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There are two distinct sides to this product. One is the extremely good value for the components alone - including two seemingly decent batteries and a matching charger. The other is the fact it's a competent little chainsaw with absolutely no interlock to reduce the risk of accidental operation. And that's not a great thing for chainsaws as they have a voracious appetite for human flesh.
The unit does at least come with a small shield to reduce the risk of injury due to kickback (When the blade suddenly bites and throws the unit back forcibly.)
Other gardener-style reviews of these common units rave about how long the battery lasts, and how effortlessly they cut through branches. It certainly made short work of fresh and old dried out branches when I tried it.
Internally it's very simple, just like other modern cordless tools. A fairly rugged battery connector, common pulse width modulation speed control and a motor with a thermal trip/fuse attached to the side. (Possible failure point?)
The gearbox is made of plastic with steel gears and is very minimalist. The motor cog drives directly onto a larger cogwheel with a long sleeve bearing. That larger cog has a keyed shaft for the chain drive sprocket, which is held on by a wire circlip/snap-ring.
As with most other chainsaws the chain rides in a bar, which is a sandwich of two metal plates spaced apart to guide tabs on the inside of the chain. That bar can be moved forwards or backwards to tension the chain correctly at a point where it's not so tight that it binds on the guide bar, and not so loose that it can skip out.
Full size chainsaws have a simple oil wicking system that keeps the chain lubricated with a very sticky oil. This one has no lubricator and is not supplied with oil. I added some around the chain and bar before using it.
The charger's LED indicator is a very crude current sensing circuit that will indicate that the pack is at least near full charge. It appears to be using the lower voltage of the red LED to extinguish the higher voltage green one.
If you get one of these units I strongly recommend removing the battery when not in use, as an accidental operation of the trigger will cause serious wounds. Definitely make sure the battery is removed before adjusting the chain. Keep it away from kids and make sure you attach the anti-kickback guard. This unit will require extra care in use as its size and convenience belie its dangers.
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Lithium, electric tool mini cordless electric chainsaw. Let me get this out of the box and describe well what's inside. Let me show you that it's like an unboxing, that's nice! I don't do many unboxings instructions, uh written in english, very odd instructions. It's like someone deleted all the spaces and then added them in random positions.

What we have in here is an unusually light charger. I tried opening this already on a live stream. Recently, it's very hard to open it's unusually light. It's really bizarre.

We have a spare chain and it says it's an expert chain, but it also says angel of chain angle of chain and angel of filling angle of filing. It comes with two rechargeable lithium batteries, which are apparently possibly makita type clones uh rated 21 volts. They say it comes with a pair of gloves to stop. You chopping your hands off, that's not going to work and it comes with the handheld chainsaw right too.

Let's get this out. I have just knocked over some bottles of flux and stuff like that, but i also have a bottle here. I had a bottle here: i've misplaced it of chainsaw oil because i'm going to uh oil this thing and then i'm going to take it out and we're going to chop something up. But let me just show you initially.

Let me just focus down on here: that's better! Let me just show you i'm going to connect this, but i'm going to be very careful, because this thing has no safety interlocks, there's nothing it only as soon as you pull this trigger. This chainsaw blade is going to start running, so let me connect a battery to it and give it a quick zap there. We go perfect right today. What i'm going to take the battery off now for safety reasons, and i'm going to take it outside oil.

It and uh chop some wood and we'll see how well it cuts wood old, dry, wood cuts. Okay, fresh greenwood also cuts okay, not bad right, let's explore so. The only thing that wasn't supplied with this you've got some basic tools and a replacement chain. The only thing that wasn't supplied was chain oil for chainsaws, and this oil is a very sticky gooey oil.

It's designed to actually cling onto the blades and not get sort of thrown off or or basically spread onto them. Ultimately, it does, but it doesn't have an oil feeder, so you're going to have to oil it. I don't know if they recommend that i didn't read the instructions. Well, there we go the chain yep right, i'm not really sure how you'd specify i'm not really used to changing chainsaw blades, i usually just buy them for specific models.

