Filling thread hole

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I was doin some work on my atvs cylinder and I need to fill the hole where the thread used to be, kinda new to the welding process and have been told I can fill it in with a mig welder, the hole is about 1/2in in diameter and 1/2 deep, just wondering if its possible to fill it in with a mig and what steps I need to take to make sure the weld holds up strong enough for me to drill it and tap it for new threads/studs.                          Thanks Attached Images
Reply:is a helicoil not an option? you can fill it in but i'll let someone with more aluminum xperience chime inStangnetShop Full Of Stuff. Joey
Reply:I would not try to fill it in with mig. The aluminum will have a lot of pits and holes in it you wont be able to see when done. You will see this when you start drilling and tapping. You need 100% fill so use tig.Yes I can tack it for you.    I know that won't hold but that is what you asked me to do.  Millermatic 350P XR Aluma-Pro push/pullMillermatic 185/spool gunMiller Dialarc 250 HF Water cooledThermal Dynamics Plasma
Reply:would a local machine shop fill it in for me or would I have to find one of my buddies to do it? or could i mig a steel thread insert into the hole?Last edited by QuadWelder; 08-02-2005 at 02:54 PM.
Reply:local machine shop should do it.  Thats where id first go.  CHRIS
Reply:u know a price range to do that sort of thing?
Reply:its gonna be strictly up to the machine shop, and to that extent, often the shop itself wont have a welder onhand, sometimes they do.  Either way they should work with a welder.   This welder would be the one they call on to do the repairs in aluminum cylinder head cracks.  Either way, the shop should be able to tell you what the rate would be, or even give you a rough guess as to how long it will take.  My personal guess would be youre within the minimum time factor.  Though, as I mentioned each shop picks their own rate so its completely dependant.  You may want to shop around, but really given the lil amount of time to do this job, might not even be worth it.  Would be nice though to give it to a machine shop as they may want to take a look at it before releasing to you.  That way if machining is necessary it can be done.  I dont have much experience with this besides taking in my own parts.  I am a welder and even I dont do certain work.   This makes things a lot easier.  CHRIS
Reply:would i be able to mig a steel thread insert into the hole? or if i did fill it and it had pits and stuff would they be big pits , i dont need sometyhing perfect or forever just something temporary.
Reply:Well wait, for some reason I was thinking this was alum.  If its cast iron thats gonna be a trick for mig anyway.  and to that extent I would say mig is not the right process for this job.  Stick would do a much better job if its cast, yet tig is ideal.  In either situation a nickle alloy rod is the filler to use on cast iron.  Also with either alum or cast iron a rather substantial preheat would be necessary I would think.  I sure hope your oxyfuel rig is up for the challenge.   As I said before,  Im a pro welder.  Ive got my own rig and all.  Yet quite frankly with all there is to go wrong I personally wouldnt handle this job merely because even if you go into it for a patch, and a very mediocre patch at best, you could actually do more harm than good.  I know this prolly just thowed a monkey wrench in your plans.  As far as the pits go, Id say they could be pretty big, or they might be smaller, but more bigger then smaller.  Probably is your filling in a hole on rather thick material and the wire will really reach out a bit before initial contact.   End of your weld might not look too bad, but the underneath, the root as you may will look aweful.  There will be cold lapping, pitting, the good lord only knows really.   Anohter consideration I dint think that a machine shop is good for is they have chemical cleaners that they can really get any and all gunk goop or other contaments outta that threading before it goes for weld.  This also will go a long way to making it right.  When your welding youre doing more than just adding metal.  You are risking changing the metals molecular composition in a way that will be determinetal.  In the end partner, its your cylinder for your atv.  But I think the cost of getting this work done is much less then the cost of a new cylinder.  If you havent already, call around.  You may need to go in and ask the machine shops.  There is a possibility one will come up with a better solution to this repair than welding.  Them machine shops are funny that way.  A lot of these are more patch work but they are upfront in letting you know the pros and cons and the sucess rate and give you the option.  As a welder haveing a good machine shop around isnt really a bad thing.  One I know does it on the side in his garage and its really nice when you get a part that needs welding and machining.  Anyway, call around.  They are like welding shops, very variable in pricing.  Ive never known a shop to not give you atleast an est of what the  job will take.  LOoks like a fairly straight forward repair so there shouldnt be any surprises either.   Good luckCHRIS
Reply:As close as the enlarged hole is to the cylinder hole any welding will  most likely cause it to crack into the cylinder wall.  What I would do if you were to bring it to  my shop would be to tap the hole and install a threaded rod with high temp  lock tite  and pin the threads away from the cylinder to lock the insert  permanatly  machine the top of the insert  and then mark where the original stud  was located and drill and tap for new stud.Good luckJ.W.by the way  How did that hole get so big in the first place  ? ?
