Tips on fixing a three point roto-tiller

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Hello all,This is my first posting in this forum.  A poster from a tractor forum sent me here I have a 4-feet wide three point tiller, and the housing of the gears on the side of the tiller just cracked. See pics below:I have some experience welding mild steel (stick, oxy-acetylene), but I have never welded cast iron (I am pretty sure the housing is made of cast iron.  How can I confirm by the way?).  I read this thread http://weldingweb.com/vbb/showthread.php...ight=cast+iron with excellent tips to weld cast iron but I was wondering if you could give me some additional ideas on how to repair this. A poster from the tractor forum suggested I take the crack to a welding shop, and then on top I should add a gusset with plug welds, which sounds like a great idea to me.  Any other suggestions/tips I might follow?  By the way, I have a Lincoln AC/DC welder with max output of 225 amps (AC), and a torch setup.Thanks in advance for your help!G
Reply:If you grind on it with an abrasive wheel and it has very minimal sparks then its cast, regular still will shoot alot of sparks. That is what I have heard and I have done it on parts I know are cast and they dont spark near as much. I welded some cast on a tractor with a MIG I just preheated it, welded it, then let it cool slowly and wrapped it up in a leather rag. It isnt a very critical piece and hasnt broke yetHTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:get that label interpreted, might be factory knew it was gonna crack and attached instructions for the repair lol
Reply:Hello Gerifalte, I think you're right, looks like cast iron from here, probably a low grade too. I probably wouldn't consider anything but a heavy "V" and  braze repair on the housing.If there are precision bearing or gear centers inside, the crack should be closed up to original before brazing. How about another picture, with the cover or flange removed?As for reinforcement; If you know why it cracked, and how thick it is,  that  would have a bearing on type of reinforcement. Plug welds in low grade cast, probably aren't the answer. I worked with Master Brazeman, who would put exploded gearboxes back together from pieces. He had some interesting stories of massive locomotive castings he had repaired. He was very secretive, and would hardly ever let anyone watch or help; but I did my due spy work!Good LuckLast edited by denrep; 04-07-2008 at 07:21 AM.
Reply:It is Cast iron, as I have worked on three of those in the past.  Usually that crack results from the tiller blades hitting a rock or stump.  I have attempted to weld the first one I repaired without much luck.  Brazing seems to be the best solution in my opinion.  You need to open it u, and make sure your chain and sprockets inside are in good shape as well as your bearings.  if you haven't worked on much cast iron I would probably take it down and have a welding shop repair it for you.  It should not cost much for that repair in my opinion.  As far as reinforcement I personally am not a fan of adding to cast iron.  In my experience you cause more problems with the added heat from welding or brazing, and create more "problem areas"  Good luck.  ~JacksonI'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Thanks for all your useful replies!From your responses it seems to me there are too many secrets to this cast iron deal to just take this task on my own, so I will take it to a shop for a repair. We use this implement quite often, so I want to make sure it is fixed properly. Jackson, this tiller doesn't use a chain, just gears.  If I recall correctly from the last time I opened it, there are three gears, so the crack is roughly at the height of the gear connecting to a shaft that comes from the gearbox.  I will inspect those parts to ensure they are working properly. I sure hope I don't have any broken gears!Denrep, sorry for my ignorance but what is a "bearing on type of reinforcement"?  I am interested on any ways to beef up this part, so a picture, link, etc would be highly appreciated I will post more pictures later this week when I get a chance to take it apart and take it to a welding shop.Thank you all for your kind advice!G
Reply:I totally agree with with Hammack. If you don' have some experience with cast iron take it to some who does. It is worth the cost. Although I've repaired a lot of cast iron I hate to work on the stuff. Just did it to keep the customer.
Reply:Thanks Oldtimer.  I will indeed take it to a pro.  Don't want the piece to crack again on me!F
Reply:Originally Posted by gerifalteDenrep, ...what is "bearing on type of reinforcement"?  I am interested on any ways to beef up this part, so a picture, link, etc would be highly appreciated
Reply:Thanks again for your sound advice Denrep; just so you know my ignorance, I thought bolts would be as strong as a threaded stud.  I will post pictures once this piece is fixed.  Thanks againG
Reply:Originally Posted by gerifalte...I thought bolts would be as strong as a threaded stud....
