New Rotary Cutter, Stump Jumper, Blade Pan out of alignment, Thoughts?

[xcgreene]

I wanted to see what folks thought about this new stump jumper. Seems too far out of wack to me. As the photos show, run out difference is about 1/4". When mounted to the mower, one blade hangs exactly at the bottom of the cutter walls, and the other is about 1.5" higher. I have a video of this, But screen shots are easier.

Thoughts?

 

[ruffdog]

Did the old SJ run true? What shape is the shaft/spline? If you remove the SJ and re-install it 180 degrees from what it is now, how does it measure? If the error follows the SJ, that tells you something is wrong with it. If the error stays with the shaft, something is wrong with the shaft.

 

[xcgreene]

Did the old SJ run true? What shape is the shaft/spline? If you remove the SJ and re-install it 180 degrees from what it is now, how does it measure? If the error follows the SJ, that tells you something is wrong with it. If the error stays with the shaft, something is wrong with the shaft.

This is from a brand new 6ft rotary cutter. I had noticed much more vibration than there should be upon first start up. both blades threw out freely, but saw the stump jumper wobble.

*Jumper pinion Nut, Tight to jumper and shaft. But I could feel a wobble, indicating gearbox at this point.
*Removed jumper, gearbox lower seal was leaking and shaft was very rusty, and shaft had play. After contacting Mfg, they agreed to send me a new gearbox, and send them back the original one.
*After installing new gearbox, Cutter still vibrates, not as badly, but more than a Brand new cutter should. New gearbox shaft has zero play, and is good.
*Blades are identical in weight, balance, shape. no issues there.

But, when I checked the run out on the jumper, that's what I see in the pictures there. This run out can also still clearly be seen with everything mounted, looking under the mower when running. The pictures in my first post, are of the jump on my table top, in a centering jig.

 

[countrybumpkin]

Flip the pan over and check to see if the blade bar and the splined collar that slides onto the gear box shaft are welded at a perfect 90 degree , my guess is it’s not.

 

[xcgreene]

Flip the pan over and check to see if the blade bar and the splined collar that slides onto the gear box shaft are welded at a perfect 90 degree , my guess is it’s not.

Ill be removing the stump jumper again here in a few days, but from my photo stock pile, you can see here, that the blade bar is a riser type. The spindle collar appears to be mounted flat to the bar, and the bars both ends appear to be welded flat to the pan, but I think the riser bends in the bar are not correct.

This is just a picture of the "hold in place" jig I scrapped together so the jumper wouldn't slide across the table top while I turned the jumper by hand, so I could get an accurate measurement.

 

[countrybumpkin]

Ah ok, yes I’d say the bends are not formed correctly.

 

[xcgreene]

Ah ok, yes I’d say the bends are not formed correctly.

I agree. Just wanted another opinion about the acceptable amount of run out before I pushed for a new jumper from the Mfg. They were hesitant to entertain a replacement, with just a conversation over the phone. I'll send them the video of the run out and these pictures, and see what they'll say. They were reasonable about the bad gearbox exchange, I'm hoping they'll send me a proper jumper and I can be done with all this.

Its a brand new cutter I've had to completely disassemble. Gearbox weights almost 90lbs. Jumper and blades have come off a couple times now too. And she hasn't cut a single blade of grass. Glad I fired it up before I needed it. And I'm getting the opportunity to put some good anti-seize in places it needs to be while its new, so I'm sure I'll be grateful for that some day.

 

[countrybumpkin]

Wow hate to hear that your having that much issues with a brand new cutter. Just curios have you checked the weight of the blades to see if there even close to the same , if there not that also would contribute to vibration.

 

[xcgreene]

Wow hate to hear that your having that much issues with a brand new cutter. Just curios have you checked the weight of the blades to see if there even close to the same , if there not that also would contribute to vibration.

I have. Both spot on at 15.6lbs, Identical in bend pattern when stacked together. Balance at the exact same point when placed on a trailer ball. They are using great blades on this cutter.

I've sent an email last night, to the mfg, with the jumper run out info. I hope for a smooth transaction. But if all else fails, I suppose I could grind all the welds off from the blade bar to pan, with the exception of what I'll call a "hinge weld" at the far low side, then lift the blade bar 1/4 in. away from the pan on the high side, and weld in a 1/4" spacer. Do a quick tack on balance weight back over on the low side, and Bobs your uncle.

 

[ruffdog]

Your assuming that the surface you are sitting on has been machined perpendicular to the bore. If it were mine, I would check the SJ in multiple positions mounted on the shaft, while recording TIR each time. That is real info you can use. You should be able to tack it within 0.020" if you are eyeing it while spinning on the box.