jack shaft with many problems

[Barrie2777]

Just when you think you have seen everything!!!! Along with a rusted-in-place bearing and rusted-in-place woodruff key, the bolt to retain the sprocket had been twisted off many moons ago. I chucked the jackshaft in a lathe and proceded to drill out the bolt so I could retap the threads to their original glory of 5/16" x 24 TPI. Much to my surprise, when the bit passed through the splined end, it separated from the rest of the jackshaft. THIS JUST SHOULDN'T HAPPEN. The question to all you readers is "How do I reattach this splined end?"

[Go Go Diablo]

Superglue?

[swen]

New jack shaft:)

[fap67]

That is what I call "Tired Iron"! You must have another one in the parts collection?

[Barrie2777]

I never like to give up on unreplacable parts. This piece came off showing no signs of ever having been attached.

[Go Go Diablo]

Barries Shaft.jpg (133.66KiB)Viewed 6736 times

I lightened the picture up a little. First off, I'm still unsure of the failure. I don't recognize an area where one piece might have been shrink fitted into another or something like that. With this sort of piece, I wonder if the shaft would be made of a different material than the spline that just came off. If the shaft is soft, one would think the spline would be hard.

[devil dog]

I would say bevel both pieces and weld. The sprocket is a little narrower than the splines on the shaft so you can lose a little bit of spline on the inside and still be OK.The groove behind the splines can be filled with weld. Then drill and tap and put a longer bolt in it. Not an easy fix for sure.You dont have much to lose I guess. For the rusted woodriff key, soak in penetrating oil as long as possibile . Then support on solid wood and take a pointed punch or chisel and pound down on one end of key. The opposite end will rock upward because of the half-moon shape of the slot and key. When it comes up enough, you can hit it the rest of the way out. The key will be ruined though.

[blimkijw]

I think you should of used a left hand drill bit to extract the bolt, next time center drill with a #3 c-drill then use a smaller drill than the tap drill size (1 divided by # threads per inch and subtract from the nominal size) I usually stay 1/32 under the TDS to extract, once that is calculated put the drill in the chuck and run the lathe in reverse and drill using the tail stock not locked in position. It will drill a hole for a bit then catch and will unthread the broken stud, Works all the time, sometime before attempting i will soak the part in diesel fuel.

As for fixing it will never be the same, although some 9 and 10 tooth sprokets come with a casted hub on the sproket with 2 set screws and a key slot, the bore i believe is .750 so if it were to line up, just turn your shaft to the bore size then drill 2 divits in the shaft for the set screws and cut a key ways in a mill. Up here in chalk us hus-ski boys all turnt off our splines or to accept new sprockets in the past

[Barrie2777]

The problem wasn't in the removal of the bolt but that the splined part was, for unknown reasons, separated from the shaft.

[blimkijw]

I figure when removing the bolt, the drill in the tail stock may not be on center therefore caused the drill to cut oversive and nock off the splined section, the wall thickness of that area of the part is minimal. Its not like these machine as powerhouses or that the steel is so old that its fatigued beyond usage. I had a guy back 8 yrs ago bring me a jackshaft that came from this family to my machine shop. I had a spare sprocket which came from fastenal with the extended casted side hub then just turn the shaft to suite the hub and cut a key way. His shaft broke also from shearing of the bolt and trying to drill it out. Common knowledge if a bolt wont come out, heat it up then let is cool slowly, and if that does'nt work let it soak in diesel fuel or a penetrant oil, I favor dunking it in diesel fuel. From what I see from the pics this jackhaft doesn't have a problem just a situation and looks possible fix. If anything it would be better beacuse then you can have sprocket readily available as sprockets with that spline are not a off the shelf item anymore.