Now that's an impressive failure! What a sturdy gearbox that must be. I think you could do with shorter blades so there isn't so much leverage reacting back on the shaft. Really I think you might consider a hydraulic ram, a simple wood splitter modified with a guillotine style shear on the end. That seems a more reasonable way to get the kind of force you're looking for with perhaps foot pedal actuation. I'm sure the gearbox wouldn't go to waste as you'd quickly find something else to do with it. This made for an excellent video in any case!
Yes, smaller diameter and also "slower" spiral (so it takes more shaft rotation to push a given distance into the wood). Should help reduce the forces on internal components and/or increase the possible force on the wood.
@@wayoutwest-workshopstuff6299 If you're wanting to make hundreds of small cuts like this, I think you're right. It's useful for splitting bigger logs into firewood but cutting very long lengths of relatively narrow stuff like this, less so. Though in fairness the travel would be fairly small, so the two factors (speed and travel) might balance out in the end.
I know, I was thinking the same thing. I was also thinking that we would get a video in the future from the wife saying there was an accident. Notice I said from the wife..... You know, It sucks the machine broke, but part of me is glad the machine died the way it did.
Great project Tim! Perhaps you could guide the whole blade within a circular guard casing around the tip of the blade. I feel that a flat bed for resting the branches on could help in shoving them forward. A guard around most of the blades could help you with 19th century safety (and one for the engine shaft too!)
Perhaps a shear pin or a brass key would help if you want to continue to use the gear reduction? That way it would fail in a safe and easy to fix kind of way.
@@wayoutwest-workshopstuff6299 I see what you mean, but it seems like with the very large gear ratio in that gear box, you will have a hard time finding the sweet spot with belt tension where it transmits enough torque for larger logs, but slips well when stalled out. Belt wear, stretch, and glazing are going to be constantly changing the correct tension to balance safety slippage and good working power. A shear pin should have a specified strength that could be calculated into an appropriate torque limit. I do see how a shear pin makes the design more complex, but it seems like this scenario might justify the extra time and effort. Fun project all around. I look forward to seeing how you solve the issues!
@@wayoutwest-workshopstuff6299 They're correct. On general principles, one should always reject "I'll get it right next time" as an adequate failsafe being implemented. At least not with anything over 1/4 horsepower. A true failsafe does something almost magical. It pins down the future. An uncompensated failure can happen infinite ways, and sometimes the machine takes people with it. An engineered failsafe eliminates those wretched and nearly unthinkable possible futures and pins the future down to one where you simply scowl at a machine and sigh at the ten minutes or so of extra work you now have to do.
Just what we love to watch .My husband love’s to what you are up to Tim .We haven’t had a good day lovely to unwind with you .Best regards we love Ireland as well.Happy St Patrick Day to you both.Good luck 🍀.🧚🧚☘️☘️☘️🍀🍀🍀🇮🇪🇮🇪🇮🇪🇮🇪
One of my all-time favourite videos. It has an excavator, concrete being poured and a very large and sharp spinning blade. What could possibly go wrong. Just glad everyone is safe and look forward to the next installment.
@7:50 - I almost watched the later video when you rebuilt this, but I am glad I paused that one to come find this one. In my head, I pictured this thing wailing and gnashing away at a fevered pitch. Instead, I am pleased to see a contrivance of quiet, unrelenting power that is hypnotic to watch. I think I shall subscribe to your channel, sir. Well done.
I absolutely love seeing your whole process including the failures and improvements. You could just release 10 second videos titled ‘easy peasy’ but showing the whole journey is *so much* more valuable and real. Thank you!
Me seeing the notification to this video: "Let's go!" Me when i read the title: "Wait- what?!" There has been built a ballast truck, 5 wood trucks for wood, even a log chopper and a boiler, that's amazing.
Take care. That machine doesn't know the difference between arms and logs. A slip clutch or shear pin might be a good idea. An emergency stop for the engine ? Some farm machinery have spring loaded clutches. The PTO on a small old fashioned baler comes to mind. I think your place of cutting should be moved nearer the centre of the chomper. More cutting force and more overlap for the blades in the slot.
@Gerry they didn't appear to have any means of stopping it. If they had cut the ignition when it was nearly stalled, it would have stopped quickly enough.
The blade really is too long, plus it's on a wide hub. You're cutting nearly half a meter from the point of rotation. You should be cutting as close to the axle as possible for maximum torque.
I think what you need isn't knife blades, but a saw blade. Shape it with an expanding radius like your knives, but allow it to take only one bite per revolution. Shape the teeth with deep gullets so they have room to hold all the chips generated by the tooth's passage through the log until they get clear, with alternating peaks on the teeth to reduce the load on each. That is one hell of a gearbox.
Two classes of things are clearly needed: 1. An obvious, safe, planned way for the machine to safely disengage when the inevitable un-choppable object is inserted. 2. A WHOLE BUNCH of safety guards! Think about all the different ways that human fingers, arms, etc., might encounter those blades, belts, shafts, and any other moving parts (or even sharp non-moving parts!).
An example of #1 would be the shear pin found in most rotary power mowers, which shear instead of the crankshaft shearing when you hit a rock, pipe, etc.
Looking at the whole set up, I think we are beyond safety at this point. Best sacrifice a few unwilling limbs a month to keep the machine spirt satisfied lest it start demanding heads.
