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Thread: Building up material on SG Cast Iron

  1. #26
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by Welder Dave View Post
    I think this is another case where somebody made a mistake and wants to wave wand over it and it's magically repaired. Someone with experience may be able to restore it but that person likely wouldn't have made the mistake of grinding too much material off. This seems like a thread that could go on indefinitely until the OP gets the answer he's looking for to try and repair his mistake. If it's not broke don't fix it. Trying to fix it might make it worse. Don't know what else can said.

    FFS even the best make mistakes mate. Why would I be asking for good info on the correct procedures if I wanted to wave a magic wand. As for not getting the answer I want, how about you’re not getting the agreement you want.

    Regardless of whether or not I go ahead with it ( still undecided) there has been a good base start of proceedure, but no discussion of temps , amps. Some discussion on rod but no tech behind that. ( just preference)

    If TIG is going to put less heat in , I’m happy to do that.

    So worst case, it seems the best technique will be TIG braze. Ok, what are the choices of filler rod, Nickle Bronze, Silicone Bronze or other...

    Pre heat temp? It’s about 1/4” thick

    I was thinking I could possibly turn up a plate that bolts where the spindle does to help keep distortion down.

  2. #27
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by scsmith42 View Post
    I think that TheGary has done a good job above of recommending how to proceed.
    Yes, and your input was good too, appreciated mate.

    I’m still keen on some base numbers of pre heat and amps. The main body of the casting is 1/4” thick with those two thick areas being 3/8-12” and the machined face (where spindle is mounted) , top and bottom mounting points and rear face are all 3/8-1/2 thick

    I’m hearing Nickle Bronze is a harder material in its finish form than Silicon Bronze , what are your thoughts on the two (or others) , not just finished but “bonding” to the cast etc

    Cheers

  3. #28
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by thegary View Post
    I personally would not be concerned with the tapered hole. Just use common sense when installing the plug and only tighten enough to seal it with a little pipe sealant on it. If it makes you sleep better at night then I would say go ahead and braze it. The braze will definatly increase the strength of the part near the tapered hole. To O/A braze it you will need to put a lot of heat into the part . I would probably tig braze it if it were mine but if you have not tig brazed I would practice on some other parts first. When tig brazing it is quite easy to melt the base metal . If you do then you will have a heat effected zone like you would if welding cast iron. If you do braze it do use a carbide burr to remove the carbon smeared layer from the area to be brazed. If you hand filed the area after grinding then the carbon smeared layer has already been removed. If tig brazing it you need to choose what filler to use for the brazing. I would probably just use silicon bronze for this particular repair but there are other alloys that can be used .
    I had read this from you also, and just re read it again

    ď I hate to get into a thread late but in this case I feel I must. If you are going to melt the base metal of the cast iron preheat and post heat are needed. If you are going to braze it ( heat but not melt the base metal) heating is only needed until the brass flows aided by the flux if using O/A. Post heating is not needed, just cover the part and let it lay in an area where there is no air movement . The biggest mistake made when brazing is in the prep. If you grind the area to prep it you smear the carbon around and it makes the brass not want to flow into the casting. If you need to grind it out that is fine but the very last thing you need to do is take a carbide burr to the area to take off the carbon smeared layer of metal. This is true if O/A brazing or tig brazing.Ē

    Iím a little confused as you say in your reply to me if I O/A braze it I will need to put a lot of heat into the part, yet you say for the pinion gear , again for O\A braze, heating is only needed until the brass flows aided by the flux...

    Maybe Iím missing something , is it the shape and mass difference that will mean my part will need more or lots of heat?

    Again, what is the pre heat figure for TIG Braze.?

    To everyone reading and or who had commented in this thread, I understand the opinions of most has been not to do it, but at the end of the day, that is up to me. I came here because this is welding forum. I took on board more than once that it may be better to not do anything and have stated I still might not. But why the ****s when Iím asking exactly what this forum is for.

