Repairing a cast wacker plate base

[reb78]

I'm not sure where to put this on the forum, so thought i would ask here first.

A friend lent me a wacker plate to do my driveway. The base was already cracked when he lent it to me, but i would like to return it repaired if possible. I cleaned up the crack and tried to give it a go with my MIG. It was at that point i realised it was cast as it started tinkling and cracking. The result was a bit of a waste of time as the welds i put on it have all cracked.

What are the options?

Some pics (these were after my failed attempt to weld it and grind it flat):

 

[Chris Stevens]

Whats on the other side?

 

[Screwdriver]

Braze it.

 

[WorkshopChris]

That's going to be a big lump to pre heat, i have found brazing with good pre heating and post slow cooling is very successful if and its a BIG IF you can completely v out the crack completely. And i would imagine from what we can see that's going to be almost from side to side and end to end.
You may have some luck with a nickel based rod, but i have no experience with the prep required for that.
Most cast repairs i have worked on were as a result of some sort of external damage, but that's probably some internal stress coupled with the fact its naturally trying to shake it self apart when running.

 

[Bill Edwards]

Unless you're well equipped to remove the base and put it in an oven for preheat and post cooling I'd forget about brazing.

I'd be surprised if the cast is iron not steel, using something brittle such as cast iron for a whacker plate seems odd to me, but I have no experience of them.

V it out, if the grinder sparks are yellow it's not iron and so weld it with 312 (dissimilar) rods, avoid it getting too hot.
If the sparks are a dull red it's cast iron and you need cast welding rods, which are high in nickel content. Be warned though, they are not cheap and you must only weld a very small lump at a time (maybe an inch at a time on something like that) and tap the weld gently (called peening) as it cools. Never get it too hot to keep your hand on. A piece that size could take you most of a morning to do properly.

Unless it is cast steel in which case dissimilar wire is available (at a cost) you're looking at stick welding, not MIG.

 

[BChild]

I'm glad it's not me that borrows stuff from people and returns it in better condition than when it was borrowed - good on you for at least trying

I needed to do some concreting so borrowed a local jobbing builders mixer (he lives 3 doors down) - the drum had 3 or four holes in it and the paddles were flapping around in side - he uses the "chuck a load of brick rubble in it with a few buckets of water" cleaning method so it probably suffered from that. The pull cord had snapped and as a result was only just long enough to get it to catch and start, the oil in the engine was minging and how it breathed thro a caked up air filter I don't know!!!

So a quick oil change, clean the air filter and re-oil and replace the pull coard with some rope left over from my boating days

However the holes in the drum would be a bit trickier - it was coated in concrete

But as I was doing the decking and I had a tonne of pea shingle (see other thread) that wouldn't be seen once spread under the decking I used that and some water to clean it up

Once cleaned I cut a few sections out and replaced with new steel and welded up and braced the paddles

At least then it didn't drip concrete on my brick weave while I was using it.....

He was chuffed to bits when he got it back as he was considering buying a new one as he thought it was on it's last legs - it's not like it took me long or cost me much to do what I did and it was certainly cheaper than a proper hire

 

[wookie]

I'm not sure where to put this on the forum, so thought i would ask here first.

A friend lent me a wacker plate to do my driveway. The base was already cracked when he lent it to me, but i would like to return it repaired if possible. I cleaned up the crack and tried to give it a go with my MIG. It was at that point i realised it was cast as it started tinkling and cracking. The result was a bit of a waste of time as the welds i put on it have all cracked.

What are the options?

Some pics (these were after my failed attempt to weld it and grind it flat):

That is exactly the same pattern of cracking as the one I repaired, it cracks inline with the engine mounts, it was cast steel so I ground a deep V along the crack (nearly through) and welded it up with the Mig and it was fine.

 

[reb78]

That is exactly the same pattern of cracking as the one I repaired, it cracks inline with the engine mounts, it was cast steel so I ground a deep V along the crack (nearly through) and welded it up with the Mig and it was fine.

That's exactly where it's gone, all in line with the engine mounts. I ground along the cracks to open them up and then ran along with the MIG, so what do you think I've done wrong here?

 

[reb78]

Unless you're well equipped to remove the base and put it in an oven for preheat and post cooling I'd forget about brazing.

I'd be surprised if the cast is iron not steel, using something brittle such as cast iron for a whacker plate seems odd to me, but I have no experience of them.

V it out, if the grinder sparks are yellow it's not iron and so weld it with 312 (dissimilar) rods, avoid it getting too hot.
If the sparks are a dull red it's cast iron and you need cast welding rods, which are high in nickel content. Be warned though, they are not cheap and you must only weld a very small lump at a time (maybe an inch at a time on something like that) and tap the weld gently (called peening) as it cools. Never get it too hot to keep your hand on. A piece that size could take you most of a morning to do properly.

Unless it is cast steel in which case dissimilar wire is available (at a cost) you're looking at stick welding, not MIG.

I'll take a look at the sparks tomorrow and report back. I do have an arc available, bit I've never used it!

 

[reb78]

Whats on the other side?

It's the engine mounts in the casting. It's cracked inline with them.

 

[Screwdriver]

Brazing will be the best option if it's cast iron which I assume it is. You can easily pre heat it to a sufficient temperature to prevent cracking and braze, being a softer more ductile material will resist cracking when in use. If it's a cast steel, you might consider preheating before MIG or doing an inch at a time and allowing it to cool in between short sections of weld. Ultimately you could weld a new quarter inch plate across the entire surface and be done with it. Probably have to plug weld it all over the base though.

<edit> On second thoughts, it's almost got to be a cast steel. really need to see the other side of the plate where the fixtures are.

 

[roofman]

Ive welded wacker bases in the past with great success with straps on the top side...ive never come across a cast iron base on one ever

 

[reb78]

I'm assuming it's cast from it's reaction to the heat. I'm not saying iron or steel though. The part number for the base just describes it as cast (the part is £250+, so not really worth replacing as a second hand machine on ebay is less.

 

[reb78]

This is the other side. You can just about make out the crack. Same thing on the other side too

 

[Ton-up]

Weld it both sides the best you can then get a plate of 12mm steel and bolt it on using CSK bolts.

 

[the snooper]

Ive welded wacker bases in the past with great success with straps on the top side...ive never come across a cast iron base on one ever

I don't think cast and wacker plates go together cast is brittle so would crack easily in use

 

[wookie]

That's exactly where it's gone, all in line with the engine mounts. I ground along the cracks to open them up and then ran along with the MIG, so what do you think I've done wrong here?

Not sure what you're doing wrong, I just used standard 1.0mm Mig wire, I tacked it every inch and then did short welds between a pair of tacks then another 3 or 4 inches away, alternating between the 2 cracks to try and keep the heat down, having said that I stuck to my normal power settings rather than turn it down.

Originally I was going to make a new base from 6mm plate as I wasn't sure it would weld well but the guy just wanted a cheap quick repair, anyway it lasted. Sorry I can't be more helpful.

 

[reb78]

I don't think cast and wacker plates go together cast is brittle so would crack easily in use

It's described as cast here:

http://www.bellegroup.com/?p=parts&as=61

Part no.1

 

[Kent]

If you're messing with a casting always get a proper agreement about when sh1t happens and don't do anything safety critical
Two rules before you do anything
Spark test it, unlikely to be cast iron I should have thought

 

[Kent]

Cast steel mailable or cast iron?