Harbor Freight has a new Hercules beam cutting attachment that turns your 7-1/4″ standard circular saw into a beam cutter.
They advertise that the new beam cutter can cut beams up to 12″ thick in a single pass, and that it can be used to cut beams, posts, rafters, stair stringers, railroad ties, and logs.
Regarding tool compatibility, the “chainsaw bar and chain mounts securely to most 7-1/4″ circular saws.” Harbor Freight also says it can “securely mount to both conventional and worm drive saws.
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The Hercules beam cutter attachment features a low-profile anti-kickback chain, guide bar the entire length of the chain, and automatic oiling system.
Harbor Freight encourages shoppers to compare their new Hercules chainsaw attachment with the Prazi beam cutter attachment, which is currently priced at $169 at Amazon.
There are other attachments from generic no-name brands that are less expensive than the Prazi, but I haven’t seen any as low as the $60 Harbor Freight is charging for the Hercules.
Price: $60
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Mopar
I don’t see a replacement chain or a chain spec listed or printed on the bar for the HF one.
Prazi does not list a chain spec either, but their branded replacement chains are readily available.
Prazi is very clear about only using theirs on worm drives. I wonder if using the HF one on a conventional saw would actually overstress it? As we all (should) know; what you CAN do with a tool is not always the same as what you SHOULD do with a tool.
Jammer
Hmm. Not sure why a sidewinder would not be recommended over a worm drive. They clearly show a sidewinder in the picture.
MM
The worm saw generally has more torque, so I suspect they’re recommending it to be used on a worm saw because they are concerned that a sidewinder might not have enough oomph to pull the chain through a tough cut. Although, I will say that generalization may have been true back in the corded days but it’s certainly not true now. Today we have cordless sidewinders which absolutely spank a corded worm saw in terms of power.
Another thought is the adapter for the chain might require the “diamond” sort of arbor which is standard for worms saws but not for sidewinders.
Kirk
Could be most worm drive saws are left sided blade cutting, clockwise and you have to flip the blade over label in ,teeth cutting from under material and through to the top. Maybe chain will run the wrong way forcing your saw up and away from the beam?
Larry L Davis
You could flip chain to run the other way.
Uncle will
With regards to the popular circular saw topic of “corded vs uncorded” That’s the most wildly absurd statement I’ve heard to date. You find me a battery operated sidewinder that can out power a 15a corded Skill hd77 worm drive and I’ll buy you a brand new one.
MM
Many of today’s “higher power” battery platforms like Flexvolt, Makita’s 40V, Flex, etc, will do that. Handily.
For example, this demonstration from 4 years ago:
https://www.youtube.com/watch?v=q5_x_h4EG-w
The reason is very easy to understand. A corded tool has a bottleneck of however much power the wall outlet can provide. For a 15 amp saw running on 120V that’s 15 x 120 = 1800 watts it can draw. Its output will be lower than that because nothing is 100% efficient. Meanwhile, the DCS578 (for example) has a power OUTPUT of over 2400 watts because it no longer has that wall-outlet bottleneck. That is just one example, there are others too.
Chrito
MM got him a new saw. I’ll take it if you don’t want it.
CRAIG B DAVEY
You better go buy one then…because numerous side by side tests on youtube show a number of brands cordless world rives out classed the corded versions
TimNotTheToolman
With all respect, don’t believe MM’s math on the output power of the DeWalt’s battery powered saws vs. a corded one.
Years ago, DeWalt started using Unit Watts Out (UWO). For drills, this makes sense, as at the time, the “power” of a drill was often listed as its max torque, which is only one part of “how fast can this drill get a job done.” UWO incorporates the other – the angular speed of the motor. ToolGuyd and others explain this well.
THEN DeWalt started describing OTHER power tools in terms of “UWO” which a lot of Internet reviews and comments just call “watts” which is VERY misleading. AT BEST, you could say that the DCS578 puts out “2400 watts” up to the point that you start making a cut, at which point the speed of the motor will slow down.
It makes sense when you think of how the Flexvolt batteries are put together – the 6Ah battery pack (which is also a bit misleading, since it’s 6Ah at 20V, or 1.5Ah at 60V) consists of 15 Samsung 20S 18650 cells (or at least, mine does – they may use source multiple manufacturers but regardless, they’d likely stick to the same performance characteristics, otherwise some packs would work differently than others).
