Airhammer - Cracking in two! :(

[Alveprins]

Guys...

 

I am in serious trouble.

Remember the 16kg Chinese Airhammer I bought a few years ago?

Well - it seems to be cracking into two pieces. I only noticed this today. Pic below:

 

Ignore the crack around the cover. Thats just he paint and stuff since I've used the access hatch.

It is the "hairline" crack that extends all the way from the back of the hammer, into the access hatch, then continues at the bottom along the wall behind the anvil. It goes all the way around to the identical access hatch on the other side of the hammer.

 

I am at a total loss of what to do here, as there is no way I can afford another hammer in this current economy, and without it I think I'm pretty much screwed....

 

I consulted a friend of mine who does a bit of welding on his spare time, and informed him that I think it is made from cast iron. He said that I'd need a specialist welder to do this kind of job. Also - from what YouTube tells me - it's pretty much a 50/50 chance of success when welding cast iron...

 

What to do? Any tips and/or suggestions?

 

Sincerely, Alveprins.

Edited April 28, 2020 by Alveprins

[Alan Longmire]

There are a few things you can do, welding is only one option.  To weld it, you'd need to take the guts out and weld just the bare casting.  That would involve grinding out the crack to a deep V, preheating, nickel rod, and post heating with a slow cooldown.  

The cheap way to try and save it is a two-part process: First, find the very ends of the crack, and drill a small (ca. 5mm) hole through the casting at the very ends of the crack.  This usually stops the crack from propagating further.  Next, get a piece of thick mild steel plate big enough to cover the crack with 5 to 10 cm to spare on both sides of the crack.  Drill larger, say 13mm or so, holes through both the plate and the casting spaced every 3cm or so, and use bolts though both the plate and the casting to tie it all together.  If possible, a steel plate on both the inside and the outside of the casting is best, with two offset rows of bolts on both sides of the crack

 

This might be hard to do on that angle behind the lower die, but it beats welding.   I've seen more than one mechanical hammer that has cracked fully in half across the frame salvaged with this method.  

[Gazz]

That's a shame.  I think you have several options.  

1. Mechanical fasteners - adding bolted on plates that bridge the cracks which would require drilling and tapping into the hammer body.  You would need to be cautious about the drilled holes to be sure that metal chips or the bolts themselves do not interfere with the internal workings.  Not the best solution but this kind of repair has been done before with success.

2. Braze - this would require complete disassembly of the hammer, preheat in either a large oven or by builing a fire in and around the hammer.  The cracks would need to be grooved out or V'd and then filled with braze by oxy/acet torch.

3. Nickel Rod - similar to the above, the preheat is important.  V out the cracks and electric weld with nickel rods.  I think there are other newer tech rods available for this kind of thing as well.

What is your hammer foundation like?

[Brian Myers]

I would go with Alan's second suggestion. Stop the crack from going any further, then clench that thing down tight with some uber thick bracing and a multitude of bolts. Even mild steel plating will hold up for a long time, possibly for decades if its clamped tight enough. All it would take is one stupid inclusion in the weld to let the process start again.

[Jeremy Blohm]

This has me nervous about my hammer. I almost bought a 2 piece with the sow block separate but thought the 1 piece was easier to set up and have running faster. 

What brand hammer is this one? Mine is a TZ Runfa .

Edited April 28, 2020 by Jeremy Blohm

[Brian Dougherty]

I can't add anything but my moral support.  I remember when you bought it, and followed your process as you set it up.

 

I bet the bracing idea would work well.  Makes sense to me.

[James Higson]

I'd be a little careful with anything that needs you to heat the casting, especially building a fire around it. The ram casing has some pretty small tolerances and warps could bugger the whole lot. That said, my old hammer went through my workshop fire that destroyed everything and John Nicholson managed to get it up and running again!

 

My tuppence would be, bolt the living hell out of it as alan said. 

[Alveprins]

On 4/28/2020 at 9:23 PM, Alan Longmire said:

...The cheap way to try and save it is a two-part process: ...get a piece of thick mild steel plate big enough to cover the crack with 5 to 10 cm to spare on both sides of the crack.  Drill larger, say 13mm or so, holes through both the plate and the casting spaced every 3cm... This might be hard to do on that angle behind the lower die, but it beats welding...

I went with thick saw-blade steel. Heated to critical, and cooled down.

I forged the piece for the "angled" area of the hammer, and used a square cut-out for the flat area on the side.

Bolts are 10mm as 13 seemed a bit too big. You can see the dimensions on the pictures below.

I did not put metal sheet on the inside though.

 

On 4/28/2020 at 9:29 PM, Gazz said:

...to be sure that metal chips or the bolts themselves do not interfere with the internal workings...

What is your hammer foundation like?

I ground down two of the bolts so they did not touch the strut inside the body. Middle one was kept normal.

Foundation is one huge wood block. I made it like that so I would not have to dig and cast concrete.