Very exciting as usual. Two ideas: 1* blades should be attached to flywheel, to reduce load to gearbox, shaft and frame. Due low speed, the flywheel needs to be very heavy of course. Perhaps a truck flywheel/clutch assembly would work. Could use the clutch to disengage the blades too. 2* cutting disk could be coupled to shaft via impact driver style clutch. You know the spring loaded spiral thingy. It would prevent excessive loads to components when blade gets stuck and would hammer through the bigger branches.
I see many others saying to cut closer to the shaft for better leverage, but I also suggest that the blade be designed such that it begins to slice the logs at a more oblique angle. It will start the cut easier and once the cut starts, it is easier for it to keep going. Good luck! 👍😉
Seeing how mangled it got really shows you how much power you had to work with, looks like it would've gone through a whole tree if you could fit it in! For your next iteration, and I'm sure you already worked it out after your experience, you may want to look into adding some sacrificial parts that will fail before something like that is able to happen 😱
yeah I was thinking that enclosing the hole blade in which will prevent the blade wobble and the worse that can happen is the blade will rub on the housing. This thing looks like it has the power to cut very large logs 6 inches or more. Reduction gears are really strong.
@@chox2001 There are a few videos out there with ram guillotines and they have one major problem is that they are slow and they tend to crush the log rather than slice it, of the ones I have seen. which is why buzz saws were used for a very long time. My main video is myself using a buzz saw.
There was a distinct lack of burning in this video. I came here for a disaster! Really satisfying to see the blade just slowly slice straight through those branches.
Your videos are a welcome diversion. I love that you just get an idea, and build it. Reminds me of how I used to think anything was possible when I was a child.
A flat belt would work better than a V belt, they slip/clutch better than V belts. Thinking about it you really need a jackshaft with fixed and loose pulleys & a shifting fork, that would be the only real safe/effective way to run such a setup. I can research it if you like but I think they can both be flat, not crowned. Your buddy with the lathe can crown them if not. A disc brake would be a good idea as well. Keep an eye out for crowned pulleys at flea markets/rummage sales, there are lots of the out there. Cheers.
I love how you run counter to ever increasing health and safety requirements. Seems that each project becomes more lethal than the last. I'm astonished at the diameters it could slice through though: the stresses must be enormous!
Great project! I always love videos like this where one analyses mistakes made so we can all learn. I am also glad to hear the gearbox is fine. Some stuff I have noticed from watching tons of these wood chunker videos online and attempting to build one for myself: - Blades that have only a single cut, tend to perform best. Chunkers like yours that have two cuts seem to put more pressure in a shorter span of time. Maybe try a single, spiral blade next? - Cuts made at a right angle to the wood are harder. Imagine chopping a tree by chopping ONLY at right angles. That's hard because it goes against the wood fibers. Try setting up the blade so that the wood will be cut at a diagonal across the wood. Really great progress though! This is such a beautiful setup you have there and I am completely convinced you will get there! Edit: and as others have mentioned some kind of mechanical fuse / sheer pin might be in order. I am planning to put one on my chunker as well. Shaft comes out the reducer, has a hole drilled into it. Over this shaft fits another, much bigger shaft with a hole in that one too. This last shaft connects to the blade. Then I'd place a tractor sheerpin into the two holes connecting the shafts. Should a similar situation happen again as in this video, you don't run the risk of ruining the gearbox.
@@wayoutwest-workshopstuff6299 I can agree with you that the slope/angle of the cut is not such a huge deal. You can see that when the gearbox was cutting clean through those massive pieces of willow! So keep that current setup if you don't want to change it. What seems to make the most sense in my mind is to change the cut from two blades to a single one. Your current setup has the blades sticking out quite a bit, this creates an extra leverage effect on the axle. The closer the cutting edge is to the axle, the least amount of leverage occurs... Also, if there is only one cut per rotation you halve the pressure on the axle again because it takes double the time to cut through the wood fibers. If I saw the output RPM on the gearbox towards the end, it is plenty fast enough for this to work like a charm. Here's an example of a great spiral blade IMO: th-cam.com/users/shorts8PGn0pbD1yc
You might consider a single shear pin in the system. Perhaps holding a drive plate attached to the gearbox, to a blade plate attached to the blades. You can make your own shear pins by grinding a bit of a notch in a bolt where the two plates would slip if the bolt was not installed. On my brush hog, the shear pin is a single grade 8 bolt, but that's a bit unusual usage of a bolt, normally they are special bolts designed specifically as shear pins. It does however do a great job of snapping off when I mow over a stump or something big. Lots of stuff about shear pins online regarding snow blowers, including lots of home made shear pins from bolts etc, so it should be easy to research if you go this direction.
Well the beast has shown it's strength! If you want to reduce the stress in it you could move the point where the blade meets the log closer to the centre of rotation. This would allow smaller blades if you want too. Everything else you could do would add complications to the machine. Have you considered using a different blade type? I have seen some impressive results from a car wheel rim cut to form a blade with the cutting edge in line with the rotation and would not be susceptible to bending! Whatever you do, it is a fascinating experience seeing and hearing you talk about it! Please do not stop!
My two pence worth, your problem issue is the blade design. The blades need to be able to swivel so that centrifugal force holds them out. In this way, they chomp at the log until they work through it. Then the shear pin issue disappears. You also need it to run it about 1.5 times faster for greater shear power.
