I wonder if that one takes just as big chunks as mine, if not bigger.
I made 36 bags today and it took me several hours, hmm.
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Made some progress for a few hours
These are the brackets for fastening the bearings
And this gives you the idea how it is being put together
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Wow, that frame could take 50hp 
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I do know my drawbacks and I was not kidding 
I do not like when stuff flexes, they need to be rigid to not put stress on the materials, perhaps a little bit overkill but also this is what I have 
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I just realized while browsing through thread topics that I named this thread very much like your rebak thread, J-O. Not on purpose, I just thought it was a direct to-the-point name, just as you thought, it seems
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Made the frame today, had to narrow the width a bit, it was 150mm (6”) and I was a little concerned about the axles so I narrowed it to 110mm (4 3/8”).
Drilled and threaded holes for the bearing brackets, used an old lightbulb carton as a template for the holes
Used doublefolded A4 paper as a distance between the sprockets
Assembled it roughly to get an idea about how it’ll be
I thought I’d give it a shot and use the compression fittings that came with the sprockets but I’m afraid that they will slide on the axles, but nothing will be damaged if that really happens so we’ll see. If needed I’ll have to make bushings for the sprockets.
I guess the next step will be the knives.
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Oh, you’re going with sprockets both sides? Now, that’s overkill If you add 4 flywheels as well, nothing will stop this beast
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Hehe
I am not so sure I dare to add flywheels at all, I intend to use a direct driven wormgearbox.
First I was thinking of making a shear pin coupling and then I was considering a belt drive from the gear box to speed it up a little and then the belt could slip but now I am thinking of using the gearbox directly on the axle and flywheels can not drive the motor through a worm gearbox, there will be lots of force on the gears.
Better then to use a straight gearbox. As you probably notice I am a little unsure which way to go.
The motor/gearbox is 1400/74 rpm.
The rebak could well be tractor driven too if wanted, it is an option if the motor isn’t strong enough.
Then the speed can be chosen too. I have never measured how fast the pto runs on idle…
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Since you’re not worried about weight, big enough flywheels would do some good even on the 74rpm sprocket axles.
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You don’t think the ’live’ force of added flywheels are damaging to the worm gear?
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Yes, if the flywheel weight sits on the motor side of the gear, it will put extra stress on it. Downstream the gear, on the sprocket axles, it will even the load out.
But, again - 74rpm is such a slow speed, it would take a massive flywheel to make a difference.
Since I don’t use a worm gear, I use a two step reduction. Even though my 1/2m dia and 10-15 kg flywheel sits on the 300rpm middle axle, it makes very little difference.
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I was thinking the other way around, if the weight is on the motor side it can turn the motor and the gear if the motor stops and if the knives jam but if the weight is on the knife side it can’t turn the motor when turning off the motor and more weight there puts more stress on the gear.
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Did you mention whether this is going to be powered by an engine or electric motor?.
I’m pretty weak on electronics but is there some kind of sensor that would shut down the power to the motor if it locked up?
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Johan,
You would need some kind of slip clutch on the flywheel itself, that would hold for normal operation, but slip when the blades jam with an un-choppable object. If you don’t, I believe you will break a drive or driven shaft. especially with a worm gear reduction drive. Example would be a spring-pressed brake/clutch disk, like a tractor PTO may have. 
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You think like this, the engine drives the device and we want the torque on the shaft to be as even as possible, so the shaft and gears in the gearbox do not suffer, so a flywheel on the device’s PTO shaft is welcome. If we want to soften the shocks of chopping and thus relieve the gear of the device, it is also good to have flywheels on both shafts of the chopper. Flywheels will not make starting significantly more difficult, but they will help a lot
even and stable operation and durability of the device. For example, let me say that with my stone crusher the weight of the flywheels is approx. 1200 kg, without which operation is impossible.
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No progress today at all on the rebak, had to take off and renovate a hydraulic cylinder on the tractordigger, it was beyond dripping.
That’s what you get for having old machines, lots of breakdowns.
There was still paint in the allen screws holding the cylinder together so noone has taken that apart since it was new. So about 50 years is whay you can expect from hydraulic cylinder seals
Sorry, I believe I didn’t mention that, I am planning on having a electric motor on it but if the motor is not strong enough it’s anybody’s guess if it will be electric or pto driven.
There is sensors to put on that senses if something is spinning and if it is not then cuts the power.
Yes, if flywheels are added I think it is necessary to have something that slips or breaks, I was thinking a shear pin connector.
I totally agree if it is a normal gearbox to have the flywheels where the load is, it’s just the worm gear I am worried about when the motor stops and there are flywheels on the rebak, not if the rebak stops, that is not such a big problem.
Wait, I just had a revelation. If I make it pto-driven completly then I could have a pto-axle with a slip-clutch on it, as Mike said, and then choose if I have a tractor or an electric worm-drive gearbox driving the pto.
Then I can fertilize the whole thing with flywheels all over the place 
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But wait, I have 20mm axles only. A spring-pressed brake/clutch pto connector does not slip before the axles are like spaghetti but it slips if flywheels are added and the rebak is trying to run the motor so there perhaps should be a shear pin connector also…
An ordinary belt drive seems appealing right now… this is getting complicated. Or actually, I am making it complicated.
Perhaps I should just try it and see what happens.
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I’m on a belt drive, so it can slip.
Doesn’t JO have it?
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Yes, J-O have a belt too.
Perhaps that would be the best
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There you go
You will produce chunks, with or without the flywheel 
Btw, what dia is the outgoing axle on the gearbox?
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