I shall investigate this, but it's a nice sharp chain and, as usual with these things, you can sharpen them. If you have the correct tools which is kind of essential for chainsaws, the batteries are quite heavy. The batteries weigh about 310 grams, each. The charger weighs 69 grams.

The unit weighs 743 grams. When you add the battery on it comes up to just over a kilogram at 1053 grams. This is a safety guard. You've got two screws on the front here.

One is for adjusting the blade tension. One is for the safety guard now, i'm guessing the safety guard is for two things. I guess really it's an anti-kickback guard to try and stop it. Carving up your face is the first thing that comes to mind.

I should have put that on before i used it, but i didn't: let's uh take something to bits. I shall take this apart first, so let's go into this, you undo the cover over the chain mechanism and if you undo this screw here, this is a double-edged double-sided screwdriver. It supplies. I know this because it popped apart when i was taking it initially.

There is a screw down here and when you're actually set setting this up, this moves this pin to actually slide this bar back so forwards. It tensions the chain. The chain should be tight enough that it's not taut, but just tight enough that you can just pull it and it's got a little bit of slack coming out there too tightened. It puts excess wear on this and the chain too loose, and it may actually skip right out of the actual chamber that gets adjusted by this little screw here, which i shall loosen off now and when i loosen it off that should loosen it enough that i Can then lift the chain bar off and the chain the chain is just driven round by this sprocket.

There is the mechanism slight that slides backwards and forwards. Very simple: don't do what i didn't tighten that one thinking that was a tensioning system. It's not let's go into this a bit deeper. I think i was going to drop out here.

Probably it is held together by torx screws, which i've already pre-measured so to get the correct screwdriver, not sure if all the screws are going to be the same length. It'd be really nice if it was it's always a good good thing, when the screws are all identical length, but sometimes they're, not that's a good start so far. The lack of safety is a concern in this. If you have one of these, i strongly recommend taking expectations wearing gloves to at least provide some protection thick gloves, but making sure that when you're not using it take the batteries out of it.

If you had this in a toolbox and you reached and pressed that button down, even though it's got a fair, decent, mount spring tip, if it started off, the blade would make short work of your of your hand, which is not good. So far, all the screws have been the correct eye, the same size. This is good. This one is recessed deeply, which is a bit annoying, but that's all right.

I have the. I have my deep torques to get that out, and this should be the last one. It mentions in some listings that this is a brushless motor kind of skeptical about that, but you know what let's find out: oh, does it come apart easily i got more screws to take out. Let's loosen this off.

Is there anything i'm missing here? Have i missed a screw, i don't think i've missed a screw. I think it's just tight fit, which it should be. Maybe i should pick that up. No there it goes it is not.

It is not an electronically commutated motor. It's a plastic gearbox. It's got a standard variable speed control system with a little heatsink on the outside it'll, be super mass produced uh. Can i get this out for that? Gon na need another screwdriver bit to get this out? Is it gon na reveal much other than the fact that this is a plastic gearbox? I suppose really in the spirit of eve, i should be going deeper.

Oh, it's actually, the same the same bit! That's nice! Again! I looked when i saw this online. I was very skeptical about it. I looked at reviews on youtube. People had bought these and they were all raving about how much stuff it cut.

I think, ultimately, that uh the plastic gearbox does allude to certain disposability. It's going to come out anything else holding it in. I don't see anything else holding it in. Is it latched in somewhere? Is it some spring-loaded mechanism? I shall push in the front or has all this has been added afterwards and i don't think there's a grub screw.

I think this has been pressed on. I don't know if this is going to come out, then it looks as though this wheel has been right. Give me one moment: i'm just going to actually you know, let's not pause, let's just try and grip that, let's see if that's gon na unscrew, no, it's just rotating the whole thing. Hmm, it's just a gearbox, but you know i feel the need to take it out at one moment.