You're using about 30 degrees of rotation per cut, make a blade that takes 180 degrees to cut, spread the load/work over more time and move them towards the centre like other people have said
If you cut closer to the shaft mechanical advantage would be on your side and the blade would be in the slot and less chance of twisting or bending. A shear pin on the blade will let the blade flop back. A greater angle will cut slower and be an advantage.
Have a look at some of the Yanky You Tube log chompers and you will see that they use a wheel with the rim cut into a cam shape and sharpened all the way round, which give continuous progressive cutting with the log being fed in on a slightly slanted flat plate so after a cut the log is slid down to a stop for the length required and the cutting action begins.
The two pieces of angle iron that the blade runs between can be arranged even closer and in such a way that they prevent the blades from bending sideways. Should do the trick. Then it's on to the next failure point.
I once saw an illustration of a machine used to cut firewood for steam boats in British Columbia, Canada. It resembled a small guillotine with a blade that dropped vertically on the wood. Perhaps something along this line (although it wouldn't cut as quickly)?
Have you considered using an old car wheel rim as your cutter, ive seen this work before, you sharpen the edge of the wheel in a decreasing radius, and you could use a wheel hub with lugnuts for attaching it to the gear box, it woukd be a stronger connection and the curve you cut into the rim can act like a curved knife to cut the logs. Search youtube for an example, there are lots of videos where this method is used, hope that helps. Love your channel and videos, and i hope you have a wonderful day!
Quite a lot of your blade cannot be used as it is behind the log support. If you reshaped the curve of the blade you can get more ‘slice’ over the arc and therefore cut with less difficulty. Fun video thanks!
In Engineering we have a saying "Failure is NOT an option! It's a topic," We design in places where 'Low Cost easily replace' parts blow up before sometihing dangerous/expensive breaks.
Might be worth extending your angle iron wood rest up some and splaying it at the top, so if the blade wanders for any reason, the guide brings it back into place instead of letting it get caught up like that. Seeing how wonky the blade hub was afterwards makes me wonder if the hub wasn't starting to give before the failure, which was why the blade got out of alignment in the first place.
Judging from the sparks off that key, it was high carbon steel---probably was fairly hard, judging from the damage. See if you can get something softer. McMaster (in the US) sells machine keys that are Rockwell B 50 or 100. The B scale is so soft it is tested with a ball bearing, not a diamond point.
I think the only safe assumption is that the gearbox will fail later, but prematurely due to internal wear. It's just very hard to believe that it could shear the keyway without putting some degree of twist in the shaft. I can only assume that when under load it's going to waste more energy to higher friction than previously. Probably not a deal breaker because it's not running a grain elevator 24/7 or anything like that, but I'd still just keep my eyes open for a similar one drifting about.
Wonderful video Tim! I think others have said the same, but if you use shorter blades, or put the log closer so it uses more of the blade to slide perhaps, combined with a blade slot that engages at the tip of the blade for the entire cutting stroke. Super fun to watch you and your experiments, keep it up!
Keep the blade stationary. Come up with an oscillating mechanism to crush the branch onto the blade. Support the crushing arm pivot on both sides. More rigid and takes the bending load off the gearbox shaft. The logs don't have to be cropped first time, chomping down a tapered aperture.
A stationary blade would seem to be a bit safer than having to mind a pair of spinning blades should things go awry. Perhaps a sliding plate with a sharpened hole sliding on a stationary plate with a sharpened hole, like a cigar cutter. This would unfortunately do away with any slicing action on the blade and make it strictly a chopper. Wonderful video! Thanks to Tim for taking us along for the ride.
Hi, perhaps grinding a centimeter or so of of the out going side of the anvil would help alot. Or even going with a single sided "bypass" anvil, rather than a slot. I think you are getting alot of pinch back on the blades. Cheers.
my ideas, remove the slot for the blades or make the slots wider, also add a safety coupling with a shear pin that is going to snap in half and stop the machine from destroying itself in case the machine jammes again
I'm just thinking, when the machine was working you can hear one blade scraping against the frame every revolution. At the large pulley speed I think only one blade would suffice and maybe some tapered blade guides . Difficult to get the right belt tension between to tight to slip and slipping during normal use, some old agricultural machines had slip clutches as part of the PTO shaft, maybe a modification but normally they just rust up. Cheers
If you change the flat bar on which you lay the limb to be cut so that the blade slices more diagonally through the limb then the torque required will be reduced. Easy to test with a temporary wedge in place. Think of trying to slice through a small branch with a knife. You would naturally angle it to reduce the effort……
Oh my God. That rotary guillotine gives me nightmares. No safety shut off, no safety shield, no emergency stop. Just one slide away from a deadly slip up. Lucky it killed itself first.
If you guided the blades into the slot you could keep that from happening. And if you make the curve on the blades shallower then it will take less force to chop through them.
instead of brut force us overwhelming force. Increasing your RPM will increase potential kinetic energy, thus over coming resistance. This will also decrease the blades desire to twist or deflect while under load ... It sure looks awesome thou, in a Mad Max kinda way.... I like it :)
If I may suggest, (For reference, viewed from the end of the shaft, rotation is clockwise.) I see that the cutting edges are nearly at a 180 degree plane to the drive shaft rather than at a very sharp angle. If arranged as such it would slice the wood rather than chop it. If the blade engages the wood closer to the shaft, the resistance has less leverage to impede the travel. Liken this concept to choking up on a baseball bat or a hammer. That may reduce the force needed from the drive train to pass the knife through the wood. I believe much efficiency would be gained and it may help your belt slippage problem.