When powering a 60V tool, they’re wired in series (to increase voltage), which means you’re limited to the max current of one cell – 30A – and that’s at the 3.6V the cell normally puts out, not the 4V “max” figure. Watts = Volts * Amps, so the max watt output of the pack is :
4V (3.6 volts * 15 cells in series) * 30A = 1620W
And that’s a theoretical max draw from the pack. On their website, DeWalt says the 6Ah Flexvolt battery’s max output is “800” (and doesn’t specify units – no other packs say anything, so… I have no idea), so they might actually limit the draw to something closer to 15A, which would prolong cell life significantly and prevent overheating, since none of their packs have active cooling (and actually, are pretty well-sealed in so they can be used outside on a jobsite).
So the tools are impressive, and blown a ton of money walking out of stores with yellow & black boxes over the years, but at this point, batteries just don’t have anything close to the energy density to outpower corded tools and still provide decent runtime (at least, assuming that the tool was handheld).
Stuart
When is the last time power tool brands put R&D resources into AC motor design? It is possible for a modern brushless motor to outperform an AC motor, even at lower current drawer.
Consider LED vs. incandescent light bulbs. New vs. older technologies often make direct comparisons difficult and complex.
Crispin Pemberton-Pigott
Tim not the tool man
I agree with your final point but differ on a number of earlier ones. At 2400 Watts output, a measure of the rotating speed alone is not indication enough. When spinning and not cutting, it is consuming (and putting out) far less than 2400 because there is no load. When you start to cut and it slows down, the the motor tries to “keep up” and extra power is drawn from the battery. As it slows, the power output increases because power is speed x torque. If it is slowed enough, the power will drop, but not until the product of torque x speed is maxed which usually happens at the point when the current is maximized (due to internal limits).
The power rating of a battery is thus not dependent on the open circuit voltage (at which it can deliver very little current). There are industry standard methods for rating the power. A “12 volt” solar panel is a good analogy. With no load the voltage is maybe 21. Load the panel at its rated capacity, say 200 W, and the voltage drops to 13.5 and delivers 14.8 amps (200 W). Connect it to a 10 v battery and the voltage will drop to about 10.5 and deliver a sub-optimal 17 amps (180 Watts).
The same applies to all battery powered devices. A car battery is sized so that when starting, the 6 volt starter motor (in a 12 v car) has the requisite 200 amps available. It says “12 v” on the motor, but it is really 6 because the battery voltage drops to 6 under that load.
If you measure the voltage at the motor of a “20 v” power tool, it is not 20. It is whatever it was designed for. The wattage consumed is volts time amps under a particular load. The wattage delivered is the motor torque times rotating speed, at that time.
MM
@TimNotTheToolman
The math isn’t perfect but it gets the point across. One can argue all day long about how it’s based on estimates and approximations–which is true–but the videos don’t lie, and there are plenty of them to go around. Today’s higher end cordless saws dominate corded.
I also disagree with your analysis, even on a very basic level it’s flawed. You wrote: “up to the point that you start making a cut, at which point the speed of the motor will slow down.”
That sound to me like you’re implying the Dewalt saw will generate its maximum power under no load at all, and the power consumption will somehow *go down* once the saw is loaded in a cut? That’s completely backwards. Any tool will show minimum power consumption under no load, and any sort of maximum power figure will always be under load. Obviously the rotational speed of a tool will decrease as it is loaded, however that is also when additional current will be drawn from the motor.
Crispin Pemberton-Pigott
Worm drives are notoriously inefficient, mechanically. Typical efficiency is 45%. It could be there is more control because the saw is longer in the direction of the cut and thus more controllable. I suggest adding a length of wood to the plate to serve as a steering arm, parallel to the cut.
Ray
The worm gear, while inefficient, produces more torque than a direct drive saw, so the blade doesn’t bog as much in rough use.
That said, many modern saws, such as the dewalt 60v rear handle, feature planetary gear reduction, which gives you the additional torque without nearly as much inefficiency.
Josh Walters
Idk if that’s the case anymore, the wormdrive “style” saws don’t have the actual wormdrive gears just a spinning motor like a sidewinder. For example the blade left and blade right Flevolts both have 5,800 rpm blade speed. Iirc only the actual skil saw cordless still has the wormdrive.
MM
I completely agree. That’s why I wrote “that generalization may have been true back in the corded days but itâs certainly not true now.” As you said, pretty much all of today’s cordless circ saws are built with spur gears, aka sidewinders. Therefore the idea that a modern “worm saw” performs differently than a “sidewinder” doesn’t mean anything today, as they are all sidewinders inside.
