Welding Sprocket onto Floor Roller of New Holland 648 Round Baler.

I need to weld a heavy sprocket onto a 1.5” shaft. This is for a hay baler. The roller/shaft for this machine is no longer available. Originally, it was splined, but the splines have stripped out on both the shaft and the sprocket. The sprocket is still available, so we ordered it hoping the shaft would fit tighter. I can’t get to the back side of the sprocket (too close to the bearing), so I can only weld the exposed side. I was thinking of chamfering the sprocket’s face and the end of the shaft. Then maybe cut in four slots between the sprocket and shaft with a deburring tool… then weld those first. I was hoping that would help lock the sprocket onto the shaft. I am planning on doing this with a mig welder (0.35 cranked up hot). I can’t get the machine in the shop to my tig welder. I was thinking of preheating the sprocket/shaft with a rosebud, but I need to be careful with the bearing behind the sprocket. I don’t think the sprocket would crack when it cools, but I’m not sure. If the machine lasts another year or two, the farmer says he’ll be happy. Any advice would be much appreciated.

Another way is to use a taper lock pulley bush and bore the sprocket to suit. A keyway would have to be cut into the shaft. That way you preserve the bearing and make it easier to repair next time

Whats the plan once the bearing fails? Like Tones said it would be getting a key way or reshafted to something else. And refit

Tyler d4c said: Whats the plan once the bearing fails? Like Tones said it would be getting a key way or reshafted to something else. And refit Click to expand... Thanks, Tyler. I just put a new bearing in that side. The previous bearing was 25yrs old and still good, so I suspect the new one will make it a few more years. The baler itself is 25yrs old and the farmer just wants it to last another couple of years. The shaft goes into a large roller (not sure if goes through or is just welded) and that roller is no longer manufactured. The farmer who owns it says he had another baler like this one and it did the same thing, so they just junked it. The dealer had taken it apart and left all the parts in a bucket outside... which was filled with rainwater were ruined. Thanks, again.

I do not thank you have to worry about the gear. It is a steel plate welded to a hub. Not cast. See if it is the same as a 650. I thank I have the whole deal in the junk pile.

Tones said: Another way is to use a taper lock pulley bush and bore the sprocket to suit. A keyway would have to be cut into the shaft. That way you preserve the bearing and make it easier to repair next time Click to expand... Is a key an absolute necessity ? I thought taper locks hold very tight because of their very shallow taper angle.

Lee_in_Georgia said: Thanks, Tyler. I just put a new bearing in that side. The previous bearing was 25yrs old and still good, so I suspect the new one will make it a few more years. The baler itself is 25yrs old and the farmer just wants it to last another couple of years. The shaft goes into a large roller (not sure if goes through or is just welded) and that roller is no longer manufactured. The farmer who owns it says he had another baler like this one and it did the same thing, so they just junked it. The dealer had taken it apart and left all the parts in a bucket outside... which was filled with rainwater were ruined. Thanks, again. Click to expand... The shaft does not go through. Stops at another disc about a foot up in the roller.

DDoug said: Is a key an absolute necessity ? I thought taper locks hold very tight because of their very shallow taper angle. Click to expand... Taper locks have a keyway in them were they fit onto the shaft, never seen them without. https://search.brave.com/images?q=taper+lock+pulleys&source=web The pulley is clamped onto the bush by 2 or 3 bolts and act similar to a key. Hope this helps explain

If you only need it to last a short time welding the sprocket from the outside would be plenty strong enough. Have to make sure the sprocket is straight. I'd make 3 or 4 short welds and let it cool off between them so you don't cook the bearings. Just took another look and see the shaft is threaded. What if you made a plate with 2 or more holes to bolt the sprocket on and then used a strong bolt and red Loctite to keep it tight. I suppose you could weld the plate to the sprocket and use a bolt. You could also use something like Loctite 660 on the shaft or even some kind of epoxy.

Tones said: Taper locks have a keyway in them were they fit onto the shaft, never seen them without. https://search.brave.com/images?q=taper+lock+pulleys&source=web The pulley is clamped onto the bush by 2 or 3 bolts and act similar to a key. Hope this helps explain Click to expand... They do make taper locks without a key. They typically are not used in a high torque application, more for speed. Seeing as how it striped out the splines, I do not see welding from one side, lasting very long. I would try and put a cross bolt through the hub and shaft, put a low grade bolt through it, and let it act like a shear bolt. Then go up in strength as needed. You also could after tack welding the sprocket on straight, drill some holes, carefully, through the split between the shaft and the sprocket. Acting like clamp bolts that go through the split of some taper locks. For this I would use a mag drill as that looks doable in situ.

I've spent more hours than I care to think about running and fixing a 688. I think in this situation the splines stripped from being loose and wearing more than too much torque. I would be fairly confident that a decent weld on one side would last for as long as he needs it too

Just make sure it's a good weld with 7018. Wouldn't use Mig or 6011 or 6013. Preheat till warm to the touch and weld being careful not to get it super hot where it cooks the bearings. Weld from the bottom up on both sides. Welding downhill has poor penetration and weld reinforcement.