Excellent point! The other versions I've seen progressively slide through the branch. I've even seen a car wheel rim notched so that it gradually widens used as a cutter
I agree that better blade shape is Important in making a more progressive cut - at the moment the torque is going high very quickly for not very long, a better blade shape will apply torque for a larger part of each cycle and reduce the shock loading on the drive train.
Dang it! On the one I just completed, I run off a tractor PTO @ 540 RPM and through a 48/1 box. Currently I use just one slicing blade but tomorrows task it to make a two blade unit, similar to yours. I made mine out of 1/2" mild steel andit is plenty strong and the edge seems to hold up fine. I had thought about running the blade through a slot like yours but instead I run the blade up against one side of some heavy angle. I also only sharpened one side of the blade similar to pruning shears. That way the cutting force drives against the heavy angle and keeps some of the pressures during the cut, off the actual gearbox. It looked like your blade was sharpened equally on both sides. I use a shear pin which is just a 5/16" bolt. It is on the input shaft and easy to replace. I have been cutting dry cherry wood from 3" dia. on down and been really impressed. I also noticed if I fed the wood at a slight angle it seemed to cut easier than just going at a right angle to the grain. Keep up the good work and thank you!
In old milling machines the gearbox has a safety pin that shears before the gearbox or motor stuffers. The pin is usually out of aluminium. Maybe you need one of those to protect your lovely engine or expensive gearbox.
I'm sure you are already aware, but it takes surprisingly little crown to make a belt track properly. I restored a few shipbuilders compass band saws, these originally had a sort of bakelite tire with the crown cast in. Well, bakelite or whatever it was was not nearly as durable as the builder had hoped. I was very wary about cutting into the original castings at all, but I could not find an alternative. I ended up crowning the wheels with nothing but an orbital sander. Have yet to have a problem
@@wayoutwest-workshopstuff6299 I'm ashamed to admit I did not take very precise measurements. I mostly used a blade and trial and error to make the adjustment land in the middle. I've noticed the old fashioned tractors that take the very wide flat belts, they seem to have a remarkably little crown, less than a quarter inch
Now that's an impressive failure! What a sturdy gearbox that must be. I think you could do with shorter blades so there isn't so much leverage reacting back on the shaft. Really I think you might consider a hydraulic ram, a simple wood splitter modified with a guillotine style shear on the end. That seems a more reasonable way to get the kind of force you're looking for with perhaps foot pedal actuation. I'm sure the gearbox wouldn't go to waste as you'd quickly find something else to do with it.
This made for an excellent video in any case!
Yea I agree. If he could make it with half the outer diameter it might work tho. But the torque this thing has to deliver/withstand…
I agree about the blade length, Ben, but the ram might be frustratingly slow?
Yes, smaller diameter and also "slower" spiral (so it takes more shaft rotation to push a given distance into the wood). Should help reduce the forces on internal components and/or increase the possible force on the wood.
@@wayoutwest-workshopstuff6299 If you're wanting to make hundreds of small cuts like this, I think you're right. It's useful for splitting bigger logs into firewood but cutting very long lengths of relatively narrow stuff like this, less so. Though in fairness the travel would be fairly small, so the two factors (speed and travel) might balance out in the end.
When i find you in the comments, I usually end up subscribing to the channel if I am not already.
That's the most frightening machine I've ever seen, fantastic!
I know, I was thinking the same thing. I was also thinking that we would get a video in the future from the wife saying there was an accident. Notice I said from the wife.....
You know, It sucks the machine broke, but part of me is glad the machine died the way it did.
My dad's grasscutter beats that ! Like a flymo with no guards ! Much faster blade !
I've worked some pretty scary machines in my life and I'm not even 27 yet. This one's pretty dangerous and janky but I love it
This is downright friendly compared to some homemade log splitters you should really see.
Great project Tim! Perhaps you could guide the whole blade within a circular guard casing around the tip of the blade. I feel that a flat bed for resting the branches on could help in shoving them forward. A guard around most of the blades could help you with 19th century safety (and one for the engine shaft too!)
Perhaps a shear pin or a brass key would help if you want to continue to use the gear reduction? That way it would fail in a safe and easy to fix kind of way.
some kind of torque limiter for sure, that's one of the saving graces of a slipping belt, it prevents the machine from tearing itself apart
my problem was the belt was just too tight, otherwise it would have just slipped
@@wayoutwest-workshopstuff6299 I see what you mean, but it seems like with the very large gear ratio in that gear box, you will have a hard time finding the sweet spot with belt tension where it transmits enough torque for larger logs, but slips well when stalled out. Belt wear, stretch, and glazing are going to be constantly changing the correct tension to balance safety slippage and good working power. A shear pin should have a specified strength that could be calculated into an appropriate torque limit. I do see how a shear pin makes the design more complex, but it seems like this scenario might justify the extra time and effort.
Fun project all around. I look forward to seeing how you solve the issues!
@@wayoutwest-workshopstuff6299 They're correct. On general principles, one should always reject "I'll get it right next time" as an adequate failsafe being implemented. At least not with anything over 1/4 horsepower.
A true failsafe does something almost magical. It pins down the future. An uncompensated failure can happen infinite ways, and sometimes the machine takes people with it. An engineered failsafe eliminates those wretched and nearly unthinkable possible futures and pins the future down to one where you simply scowl at a machine and sigh at the ten minutes or so of extra work you now have to do.