Jeremiah D
I believe generally worm drives have more torque and they may run at a slightly lower rpm? I think(gas) chainsaws generally have a higher rpm than circ saws though.
Mopar
OK, I looked at bit further. Apparently Prazi has different 12″ models for sidewinder vs worm drive. So that probably leaves the strength/wear thing out Wonder what the difference is, and why HF doesn’t feel the need to make 2 different models.
Je
Buy a damn chainsaw. Be safe
Rasd1216
Yeah this isn’t for cutting branches off the tree… It’s for cutting BEAMS. This is MUCH safer than your damn chain saw suggestion chief
Trevor Sherman
It’s for making more square cuts than, “just eye ball it.” The idea is to use a tool you already have and not have to spend multiple hundreds of dollars (not including blades) on a large beam saw.
Kirk
Could be most worm drive saws are left sided blade cutting, clockwise and you have to flip the blade over label in ,teeth cutting from under material and through to the top. Maybe chain will run the wrong way forcing your saw up and away from the beam?
Jemccu
There is no need to turn the bar over, all you need to do is turn the chain over.
Hedgefarmer
Most chainsaw bars are designed to be flipped. It evens out the ware. Most bars will outlast several chains.clean the groove, make sure the roller is lubricated, use plenty of goodbar oil and you get long service out of a bar
Trevor Sherman
I would think you just need to put the whole thing on with the label facing the right side of the saw (considering its the side winder style), and then it would still be rotating the right direction. There is a chance that a critical portion of the drive assembly can not be installed this way.
Jack Smith
A worm drive has reduction gearing, which will reduce the load on the motor. That’s why they run at lower RPM and have more torque. I’ve never seen anything like this and the first thing I thought was a worm drive would be great with this and I don’t even like worm drive saws. I’m sure a regular saw will cut just fine but it would be probably hard on the motor.
Jack Smith
You should be able to flip the chain over to make up for the shaft being on the wrong side.
Mark F. Falanga Jr.
Prazi has a model that does work on sidewinders also.the main difference is right or left hand mounting
N
Not true . I believe Prazi has offered a kit for regular circular saws and not so true worm drives like the Flexvolt Dewalt for a while now. If it works with no danger , might have to try it at that price point.
Ray
Prazi makes a version to fit a sidewinder, which is a mirror image of the worm drive model. It would seem that harbor freight has worked out a way to be able to put the same model on either type of saw.
Also, it would make sense, given the market that exists for standardized bar and chain, that harbor freight would be using something standard instead of developing their own mount.
Nathan
gearing on the chain drive and thickness of the chain makes up the torque requirements.
It’s interesting to see, I suspect they don’t want to to replace the chain or even consider it you should use it till it dies and buy a new one.
Like most HF stuff it’s for the person that has the one project that needs a certain tool thing to get used once and put back on a shelf. vs you know renting a beam saw from HD or whomever. assuming they can be rented, I imagine they can be.
I would say if I had to cut beams like that I’m consider it.
Mopar
I kinda doubt there are many places that even rent dedicated beam chainsaws. Surely not your local HD. They are such a niche market. And generally crazy expensive because of it.
I guess I’m not seeing much market beyond the “gee wizz, that’s cool!” market, which I guess suites Harbor Freight. I think if I had a one time project that required semi-accurate cuts on 10=12″ thick beams I would just go with one of the beam cutter plates for my chain saw. But that’s me. And if I did it for a living, I’d be dumping $7-8K on a real beam saw.
MM
That’s basically my take on it. I have been to a lot of tool rental shops over the years, everything from HD’s rental section to full size heavy equipment and I’ve never seen a chain-type beam saw for rent.
I’d assume someone who only needs to make a small number of cuts can get by with a standard chainsaw or even a handsaw, and someone who has a lot of work to do would buy a dedicated beam saw, whether that’s a high-end model like a Mafell or something more like the Skil SPT55-11
Now incidentally, I have seen the Makita 16-5/16″ circular saw for rent before.
Ray
The prazi is very popular with professional timber workers because it produces professional results for minimal cost. They’ve gotten more popular lately because it was found to fit on a dewalt 60v rear handle saw, making a cordless beam cutter, which is unlike anything else on the market. The main issue with it is the lack of an oiler, which apparently this kit offers.
