Stump Saw

I wonder if any sort of curved saw similar to this "Stump Saw" exists. I have a bunch of bamboo stumps clumped together that I need to deal with, and I'd like to cut them below ground level.

So, I wish something like this exists. The blade is very thin, to minimize the amount of material that needs to be sawed (in contrast, a chain saw is relatively thick). It uses its curved shape to keep the blade perpendicular to the desired cut direction - which is "sideways". The idea is to cut below ground level by sawing a shallow "scoop" shape.

In the design pictured, the saw belt has holes for engagement with a sprocket belt. The sprocket belt is thicker, with teeth to engage the saw belt, as well as a toothed edge that the motor engages. The sprocket belt is wider than the saw belt, so it prevents the saw teeth from rubbing against the guide.

You hold the tool by the belt guide, giving you good control and letting you operate the tool without bending over too much.

I'm guessing I could DIY a crude hand powered version which is simply a flexible saw blade between two handles, but I figure it would be hard to get the thing going without some sort of guide. Maybe a cylindrical drum could serve as a guide ... first hold the drum down against the stump, and wrap the saw around it. Maybe first hammer a nail into the stump to help hold the drum in place ...

I have seen something like this: in making shamisen, people use a bandsaw blade tightly constrained to force it into a curved open shape so it can cut U-shaped trenches.
The kerf (specifically dirt) is going to be very hard to deal with as it'll tend to jam the blade.
Yeah, maybe if the saw teeth were designed more like a circular saw's teeth - to "dig" and carry away the material. But I have no idea how to design such things, much less make them.

I was thinking maybe I could try to DIY something using a cheap off-the-shelf bandsaw blade, but they're super narrow so I don't think the drum idea will work as a starting guide. With a wide blade (like a typical hand saw), the drum could act as a guide for a few inches. But a hand saw's blade is not so flexible. I mean, it'll flex far enough, but only if you apply a lot of force.
Oh wait. Maybe the guide can just be a curved sheet with a U shaped notch in it. The notch goes around the target stump. I can use a mallet or hammer to jam the guide through the soil. Then I take my DIY flexible saw and wrap around the guide...

Of course, an off-the-shelf bandsaw blade only cuts on one direction, but it's worth a shot.

Still, I've got a big problem that my bamboo clumps are just so dense that I typically don't have space for the guide...
I once "dug" up bamboo roots... with an axe.
I was wrong: it was forming a koto not a shamisen. I still haven't found the video.
Bandsaw blades are just carbon steel so you could file them to be bidirectional.

I'd be tempted to use a cable saw of some sort. Dig on far side, loop the cable over the thing you hate using the dug hole, put tension on it, and start dragging it through. That's how they cut out giant rocks in quarries. For that they use abrasive slurry, but bamboo will give to just being cut through by woven multistrand steel cable.
I may have to try an axe or something, although my wife doesn't want me to use an axe (for anything).
@[email protected] Ooh! Cable saw!

That looks perfect for what I need, actually!

I tried looking them up, but I didn't know what to call it so I ended up searching for "hand chain saw", which is a similar device but with a chain saw rather than a cable. What I found was not entirely promising. But I think a cable saw would work better for what I need.

I think.
There are some that have abrasive particles brazed onto the cabling.
Some are just two rings with cable between them, that can cut down a tree if you're patient.
What I would LOVE is some sort of machine that just pulls on giant loop of abrasive cable that slowly but surely cuts through this 9 foot diameter cluster of stumps over ... however long it takes. Days, or even weeks.
These things:
can cut through a skyscraper or a ship.
But they're not cheap.
I've never seen a small diy version, unfortunately. For stump cutting this would be pretty useful.
Oh yeah, that's precisely it!

Maybe a DIY version could use a reciprocating wire. That way, the engine or motor simply drives a wheel and the wire is driven by an off center knob. Thus, you could adjust things ... putting the knob near the center gives you a lot of leverage but less motion. Putting the knob near the rim gives you a lot of motion but less force. The other end of the wire would have your tension system... I'm guessing the easiest thing would be a simple weight at the end and a pulley at the top of a pole.

