Poor mans anvil AKA Big Thing For Beating On

[OxxAndBert]

My grandkids are getting to the age where they will sit still long enough to listen to instructions, and I'd like to try and start passing on a few metalworking/mechanical skills and hopefully growing some interest there.
They're not quite up to machining or welding yet, but I reckon they might enjoy bashing a few bits of hot metal - hopefully eventually even them into something useful.

A perfect excuse to find something solid and heavy to beat on which would be a useful addition to the workshop regardless.

I've got some forklift tines that would likely make a good post anvil, but wanted something with a bit more area that would be easier for them to aim at...

Found this large gear that I salvaged from the old workshop at work prior to its demolition:
Roughly 330 diam, 95 thick and I reckon weighs close to 70kg.





Took a file to it, and its not hardened at all.
In hindsight I probably should have just cut the teeth off 2 sides, made up a press fit steel plug for the bore, stenciled BTFBO (Big thing for beating on) onto it and called it quits.
Even for me that seemed a bit too agricultural.......


Managed to get it onto the bandsaw, and cut it into 2 pieces.
First blade must have been dull on one side and cut like a banana, but a new blade went through nicely.




Onto the mill to clean up the cut surface, and knock the teeth off the opposite sides. In hindsight the bandsaw would have been better for the teeth removal.




A lesson about inadequate workholding - hence resorting to the facemill.




All cleaned up and ready to stick back together in a better shape (or at least show I put in some effort):





Steve

[OxxAndBert]

Obviously I don't know what the steel is.
Quick spark test was exactly the same as a piece of hot rolled flat bar I purchased recently. That steel is 300Plus - just a structural mild steel.
Machined more like a alloy steel though so not confident how welding it will go.

I tossed up whether to just hit it with the MIG and standard ER70S6 wire, but thought it would be a good excuse to try out some 7016 stick rods that I picked up from a discount bin a while back.
The Eutectic 680's I've got in my stash from the 1980's would have been perfect, but that stash is dwindling so keeping those for special occasions.




My stick welding skills are relatively low, but I can run reasonable beads. How hard can it be right??
Found a piece of 6mm mild steel rod to space the pieces apart and make a backer for the initial pass then did some very rough bevelling on one piece with torch and grinder before I lost interest.

Ran a couple of rods, needle scaler between passes to remove flux then turned it over and ran a few the same on the other side. Then heard a dreaded "tink"
First side had cracked at the edge of the bead where it met the half I hadn't had used the cutting torch on (ie still basically cold). Think it needed some preheat.
Propped the whole thing up a bit to get a better angle/view of the crack area and just ran another nice hot bead through the crack. Left it for a couple of minutes, belted it with a hammer a few times and no sign of it re-cracking.
I know you real welders out there are cringing and squirming in your seats at this point !!!
25 rods later I was out of rods and it looked like this:




Wrapped it up in a big fibreglass fire blanket and left it to cool slowly.
The blanket was surprisingly effective. It was still about 40deg this morning - 12 hrs later.

Steve

[kwijibo99]

Should be the business Steve.
You could probably weld a couple of sections of forklift tine onto the faces to give you the hardness of the tine with the mass of the gear behind it.
Cheers,
Greg.

[OxxAndBert]

Thanks Greg. I couldn't resist the urge and had a quick beat on the smaller half after I machined it.
Some 8mm mild steel rod, only cherry red and not a good forging yellow colour, but it was lovely to use and hardly even took the shine off the machined surface.
Definitely didn't bruise it at all.

My dilemma now is what to use to complete the welding. Do I just grab some more 7016's, or have at it with the MIG, or get something like some 29/9 chrome/nickel rods that are even less likely to crack...

Steve

[OxxAndBert]

Realised I had a sample piece of the material left over from removing the bandsaw banana cut.

Did a quick quench test in oil to see if it hardens. Definitely does.

Cut it in half and welded it with the MIG - a quick bead down either side. Don’t judge
Mainly want to see if it becomes brittle or cracks at the edge of the weld.



Put it in the vice and have it a beating with a carpenters hammer as it was the nearest one I had.



That was as far as I could bend it without going to a bigger hammer and I was getting worried about damaging the vice.
Certainly no sign of issues at the weld so I reckon I’m good to finish the rest of the welding with the MIG.

Steve

[Michael G]

Unless the gear was from something special, it was probably something like 1040. Should be good to go.

Michael

[OxxAndBert]

Thanks Michael.
It likely would have been from a very slow moving machine like a cable drum roller.

Gave the MIG a workout and glued the rest of it together.
All done and put to bed for the night in the fire blanket.




Steve

[snapatap]

You can use mig as an alternative to low hydrogen rods. that's what we do at work. Preheat and slow post weld cooling is the most important thing if you think you are welding anything with more carbon than mild steel.

[OxxAndBert]

Thanks Snapa.
I think I’ve got the slow cooldown sorted by using the fire blanket. Actually very surprised how warm it was after 20hrs in the blanket.
What would be a typical preheat temp for something like this?
I didn’t check with the thermometer but guessing I got it up to about 100C with the oxy before starting with the MIG and it seemed to be ok. I think I’ve seen references to needing more like 200degC ??

Steve

[snapatap]

The old rule of thumb was when your spit sizzles on it. I think somewhere in the 150-180c range. if you get to light straw color its probably a bit too much preheat.

[OxxAndBert]

Apparently real anvils should have good rebound when tested by dropping a hardened steel ball on the surface.
Above 85% rebound indicates a high hardness quality anvil.

The BTFBO achieved about 50% rebound.
About the same as I get from a decent lump of forklift tine stood on its end.
Should do the job I think..

Steve

[OxxAndBert]

Finished!!!



Steve

[BaronJ]

Hi Steve,

You will get a hernia shifting that it looks bloody heavy !

[OxxAndBert]

Hi Steve,

You will get a hernia shifting that it looks bloody heavy !

Definitely bloody heavy!!
I reckon close to 100kg all up so should stay put when being used.
Good thing is it’s way above my physical lifting capacity so will be mechanical means only to relocate it to a more permanent home. I love my dodgy old forklift

Steve