, not worth welding, bad stress crack area.

 

H-A

[agg221]

OK, for what it's worth, the process I would follow would be:

 

Take the bits off, strip any plastic/paint/grips and clean by washing down with acetone, followed by Decon 90 in an ultrasonic bath. I would then wire brush over the areas to be welded, which includes the area where cracks can be seen. The cracks are related to the forming of the shape by compressing the tube, followed by wear at that point so will need some attention.

 

I would then clamp the parts up in a vice to hold them correctly orientated. I would put copper blocks in the jaws to heat-sink it and make sure the part to be welded was held as close as possible to the blocks. I would then use a thoriated tungsten electrode ground with a coarse taper and balled on the end, spot-tack it autogenously, on both sides and the bottom face, then flip it over and put a couple more spot tacks in on the upper face.

 

I would run the main weld with the power set for full penetration, running a 1/2" length of bead around the two sides, mostly as an autogenous weld but adding a bit of high silicon filler to the pool to build it up about 1/8" in the centre. I would then complete the weld on the top in two more runs.

 

I would then grind back the surface. If I found porosity (which is likely in lower grade alloys such as die castings, but less likely here in a drawn tube) I would grind off the built-up layer flush and repeat the weld cycle as above, grind off to check that I had cleared the issues with porosity by 'floating' it all out, and if not, repeat (this is highly unlikely to be needed). Once I found no porosity, I would leave the surface raised by about 1/16" at the weld bead.

 

I would then turn to the underside. I would repeat the above, but also run welds down the crease where the tube has been formed concave and worn away on the edges of the folds. These would be autogenous welds if possible (ie no porosity having been observed) with minimum filler to rebuild any wear. If not I would repeat the above to get clean welds.

 

Finally, I would add some extra thickness by filling in the depression across the broken region. I would probably run about half an inch either side, building up with a series of weld overlays, looking to leave a neat lateral profile tapering from the full tube diameter to zero, ie ending up with a wedge-shaped overlay, which will take a lot of the stress concentrating features out. I would grind this off to a smooth profile for the above reason.

 

I would not expect the above to fail at the same point in the future.

 

Alec

[H-A]

I would not expect the above to fail at the same point in the future.

 

Alec

 

I would expect in the future, for it to fail right next to the weld:biggrin:

 

H-A

[daltontrees]

Please keep going, I am learning so much and the quality of the debate is beautiful.

[daltontrees]

I would expect in the future, for it to fail right next to the weld:biggrin:

 

H-A

 

I think the purpose of the tapering off of the weld might have been to reduce this risk. Or would the heat of the welding weaken the adjacent area?

[Chippy]

File or grind a round steel bar to fit inside the curved part, drill 2 tapping size holes in the bar and clamp this to the handle, then with the same size drill go through both holes again this time going through the handle as well.tap both the handle and steel bar at the same time with the clamp still in place.

Use some loctite bearing fit on the screws, I would use allen cap heads, also pour a bit of bearing fit all round the steel bar and leave to cure for 24 hours.

Looking at the size use either 4 or 5 mm screws.