  4. #29
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by husq2100 View Post
    To everyone reading and or who had commented in this thread, I understand the opinions of most has been not to do it, but at the end of the day, that is up to me. I came here because this is welding forum. I took on board more than once that it may be better to not do anything and have stated I still might not. But why the ****s when I’m asking exactly what this forum is for.
    One of the reasons I would leave it alone is because I'm assuming you don't really know what grade of Nodular iron it is. Some grades and chemistries would require post weld heat treatment. The nodular structure of the graphite is achieved by treatment of the molten metal when the casting was poured and may have been refined by post casting heat treatment. You will not be able to replicate those situations in a weld and the welding process can result in structure changes within the casting, particularly right under the weld. It may or may not make the casting weaker and more brittle. Read and understand the pdf I linked to and maybe find the references listed at the bottom of the article and read them. If it was gray iron it wouldn't bother me in the least to braze it but nodular irons are a different article. You may need to clean the thread in the fill hole if you weld it as well. As you said it is up to you I'm just giving you my opinion. Have fun.
    ---Meltedmetal

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  6. #30
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by Meltedmetal View Post
    One of the reasons I would leave it alone is because I'm assuming you don't really know what grade of Nodular iron it is. Some grades and chemistries would require post weld heat treatment. The nodular structure of the graphite is achieved by treatment of the molten metal when the casting was poured and may have been refined by post casting heat treatment. You will not be able to replicate those situations in a weld and the welding process can result in structure changes within the casting, particularly right under the weld. It may or may not make the casting weaker and more brittle. Read and understand the pdf I linked to and maybe find the references listed at the bottom of the article and read them. If it was gray iron it wouldn't bother me in the least to braze it but nodular irons are a different article. You may need to clean the thread in the fill hole if you weld it as well. As you said it is up to you I'm just giving you my opinion. Have fun.

    I did read it when you linked it, as im new to the "cast" world, I was getting thrown off by the fact that Ductile, is Nodular is SG....You are correct, I doubt anyone but the manufacture knows exactly what grade it is.

    I was also not quite sure of the info in that link as I had originally asked about brazing, and brazing was recommended by others in this thread. But some good info just now, thanks mate.

    I would buy another one if I could, but they are hard to come by (short production run of a few years) and Id have to figure out all the custom machining as well. I dont want to touch it if I dont have to, but would like to have some insight if I do ( or even get a specialist to do it)

  7. #31
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by husq2100 View Post
    I had read this from you also, and just re read it again

    “ I hate to get into a thread late but in this case I feel I must. If you are going to melt the base metal of the cast iron preheat and post heat are needed. If you are going to braze it ( heat but not melt the base metal) heating is only needed until the brass flows aided by the flux if using O/A. Post heating is not needed, just cover the part and let it lay in an area where there is no air movement . The biggest mistake made when brazing is in the prep. If you grind the area to prep it you smear the carbon around and it makes the brass not want to flow into the casting. If you need to grind it out that is fine but the very last thing you need to do is take a carbide burr to the area to take off the carbon smeared layer of metal. This is true if O/A brazing or tig brazing.”

    I’m a little confused as you say in your reply to me if I O/A braze it I will need to put a lot of heat into the part, yet you say for the pinion gear , again for O\A braze, heating is only needed until the brass flows aided by the flux...

    Maybe I’m missing something , is it the shape and mass difference that will mean my part will need more or lots of heat?

    Again, what is the pre heat figure for TIG Braze.?

    To everyone reading and or who had commented in this thread, I understand the opinions of most has been not to do it, but at the end of the day, that is up to me. I came here because this is welding forum. I took on board more than once that it may be better to not do anything and have stated I still might not. But why the ****s when I’m asking exactly what this forum is for.
    Ok I am going to answer this as basic as I can. First I want to say that anyone who has any O/A or tig experience could accomplish this job with the info I have given all ready . You own the equipment I assumed you had a basic understanding of the processes . When O/A brazing the part has to be hot like dull red for the flux and brass to flow into the pores of the metal. ( mechanical bond ) on a part with a lot of mass and trying to do an inside corner that equates to much if not all the part to be close to a dull red ( 1200 degrees ) .

    Now if doing an outside corner it is possible to make that corner dull red without the whole part getting much more than a few hundred degrees. The flame of an O/A torch does not concentrate heat like an electric arc can. The O/A flame heats a larger area and thus must put more total heat into the part to get the area you want to braze hot enough to have the brass flow.

    With a tig electric arc the heat is concentrated at the very tip of the tungsten , basically a pin point. It is capable of heating a very small spot to high heat rather fast. In the case of this part I would do the inside corner of the ground down area first with a tig machine with a foot pedal . I would set the amps at around 150 -200 at the machine and use the foot pedal to sneak up the heat while keeping the silicon bronze rod in or near the arc testing to see if the rod will flow out onto the casting . All the time making sure not to have the arc hot enough to melt the casting where the arc is concentrated.

