Wacker Plate & Metal fatigue

[Paul99]

Thought I'd put this up as a classic example of metal fatigue as it's by far the worst case I've ever seen.

That crack wasn't there 2 hours previously! well at least not those in the sole plate - the cracks in the two frame rails look old which likely started the other cracks off - the previous repairs are not my doing, they don't look so bad in the photo but to be fair they've held fine and will be left alone. Luckily it lasted just long enough to finish the job before starting to run too rough - I could see why when I checked - it was flexing all over the place .

I've not yet decided whether to use the arc on it as is (I'm lazy) or take a bit more care to clean the metal off and mig it - being as it's only 6mm plate no big deal either way, my temper / patience at the time will dictate . While I'm at it I might as well try and straighten the sole plate out a little too as it's needed doing since we had it. Photos of the end result to come - when I get around to it...

 

[zzr1200]

It may ONLY be 6mm plate but theres a good chance its 6mm Hardox Type Steel not 6mm Mild Steel....

 

[Paul99]

It may ONLY be 6mm plate but theres a good chance its 6mm Hardox Type Steel not 6mm Mild Steel....

That thought had crossed my mind... but figured on treating it as mild steel whatever the case. I bought it a few years ago as a non runner for £50 but told it did run when it was last used several years previously though he couldn't see it running again. The vibrating unit was seized and the engine wouldn't start but literally 5mins on each and away it went - it's been reliable ever since. The cost was covered in it's first ever job so it doesn't owe us anything - each time it's needed it saves £25 -£30 rental.

As I see it I got nothing to loose by attacking it with 6013s or the mig - as it happens the site tutorials suggest normal mig wire for hardox anyway which is a bonus - I'll not attempt any heat treatment first as I've not got the kit but being 6mm again should get away with it. I think for speed and ease (and the opportunity to use the mig at the higher settings for once) I'll use that. Warping from the heat does concern me a bit so doing it all in one run might be out - that's one thing I struggle with after using Arc for so long - the length of the rod determined when to stop and you had no choice but to stop - but it's too easy to get carried away with the mig

If all else fails I'll just make up a new MS plate and frame for it at some point - for the amount we use it (we're only a two man band) I'm sure I could put something functional together should the repairs not be up to the job.

 

[pedrobedro]

It will more likely be mild steel treating the base as a disposable item. I'd look at putting another piece underneath it the same thickness give it a bit more weight as well.

 

[dan.taylor.1]

Depending how worn the rest of the plate is I don't think they are that dear to buy replacement plates for?

Dan

 

[Paul99]

Just got home from work and decided to have another look at it. I was able to scratch the plate with a piece of mild steel so 99% sure it wasn't hardox or other exotic steel. I'm sure you can get replacement sole plates but even relatively cheap is still more expensive than 15mins work, a few ltrs of gas and a few meters of welding wire so decided to bite the bullet and give it a go.

I gave the cracks a quick going over with the grinder, cranked the mig to near flat out (Tec-arc 251) and set to it. I definitely acheived enough penetration in fact too much in places so will need some grinding back flat on the underneath but it welded better than I had expected (poor / beginner mig welding skills aside) and with a few minutes more work it should be back up and running again for a while. Given that the plate has definitely worn thinner in a few places I'm sure more stress cracks will form eventually but being as the plate is so knackered I'll just keep adding more weld to keep it going . For the amount we use it I'm sure this bodge it approach will be good enough - obviously wouldn't pay if it was being hired out etc but not got to worry about that.

I may well add another new plate to the underneath as suggested at some point or if we get a spell of artic weather over the winter bad enough to down tools for a few days I may make a whole new plate as there's very little to it.

I'll get some pictures up later on...

 

[Paul99]

Mig welding definitely needs more practice...

Though penetration is mostly fine, touched up a bit where I turned the power down a bit too much:

Ground back - need to fill in those two small craters but should hold up ok I reckon:

Time and use will tell if it was worth doing, I'll let you know either way after the next use...
Paul.