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Hi Folks, I've been playing with the idea of welding up a blown spark plug hole in a ford v10 head. I got a scrap head from a yard, and made the spark plug hole so it looks like tha one I'm needing to repair. here's what I got on attempt #1
http://i985.photobucket.com/albums/a...65/head033.jpg
looks awful. any ideas??
3.
Here's pic number 2. Notice that I couldn't get into the hole, all i got was black smoke and a mess!
http://i985.photobucket.com/albums/a...65/head032.jpg
If anyone has ever done this type of welding, please reply. I'm thinking that I'll start a similar thread in the TIG section and try to get a few bites there, too
You will likely need to pre-heat the head in order to get it to weld well since it is a huge heatsink. You will need to clean it very well also as the casting is likely pretty dirty. Welding inside a hole or in a corner is difficult in itself since the arc will want to wander around adn "jump out of the hole". This is due to the magnetic flux that develops from teh electricity traveling through the base material.
Looks like you are just blobbing filler onto cold metal. th ebase needs to be hotter in order to actually make a weld.
What filler are you using?
Can you use a "Timesert" insert on the plug threads? The timeserts basically are a complete solid body thread insert.
It looks like you've got some bad oxidation going on there. If you weld aluminum with too much oxidation, the oxidation "skin" will cover up your molten puddle, making the puddle sluggish and impeding its ability to flow, and your ability to control it.
So - the question is, why is the oxidation occurring?
There could be a multitude of answers. I'm not going to spoon feed you every possible problem and solution it could be, because there is plenty of info available if you do a little searching. I will by throwing you a few questions which should give you a few things to think about, maybe research some more about and try out on your own:
1. Are you preparing your metals properly for TIG welding, by removing the existing surface oxides before welding them? The TIG arc even in a "max cleaning" (high EP balance %) mode, has only a limited ability to remove aluminum oxides that are very thick. So you would be advised to physically remove all surface oxides and start welding "fresh aluminum" before you start your TIG arc.
2. Do you have appropriate inert gas flow rate settings for your gas cup size?
3. Are you running an appropriate amount of "tungsten stickout" and arc length? (for best gas shielding, the less you need, the better.)
4. Are you exceeding the power and duty cycle capacity of your TIG torch & cable? What is the type of TIG torch you are using? It is possible you could be overheating a one-piece aircooled Torch's power cable, where the conductor inside the cable gets hot enough to melt the pvc jacket that surrounds it. The vaporized PVC contaminates the argon gas flowing inside the pvc jacket and this contaminated argon can cause contamination (and oxidation) of both your tungsten electrode and of your work when it happens. If you are using a watercooled torch, do you have the coolant hooked up and circulating through the torch?
PS - when welding aluminum is working properly, without excessive oxidation build up on the surface, your molten aluminum puddle will have a shiney, mirror-like appearance.
OK I got some interest, so here's more details. Here's the gas that I paid DEARLY to rent a tank of.
http://i985.photobucket.com/albums/a...65/head051.jpg
My LWS hit me $75.00 for this little bugger :mad:plus opened up a whole can of worms regarding demurrage (rent) on my dad's 40 plus year old account. This led to me opening up my own account. But I digress. I plan on eventually going to a separate helium tank with a y-valve to custom mix in the near future.
Here's a picture of the cross section of the hole I'm trying to fill in. This is a screen shot of a good head that's been cut away to show the problem area.
http://i985.photobucket.com/albums/a...65/head057.jpg
On my bad head, the previous owner tried to use a lawnmower repair kit to fix the stripped heads. When I got the head out, there was a stubby helicoil style tap taped to a socket stuck in the hole. I own the $450.00 Timesert kit, as I install these on any triton head that I work on by default, but this head was too far gone, welding is the only option. Here's the prepped head
http://i985.photobucket.com/albums/a...65/head035.jpg
I figured that with what I'm doing that a backer was in order so I took a copper pipe cap and sized it in a lathe to slip in from the top of the head.
http://i985.photobucket.com/albums/a...65/head025.jpg
so for prep, I used a 1/4 carbide bur, followed by NEW stainless brushes and multiple washes and rinses with acetone and denatured alcohol. The pics may not show it, but that metal was CLEAN!!!:D
Here's more detail on the setup. I currently have a WP20 water-cooled torch, I used a gas lens with a #7 cup and 3/32 thoriated tungsten. I tried to stick the tungsten waay out there to reach all the way to the bottom of the hole.
http://i985.photobucket.com/albums/a.../head044-1.jpg
Next I used my cherry picker to suspend the head over my turkey fryer burner for preheat. If you've ever used a turkey fryer, you know that the 6" diameter burner is capable of throwing some serious heat:D I kept the head about 20" above the head for even heating. I used a IR thermometer and pointed a laser at the work area, and slowly brought the head up to about 220F. The comment about a piece of aluminum this big being a heat sink was spot on, I found that if I got just the area of concern up to temp and removed it from the heat, by the time I moved, the heat had dissipated throughout the rest of the head:mad: it took about 30 minutes to get the WHOLE head up to 200F.