Please and the secret is apparently this little circlip that was around that which is now off letting this lift off and now the gearbox drops out. Oh really, that's it not much gearing it is this little direct drive from the motor shaft onto this, which is going through a fairly deep bearing to the back of the unit for extra uh stability. There's really not much in here ave would be analyzing all the metals and things like that. I'm not going to analyze all the metals i'll animal analyze, the electronic stuff.

The speed control will be a standard, speed control right. What's next to open up now, i've taken that into bits all right tell you what i'm just going to uh i'm going to pause when i put this together just so, i don't mix all the hardware up and then we'll go into the battery packs. One moment please right battery time, but before i go into the battery things worth i mentioned, there's a 100 degrees celsius, thermal cutout on the side of this. So that's quite interesting.

Wonderful. I hope it's a self-resetting one. I think it is, but it's just if you've got one of these and you're using excess in the garden it cuts out. It may be that also a potential point of failure.

I'm going to put this down the ground now and make sure i don't smash my feet into it. Let's take one of the batteries apart. It feels hefty. This doesn't always mean anything.

It might be full of metal. Hopefully it is full of metal battery metal. It's interesting to know that you can get 21 volt ones. You can get at four to eight volt ones, 56 and well.

This uh charger actually says it goes from uh output, 21, volt to 98 vf one amp dc by 9 to 8 vf. It means fake, because this is just a 18 volt charger effectively. This probably has five cells in it, because that's what you'd typically find an 18 volt battery pack with five cells and a charge control circuit board. Well, a protection circuit board right at one moment.

Please i'm just going to take a picture of this and explore it, try and find what the chip is and we'll analyze the battery. At this point in the battery says uh inr or 18650p 2000 milliamp hour. That would be quite respectable. Actually, if it was two thousand milliamp hour interesting stuff, one moment please and resume uh very interesting.

The chip it's using is a cm 105 one which is a five cell protection pack. There is the output to the actual tool, because the charging port is in the back here. You basically plug into this little charge port, but the output for protection of the mosfets. It has a back emf, diode wired across those two pins.

I wonder what that was. Initially, the mosfet here is the discharge. Mosfet, that's used to basically shut the battery pack off when the voltage is too low or potentially a monitor for an overload situation as well, where the voltage it measures the voltage across this mosfet and if it gets too high. It detects that as high current overload and the chip will switch off, there is the option for putting two mosfets in parallel.

I was thinking so where's the charge protection well the charge protection. Is this tiny little mosfet here, because the charge current is somewhere between 500 milliamps to one amp so from the charge port we've got uh a connection via a diode and then over to the negative connection via the mosfet, so the chip schematic it gives a couple Of options for the wiring, it gives one where you've got the inverse uh series mosfets for controlling charge and discharge. But this is the circuit they've used down here, which is where there's two separate mosfets used. So the only the big mosfet is needed to switch.

The current out and the charge mosfet is that tiny little one, but everything else is more or less textbook. There is the facility in that chip for a temperature sensor, which is bypassed by this little resistor. That's been sorted across that position, so they're, not monitoring for a temperature situation in the pack. Anything else worth mentioning here, not really it pretty much fulfills the thing each each cell is monitored via its own resistor and capacitor, just forming a sort of like a simple decoupling circuit, so that you get a fairly smooth, consistent input where it monitors that voltage.

There's no balancing at all, as there is an even posh battery packs. All it does is, if say, for instance, that something had happened, a packet got wet. This seems to be a common thing and it caused a pool of water had caused this battery to go low, this lithium cell, to go low if these ones are say fully charged 4.2 volt and that one was way down low. It was almost the point of cutting off, then it won't balance them again.

