how to fix a broken part

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A friend asked if I could weld a broken frame piece on a new husqvarne partner k750 cut off saw, he said the guy he got it from says the frame is aluminium, but not 100% on that, I grinded it clean then stainless steel brushed it real clean. and tried tigging it with 5356 rod, It pulled apart real easy and was flakey. Im more questioning that the material is some alloy other than aluminium, it is definetaly a cast material non magnetic, mabe magnesium or some mix, does anyone know what the frame on this saw is made of so I can use the right rod to tig it? thanxs  ill try and post some pics..
Reply:here are some picsLast edited by roadkillbobb; 07-31-2012 at 03:38 PM.
Reply:some form of plastic? (probably a dumb question)Drink a Guinness Draught....Millermatic 140Do you still rememberDecember's foggy freeze --when the ice thatclings on to your beard isscreaming agony.
Reply:A lot of chainsaws now have mag castings not aluminumLincoln 300 Vantage 2008300 Commander 1999SA250 1999SA200 1968Miller Syncrowave 200XMT350MPA/S-52E/xr-15Xtreme 12vs Millermatic 251 w/30A  Millermatic 251 Dialarc 250 Hypertherm 1250 GEKA & Bantom Ironwokers
Reply:Originally Posted by GiddyWeldersome form of plastic? (probably a dumb question)
Reply:This is from the Husquvarna Site's production deptHusqvarna’s own foundryAt Husqvarna we have our own foundry for pressure die casting where we produce parts for chain saw crankcases, oil pump housings, clutch covers, flywheels and cylinders. At the foundry we work with two types of metals: magnesium and aluminium. Magnesium is used for chain saw crankcases, oil pump housings and clutch covers. Aluminium is used for flywheels and cylinders.Hope that helpsTomCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:Pics look like you tried to weld aluminum filler to mag, try to get puddle w/no filler. Then puddle alu no filler, the mag has an odd hue (color) to the welding process. If you did get puddle w/no filler its weldable. My guess its mag from pics.Peter
Reply:thankyou for the responses, yep I tried tigging with aluminium filler and got a glop of crap, but i fiqured id give it a try, ill try without any filler and if its weldable ill try the lws for magnisium rods, and thanxs for the info from the husky sight , i tried looking it up but couldnt find any production info..
Reply:You can check if its alum or mag by dripping some vinegar on it...Mag will bubble, alum wont...
Reply:Originally Posted by TEKYou can check if its alum or mag by dripping some vinegar on it...Mag will bubble, alum wont...
Reply:From what I've read, magnesium alloys are rather temperamental wrt intergranular corrosion and weird crystallization when they get welded with the wrong alloy or are contaminated by the wrong metals. I suggest you call a local shop which repairs Husky equipment and see if you can get a broken piece pf casting from them which you can clean up and use as filler. That way, the alloy should be exactly the same, not counting any changes from welding, like loss of zinc (which is present in some magnesium alloys).
Reply:You could always try http://new.arboristsite.com.  They have lots about chainsaws there and many with knowledge of welding them.Gordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:ok after all the info and trying ti tig it, and it not being my saw.my friend got it free from buying an amount of diamond blades, also the replacement part is a couple of hundred and the whole saw has to come apert...sooo I did the unthinkable and bolted and epoxyed a steel plate for the repair, if it holds great if not he can splurge for the new part..so much for freebee favors....the end...Last edited by roadkillbobb; 07-31-2012 at 03:38 PM.
Reply:Looks like the repair might outlast the saw. Good thinking.