Gear reduction, but it needs a bigger shaft. Thank god I’m here to help.
there's the first impression right there Tim digger
Just what we love to watch .My husband love’s to what you are up to Tim .We haven’t had a good day lovely to unwind with you .Best regards we love Ireland as well.Happy St Patrick Day to you both.Good luck 🍀.🧚🧚☘️☘️☘️🍀🍀🍀🇮🇪🇮🇪🇮🇪🇮🇪
Sorry about your bad day! Hope things get better soon. x
One of my all-time favourite videos. It has an excavator, concrete being poured and a very large and sharp spinning blade. What could possibly go wrong.
Just glad everyone is safe and look forward to the next installment.
"...tragic, interesting, and amusing." Yeah I'd have to agree with that one. Thanks so much for the smiles and even chuckles, in these trying times.
Now that's a widdow maker! Well done. Keep your fingies out of it!
Ok then : - )
Love this channel. That contraption looks like it could maim you 42 different ways. Stay safe out there and good luck with the railway!
I Hope this does not all end in tears
@7:50 - I almost watched the later video when you rebuilt this, but I am glad I paused that one to come find this one. In my head, I pictured this thing wailing and gnashing away at a fevered pitch. Instead, I am pleased to see a contrivance of quiet, unrelenting power that is hypnotic to watch. I think I shall subscribe to your channel, sir. Well done.
I absolutely love seeing your whole process including the failures and improvements. You could just release 10 second videos titled ‘easy peasy’ but showing the whole journey is *so much* more valuable and real. Thank you!
Bandsaw frames like that are priceless around here. I'm happy for you that you found one. I'm grateful for your videos.
Me seeing the notification to this video: "Let's go!"
Me when i read the title: "Wait- what?!"
There has been built a ballast truck, 5 wood trucks for wood, even a log chopper and a boiler, that's amazing.
He builds all sorts of interesting things that I could never manage with what I’ve got
Take care.
That machine doesn't know the difference between arms and logs.
A slip clutch or shear pin might be a good idea.
An emergency stop for the engine ?
Some farm machinery have spring loaded clutches.
The PTO on a small old fashioned baler comes to mind.
I think your place of cutting should be moved nearer the centre of the chomper.
More cutting force and more overlap for the blades in the slot.
An emergency stop for the engine - LOL - that'd be one way of breaking it !
@@millomweb yep, probably would break it, but its better than cutting off your own arm and dying, so...
There's so much inertia in that engine that an emergency stop would do little to help.
@@gerry343 As I said, it'd break the engine.
@Gerry they didn't appear to have any means of stopping it.
If they had cut the ignition when it was nearly stalled, it would have stopped quickly enough.
You'll figure it out, and make it work. I admire your tenacity, as well as your ingenuity!
The blade really is too long, plus it's on a wide hub. You're cutting nearly half a meter from the point of rotation. You should be cutting as close to the axle as possible for maximum torque.
I think what you need isn't knife blades, but a saw blade. Shape it with an expanding radius like your knives, but allow it to take only one bite per revolution. Shape the teeth with deep gullets so they have room to hold all the chips generated by the tooth's passage through the log until they get clear, with alternating peaks on the teeth to reduce the load on each.
That is one hell of a gearbox.
Two classes of things are clearly needed:
1. An obvious, safe, planned way for the machine to safely disengage when the inevitable un-choppable object is inserted.
2. A WHOLE BUNCH of safety guards! Think about all the different ways that human fingers, arms, etc., might encounter those blades, belts, shafts, and any other moving parts (or even sharp non-moving parts!).
An example of #1 would be the shear pin found in most rotary power mowers, which shear instead of the crankshaft shearing when you hit a rock, pipe, etc.
Meh
Looking at the whole set up, I think we are beyond safety at this point. Best sacrifice a few unwilling limbs a month to keep the machine spirt satisfied lest it start demanding heads.
Very exciting as usual.
Two ideas:
1* blades should be attached to flywheel, to reduce load to gearbox, shaft and frame. Due low speed, the flywheel needs to be very heavy of course. Perhaps a truck flywheel/clutch assembly would work. Could use the clutch to disengage the blades too.
2* cutting disk could be coupled to shaft via impact driver style clutch. You know the spring loaded spiral thingy. It would prevent excessive loads to components when blade gets stuck and would hammer through the bigger branches.
hmmm, I wonder where I'd get one of those?
Wowee! What a great illustration of the forces you were wondering about!
It's like watching the industrial revolution Tim, make a tool to improve another tool, cheers.
I see many others saying to cut closer to the shaft for better leverage, but I also suggest that the blade be designed such that it begins to slice the logs at a more oblique angle. It will start the cut easier and once the cut starts, it is easier for it to keep going. Good luck! 👍😉
Seeing how mangled it got really shows you how much power you had to work with, looks like it would've gone through a whole tree if you could fit it in!
For your next iteration, and I'm sure you already worked it out after your experience, you may want to look into adding some sacrificial parts that will fail before something like that is able to happen 😱
yeah I was thinking that enclosing the hole blade in which will prevent the blade wobble and the worse that can happen is the blade will rub on the housing. This thing looks like it has the power to cut very large logs 6 inches or more. Reduction gears are really strong.