If you put that on to charge uh, it will terminate on the batteries that are already full, but if you plug it into the tool it will terminate on the one that was almost discharged already so you'll end up, the battery pack just doesn't have much capacity. The answer there is, if it's not damaged, if it's not got a bad cell, is to measure the voltage across all the cells individually find the one that was rogue, that there was low and just uh gently, bring it up to the same vultures, other ones and Equalize the voltage accurately to the 10th of a vote across the mall, and that will restore the battery pack if it loses capacity again suspect that one of the batteries is damaged and it's time to dispose of a controlled manner. Discharging all the cells completely before disposing of it in a suitable place, the in the contents of lithium cells, it's actually a mixture of copper and aluminium and graphite and lithium iron cobalt. I think it is all fairly inert materials.

It's the energy they store. That is the danger. This is a one of the things the battery manufacturers all distance themselves i should have. I should make a video about that.

They distance themselves from people using these cells out with things like packs, 18650s are designed for use in packs, and they basically put a bulk disclaimer out all together. It must have been the battery manufacturers association organized it to basically say if you use these individually. We are not responsible if they blow up your pocket when you short them out in your keys, because that's what's happening with the vapors uh. So that's it really not much this little tiny, uh mosfet for charging this big one for switching the output with the option to boost it up and add a thermal sensor.

It's a typical battery pack to be honest right. How am i going to get into this little thing because this i'm going to have to use brute force? I have sponged this unsuccessfully to the point. I actually bent the spudger a bit. I can get the spudger in like that.

I can slide it along, but uh there's no obvious screws. I i rank there's glued pillars in here, so i'm going to have to get destructive. I may have to get eve's hammer out and just give it a little tappy tap tap and see. If i can get into this one moment, please the eve hammer of ultimate knowledge did free the truth.

The truth is now free for us to explore interesting case. The case was kind of held together with pillars in reality. It's got a clips here here here and here, but with supporting pillars to actually make those clips hard to part. So once you force this together, it's actually extremely hard to get apart for reference.

The case is called an xy 207, not sure who makes that it's quite a good case. It's very, very robust stuff, ricocheted out. I think it was just an insulation plate. There was also bits of foam holding this circuit board in place.

The circuit board has the main voltage switch mode circuitry on this side, driving this transformer. What looks like a class by capacitor but isn't its part of the snubbing network? There is no class, wise capacitor and then the output side. It's really just um a voltage monitor an lm358 to monitor the voltage to actually light this led to show it's charged it doesn't. The current regulation is simply the energy capacity of this inductor when fully charged from the primary side, the flyback circuitry, and then, when this side turns off and that dumps it puts out a portion of energy.

So the current limiting is ultimately in the transformer. Let's take a look at the circuit board: we have the incoming supply, which has a fusible resistor, 4.7 ohm, leading to a bridge rectifier and then there's a smoothing. Capacitor we've got the fm three seven eight three ga chip and it just has a support components. It has a snubber network, it has a the current sense circuitry, it's got feedback circuitry and it's also bootstrap i'll show you this on the drawing the bootstrap is consisting of this diode here and this little electrolytic capacitor.

Here on the output, we have the rectifier, diode and smoothing capacitor, not very big uh, and then we've got the lm358 to actually monitor the voltage and just switch the led. That's all. It does not too much to say about that horrible contrast of circuit board. This is much better.

Let's take a closer look, i didn't draw the op-amp and maybe i should have, but i didn't incoming supply 4.7 ohm resistor. There's the bridge rectifier, it's a discrete single package project. Far there's capacitor 6.8 microfarad, a few components missing a few components. Added uh the bootstrap circuit for this chip.

The way it powers itself is initially current flows from the positive supply rail. Through this one mega ohm resistor to this capacitor charges it up once it's charged up to suitable level. This then starts once it's started. If everything is working, if the output is not short-circuited uh, it also as well as powering the output, also powers via this diode, it keeps that capacitor charged up and that's how this chip powers itself.

