Magnesium Case Repair - Weld, JB Weld, or ???

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bulletpruf

bulletpruf

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Fellas -

I have a few Stihl Contra's that I'm going through, among other things and there are cracks here and there. One common area seems to be where the handle attaches to the case - gets over-tightened and then cracks.

The easy way would be to give it a good cleaning and work some JB Weld into the crack, but what are my other options?

I have a MIG welder and have access to a stick welder. I could probably ask someone to TIG it, too. I have done a fair bit of reading and understand the perils of welding magnesium, flammability, etc.

Anyway, curious to hear what y'all are doing here - welding, JB weld, or is there another fix?

Thanks in advance for any info.

Scott
 
There used to be a kit available ( a low temp repair for mag cases etc ) it comprised of a special wire brush IIRC stainless + some sticks of what looked like soft solder you had ti "V" out the crack a small butane type blow lamp would generate enough heat & melt the stick into the cracks following the instructions supplied I never used it on chainsaws but had success with Motor Cycle castings I understand it depends on the mag grade as to if it goes" Poof" & disappears in a molten blobNo idea if this kit is still available as it was some years back when I last used it. PS just looked it up Its called LUMIWELD & still available on Ebay.co.uk at least
 
Welding is the way to go, but finding somebody able to do a decent job these days is getting very hard.
There used to be a place in Milan which did all sorts of light alloy repairs but since the original owner died and his sons took over quality has gone way way way south.

I can try asking around if there's someone working on old German motorcycles (I bet the sandcast cases used on 50's and 60's Heinkel's, Kreidler's and Victoria's are very similar to Stihl's in material) but I cannot guarantee anything.
 
blsnelling said:
There are applications where I would consider JBWeld a 100% permanent repair. IMHO, a crack in a high stress area is not one of those. You need to find someone good with a TIG.
Click to expand...

Brad - what about a spool gun on a MIG? I have a Miller 211; have planned to get a spool gun for it; this might be my excuse.

drf255 said:
Pics would help.

JB is a band-aid. Not a real repair.

Only Tig would repair it correctly.
Click to expand...

I'll get some pics posted later on. Same question as I posed to Brad - can I make this repair with a spool gun on my MIG?

Little Al said:
There used to be a kit available ( a low temp repair for mag cases etc ) it comprised of a special wire brush IIRC stainless + some sticks of what looked like soft solder you had ti "V" out the crack a small butane type blow lamp would generate enough heat & melt the stick into the cracks following the instructions supplied I never used it on chainsaws but had success with Motor Cycle castings I understand it depends on the mag grade as to if it goes" Poof" & disappears in a molten blobNo idea if this kit is still available as it was some years back when I last used it. PS just looked it up Its called LUMIWELD & still available on Ebay.co.uk at least
Click to expand...

Little Al - ordered the Lumiweld kit from eBay.co.uk - not sure if I'll go this route, but it was only $30 US, and if I don't use it here, I'll eventually use it. I watched the youtube video, too. Looks like good stuff. Will do more research on flammability of magnesium before I try this.

Conquistador3 said:
Welding is the way to go, but finding somebody able to do a decent job these days is getting very hard.
There used to be a place in Milan which did all sorts of light alloy repairs but since the original owner died and his sons took over quality has gone way way way south.

I can try asking around if there's someone working on old German motorcycles (I bet the sandcast cases used on 50's and 60's Heinkel's, Kreidler's and Victoria's are very similar to Stihl's in material) but I cannot guarantee anything.
Click to expand...

I will probably tackle this myself, unless I ask someone to TIG it locally. Thanks for the input.

Maybe I need to check out the inexpensive Chinese TIG machines, too...
 
drf255 said:
A spoolgun is a great way to ruin it.

I've not seen mag spoolgun wire myself, it may exist.

Unless you've got a super expensive machine with high speed pulse, a spoolgun cant be used on anything remotely thin.

It needs to be TIG welded.
Click to expand...

Ok. I think this is my excuse to pick up a TIG machine.

ValleyFirewood said:
Fire isn't a real issue. It's a magnesium alloy.
Click to expand...