That’s why sheer pins were used on equipment that can stop suddenly.
Maybe a fast acting hydraulic ram and a guillotine could be safer
@@chox2001 There are a few videos out there with ram guillotines and they have one major problem is that they are slow and they tend to crush the log rather than slice it, of the ones I have seen. which is why buzz saws were used for a very long time. My main video is myself using a buzz saw.
@@kameljoe21 thank you that’s interesting
@@chox2001 All hail the Sheer Pin. The engineers 'mechanical fuse'.
There was a distinct lack of burning in this video. I came here for a disaster!
Really satisfying to see the blade just slowly slice straight through those branches.
Your videos are a welcome diversion. I love that you just get an idea, and build it. Reminds me of how I used to think anything was possible when I was a child.
Very good, Tim! Never give up, never surrender! Perseverance!
Onwards!
An unexpected education comes from all angles ... or indeed revolutions. Thanks for the honest entertainment 😃
It all one big test , big thanks for posting all your lessons
That was satisfying to see it chop through those willows like a hot knife through butter--until the end. :)
"Never fear!" he says, as I'm clenching my teeth through the whole video! Stay safe, Tim!
Yes, I was feeling the same way too, Sandra : - )
You have no idea how much I enjoy watching these videos - nevertheless that I don’t understand the first thing about it
Always a fun adventure on this channel.
Still my all time favorite tinkerer...(all we need now is a tailor, soldier and a spy) :)
Fantastic ingenuity
Bigger and stronger than before….. and safer too, I hope! Had me on the edge of my seat!!
interesting... the forces must be very large....good project
That's the spirit, never give up! (But stay safe, I don't fancy watching an amputation.)
A flat belt would work better than a V belt, they slip/clutch better than V belts.
Thinking about it you really need a jackshaft with fixed and loose pulleys & a shifting fork, that would be the only real safe/effective way to run such a setup.
I can research it if you like but I think they can both be flat, not crowned.
Your buddy with the lathe can crown them if not.
A disc brake would be a good idea as well.
Keep an eye out for crowned pulleys at flea markets/rummage sales, there are lots of the out there.
Cheers.
Hurrah! Thank-you!
From Littlehampton, West Sussex.
Marvellous videos!
Perhaps a new site address of 'Danger Man' might be in order. Exciting stuff. I admire your patience and persistence. Keep it up, Tim.
I love how you run counter to ever increasing health and safety requirements. Seems that each project becomes more lethal than the last. I'm astonished at the diameters it could slice through though: the stresses must be enormous!
Loved the updates at the beginning. Very nice concrete
Great project! I always love videos like this where one analyses mistakes made so we can all learn. I am also glad to hear the gearbox is fine.
Some stuff I have noticed from watching tons of these wood chunker videos online and attempting to build one for myself:
- Blades that have only a single cut, tend to perform best. Chunkers like yours that have two cuts seem to put more pressure in a shorter span of time. Maybe try a single, spiral blade next?
- Cuts made at a right angle to the wood are harder. Imagine chopping a tree by chopping ONLY at right angles. That's hard because it goes against the wood fibers. Try setting up the blade so that the wood will be cut at a diagonal across the wood.
Really great progress though! This is such a beautiful setup you have there and I am completely convinced you will get there!
Edit: and as others have mentioned some kind of mechanical fuse / sheer pin might be in order. I am planning to put one on my chunker as well. Shaft comes out the reducer, has a hole drilled into it. Over this shaft fits another, much bigger shaft with a hole in that one too. This last shaft connects to the blade. Then I'd place a tractor sheerpin into the two holes connecting the shafts. Should a similar situation happen again as in this video, you don't run the risk of ruining the gearbox.
Thanks, FD, but I spent a lot of time designing the blades so they do cut at a slope. Maybe more is needed though
@@wayoutwest-workshopstuff6299
I can agree with you that the slope/angle of the cut is not such a huge deal. You can see that when the gearbox was cutting clean through those massive pieces of willow! So keep that current setup if you don't want to change it.
What seems to make the most sense in my mind is to change the cut from two blades to a single one. Your current setup has the blades sticking out quite a bit, this creates an extra leverage effect on the axle. The closer the cutting edge is to the axle, the least amount of leverage occurs... Also, if there is only one cut per rotation you halve the pressure on the axle again because it takes double the time to cut through the wood fibers.
If I saw the output RPM on the gearbox towards the end, it is plenty fast enough for this to work like a charm.
Here's an example of a great spiral blade IMO:
th-cam.com/users/shorts8PGn0pbD1yc
Very entertaining. It is potentially a winner, just a few more hurdles.
You might consider a single shear pin in the system. Perhaps holding a drive plate attached to the gearbox, to a blade plate attached to the blades. You can make your own shear pins by grinding a bit of a notch in a bolt where the two plates would slip if the bolt was not installed. On my brush hog, the shear pin is a single grade 8 bolt, but that's a bit unusual usage of a bolt, normally they are special bolts designed specifically as shear pins. It does however do a great job of snapping off when I mow over a stump or something big.
Lots of stuff about shear pins online regarding snow blowers, including lots of home made shear pins from bolts etc, so it should be easy to research if you go this direction.
Thanks, Nope - yes, that all makes sense
When it was working it was soooo satisfying to watch.
Well the beast has shown it's strength!
If you want to reduce the stress in it you could move the point where the blade meets the log closer to the centre of rotation. This would allow smaller blades if you want too. Everything else you could do would add complications to the machine.
