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Tiller gear drive shaft repair suggestions.

3174 Views 11 Replies 9 Participants Last post by  rdolinski, 
thudpucker
I dont know for sure which forum to put this question.

I have a 'parts n pieces' little garden tiller.
It has a Sears gearbox, a different frame and a different motor.

The motor is a small CC Two stroke. This little tiller is almost a hand-held weed eater with rotating tines.

The engine output shaft has a octagonal (allen head) which fits into a sleeve.
That sleeve is screwed onto the Helical gear drive shaft of the tiller gear box.

You can barely see in the photos that the threads the connect the coupler to the Helical Gear Drive shaft are stripped. I dont know for sure how this happend because we've been using if for a long time.
The Daughter uses it to keep the weeds down between the Garden plants.

So the threads are stripped!
Now I have to figure out how to re-connect that coupler to the shaft in a Removable way.
Brass Metal
Hand


I have a thought on it, what do you guys think?:praying:
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M
the fact that the threads striped tells me it not harden. So, cut it off, chuck into lathe. drill new hole in end of shaft. thread that hole the same as the one that is striped. use locktite, JB weild too keep it in there. Good luck
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V
drill a hole through it and put in a roll pin
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thudpucker
The problem to beat is the "Jack Hammer effect" of the little two cycle engine working against the tiller blades.
I thought I'd put set screws through that Drive sleeve.
However I may not be able to drill through it. It's hard!

I was going to drill dimples in the shaft, drive one set screw down into the dimple, and another set screw down on top of the first to lock it.
Three equal sets like that should hold against the hammering.

I roll pin is good for strength. Shocks like this take are too much for the shaft to handle if I drilled out the shaft.

Keep trying to help!:thThumbsU
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B
I really like the roll pin idea!
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thudpucker
A single roll pin would certainly be the easiest thing to do.
I wonder about the strength of a Roll pin in that little 3/8" inch shaft; ie; is the shaft strong enough to hold and not twist off at the Roll Pin hole?

I guess I could fill the coupler/shaft junction up with JB weld, then drive the Roll pin in and let it set overnight. That should take up any extra movment the fit might have had. If it dont wobble or rattle, it might just hold.

A roll pin through the coupler would hold up well.
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S
wat about drilling it out and retapping then put in a heli coil
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Tractor-Holic
Can you use a coupler on the O.D. of both peices ,or is it in a confined area the shaft has little clearance?..if there is room you could try helicoiling the couple,or J-B welding the stripped threads ,(Or use Permatex "Quick Metal" repair compund)--get it screwed back together someway--then use a coupler slid over both peices with set screws and dimples or flat spots ground into the shafts for the set screws to bite into..

I think the higher grades of loctitie will keep the set screws tight,no need to double up on them..I like the roll pin idea,other than the fact those peices could be tought to drill if they are hardened,have to use a carbide bit or end mill--and the fact the pin might tend to crack the coupler when it gets a shock load..evidently you cant get the "right" parts to fix it,huh?...
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LLigetfa
thudpucker said:
Now I have to figure out how to re-connect that coupler to the shaft in a Removable way.
Click to expand...
Removable rules out JB Weld. The rollpin idea is good and you could double up if need be. The rollpins should be drilled off-centre so that they are not in direct shear.

Helicoil should work for a while but might suffer the same fate.

Grinding flats on the male portion and tapping the collar for setscrews would be stronger than rollpins.
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5
If it is chuckable in a lath . Drill out the old stripped male threads and insert a set screw of the same type and lock tight it in . If the female part is striped then either Heli-coil, or tap larger and the same as the set screw. Remember if its standard thread , metrics will fall between standard sizes. That way yo dont have to go to the next full size thread.
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thudpucker
Boy that Helicoil idea sounds good.
I tried to drill the collar. It's harder than supermans fist.

If I could find a Helicoil, I think I can use my Air Hammer to drive the two pieces together hard enough to stay. That's the safest suggestion so far.
Boy am I glad I posted this.
I'm amazed that my mind is so dull. I never thought of Roll pins or Helicoils.
You guys are allright, no matter what them girl friends are saying about you!
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rdolinski
How about cutting the stripped threads off, then drill out the end of the rod where the threads used to be and tap it, then you could thread in a stud that would sit in place of where the threaded section used to be.

Are the inner threads in the coupler damaged as well? If they are then fill it with a good quality weld so the hole is filled solid, then drill it out again, the weld will be a hard material but you should be able to drill it, then tap the hole with new threads, you should be back working again.
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