 

On 4/28/2020 at 11:24 PM, Brian Myers said:

...then clench that thing down tight with some uber thick bracing and a multitude of bolts.

Yeah, the saw-blade steel I used is pretty thick. Almost as thick as the original casting. I felt I've perhaps used a bit too few bolts? I decided to go with Mr. Longmire's suggestion of 13mm, although I scaled it down slightly to 10mm. If I had went with 8mm - I could have placed more bolts. But they would not be as thick, or able to withstand the amount of tightening I've put into those 10mm self-locking nuts.

 

On 4/28/2020 at 11:49 PM, Jeremy Blohm said:

...What brand hammer is this one? Mine is a TZ Runfa .

ZhaoZhuang Make Machinery (Chinese producer)

 

On 4/29/2020 at 10:06 AM, James Higson said:

...My tuppence would be, bolt the living hell out of it as alan said. 

Done!

 

 

I really hope this does it, and that I will not get more problems - at least not for a few more years. Fingers crossed!

 

Thank you for all the quick, thorough and extremely helpful tips and feedback everyone! And of course - moral support!

 

Now I just need to use it for a while, and see what happens I suppose....

 

Sincerely, Alveprins.

 

[Brian Myers]

That should do it! Now the strain will be taken up by the patch and the cast iron should stop cracking. Did you drill out the ends of the crack to stop its progress??

[billyO]

Best of luck, my brother! 

Be sure to give us an update after a bit of use.

 

[Alan Longmire]

Looks good!  I forgot you have the smaller hammer, I was thinking of the 88kg one when I suggested 13mm bolts.  You chose well. 

[Alveprins]

2 hours ago, Brian Myers said:

...Did you drill out the ends of the crack to stop its progress??

The long crack that goes across the entire hammer - goes from service hatch to service hatch - so it ends there - on each side.

 

The crack on the side of the hammer goes from a bit around the corner, down to the service hatch.

I have not yet drilled the "start" if you will - of the second crack. I have to rotate the hammer around in order to do it. I will have to build a kind of scaffold, and lift it using a lifting tackle. Everything is closed atm, and I'll need to go buy wood for that.

[Alveprins]

2 hours ago, billyO said:

Best of luck, my brother! 

Be sure to give us an update after a bit of use.

 

Thanks!

You guys will be the first to know if I get more problems - be certain of that!

[billyO]

49 minutes ago, Alveprins said:

You guys will be the first to know if I get more problems - be certain of that!

No offense then, but i hope we never hear from you....

[Brian Myers]

2 hours ago, Alveprins said:

The long crack that goes across the entire hammer - goes from service hatch to service hatch - so it ends there - on each side.

 

The crack on the side of the hammer goes from a bit around the corner, down to the service hatch.

I have not yet drilled the "start" if you will - of the second crack. I have to rotate the hammer around in order to do it. I will have to build a kind of scaffold, and lift it using a lifting tackle. Everything is closed atm, and I'll need to go buy wood for that.

Well you have your patches in place, so even if the crack continues it won't really do anything. Best of luck bud!

[Alveprins]

Alright, so I've forged for an hour and a half on this piece of WASP Alloy - and I noticed this on the brace of my hammer:

 

 

Seems it has been scraping a bit of paint from the top of the brace. Note though, that the paint is rather thick, and obviously soft in comparison with the cast iron and steel.

Perhaps I should have ground off the paint before placing the brace - so that it would be in direct contact with the cast iron body, not having a "spacer" of thick paint in between?

 

Edited May 3, 2020 by Alveprins

[Alan Longmire]

I would just keep an eye on it and tighten the bolts every so often.

[Brian Myers]

Yeah. There will always be a bit of flex...but from the looks of that paint roll its maybe three mil? If it bothers you, heavier patches and more bolts can always be added. For now just keep the bolts tight like Alan said.

[Alveprins]

1 hour ago, Alan Longmire said:

I would just keep an eye on it and tighten the bolts every so often.

 

1 hour ago, Brian Myers said:

Yeah. There will always be a bit of flex...but from the looks of that paint roll its maybe three mil? If it bothers you, heavier patches and more bolts can always be added. For now just keep the bolts tight like Alan said.

 

Alright, will do.

[Alan Longmire]

Chinese made machine tools usually have about 1.5 mm of putty, paint, auto body filler, and unidentifiable mystery crud between the outer air and the surface of the cast iron.  

[Doug Adams]

If your bolt holes are bigger than your bolts it could let it move a little. You might try a couple of dial pins.

[Chris Christenberry]

"dial pins"?????  Never heard of such a thing.

[Brian Dougherty]

I suspect autocorrect changed that from dowel pin...

[Chris Christenberry]

Sorry, never thought of that.  I never use auto-correct on any device.

[Alan Longmire]

4 hours ago, Chris Christenberry said:

I never use auto-correct on any device.

 

Me either.  If autocorrect worked at above a third-grade reading level it might be useful, but as it is, it's worthless for anything the slightest bit technical.