So, until my situation changes for the better, and I actually get my EVERLAST welder(s), here's the machine I'm using to learn TIG
http://i985.photobucket.com/albums/a...65/head046.jpg
Big, old, heavy sine-wave, transformer machine. Just checked out as good for 380 amps on a load bank, but I'm limited to about 220, due to having only 50 amps available in my shop. There's no AC balance or freq control, but it has these 2 controls.
http://i985.photobucket.com/albums/a...65/head047.jpg
They do focus the arc somewhat, but not like a modern square wave machine does.
So Here's the rundown in a nutshell.
-Fully cleaned down to shiny aluminum using dedicated aluminum cleaning tools
-Rinsed and degreased with Acetone and Denatured Alcohol
-Copper backing plug cleaned and fit to the hole
-Preheat the head to 200F
-75% Helium/25% Argon mix -expensive
-WP20 water-cooled torch
-3/32 thoriated tungsten, gas lens with #7 cup
-Big Ethyl, my monster TIG power source
Really looking for suggestions, and more importantly, WHICH Everlast Tig machine will be most suited to this type of work? Thanks in advance.
Good info. I'm leaning towards your shielding gas not getting to the hot metal. That looks like about 1.25x - 1.5x cup diameter stickout from the pic. That's an awful lot, but I understand you are trying to weld down into a hole and need to get the heat down there somehow. On a flat surface I wouldn't think it would work but maybe down in the hole it will. You might consider getting an extended length cup to let it reach down into the hole a bit. Another idea is to use your carbide burr to heavily chamfer the top edges of the hole to give you better access to the bottom of the hole. I usually chamfer my aluminum 45 degrees or so although you probably don't want to remove that much "meat". (Then you weld from the bottom up and eventually redeposit the removed material towards the end of the weld process.) If you are going to keep your cup on top of the hole and stick your tungsten way down there like you are doing, you may need to invest in a bigger size gas lens cup than your #7 to be able to stick your tungsten out that far. Such as a gas lens/cup setup designed for welding Titanium. That would allow you to stickout your tungsten much further than the #7. I would generally try to not stick the tungsten out to more than 1x your cup inside diameter, if you've got a gas lens. (Or 1/2 the cup diameter, if you've got a standard collet body.)
75% Helium is also a pretty good hit of the stuff, which is lighter than air and generally in high concentrations, tends to lift away from your workpiece as you are welding, without extra gas flow to keep the gas down on your weld joint. (From what I have read at least; I have not actually welded with the stuff before.) Now some experimentation on gas flow rate should be in order, but consulting the CK worldwide gas flow selection chart, I'm going to take a stab that you might be needing to use ~30 cfh or so for your 75% He mix with the #7 gas lens cup. Note the text about Helium at the bottom of the CK worldwide gas flow selection chart:
http://www.ckworldwide.com/tech-3.pdf
"For pure helium gas, double figures shown. For Argon-Helium mixes with below 30% Helium content, use figures shown. Always adjust gas flows to accomodate best shielding results." I think your 75% He mix puts you into the "double figures shown" category. And they are showing you should be using 10-20cfh Argon. So I would guess you should try 30cfh (middle of 20-40cfh range) of your Helium mix.
If your molten aluminum puddle gets a dark skin on it while welding, that's a sign you have bad gas shielding. You are looking for the bright shiney puddle, when the shielding is right.
I had a project this reminds me of where I had to reach into a hole and weld deep on the side of it, that I ground the edge of one side of a cup off to allow the cup to come closer to the molten puddle. Even without a gas lens, and even though I couldn't even see the puddle as I was welding, it let me get the job done and I've even held onto it and used it a few times since.
By the way, if you are welding with that much stickout, (especially in a confined spot like down into a deep blind hole,) be sure to allow enough pre-flow time before starting the arc to allow the air/oxygen to purge out of the hole.
Also, once you get that thick oxide skin from welding aluminum with inadequate shielding, there is little use trying to "save" it with the TIG torch alone. Its time to stop and manually/physically grind it away before you should try welding on it again.
