Cracked 853 should I MIG weld it?

This TIG welded 'conical 853' has cracked. I use MIG welding a lot in my work. What would happen if I MIG welded this as opposed to TIG?




any other issues I should be aware of?

An unusual place for a crack to propagate - I'd have expected it to follow the edge of the weld, not to run though it at 90 degrees.

Are you sure that it is a frame crack and not just in the paint ? The only way to check (apart from X-raying it) would be to sand off the paint in that area and look very closely (under magnification if necessary) and/or dye test it.

I agree with Andy sand off a section of paint first- it would be very unusual for a crack to start on one tube go across a weld and finish on a different tube all in a straight line.

Hopefully its just a scratch!

if it is a crack
and your going to repair it
my advice would be to TIG weld it

My thoughts exactly, don't think I have ever seen a tube spontaneously crack like that. The crack on the down tube would be possible, but to then continue up to the head tube, across a weld, and then crack a tube in the middle would be impressive!

It is a crack, it weeps framesaver/waxoyl when I just ride it round the garden. More live than I thought.

I only have MIG, hence the question.

Yeah, you need to remove the paint first and see what's going on.

If it is a crack, don't MIG it: you'll end up wrecking it. TIG is the only way to go here.

I would have thought MIG-welding it would damage it further, and TIG-welding the crack won't solve it either. You need two new tubes.

You ought to send the photo to the frame builder and ask them for a free repair or a new frame. When you have a crack along the weld, it's obviously a fault in the weld. When it goes across like that, so that it is a crack in common between two separate main tubes, it must indicate a severe weakening caused by too much heat.

Although Reynolds 853 recovers from welding better than most steel, it is still weakened by welding, and more welding would weaken it further. The head tube in particular is quite a thick tube and it shouldn't crack like that unless there was either a huge impact or a bad error in building that frame.

A good frame builder ought to be embarrassed by that and should offer to see you right, especially if you're the original owner.

I pretty much agree with what you've written there Anthony. The frame builder Thorn unfortunately do not make that model any more, although it has a lifetime warranty. They have offered me an inferior replacement, which is half the price of the frame I bought almost five years ago, and is their own brand tubing. I haven't accepted!

I forwarded the pic onto Dave Yates, and he has advised not to repair it at all, especially as there is another similar crack appearing on the other side too. I kind of new that, but wanted some expert clarification really.

No MIG, no TIG !
Only brazing, (with a silver alloy if possible).
With TIG or MIG, you will destroy the steel structure of your frame (tooooo hot !)