If something goes wrong, if this gets shorted or it can't actually make up that power supply, if this purse play goes wrong as well, this capacitor it will do that bring blink blink hiccup thing, because it's repeatedly trying to start and failing to start when it turns On there's a mosfet inside that the current flows in the positive through the primary uh down through the chip and then through these current sense, resistors, there's one ohm in parallel with 9.10, which means it will just be the total volume will be just slightly less than One ohm, the lowest value, takes a precedence here and that measures that basically regulates the amount of energy put into the transformer. There's a feedback circuitry to show that things are good. Basically, they've set a resistive divider here, 15k and 7.5 k going to the feedback which also lets it monitor. What's going on the transformer that is about it.

So this thing just blindly just pumps, energize the transformer and then when it turns off the field collapses and that's when the current goes through that diode to the output. So it puts control portions uh with magnetic isolation of energy through that the one other thing worthy of note here is this 100k, in parallel with a one nanofarad capacitor and this diode from the primary. What that does is when the transistor turns off in here. There's initial quite high spike before this diode can start conducting it basically just nips off the peak of the emf, the back emf that could otherwise the high voltage can damage this mosfet.

So it diverts it to this capacitor, and this little resistor here just keeps trickle. Discharging that capacitor uh just to basically take a control chunk of that uh back emf spike, but without actually shunting too much energy. It's needed going through here. After that, it basically has an op, amp uh driving the led i'll just draw this in roughly uh and the op amp monitors the voltage across a resistor going to the output.

Is that resisting the positive negative? It's actually, i think it's in the negative, so it actually uh monitors the voltage drop across that resistor and if it sees a significant voltage drop, it knows that this battery is still charging, but if it sees the voltage equaling our side, it will signal to this Op-Amp that that there's no charge current going out and that's just when it says charged and it does that trick. There are two leds. Let me bring the drain in again. There are two leds in this package: one is powered continually and the other one uh, probably the green one and the other one, the red one is switched by the lm358 and instead of turning the green off all it does.

Is it switches the red one on it, swamps, the green out to show that it is charging and when it has charged, it turns that red led off and the green light shows, even though it was lit all the time in the background? So what my thoughts on this thing in general, the batteries are typical of a battery pack for a tool. It's not bad good, decent springy contacts, good solid contacts - i guess it is based on another brand's battery uh interesting. The charging port is built onto it. It does have the protection as the option for you to upgrade that protection with another mosfet or they'd probably have to be matched, and it does have both discharge protection.

It has charge protection with full monitoring. I should brighten this image of a wheat head there. We go it's not bad. It's a generic package um the case that for the power supply snaps together very tightly to the point, it was very hard to get apart, um the tool itself.

It has a plastic gearbox, that's no great deal, because the main components here are steel that the bearing here uh, presumably a sleeve bearing uh the motor, looks beefy. You can't really tell how well it's going to last. The little regulator will instantly disintegrate it'll be full. If i try opening, it will have a minimum number of components just for the variable control, using positive modulation and a little battery connector that slides in you know it's worth almost worth actually getting something like this just for the batteries, the charger and this sort of Bit down here the connector, because then you can tap into the battery and you could just make a little power supply.

It uses these. It's very! It's surprisingly good. I shall say how long would it last in continuous use, i'm not really sure, but the construction in general um looks pretty typical. I guess that's just what happens you mass produce things? The batteries look acceptable.

The construction of the unit looks acceptable. It just seems like a fairly decent generic unit, just lacking that safety. That is kind of essential. Just that little double function that you know uh.

You have to press make a concerted effort to push that button. That's the biggest weakness, it's a fairly stiff, springy plunger, but there's still that risk that you know, particularly if this got into the hands of kids or something like that, that you could hurt yourself because chainsaws are ruthless. They they are they're, not very friendly to hands and faces and body parts at all, but other than those uh. Those things that safety issue.

It seems: okay.

