Stuck knife head bolt — sickle bar cutter

[JRH02]

Just wait until he buys a couple boxes of tooth sections and a box of rivets.

 

[jcman]

Seville009 has the right idea. I'd use a pry bar or crow bar unless you have a very large screwdriver.

After you get it out I'd replace all the knives, make sure you get the same size. Easy way to get the knives off the bar:
1. place an anvil on the ground and support the other end of the sickle bar at the same height.
2. turn the bar so the knives point down and place the bar on the edge of the anvil with the knives clear of the anvil
3. strike the back side of the knife hard with a good sized hammer, I used a 4# sledge. this will break the rivets.
4. use a punch to drive the old rivet out of the bar.
To replace the knives:
1. make sure to put the knives on the same side of the bar as the old ones
2. put the correct length rivet in the holes
3. with the knives flat on the anvil and the rivets down (on the anvil) give the back of the rivet that sticks out a very sharp blow with a large hammer. (4# sledge works great) If you hit it hard enough you'll have a nice round retention on the back side.

 

[Bentrim]

The bolt has to be a tight fit inside the bushing and the holes in the straps that drive it. Otherwise everything would wear badly So the bolt should have some resistance when removed and installed, but if mower was not used for a while or stored in the blue shed it may have rusted and may need extra force to remove it. If possible remove the straps. then the knife and using a solid surface as a vice or a piece of pipe that the bolt head will fit in and drive the bolt out. Be aware that is or should be a special bolt.

 

[Surshot]

That looks like an old sicle bar, like we used, been near 60 years since I worked on one. But if I recall correctly the joint only comes apart in one position.
The actuator is too far back to remove the bolt, it needs to slide the teeth bar forward to line up with the large hole to remove the bolt compleatly. The bar needs to be level and supported to take pressure off that bolt. Check for a spring to hold the bar forward, some are spring loaded, if so push the bar forward and remove the spring before removing the bolt.
If you use an L shape flat bar with a nut just started, you should be able to tap the bolt out by tapping the flat bar.
Thse things are much fun to get back together, has to be aligned and on stroke.

 

[MHarryE]

Bolts seized in the bearing. That's why you can turn it without difficulty. Gotta cut and it depends on what tools you have. I'd use my Sawzall to zip through the bolt on each side of the bearing after bending the plates enough to get blade clearance.

 

[sandytrail]

One guess is that the bracket on the right has worn a groove into the bolt just below the head and it has mushroomed. That's why it won't slide to the right. I would probably cut it off with an angle grinder or hack saw and then pry it out from the left as previously suggested.