Reply:i snapped a bolt inside the old threads and instead of goinng out and getting a screw extractor set I was stupid and just drilled the hell outta the thing and now im in this problem.  So a mig welder and the proper shielding gas wouldnt be very good for the job?
Reply:the bigger problem is after you have this welded it will need to be bored out. more $$$.if it can be when you preheat the casting the cyinder sleeve can move or become loose.any way good luck.scott f
Reply:Well Quad there you have it,  I mentioned a machine shop might have better ideas on how to do this job then welding because of the destructive nature the heat can cause under the wrong circumstances.  Well as luck would have it we get a machinist, or atleast someone with machining knowledge and skills, to come in and tell us how its done right.  J.W. thanks for the input.  I hate sticking my neck out with a comment and then having someone in the machine shop disregard me lol.  Also, regarding the mig,  shielding gas isnt the issue as the filler metal.  You MUST match the filler metal (wire) to the base metal first, then you match the shielding gas to that filler.  Infortunately even at that Mig wont do a good job on a part such as this, even without the problem related to the closeness of the cylinder wall, getting a mig gun in there to make a good solid weld for the bottom part of the weld will be very close to impossible.  If you ask me just forget the mig.  Completely drop the mig idea.  Forget about mig....pretend youve never heard the term mig a day in your life!!!!  on regular welding jobs, mig is great.  But for this, mig sucks to down right dangerous.  Ok  good luck.CHRIS
Reply:Originally Posted by QuadWelderi snapped a bolt inside the old threads and instead of goinng out and getting a screw extractor set I was stupid and just drilled the hell outta the thing and now im in this problem.  So a mig welder and the proper shielding gas wouldnt be very good for the job?
Reply:lmao   I think I hear an AMEN comin for Sandy,  I love that last line...I really LOVE that last line.CHRIS
Reply:lmao I think I hear an AMEN comin for Sandy,
Reply:Amen!!!! Brother...I agree with sandy.  Have you checked the price on this part?  You dont mention what kind of atv it is, but the part might not be as expensive as the job, and in the end you might have a better result.  Just from the looks of the pictures, the cylinder appears to be separate from the head (4-stroke?) and from the bottom end.  I'd check the price of the cylinder, and a new piston and ring kit before sinking money in a job that might or might not fix the problem.Last edited by smithboy; 08-04-2005 at 03:40 PM.Reason: mistakes...and added an amenSmithboy...if it ain't broke, you ain't tryin'.
Reply:yea nvm on welding, just getting a whole new (well used) cylinder off of ebay and having it bored to the piston size i have now, btw just fyi its a 92' Yamaha Blaster 2-stroke, separate from head and bottom end but yea nvm about needin advice on welding it, seems to costly and not even positive if it can be fixed but thnx guysbtw anyone know the temperature at which iron oxide (rust) will turn molten? same with aluminum shavingsLast edited by QuadWelder; 08-04-2005 at 08:56 PM.Reason: added some stuff
Reply:alum melts at around 1200 f If i remember right.  I am not aware of iron oxide  melting.  I guess it could, but I am not quite convinced.  But shavings will melt at the same temp as parent material.  Only wiht a lot less heat.   Heat= time X temperature  hope this helpsCHRIS
Reply:Will this work on your bike?  Looks like it might replace the parts you have damaged, but the cost is a little high.http://cgi.ebay.com/ebaymotors/CYLIN...ayphotohostingSmithboy...if it ain't broke, you ain't tryin'.
Reply:yea it would, i was actually going to get that cuz it dbls my horses but i dont have that much money and so yea, 9im justy bidding on a stock cylinder
Reply:http://www.nwsleeve.com/cycle.htmlHere is a place that will sleeve the cylinder.  If you put a steel sleeve in, you might be able to reuse yours after welding, price is still kinda high, though. Just a thought.  Hope things work out.  I know how bad it stinks to be a do-it-yourselfer with a costly mistake.  That's why I suggested the upgraded cylinder, to make lemonade from the lemons you now have on hand.  You know what they say, when one door closes, another usually opens.Smithboy...if it ain't broke, you ain't tryin'.