For this application, I'd have two pulleys attached to stakes in the ground to ensure the cutting loop is at the ground level I want. Thus, the driving motor or engine and the weight tension system can be at any height.
Bill B diaspora
As i mentioned in a shared post, sawzall reciprocating saw with long pruning blade will work.
@Bill B Thanks! I do have a couple reciprocating saws, but maybe I don't know how to use them right. The vibration just gets my hands and arms sore in no time.
Bill B diaspora
They do vibrate like crazy, but that never bothered me. Some people are particularly sensitive to vibration, i noticed that when stone carving with air hammers and people would use anti-vibration gloves. But one thing, a pruning blade will cut fast and the total length of time might be tolerable.
Bill B diaspora
about the recip type saw, the material has to be fixed and not vibrate as no doubt you know. So i assume you would only use it on bamboo if you're cutting below the surface into the dirt where the roots are relatively somewhat rigid.
@Bill B Thanks again! Don't necessarily assume I know the basics, but in this case yes - I know. I've previously tried to use a reciprocating saw on branches that were too loose for effectiveness.

The part of the bamboo I'm cutting now is very firm and won't budge at all. I'm currently using these loppers but the "jaws" aren't big/wide enough to cut where the roots make it too thick to get around.
Bill B diaspora
Ah, then recip pruning saw will do just fine it reaches in far enough. I have a big holly tree stump whose root is like iron and i tried cutting its roots underground with limited success.
Bill B diaspora
And of course don't forget a simple keyhole or other narrow bladed hand saw with a long blade.
Okay, I think that maybe a DIY band saw sort of thing could be done using a couple round stakes as guides. The idea is to hammer the stakes at a steep angle to the ground astride the stump(s).

The saw is a band saw blade, cut so it's no longer a loop; with the ends attached to handles. I wrap the the blade below the two stakes, and just work it back toward me into the stump (and under the ground slightly).
Bill B diaspora
But the band is flat with teeth point down or up, so how do you keep the edge cutting horizontally? Wire saws have to use a round cable don't they?

Be much easier to use a sharp axe and work your way around it. Or hook a rope to your car, lol.
Bamboo's in so hard you'd rip your bumper off, I think.
This is an application for dynamite.

I'm not saying this is a good idea, but if you took a fairly long loop of wire and made it into a figure 8, you could loop the crossover around the tree stump, and put both of the loops over the driven wheels of a car that's up on jacks, and the rubber tires would act as capstan drives. The 8 means the two wires would be going in opposite directions so the same-direction wheels would be pulling them correctly. Sooooo you have the jackstands on industrial rollers, and a comealong hooked to the bumper, and you slowly pull the car backwards, maintaining tension on the cable system. This would be a lot easier with an old pickup that had steel bumpers, as you could hang c-clamps off the bumpers to keep the wires aligned with the tires.
@Bill B The band bends around the guide stakes, so the blade will stay aligned parallel to the plane defined by the stakes. This plane isn't completely horizontal, but rather tilted a bit (so the top of the stakes are above the ground and the tips of the stakes are below the ground).

The idea is to pull the band saw blade back and forth, while working it toward me as it cuts the stump/roots between the stakes.

I want a band saw blade rather than a wire because a wire would simply cut into the stakes. I want the blade to slide around the stakes without digging into them or cutting them.

@[email protected] I feel like the first time the wire hits a snag it'll slice your rubber tire right away. That's why I was pondering a reciprocating wire attached to a knob (via a ring or loop of normal wire or something). I feel like the failure modes would be less annoying and setting it up would be less finicky. Depending on details, a snag would likely result in either the wire snapping or the attachement to the knob snapping. Or the engine or motor just gets stuck.
Just ... be careful. Doing it with an axe was scary at times, but at least the force was directed downwards, and no engines were involved.

Engines combined with wires or blades make up several chapters of the "Dead workers book".