Have you welded on any easier aluminum pieces to get your basic skills down before trying to tackle this cylinder head repair? If not, it would be adviseable. Start with a flat piece like a simple butt joint, that doesn't require you to stick your tungsten out so far, (and maybe also doesn't require a tedious pre-heating process) and just get a hang of what the shiney aluminum puddle looks like and how to properly dab filler into it. Then once you establish a sucessfull baseline, you can do some tests, for example progressively extending your tungsten out a little bit more at a time, (or/or make some adjustments to your gas flowrate) and see how it works. See how far you can manage extending your tungsten before you get "the crud" appearing on your puddle's surface.
Thanks for the response, I had a few questions. First, the reason I couldn't chamfer the hole is because of the fear of breaking into the water jackets, as this is why i've been led to believe that most head shops will not weld this particular injury. I wanted to ask if you've ever tried a "champagne cup" type of cup and if maybe this might work better? Are those cups available in pyrex so maybe a guy could see what he's doing? You were spot on that I'm a total noob so I really didn't know what to expect, but the black crust was pervasive, and elevated to the level of soot when i tried to break through the hole. interestingly, before i made a mess, i could get the tungsten all the way to the bottom of the hole and make the arc go and stay where i wanted it to, it just wouldn't break through and allow a puddle to form. thanks again!
There are probably more than one ways you can get this to work. Your current setup might work with a gas flow adjustment. What gas flow rate did you use, and how did you determine that number to be appropriate? (IE: did do any testing?)
If you can't make the current cup you have work by gas flow adjustments, even a modest increase in cup diameter could make a world of difference in improving gas coverage at high tungsten stick-out. Like stepping from you #7 up to a #8. (which are available for your collet body by the way, I've got one, I think its made by CK.) Or up to a #10. The smaller pyrex glass cup is "supposedly" a #8 size, but when I tested one out I compared it to a #8 alumina cup I have, and found the pyrex was bigger. I don't think the huge champagne nozzle (1"+ cup diameter style) would be the right tool for this job, because it might get in the way of your vision and filler rod access into the hole. It will also need a huge step up in gas flow. But then again if you set it up with the proper gas flow it could probably be made to work. You can also put a bend in your filler rod to reach around an obstruction.
Yet another idea is if you had a dual flowmeter (or extra gas bottle and extra single flowmeter), you could get another argon hose to administer a second "purge" flow of inert gas at the bottom of the hole. That would definitely help a huge amount for keeping hot meta down there happy while welding. You could set it up by drilling a hole in the backing plug you made, and then threading, pressing, or welding a small pipe nipple onto it, and installing the secondary "purge" gas hose onto the nipple. And letting the purge gas flow a little bit before and during welding.
I would probably just start by testing adjustments to my shielding gas flow however, it if were me and I hadn't done it already. Hold a real tight arc when welding on this thick stuff to concentrate the heat near the tungsten and to make a puddle.
You can always grind away the oxide layer, and excess weld deposit, and try welding again on your scrap head.
Skimming real quick...Too much helium in the mix. You need a lot less and things will be better. Think about it: Helium is lighter than air, and it won't stay in place long, especially on those heavy, hot welds.
Argon sinks.
WAAAY too much stick out for that size cup.
Thanks for the info guys, good thing I have a practice head to get this stuff nailed down with. BTW, I ended up buying a good head to get my truck on the road, so the one with the bad hole, and the practice head are still up for grabs, experimentwise. I played with flow at 15-20 cfh, didn't make any difference. With stickout, that's the absolute minimum i could get to reach the bottom of the hole and still see any of what I am trying to reach. I think whai I will try next is to put the helium mix as a purge from the bottom of the hole, straight argon from the torch, and modify a cup the way jakeru showed. This is one of those situations where I think the 250EX would be ideal, as with my old transformer machine, I only have about 200 amps available before circuit breakers start to pop. With the 250EX being an inverter, I will be able to max it out, crank the frequency up, and tweak the balange to get it to do what I want, assuming all other issues are worked out.
It seems like you aren't using anywhere near the amount of gas flow that you need:Quote:
Originally Posted by hooda
Quote:
Originally Posted by jakeru
I think you may be better suited to practice on some clean flat stock or plate, something in the 3/16 thick range. Then, move up to a heavier piece (still a piece of plate), then even heavier, with preheat. After you figure out how to weld the thick stuff, drill some holes in it and figure out how to weld it. After all of that, then move over the the dirty cast head and try it.
Welding that hole in the head is probably one of the more difficult welding applications you ill ever come across (at least it is not overhead). Starting out on something like that will likely leave you with a big puddle of aluminum scrap.