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Old 06-09-2014, 05:46 PM
NOBLNG NOBLNG is offline
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Default Chain Tensioner

The chain tensioner on my Welty-Way coil line has given out. The pin that the sprocket rides on snapped. I had a new pin made at a local machine shop and it broke again in a few weeks. I have designed a new double shear bracket for the tensioner sprocket to ride on. My question is: will a piece of 1/2" stainless steel rod be alright to use as a shaft, or does it have to be a special material? If stainless will work, I think I can drill and tap it for the grease fitting myself.
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  #2  
Old 06-09-2014, 06:20 PM
FabberMcGee FabberMcGee is offline
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Easiest good repair I can see would be to bore out the threads in the adjuster and press in the shaft. Maybe put a small tack weld on the back side to hold it.

I go to the local hydraulic shop for chromed hardened rod when I need a bearing surface.
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Old 06-09-2014, 06:27 PM
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randydupree randydupree is offline
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yep,its the sharp edge where the threads start thats the problem.

But,nice bracket!
its hell for stout!
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Old 06-09-2014, 06:28 PM
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I think stainless would work great. Yo may have trouble drilling it tho, slower speed and steady pressure. I would think a grade 8 bolt would work and a little easier drilling.
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Old 06-09-2014, 09:26 PM
NOBLNG NOBLNG is offline
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Thanks, I like the grade 8 bolt idea. If I get one with a long enough shoulder on it, it would allow me to thread the inside leg and tighten the bolt until it jams. Then grind off the excess threads and voila... no set screws required! Rotation of that sprocket is clockwise, so it would not tend to loosen the bolt.

Last edited by NOBLNG; 06-09-2014 at 09:29 PM. Reason: spelling
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Old 06-09-2014, 09:31 PM
NOBLNG NOBLNG is offline
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Actually, I would need a set screw to be safe since the rollers in the bearing would reverse the thrust on the bolt.
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Old 06-10-2014, 02:43 AM
MrRodeoCC MrRodeoCC is offline
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Okay, my question is, is a grade 8 bolt a shear bolt or a tension bolt? We use both kinds of bolts on aircraft but our marking designations are different. You would need a shear bolt for the bracket you are using, meaning the bolt is designed to carry a shearing load rather than the tension load. I myself would drill the head of the bolt and safetywire it to the bracket. I'll can get a picture of the safetywire if you'd like. We safetywire all flight control and high vibration bolts to prevent loosening. Also the saftywiring of the bolt head would prevent damaging the threads by the setscrew which would making changing the bolt, bearings etc much easier.
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Last edited by MrRodeoCC; 06-10-2014 at 02:46 AM. Reason: spelling
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Old 06-10-2014, 04:05 AM
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GWIZ GWIZ is offline
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Not knowing what the thing does, maybe consider A precision tight tolerance shoulder screw/bolt made from alloy steel.

I don't think SS will do well with the needle bearings, maybe a bit soft.

search the link for shoulder screw
http://www.mcmaster.com/#=sceu6v
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  #9  
Old 06-10-2014, 12:12 PM
FabberMcGee FabberMcGee is offline
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Quote:
Originally Posted by NOBLNG View Post
I have designed a new double shear bracket for the tensioner sprocket to ride on.
I read your post too quickly and didn't realize you were replacing the original with the welded bracket. Sorry.

Supported on both sides puts a new light on it. GWIZ has a good plan with the precision bolt, if it's hard enough. There are hundreds of grades of SS, do you know what you have? Some is soft as butter some is very hard. A bearing journal needs to be absolutely round and harder than a woodpecker's lip.

I agree with Randy, that's a very substantial bracket. You shouldn't have any problems with that. Nice job.
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  #10  
Old 06-10-2014, 12:33 PM
NOBLNG NOBLNG is offline
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I wound up using an axle bolt from a heavy-duty 4" caster. It should be up to the task, and already had the grease fitting. I can't get a gun on it where it is so I will eventually have to install a 90 degree nipple.
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