Tiller Repair

[chknscratch]

I have a tiller that came with my tractor. I was aware a drive chain was broken on the side, but didn't realize the arm that holds the tension spring and sprocket took a blow and was bent. The arm itself is bent, but more importantly, the sidewall of the tiller is a bit twisted, where the connection bolt was attached.

Should I just beat on this steel, I think it is 10-11 gauge, with a sledge to try and flatten? Would it be appropriate to use a torch on this to heat and then hit it? The bend in the tiller sidewall and the arm is causing the arm to not apply tension to the chain, as well as the bolt connecting the arm to the tiller, will hit the chain when in operation and break the chain again, I am afraid. Attached is a shot from the manual with redlines and some photos.
The gears do line up to keep the chain along the same access, but I am pretty sure the bolt hole needs to be flattened at a minimum.
Thanks for any advice!

Manual:


Slight bend in arm:


Better View:


Tiller sidewall bent at bolt hole:

 

[BravoXray]

I don't think heat will hurt that at all. You might heat it and use an adjustable wrench on the end to straighten it, or a hammer, or both.
Good luck!

Jerry

 

[gpreuss]

Heat won't hurt. I'd also consider a couple of big washers or a reinforcing plate to strengthen the area. What could have bent it in the first place? Seems heavy enough for an idler arm.

 

[Kingcreek]

Heat and beat.
If that doesn't fix it, its an electrical problem!

 

[North Idaho Wolfman]

Just use a hammer and anvil, you keep more strength not heating it.
If you do heat it use some old motor or hydraulic oil to cool it back down.

 

[D2Cat]

As already mentioned, peen it on an anvil or old RR iron. Then reinforce the backside with a piece of iron with a new hole drilled and preferably weld to the buggered piece.

If you have a torch you probably have a welder. Drill the hole the correct size, insert a bolt thru the new piece and the back side of the buggered up hole, tighten the thing in place and weld it there.

 

[cerlawson]

Civil engineer here with some background on steel. Have you ever burned a chunk of wood with nails in it? After you pick those nails up and try to use them you will find they crumple about like spaghetti. Originally they were formed cold and developed a work hardening, as you also find with cold rolled steel. Heating to red hot and then cooling destroys that work hardening, which actually is stronger before yielding. Working steel cold increases the stress where it will yield, that is bend . You can't hurt a thing by pounding the steel back to where it should be and may make the yield point higher.. No need for heat, unless you just are not able to move things. For the typical use on the tiller, it probably makes no difference pounded or heated, but keep in mind what work hardening does. Of course a lot of bending back and forth will overstress to failure by what is called fatigue. Also you do that when you don't have your wire cutters handy out there fixing something with bailing wire and you just bend the wire back and forth until it breaks, an emergency thing I am sure all of us have done a few times. However, even then you may recall after the first bend, when reversing the pressure the wire doesn't want to bend back right there, but bends elsewhere, right? That first bend increased the yield stress.

 

[chknscratch]

Thanks everyone for the replies. The little arm that is bent should flatten out on an anvil, I believe. The picture didn't show it very well, but the sidewall of the tiller is what is bent so oddly and unevenly. To get a good wack on the steel, you really need to remove the top sprocket. I have tried and broken a few teeth off of it. I will try heating the sprocket tomorrow and removing it. Then I will beat on the sidewall to try and flatten out. I don't have any welding equipment, but always like an excuse to acquire a new tool. Now that I have a tractor and some steel attachments, it may be the right time. I will see if I can get the original hole flattened and perhaps drill a new hole if need be.

Thanks again everyone!

 

[cerlawson]

A comment about welders. For that distorted mounting hole, it is possible to add weld material and then drill a straight hole. However, don't use a stick welder. Those welds can contain slag fragments and also seem to be heat treated to make drilling almost impossible. A weld made by a MIG welder contains none of that stuff and can be machined quite nicely I find. I have not tried a welder with flux in the core, but I would think they are as bad as stick welder welds because of that. I have on of those 110 v cheapie flux-core wire feed welders from Harbor Freight, after I gave away my other big welders and so far I find it a poor substitute for a gas type MIG weld. It would not do for what you need there however, due to thickness of steel to work on.

 

[Stubbyie]

Veering slightly off topic here but responding to another poster's observation about welding processes: we get truly good results using a quality name brand 0.030-inch flux core wire AND shielding gas in our Miller MIG machine. The results are better than using either flux core wire or non-flux and shield gas alone.

 

[cerlawson]

Stubbie: That makes sense, since then you have plenty of gas around the weld. With only what comes from the core flux it sure seems like there is a shortage. I also find the cheapie welder has only very rough controls on the feed rate. It works, but with difficulty. I also noted with MIG that if gas feed is missing or in strong wind, the welds sure are bad. I developed a practice of not feeding any wire and running the gas a few seconds to be sure when starting that the gas was at the nozzle.

 

[ShaunRH]

Veering slightly off topic here but responding to another poster's observation about welding processes: we get truly good results using a quality name brand 0.030-inch flux core wire AND shielding gas in our Miller MIG machine. The results are better than using either flux core wire or non-flux and shield gas alone.

Flux core introduces slag, just like a stick, however if done properly in both instances you'll not have inclusion (porosity) problems. You can avoid inclusions by having clean metal and proper welding settings as well as proper technique.

Flux core and gas shield is overkill. Flux core uses the flux to generate the gas shield, and gas shield is just that, the shield against oxygen incursion into the weld. If you like using both, that's fine, it's just an expensive overkill that really doesn't do much for penetration or weld strength. It might help if you're welding very, very, very thin metals as it might allow a welder that can't cool down enough to get just a bit cooler but that's just a theory without having done it myself.

Back to topic...

As for straightening, I've used both heat and cold techniques. If the metal is hardened, avoid heat and use a press or hammer. If it's just mild steel, heat won't hurt it much. I've bent ¾" mild bar stock with heat and welded it onto my ancient iron for additional support, it works great. If you are using heat, don't quench it unless you intend to surface harden it. Water for brittle hard, oil for less brittle - less hard. Very slowly cool it (cover it in sand or a welding blanket) for the least disturbance to the metal structure as it will self stress release this way.

You will always be fighting the war between hard and soft metals. Hard has great durability, resists bending and damage but once over stressed > SNAP! BANG! (Visualize parts breaking and flying around here). Soft metal is flexible, bends and takes those nasty rocks and bumps. Hammer and form back into shape and back to work. However, you're always changing out wear parts, welding some crack you just noticed back together, replacing bolts that didn't take the abuse as well as the steel... etc.

Soft Metal = maintenance work
Hard Metal = cussing and replacement
Combinations thereof = cussing and replacement maintenance work...

 

[chknscratch]

Thanks for the feedback guys. I am actually a civil engineer as well and have been through many materials and lab testing classes. Although I always enjoy reading this kind of stuff to rehash it in my head and read others opinions. Unfortunately, I have been around welding very little and don't know how confident I am to do anything with a welder, without a mentor.

Also, I am thinking I need to split my tractor before I move forward with dealing with my tiller. I am almost certain the throwout bearing is messed up and I think my clutch has been stuck to the flywheel the whole time I have had it(about 6 weeks). Sometimes it does fine changing gears other times it sounds like I am grinding the transmission to death. I have adjusted the clutch length, under the pedal, with little change in performance. With the clutch pushed 100% down, it still sometimes tries to pull away.

I will try and update everyone in the next week how one of the projects is going.