    It should only take 30 seconds to a minute and a half to get the area up to temp for the rod to flow if you have the amps high enough . Run the bead along the whole inside corner then use the rod and arc to pad bronze onto the ground down flat all the way out to the outside corner. All this time you will constantly be using the foot pedal to lesson the amps because the parts has been heating from previous passes. When you get to the thin area by the taped hole you will need to back way down on the amps with the foot pedal or you will melt the thin area and blow a hole right into the side of the hole. This is why I said you need to practice. I nor anyone else can give you a specific amperage to set your machine at because no one will know, there are too many variables for a specific answer. Thus the need for the foot pedal and sneaking up on the amps.

    The reason I said I would use silicon bronze instead of some other alloy is that you are not looking for top strength and the tinsel strength of the bronze is on par with the casting ( no need for more ). It is build up not connection. If you melt the casting you will get a heat effected zone that will effect the metal around the hole and make it brittle . the end result will be worse than if you had left it alone. Thus the reason I would not recommend a weld for this repair. And also the reason why I personally do not see the drastic need for the repair at all . Like I said if it makes you sleep better then go for it.

    If you need this explained in more detail I recommend you take it to someone who can do it or leave it alone.

    FYI; the setup of the tig would be the same as welding mild steel. In this case 3/32 tungsten , 3/8 -1/2" cup , argon gas. There is alway more than one way to skin a cat and we all have our own prefrences on specific setup .
    Last edited by thegary; 4 Weeks Ago at 01:15 PM.

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  9. #32
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by thegary View Post
    Ok I am going to answer this as basic as I can. First I want to say that anyone who has any O/A or tig experience could accomplish this job with the info I have given all ready . You own the equipment I assumed you had a basic understanding of the processes . When O/A brazing the part has to be hot like dull red for the flux and brass to flow into the pores of the metal. ( mechanical bond ) on a part with a lot of mass and trying to do an inside corner that equates to much if not all the part to be close to a dull red ( 1200 degrees ) .

    Now if doing an outside corner it is possible to make that corner dull red without the whole part getting much more than a few hundred degrees. The flame of an O/A torch does not concentrate heat like an electric arc can. The O/A flame heats a larger area and thus must put more total heat into the part to get the area you want to braze hot enough to have the brass flow.

    With a tig electric arc the heat is concentrated at the very tip of the tungsten , basically a pin point. It is capable of heating a very small spot to high heat rather fast. In the case of this part I would do the inside corner of the ground down area first with a tig machine with a foot pedal . I would set the amps at around 150 -200 at the machine and use the foot pedal to sneak up the heat while keeping the silicon bronze rod in or near the arc testing to see if the rod will flow out onto the casting . All the time making sure not to have the arc hot enough to melt the casting where the arc is concentrated.

    It should only take 30 seconds to a minute and a half to get the area up to temp for the rod to flow if you have the amps high enough . Run the bead along the whole inside corner then use the rod and arc to pad bronze onto the ground down flat all the way out to the outside corner. All this time you will constantly be using the foot pedal to lesson the amps because the parts has been heating from previous passes. When you get to the thin area by the taped hole you will need to back way down on the amps with the foot pedal or you will melt the thin area and blow a hole right into the side of the hole. This is why I said you need to practice. I nor anyone else can give you a specific amperage to set your machine at because no one will know, there are too many variables for a specific answer. Thus the need for the foot pedal and sneaking up on the amps.

    The reason I said I would use silicon bronze instead of some other alloy is that you are not looking for top strength and the tinsel strength of the bronze is on par with the casting ( no need for more ). It is build up not connection. If you melt the casting you will get a heat effected zone that will effect the metal around the hole and make it brittle . the end result will be worse than if you had left it alone. Thus the reason I would not recommend a weld for this repair. And also the reason why I personally do not see the drastic need for the repair at all . Like I said if it makes you sleep better then go for it.

    If you need this explained in more detail I recommend you take it to someone who can do it or leave it alone.

    FYI; the setup of the tig would be the same as welding mild steel. In this case 3/32 tungsten , 3/8 -1/2" cup , argon gas. There is alway more than one way to skin a cat and we all have our own prefrences on specific setup .
    Excellent info Gary.

    Thats what I was looking for. Now there are many things that seem just as intutative to you as breathing, but for others they arnt, im sure in my world there are things that I wouldnt need to think about that might not be so straight forward to you. Thats not a hard concept.