Reply:Originally Posted by denrepOf course it isn't that the stud itself is stronger than a bolt, the strength is in the way a stud fits a casting.With an exact fitting stud, you're loading the casting through nearly 100% of the threads, down to the bottom of the threaded hole, rather than possibly just near the top of the hole. The filled threads also add compression strength to the casting in that area. The shoulder will be right at the parting line, and the (less than ideal) partial threads in cast iron, will not be turned while loaded.We're waiting for the pictures!
Reply:Originally Posted by TEKAfter further review.........I'm wondering if that bolt didnt have something to do with it cracking. And welding it up near a threaded hole is gonna be a trick.....
Reply:Hey, I'm not sure where your at, but if welding doesn't work hell send me the case and I'll make you one out of steel. China has about run my small machine shop in the ground so I'll do it for you just to be doing something!Chuck H.,,,, [email protected]
Reply:Originally Posted by sc6chuck9Hey, I'm not sure where your at, but if welding doesn't work hell send me the case and I'll make you one out of steel. China has about run my small machine shop in the ground so I'll do it for you just to be doing something!Chuck H.,,,, [email protected]
Reply:Hello all,So today I finally had some time to take the tiller apart.  Here is a picture of the gear system with the cover removed.  This piece seems to be intact and I couldn't see any uneven wear on the gears, so that's good news The following 2 pics show how the crack goes from side to side, and you can also see a piece of cast iron that came apart from one of the threads (piece in the bottom of the first pic).  That is evidently the point where the crack started!  There is also another thread pretty messed upThis one shows the piece after removing a protective plate and gaskets.There was some water mixed with the oil   . I am guessing this was caused by the crackI was quoted $150 for the replacement part, and a local welder wants $75-$100 to fix it, so I figure I will give it a shot ands try to fix it myself, and if I make a mess I will just buy the replacement part.  I will be a good learning experience either way The hardest part will be to make sure the weld in the inner circumference that connects to the main shaft is flush, so the parts will align well.  To be continued....
Reply:After cleaning the piece with a spray-on engine cleaner, I used a 4-1/2 grinder and a small air die grinder to make a bevel on the crackI didn't grind the crack in the inside wall (the dark area in the pic above), as that section wasn't very thick (plus, it is really hard to work in that tight space!) so I hope I got enough penetration from the outside weld. We heated the piece until it was very hot, and used 1/8" 7018 rods on 90amp DC-.  It took two passes to get a thick weld on the outside crack.  Since two threads were very messed up, we decided to plug them completely to then re-tap them.   BTWm we had to cover the gears with a piece of thin so they wouldn't get splattered (I didn't take pics of that)...Last edited by gerifalte; 04-21-2008 at 01:46 AM.
Reply:I again used the grinder to make all the inside welds flush with the rest of the walls, because that's where the gaskets fit and I don't want to have leaks. The 4-1/2 grinder fit just about perfectly in the hole, making my work way easier than using the die grinder The grinder did an amazing job!  This picture shows the places where the threads used to be.  I ended up no burying the piece after we were done, as I was a bit worried about cleaning the sand off the gears.  Instead, I closed all the windows and doors in the shop and put the piece next to a propane heater so it would cool down slowly.  I don't know if this was the ideal setting but oh well, I would rather do that than cleaning the sand off those gears! I pinned all the welds as kindly advised by several posters.  I still need to make the new threads and grind down the thick weld in the inside wall so it doesn't rub with the gears. After that, I will put it together and test it on the field!More to come...Last edited by gerifalte; 04-21-2008 at 01:47 AM.
Reply:Time will tell. Anything extra you feel like adding would mean a lot.Rather than drill and tap at the repaired crack, I would probably redrill the flange, and add two new bolts, one on each side of the repair. Thanks for the pictures.
Reply:No to shabby. Remember that you will still have to clean the inside well before reassembly to remove all the grindings that I can see in the picts on the  gear. My guess is that you will temporarily reassemble it to mark the centers of holes you to drill. Then dissassemble to drill and retap. It won't take much to have that hole not line up.
Reply:Originally Posted by denrep Rather than drill and tap at the repaired crack, I would probably redrill the flange, and add two new bolts, one on each side of the repair.
Reply:Originally Posted by DSWNo to shabby. Remember that you will still have to clean the inside well before reassembly to remove all the grindings that I can see in the picts on the  gear. My guess is that you will temporarily reassemble it to mark the centers of holes you to drill. Then dissassemble to drill and retap. It won't take much to have that hole not line up.