9 thoughts on “eBay finger-chopping pocket chainsaw”
  1. Avataaar/Circle Created with python_avatars Grumpy Old Man says:

    I used one to take down a whole tree and cut it into small enough pieces to go in my burn bin. The trunk was about 4 inches in diameter and it was around 12ft tall. It worked well but the thermal fuse started kicking in quite regularly once I'd been using it for a while, which was quite frustrating. It takes about 30 seconds for it to reset itself but to be fair, I was asking a lot of it. I only bought it for that one tree but it was cheap enough to justify the purchase. Once I started I was unsure if it would even last for the whole job but it's still going strong. I didn't have chain oil but some general purpose machine oil worked well enough. It's not the safest of tools, but I still have all 11 fingers.

  2. Avataaar/Circle Created with python_avatars Jakob says:

    Also got one of those… was like 24USD for a blue one called volewerks.. though that one do have a handguard and a safety switch and a chainsleeve that is flipped over the top of the chain with a spring.. but it arrived cracked at the base to the battery, where there are two eyes that interlock, but its a different mold than yours as yours are all one piece all the way down .. quality two-component poxy glue fixed it in my case…but obviously taking my precautions
    you get way more torque if you use a 6amp Liion-pack versus these weak ones that are bundled.
    I purchased a 6" chain and plate (was like 10USD total to Denmark ½ year back), and it works great with that also… it got a metalling roller at the front.' versus the native 4" plate that just grinding in a plate groove.. you can likely also fit the 8" plate I would reckon, but it is a small brushed motor so don't overdo it..
    it does what it says, just have a very firm hand when using it, as it is a chainsaw and it will chop anything that comes it in its way. same as those chainsaw blades you can get for angle grinders that are rapping like there is no tomorrow… so expect kickbacks etc, but still puzzles me how they can make these things at these prices, but I also live in the world most taxed nation with the worlds oldest flag..and consumer prices are ludicrously high

  3. Avataaar/Circle Created with python_avatars Seth B says:

    Gifted one of these, a slightly more improved model, different brand…I am quite impressed having tons of experience with gas saws. Does good for yard and camp. Basically don't be an idiot with this one be safe!

  4. Avataaar/Circle Created with python_avatars lexmarks567 says:

    I have one of these. Decent little deadly toy. Mine doesn't have the shield though. Also most electric Lawn edgers use a similar gearbox. I had a Weedeater brand electric lawn edger and it just had the motor with a small gear that turned a bigger gear that the blade was attached too.

  5. Avataaar/Circle Created with python_avatars tigerseye says:

    They did supply the upper fence for safety, but it should have a molded in cross handle for a second hand to help control the saw. They omitted the lower wrap -around hand guard altogether. Looks to be an effective limb saw, as long as it doesn't cut YOUR limb off. My guess, Chinese.

  6. Avataaar/Circle Created with python_avatars Jordan Shilander says:

    My friend built something like this from a cordless angle grinder and a full size bar, like 24" or so, to make a two handed chainsaw sword. I told him it was nice knowing ya, looks super dangerous. He likes chopping cardboard boxes with it.

  7. Avataaar/Circle Created with python_avatars Cake says:

    This puts the danger to a new level, Its a one handed chainsaw with no leverage or power. Because of its size and uselessness you have a tendency to hold the wood with your free hand. Just watch him use it, i can easily see it skipping around and lopping off a finger or two.

  8. Avataaar/Circle Created with python_avatars Data says:

    Lol i have one of these. Well it doesn't look exactly the same but most components are identical (battery, charger, chain, screws/bolts, and probably motor). There's tons on Amazon that are all basically the same 4" chainsaw but differ slightly in cosmetic design/colours and battery capacity. Before purchasing i spent some time looking at many of these, and unlike yours, the vast majority have trigger safety buttons, including mine. I've cut many things so far, even a large tree, which was wider than the small 4" chainsaw so i had to cut around the trunk. It still only took 90 seconds and the motor didn't struggle. It's surprisingly good for the money. The instruction manual is laughably bad though.

  9. Avataaar/Circle Created with python_avatars YouTube Censors says:

    Oh, I know! Make a small dual chainsaw shaped like opened cissors, that you operate just like a pair of scissors, squeeze the handles and the two blades come together on either side! Stupid, dangerous, and hilarious!

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