    Im not a welder by trade, or a fabricator. I have only been getting into TIG the last 6-8 months, though have been a member here longer than that. While foot pedals seem common as muck in the US, I havent met anyone or seen anyone with one here. IM sure there are plenty but Im not in the field. I do have a 200amp Kemppi. If im coming off as a prick, Im dont mean too, but reading threads over the years, it seems info on material type and thickness is asked and a mutiltude of settings for the process are usually given.

    My O/A experience is limited to cutting, and heating, again self taught from books and the odd youtube.

    Other than the jigs I posted up in my Acetylene VS LPG thread, here my the latest welding on my build. Its a far way from brazing on cast, but again we all have to start somewhere.
    Attached Images Attached Images   

  10. #33
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    Re: Building up material on SG Cast Iron

    TheGary really hit it out of the park with his response.

    Usually my TIG is set to somewhere between 150 - 200A and I feather the pedal as necessary based upon how the metal is responding.

    One risk that you run is distorting the side of the oil filler hole. When you heat it to add metal, as it cools the hole may distort or crack. Then you will need to re-tap it in order to get the threads round again, but retapping a distorted hole does not always make it concentric.

    Hence the advice to not do anything is very valid. It's one of those things that even a skilled technician can mess up because there is no way to keep the distortion from occurring.

    If I was to pre-heat with a torch, I would probably shoot for around 500 degrees. The problem with this though is that you'll be heating up a large area, which is not always good with cast (unless you can pre-heat the entire part in an oven to a much higher temp, weld, and then put back in the oven for a 24 hour slow cool).

    In all liklihood, you are better off not to do anything and just be careful not to tighten up the drain plug too much.
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  11. #34
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by scsmith42 View Post
    TheGary really hit it out of the park with his response.

    Usually my TIG is set to somewhere between 150 - 200A and I feather the pedal as necessary based upon how the metal is responding.

    One risk that you run is distorting the side of the oil filler hole. When you heat it to add metal, as it cools the hole may distort or crack. Then you will need to re-tap it in order to get the threads round again, but retapping a distorted hole does not always make it concentric.

    Hence the advice to not do anything is very valid. It's one of those things that even a skilled technician can mess up because there is no way to keep the distortion from occurring.

    If I was to pre-heat with a torch, I would probably shoot for around 500 degrees. The problem with this though is that you'll be heating up a large area, which is not always good with cast (unless you can pre-heat the entire part in an oven to a much higher temp, weld, and then put back in the oven for a 24 hour slow cool).

    In all liklihood, you are better off not to do anything and just be careful not to tighten up the drain plug too much.
    There is one way to keep the hole from distortion. Insert the plug before welding and remove it after the piece cools. Just do not install it too tight because the hole will probably shrink slightly from the repair.

  12. #35
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    Re: Building up material on SG Cast Iron

    It's not uncommon to have to run a tap through threaded holes after welding/ brazing.

  13. #36
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by thegary View Post
    There is one way to keep the hole from distortion. Insert the plug before welding and remove it after the piece cools. Just do not install it too tight because the hole will probably shrink slightly from the repair.
    This is what I was thinking ��. And getting back to my idea of turning up a blank out of mild steel, to bolt to the machined face where the spindle does to reduce distortion, good idea or does cast and mild steel have different expansion rates ?

  14. #37
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    Re: Building up material on SG Cast Iron

    Quote Originally Posted by scsmith42 View Post
    TheGary really hit it out of the park with his response.

    Usually my TIG is set to somewhere between 150 - 200A and I feather the pedal as necessary based upon how the metal is responding.

    One risk that you run is distorting the side of the oil filler hole. When you heat it to add metal, as it cools the hole may distort or crack. Then you will need to re-tap it in order to get the threads round again, but retapping a distorted hole does not always make it concentric.

    Hence the advice to not do anything is very valid. It's one of those things that even a skilled technician can mess up because there is no way to keep the distortion from occurring.

    If I was to pre-heat with a torch, I would probably shoot for around 500 degrees. The problem with this though is that you'll be heating up a large area, which is not always good with cast (unless you can pre-heat the entire part in an oven to a much higher temp, weld, and then put back in the oven for a 24 hour slow cool).

    In all liklihood, you are better off not to do anything and just be careful not to tighten up the drain plug too much.
    Yep it’s great info, and so has yours been also, thanks SC ��

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