Trouble Changing BushHog Blades

[HarleyBob]

I purchased new Bush Hog blades for my SQ600 Bushhog
rotary mower. I have removed the blade bolt nuts and lock washer from above
but cannot figure out how to get the bolts out of the blade hodler assembly. Is the blade bolt driven out from above? They seem pretty set in their ways.
Is the bolt pressed in or threaded into the blade holder assembly?
The bottom end of the bolt is round, not hex etc that would allow it to be unscrewed.
Thanks. /forums/images/graemlins/confused.gif

 

[Bird]

Have you tried getting a hold of the end of the blade and wiggling it around. They've always just fallen right out for me.

 

[HarleyBob]

Bird, Do you mean pulling down on it or just rotating it. It moves around easily and has a little bit of wobble. I have been told that
the bolt may have a keyway in it where it goes throught the holder.

 

[geneP]

Yeah, they typically have a key on the shaft that fits through the blade holder. It's probably just choked up with grass and rust. Some penetrant or oil around the bolt will help, then wiggle the end of the blade up and down, as Bird suggested, and it should loosen and fall out. The most effort it should take is to tap the threaded end of the bolt with a drift pin and hammer to knock it loose. Just hit the center of the bolt, not the threaded portion.

 

[HarleyBob]

I have been hitting it quite hard with a rod and small sledge and it is not budging. I may drop the entire blade holder and try it on the bench with some heat. That is, if the blade holder (stump jumper) is not similarly stuck. This is the first time to try and remove blades after three years of use.
I will use some anti-seeze when re-assembling.

 

[Bird]

Sounds to me as if a little corrosion has caused them to stick. Maybe a little PB Blaster, Liquid Wrench, or even WD-40 would do it, and of course, as you suggested, a little heat might work.

 

[geneP]

Some of the gear boxes have keyed and tapered output shaft so that the stump jumper won't tend to get loose as easily as a straight shaft will. If it's mounted on a tapered shaft and torqued tightly it WILL be a bugger to remove.

 

[HarleyBob]

I got the stump jumper off so I can clamp it all to my bench.
When you apply heat to loosen bolts, do you heat the nut or the bolt or both? Are you heating things so they expand and then shrink and thus loosening things up, or do you want to try and
put the wrench on it while it is still hot?
Thanks

 

[Bird]

Ideally, when trying to separate two metal objects, you would heat the outer one to get it to expand and then try to cool the inner (bolt in this case) part to get it to shrink. Of course it's frequently difficult, if not impossible, to heat one without heating the other. And yes, I've put the wrench to them while they were still hot. Personally, I'd probably heat it pretty good, then spray a little WD-40 on the bolt to both cool and lubricate it, and then try to get it out.

 

[RickB]

They come off overly hard the first time lately. I remove the nut and lock washer, then replace the nut so the top of the nut is flush with the top of the bolt. This protects the bolt and threads. Then drive the bolt down with a large pin and hammer(sledge) until the nut is flush with the bar. Remove the nut and drive the bolt out the rest of the way. Clean up the bolt shank and the bore in the blade holder before reassembly; coat threads and shank with Never-Sieze compound or grease. Very rarely do I have to resort to heat.