That's good to hear. Thanks.
 
Welding magnesium is all about heat control; it has a low melting point. TIG is the best method of welding for this material. The crack is probably impregnated with oil so grinding out and thoroughly cleaning out the weld area is necessary to prevent contamination/inclusions in the weld. You might be able to experiment with MIG, a lower temperature welding process, but pre heating will probably be necessary and as mentioned above finding mag wire may be expensive and difficult. You will have more control (temperature and filler material placement) using TIG.
 
bulletpruf said:
Brad - what about a spool gun on a MIG? I have a Miller 211; have planned to get a spool gun for it; this might be my excuse.



I'll get some pics posted later on. Same question as I posed to Brad - can I make this repair with a spool gun on my MIG?



Little Al - ordered the Lumiweld kit from eBay.co.uk - not sure if I'll go this route, but it was only $30 US, and if I don't use it here, I'll eventually use it. I watched the youtube video, too. Looks like good stuff. Will do more research on flammability of magnesium before I try this.



I will probably tackle this myself, unless I ask someone to TIG it locally. Thanks for the input.

Maybe I need to check out the inexpensive Chinese TIG machines, too...
Click to expand...
I would hate to see what a spool of mag filler cost ..... The tig rod I found was around 5$ each 3ft length I can't even imagine MIG with magnesium its bad enought with tig. The biggest problem I see with mig on mag castings is the "trash" its kindof like if you were to try welding steel with different amounts of rust and scale without cleaning them up only you can't see how much because it's burried in the material if that makes sense.... If you want an excuse to buy a spool gun build ur wife a aluminum shoe rack personally id use it as an excuse to buy a tig tho.... If you go with a tig whatever it is get something with adjustable HF the intensity of the HF seems to play a huge role in making decent weld on mag casting ... Just what I've observed so far
 
If you were in my area I'd do it just for the experience ..... I'm far from Italy tho good luck if you do decide on welding try to get a look over the shoulder of the welder and you'll understand why nobody wants to mess with mag castings ..... Srcarr52 has alot more experience with this I'm still learning his work is on point tho ..... If you had to send it somewhere I would start there
 
13TreeWorks said:
If you were in my area I'd do it just for the experience ..... I'm far from Italy tho good luck if you do decide on welding try to get a look over the shoulder of the welder and you'll understand why nobody wants to mess with mag castings ..... Srcarr52 has alot more experience with this I'm still learning his work is on point tho ..... If you had to send it somewhere I would start there
Click to expand...

Yep, I read some of Srcarr52's posts on welding. Lots of good info there.

Thanks,

Scott
 
Yeah go ahead and weld it anyway you want and it will work great, NOT. There are several welding threads on this subject with ZERO success. Mig, TIG, Solder did not work for me, but go ahead and try it again. Tell us how it went. Welding motorcycle cases is a cake walk without any issues, Chainsaws is quite another matter. JB Weld and similar epoxies work perfectly. Actually JB Weld is much stronger than the original. In my case the repairs consisted of making a patch that was at least 1'' bigger in every direction than the crack with aluminum, Of course cleaning to bare metal was essential and carefully crafting the reinforcing patch. Thanks
 
Ted Jenkins said:
Yeah go ahead and weld it anyway you want and it will work great, NOT. There are several welding threads on this subject with ZERO success. Mig, TIG, Solder did not work for me, but go ahead and try it again. Tell us how it went. Welding motorcycle cases is a cake walk without any issues, Chainsaws is quite another matter. JB Weld and similar epoxies work perfectly. Actually JB Weld is much stronger than the original. In my case the repairs consisted of making a patch that was at least 1'' bigger in every direction than the crack with aluminum, Of course cleaning to bare metal was essential and carefully crafting the reinforcing patch. Thanks
Click to expand...

Don't know where you come up with this notion of zero success with TIG welding. Where are all these threads?
With a decent TIG machine and the correct filler rod welding up mag chainsaw parts is really pretty easy, I and a few other guys here do it on a regular basis and don't seem to have any significant issues.

JB weld repairs on mag stronger than the original part? You've been watching too many commercials...
 

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