Tightening loose spline engagement

[seagull369]

Having a problem with a cheap Chinese string trimmer I own. The splines on the end of the driveshaft which engage the clutch bell up top has worn down to the point it no longer turns. The (female) splines end on the clutch bell look undamaged. I'm gonna order a replacement shaft but was wondering if there's something I could do to eliminate any slop there might be in the engagement of the two, especially since the first one wore down only after a year of light use. I thought about adding some grinding compound in there, but am not sure if that might actually wear things down faster. I also contemplated just weld-braze-solder the shaft straight to the bell, but bell is in a recessed housing that I can't seem to get apart.

Besides suggesting I buy a real trimmer, any thoughts on how to approach this?

 

[Dagny]

why grinding compound?

 

[The Cobbler]

yeah, what would the grinding compound do, other than speed up the wear?

 

[seagull369]

I've heard grinding compound can be used on stripped screw heads to help a screwdriver get a better bite. Thought that might hold true in this case.

 

[kelpaso1]

Solution is simple. Quit buying "cheap" trimmers. Ya gets what you pays for.

 

[kelpaso1]

I stopped working on trimmers. They are so cheaply built. If it lasts a couple, three years you are doing good. I don't even bother to fix my own when they break down. Welcome to the world of CHEAP, CRAPPY consumer goods.

 

[like2wheel]

Besides suggesting I buy a real trimmer, any thoughts on how to approach this?

Solution is simple. Quit buying "cheap" trimmers. Ya gets what you pays for.

Just couldn't help yourself?



In terms of tightening it up, wondering if you could crease some brass bearing shim stock to fit in there.
Or maybe assemble it with some JB Weld?

 

[ChevyEFI]

Vibration takes out splines. New shaft might last shorter time because of wear to the female splines surfaces.

A lateral hole and suitable roll pin might get you by a while.

 

[Bert_]

Just couldn't help yourself?



In terms of tightening it up, wondering if you could crease some brass bearing shim stock to fit in there.
Or maybe assemble it with some JB Weld?

Seems like a great application for jb weld.

 

[seagull369]

This is a larger displacement machine >40cc. Name-brand models are prohibitively expensive and, frankly, are not worth the inflated asking price. Much like buying stuff at Harbor Freight, I knew what I might be in for and am not complaining about it. If nothing else, it helps clear up the cobwebs upstairs to work up a solution. Up til this point, the machine's been pretty impressive, actually.

A lateral hole and suitable roll pin might get you by a while

The diameter of the shaft, especially around where the splines are at the end is unfortunately rather small to allow for much of a hole to be drilled or a suitable sized roll pin to be inserted.

JB is an idea, as is adding a shim. Perhaps a soda can might be of some use there.

Thank you for the tips thus far.

 

[Bondo]

I've heard grinding compound can be used on stripped screw heads to help a screwdriver get a better bite. Thought that might hold true in this case.

Ayuh,..... Night, 'n day comparison, 'n opposite applications,......

To slow the wear of any spline, ya can't beat plain ole Grease,.....

 

[TC16731]

Usually when a splined shaft is used the design requires lateral movement even if its only lateral thrust. Anything you use or do to "eliminate any slop" will only increase vibration or stress and probably increasing wear. That is only my humble opinion.

As for kelpaso1's comment sorry I agree. My string trimmer is a "name brand not worth the inflated price" Stihl. In May 2012 I paid including tax $413 its a KM 55R that's a kombi system so I can change from, string trimmer to blower and as of 2 years ago hedge trimmer, when I need to. Keeping in mind I had to replace 2 carbs in that time 25$ each. So I'm in for 463 $ over 9 years that is the inflated price of $51.44 a year. I run around 4 gallons of fuel through it every year. I know it will start in 3 or 4 pulls and run till it runs out of gas and I don't need to go to Harbor Freight every year to buy a new one. Again only my humble opinion.

 

[101SCOUT]

The Chinese sell by the pound. If you figure out the cost per use you paid at least 2x as much or more, Great value. Cost is what you paid Value is what you got for your money.

 

[Mick56]

I would put a coat of the thickest grease I could find on the splines. I used to have an old can of wheel bearing grease, it was so thick you could barely scoop some out with your finger.