Ajax AJ8 horizontal Mill – cracked casting

[Brian WoodParticipant @brianwood45127]

Mark,

I wouldn't try pulling it together, but I would increase the size of the stop drilling at the active end of the crack to allow a larger circumferential surface for the stress concentration in the crack tip to dissipate through. Doubling the diameter of the hole will increase the circumference by 4 times and reduce the hoop stress in the hole to 1/4 of what it was. I have seen severe cases extend beyond a stop hole after pausing there for a while.

The crack itself is probably stable enough now and bolting clamp plates, bedded down on epoxy, to either side of it will restore strength to the casting in a stress free way.

Regards

Brian

[ScrumpyParticipant @scrumpy]

many years ago a guy at our club had the same sort of problem the repair that was carried out was drilling a hole so the crack could not go any further a plate first bolted on then this plate was taper pinned as well all then covered with Belzona for cosmetic appearance

[colin hawesParticipant @colinhawes85982]

I would use an internal 5mm steel plate, tapped to accept C/S screws, bedded on resin and pinned with dowels. The screws can then be filled and painted. Colin

[Howard LewisParticipant @howardlewis46836]

+ 1 for bolting a plate on the inside. As said, it will be worthwhile cleaning the inside surface, so that the epoxy can fill all the surface irregularities and bond the plate to the parent metal.

Howard

[Mark Davison 1Participant @markdavison1]

Spent today shaping a plate, cleaning it all up and bonding and bolting it in place. With a bigger workshop I'm sure it work have been easier to bend the plate, but I got there eventually.

These photos are before I bonded it in but you get the idea.

[richardandtracyParticipant @richardandtracy]

That looks like a proper job, should stave off any problems for a few decades.

Richard.

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