Have you considered using a different blade type? I have seen some impressive results from a car wheel rim cut to form a blade with the cutting edge in line with the rotation and would not be susceptible to bending!
Whatever you do, it is a fascinating experience seeing and hearing you talk about it! Please do not stop!
the power of the engine is amazing
Wow! 84 to 1, that's quite a special gearbox. It would be one hell of a start on making a dividing head
jesus these forces are astronomical! but it's fantastic that you made it work that well even if there was a lot of trial and error
When making it again, consider a hard brass or soft steel for the key. It's an easy part to replace, and you want it to fail first.
A 1/4” grade 8 bolt on the plate, you don’t want it spinning on the gearbox shaft, it will ruin it very quickly.
I'm going to build one of these. I've dreamed of having one of these all my life!
I just caught up Tim! I like how you bring so many friends into your work. The best part was when it was time for tea with Tim and Will.
It's my go-to reaction to most things : - )
12:57 if the top of the two guard rails open up a little into a funnel shape to guide the blade into the slot, it could prevent it from slipping out?
My two pence worth, your problem issue is the blade design. The blades need to be able to swivel so that centrifugal force holds them out. In this way, they chomp at the log until they work through it. Then the shear pin issue disappears.
You also need it to run it about 1.5 times faster for greater shear power.
It makes a really satisfying chomping noise!
You're using about 30 degrees of rotation per cut, make a blade that takes 180 degrees to cut, spread the load/work over more time and move them towards the centre like other people have said
If you cut closer to the shaft mechanical advantage would be on your side and the blade would be in the slot and less chance of twisting or bending. A shear pin on the blade will let the blade flop back. A greater angle will cut slower and be an advantage.
You blokes are great. Such great self reliance
What an incredibly strong & capable machine you've built, it definatley had an impressive break.
Classic illustration of the old saw "There's a reason we have engineers"
Have a look at some of the Yanky You Tube log chompers and you will see that they use a wheel with the rim cut into a cam shape and sharpened all the way round, which give continuous progressive cutting with the log being fed in on a slightly slanted flat plate so after a cut the log is slid down to a stop for the length required and the cutting action begins.
Great vid. Thank u. Best of luck with Mark 2.
The two pieces of angle iron that the blade runs between can be arranged even closer and in such a way that they prevent the blades from bending sideways. Should do the trick. Then it's on to the next failure point.
one man's quest to build the most dangerous machine in all of Ireland
Very impressive machine you have there. Like other have said maybe a softer key or shear pin to let the blade stop if it jams again.
I once saw an illustration of a machine used to cut firewood for steam boats in British Columbia, Canada. It resembled a small guillotine with a blade that dropped vertically on the wood. Perhaps something along this line (although it wouldn't cut as quickly)?
Have you considered using an old car wheel rim as your cutter, ive seen this work before, you sharpen the edge of the wheel in a decreasing radius, and you could use a wheel hub with lugnuts for attaching it to the gear box, it woukd be a stronger connection and the curve you cut into the rim can act like a curved knife to cut the logs. Search youtube for an example, there are lots of videos where this method is used, hope that helps. Love your channel and videos, and i hope you have a wonderful day!
Thanks, Jason - I chose this design because the frame could be easier
An improvement might be to weld very thick wedges either side to both stiffen the blades and push the wood apart?
Quite a lot of your blade cannot be used as it is behind the log support. If you reshaped the curve of the blade you can get more ‘slice’ over the arc and therefore cut with less difficulty. Fun video thanks!
In Engineering we have a saying "Failure is NOT an option! It's a topic," We design in places where 'Low Cost easily replace' parts blow up before sometihing dangerous/expensive breaks.
Might be worth extending your angle iron wood rest up some and splaying it at the top, so if the blade wanders for any reason, the guide brings it back into place instead of letting it get caught up like that. Seeing how wonky the blade hub was afterwards makes me wonder if the hub wasn't starting to give before the failure, which was why the blade got out of alignment in the first place.
Judging from the sparks off that key, it was high carbon steel---probably was fairly hard, judging from the damage. See if you can get something softer. McMaster (in the US) sells machine keys that are Rockwell B 50 or 100. The B scale is so soft it is tested with a ball bearing, not a diamond point.
interesting!
As crashes-and-burns go, that was rather impressive! :)
Ha - thank you : - )
I think the only safe assumption is that the gearbox will fail later, but prematurely due to internal wear. It's just very hard to believe that it could shear the keyway without putting some degree of twist in the shaft. I can only assume that when under load it's going to waste more energy to higher friction than previously. Probably not a deal breaker because it's not running a grain elevator 24/7 or anything like that, but I'd still just keep my eyes open for a similar one drifting about.
Wonderful video Tim!
I think others have said the same, but if you use shorter blades, or put the log closer so it uses more of the blade to slide perhaps, combined with a blade slot that engages at the tip of the blade for the entire cutting stroke.
Super fun to watch you and your experiments, keep it up!
Thanks, Albert - will do!
Keep the blade stationary. Come up with an oscillating mechanism to crush the branch onto the blade. Support the crushing arm pivot on both sides. More rigid and takes the bending load off the gearbox shaft. The logs don't have to be cropped first time, chomping down a tapered aperture.