Reply:gerifalte,I though about this a little more today. The casting is definitely weaker now, reinforcement would be worthwhile.Try to at least replace the tin cover with a heavy plate, that would add a lot of strength. Again, instead of bolts, use high quality precision fit studs; like those sold by your local Caterpillar dealer.Silicone will seal any petty leaks.Good Luck
Reply:Originally Posted by denrepgerifalte,I though about this a little more today. The casting is definitely weaker now, reinforcement would be worthwhile.Try to at least replace the tin cover with a heavy plate, that would add a lot of strength. Again, instead of bolts, use high quality precision fit studs; like those sold by your local Caterpillar dealer.Silicone will seal any petty leaks.Good Luck
Reply:Hello again,Just a follow-up on my original posting:  Last weekend I finished this project.  Sorry, but I didn't take pics this time as I was too excited trying to get this done!As suggested by Denrep I drilled new holes rather than working on the original holes (I may post pictures of that later).  I also tried to drill and tap holes where the original holes were to have more grip, by I just couldn't drill through that tough 7018 material, even with a 12-speed heavy duty drill press and titanium nitride drill bits!!! For extra reinforcement I also added a 1/2 inch steel cover plate rather than the original thinner plate.  I had fun welding a little attachment out of a U-bolt to make a good circle cut with my torch! I hope this cover will help keeping the piece strong. Denrep, I could not find the plugs you mention locally so in the meantime I used just good quality bolts.  Can you point me to an online resource where I can buy the plugs?Finally, I am installing a slip clutch in the PTO shaft to reduce the pressure in the piece when I hit rocks with the tiller. I tested the tiller on light soil and is working well.  I don't want to expose it to real work until I get the slip clutch though (later this week according to UPS).Thanks so much for all your help!GLast edited by gerifalte; 04-29-2008 at 03:40 PM.Gerifalte - Nice work, glad to hear you're winning! Good that you went the extra mile and built the thick rear cover. Any extra support, means a lot with an exploded casting.Don't skip the studs, they're important too. As  mentioned before, studs are less prone to loosening, are tight in the casting with 100% thread contact, and provide a shoulder at the parting line.Most heavy truck or equipment dealers should stock them.Fastenal stocks studs, confirm the size.Here's an example: http://www.fastenal.com/web/products...x?sku=11105083Availability: In-Stock Item Package Quantity: 10 (EA)   Fastenal Part No. (Sku): 11105083 Notes: Thread Length A=11/16", Thread Length B=3/4", Round Shank  Manufacturer: DORMAN PRODUCTS  Manufacturer Part No.: 675-031 UNSPSC Code: 30102400 Double End Studs Attachment 19224I know you want to be done with this, but if you could find in your heart to weld just one more little thing: a curved saddle plate, between the front flange and rear cover, at the repair. Good LuckLast edited by denrep; 10-19-2010 at 11:27 PM.
Reply:Originally Posted by denrepGerifalte - Nice work, glad to hear you're winning! Good that you went the extra mile and built the thick rear cover. Any extra support, means a lot with an exploded casting.Don't skip the studs, they're important too. As  mentioned before, studs are less prone to loosening, are tight in the casting with 100% thread contact, and provide a shoulder at the parting line.Most heavy truck or equipment dealers should stock them.Fastenal stocks studs, confirm the size.Here's an example: http://www.fastenal.com/web/products...x?sku=11105083Availability: In-Stock Item Package Quantity: 10 (EA)   Fastenal Part No. (Sku): 11105083 Notes: Thread Length A=11/16", Thread Length B=3/4", Round Shank  Manufacturer: DORMAN PRODUCTS  Manufacturer Part No.: 675-031 UNSPSC Code: 30102400 Double End Studs Attachment 19224I know you want to be done with this, but if you could find in your heart to weld just one more little thing: a curved saddle plate, between the front flange and rear cover, at the repair. Good Luck
Reply:The strap recommendation would be good, better than the small patch I had suggested.I was thinking about a patch something like this:Attachment 19269But... You have to draw the line somewhere, and you've already done a lot. The worst case would be to buy a new casting for $150. With that in mind, I would install the studs with 100% fit in the casting, and call it good.Good LuckLast edited by denrep; 10-19-2010 at 11:27 PM.
Reply:Originally Posted by denrepThe strap recommendation would be good, better than the small patch I had suggested.I was thinking about a patch something like this:Attachment 19269But... You have to draw the line somewhere, and you've already done a lot. The worst case would be to buy a new casting for $150. With that in mind, I would install the studs with 100% fit in the casting, and call it good.Good Luck