A stationary blade would seem to be a bit safer than having to mind a pair of spinning blades should things go awry. Perhaps a sliding plate with a sharpened hole sliding on a stationary plate with a sharpened hole, like a cigar cutter. This would unfortunately do away with any slicing action on the blade and make it strictly a chopper.
Wonderful video! Thanks to Tim for taking us along for the ride.
Hi, perhaps grinding a centimeter or so of of the out going side of the anvil would help alot. Or even going with a single sided "bypass" anvil, rather than a slot. I think you are getting alot of pinch back on the blades.
Cheers.
Old square baler gearboxes are pretty sturdy.
my ideas, remove the slot for the blades or make the slots wider, also add a safety coupling with a shear pin that is going to snap in half and stop the machine from destroying itself in case the machine jammes again
I'm just thinking, when the machine was working you can hear one blade scraping against the frame every revolution. At the large pulley speed I think only one blade would suffice and maybe some tapered blade guides . Difficult to get the right belt tension between to tight to slip and slipping during normal use, some old agricultural machines had slip clutches as part of the PTO shaft, maybe a modification but normally they just rust up. Cheers
If you change the flat bar on which you lay the limb to be cut so that the blade slices more diagonally through the limb then the torque required will be reduced. Easy to test with a temporary wedge in place. Think of trying to slice through a small branch with a knife. You would naturally angle it to reduce the effort……
That chomper has all the hallmarks of a limb remover, take extra care when using!
Your doin great work out there. That's is a terrifying machine. Guess the next step is a blade guide maybe somthing semi circular
hence why engineers include specific failure points to protect the expensive stuff while replacing a cheap stuff becomes barely a hassle
Oh my God. That rotary guillotine gives me nightmares. No safety shut off, no safety shield, no emergency stop. Just one slide away from a deadly slip up. Lucky it killed itself first.
Safety things are there to give you a false sense of security. If you pay attention to what you are doing then you should be fine.
@@kameljoe21 until someone slips on a patch of mud or ice and falls head first into it.
A Victorian "maiming machine "
Love it!
Great machine. Think you may need to "up" your liability insurance though! 😄
This is how the Panama Canal was built. They admitted that they did not know to do it, so they said " do something, and correct the mistakes."
If you guided the blades into the slot you could keep that from happening. And if you make the curve on the blades shallower then it will take less force to chop through them.
instead of brut force us overwhelming force. Increasing your RPM will increase potential kinetic energy, thus over coming resistance. This will also decrease the blades desire to twist or deflect while under load ... It sure looks awesome thou, in a Mad Max kinda way.... I like it :)
If I may suggest, (For reference, viewed from the end of the shaft, rotation is clockwise.) I see that the cutting edges are nearly at a 180 degree plane to the drive shaft rather than at a very sharp angle. If arranged as such it would slice the wood rather than chop it. If the blade engages the wood closer to the shaft, the resistance has less leverage to impede the travel. Liken this concept to choking up on a baseball bat or a hammer. That may reduce the force needed from the drive train to pass the knife through the wood. I believe much efficiency would be gained and it may help your belt slippage problem.
Excellent point! The other versions I've seen progressively slide through the branch. I've even seen a car wheel rim notched so that it gradually widens used as a cutter
I agree that better blade shape is Important in making a more progressive cut - at the moment the torque is going high very quickly for not very long, a better blade shape will apply torque for a larger part of each cycle and reduce the shock loading on the drive train.
Dang it! On the one I just completed, I run off a tractor PTO @ 540 RPM and through a 48/1 box. Currently I use just one slicing blade but tomorrows task it to make a two blade unit, similar to yours. I made mine out of 1/2" mild steel andit is plenty strong and the edge seems to hold up fine. I had thought about running the blade through a slot like yours but instead I run the blade up against one side of some heavy angle. I also only sharpened one side of the blade similar to pruning shears. That way the cutting force drives against the heavy angle and keeps some of the pressures during the cut, off the actual gearbox. It looked like your blade was sharpened equally on both sides. I use a shear pin which is just a 5/16" bolt. It is on the input shaft and easy to replace. I have been cutting dry cherry wood from 3" dia. on down and been really impressed. I also noticed if I fed the wood at a slight angle it seemed to cut easier than just going at a right angle to the grain. Keep up the good work and thank you!
I'd be interested to see a video, Ben..
In old milling machines the gearbox has a safety pin that shears before the gearbox or motor stuffers. The pin is usually out of aluminium. Maybe you need one of those to protect your lovely engine or expensive gearbox.
Great determination, as always!
think with it working as well as you had it id make a half round top guide for the blade to travel along so it cant move out of alignment
Very interesting and entertaining too!👍☘️
Every time that blade makes a turn my inner safety officer has a heart attack
I'm sure you are already aware, but it takes surprisingly little crown to make a belt track properly. I restored a few shipbuilders compass band saws, these originally had a sort of bakelite tire with the crown cast in. Well, bakelite or whatever it was was not nearly as durable as the builder had hoped. I was very wary about cutting into the original castings at all, but I could not find an alternative. I ended up crowning the wheels with nothing but an orbital sander. Have yet to have a problem
Thanks, that's a good idea - what sort of height would you suggest for a 4" belt?
@@wayoutwest-workshopstuff6299 I'm ashamed to admit I did not take very precise measurements. I mostly used a blade and trial and error to make the adjustment land in the middle. I've noticed the old fashioned tractors that take the very wide flat belts, they seem to have a remarkably little crown, less than a quarter inch