I own all manor of beam saws, including a couple 16″ circular saws, a prazi, a linear link (a more extensive modification of a skil wormdrive, the prazi came out as a cheaper alternative after the linear link failed because it was too expensive), and a head cutter plate for a chainsaw, like you mentioned in your post. First of all, I should point out that a bigfoot head cutter plate is a $300 tool, and you need a good quality chainsaw to make it worth anything. Even with all that, it’s awkward to use, and I only really use it when I need additional cut depth than is allowed by one of the skilsaw based chainsaw setups.
There is a good chance I’ll be buying one of these kits due to the oiler, in order to replace my prazi, fitted to a spare dewalt 60v rear handle saw.
Trevor Sherman
We rented a beam saw at the local equipment rental store once. It wasn’t a problem.
Ray
Given that thus harbor freight kit apparently has an automatic chain oiler, it might actually be better than the prazi, given that lack of an oiler is probably the single biggest failing of the prazi.
Due to this fact, I’ll probably pick up one of these kits to fit on a spare dewalt 60v rear handle saw.
Charles
huh. Good point
Andrew
It is interesting that they show a corded Hercules circ saw, but when you go to their website, they only offer a cordless Hercules saw. I gotta think this thing would just eat up batteries.
JHM
HF has a number of corded saws , go to the store.
bg100
I can’t help but think this thing will be a nightmare to make a plumb cut with. Seems like it’s going to drift out of square and plumb on a large piece of timber. Has anyone had any hands on experience with this? I’d love to get an idea on it’s viability in the real world. Those Skil beam saws are heavy…
Mopar
30lbs and “only” a 6.25″ cut depth. Unless you mean the Skil Sawsquatch?
Bill
I have the 12″ prazi and used it to cut lap joints in 6×6 PT with a Skillsaw 77 Mag. It worked well and ate through the 6x6s no problem. It’s as square as you mount it, the cut quality is on par with what you’d expect from a chainsaw. It was easy to control and I did not experience any kick back. There is no guard so you really do need to bring the chain to a stop before maneuvering the saw and have a safe place to set the saw so it doesn’t get dropped and knocked out of square.
Jared
Just curious, are these things generally considered safe?
I once bought a chainsaw conversion kit to fit 4.5″ angle grinders. After getting it home and thinking about it a bit longer, I decided it was too scary for me and it still sits on my shelf in its box.
I mean, there’s no brake and the guards seemed flimsy.
I didn’t really need it anyway – I have a real chainsaw. It was just an impulse buy because it was on “clearance” (perhaps avoided by shoppers wiser than I đ¤) and I wondered if I could have a second smaller cordless chainsaw by attaching it to a cordless grinder.
Anyway, that’s what came to mind when I saw this beam cutter. I do like that the riving knife basically forms a sort of guard for the backside of the blade.
Bonnie
Since these are intended for cuts in square beams I think the traditional chainsaw brake is less necessary since you should be working from a stable position rather than leaning over/towards a saw buried in a round tree. That said these kind of after-market attachments scare the hell out of me.
Trevor Sherman
If you’re to scared to put it on, then you probably shouldn’t.
fred
Many years ago – timber-framing (real and faux) seemed to be all the rage among some of our well-heeled clients. We undertook to learn something about the skils needed – and bought some tools. At that time we thought about the Prazi, had some Skil 77’s already converted to bigfoot, looked at Mafell and ended up buying Makita.
The Makita chain mortiser, beam saw and big planes were perhaps not in the class of the Mafell alternatives. But they were way cheaper. Thay proved to be a good thing – because after the flurry of jobs we did – the appeal of timber-framing seemed to dry up to a trickle.
Using someting like this Hercules – or the Prazi might be OK for beam cutting – but would probably be dangerous trying it for mortising – better done with a dedicated tool:
https://www.amazon.com/Makita-7104L-10-5-Chain-Mortiser/dp/B0002HC2VQ
I also heard from the guys that cutting beams with the Makita beam saw was no picnic without resorting to a bench/jig made for the purpose:
https://www.amazon.com/Makita-5402NA-16-5-16-Inch-Circular/dp/B0000614UR
Mike+McFalls
I love how the Makita listing states âweighs ONLY 32 lbsâ. đ
fred
Yep – for convenient one-handed operation on overhead cuts. But that’s only if your name is Paul Bunyon
Mopar
I know when I was toying with the idea of building a log cabin, a lot of the guys at the time seemed to just use a cheap plug-in electric chainsaw and some jigs. The electrics run slower, less likely to overcut i guess, and you could get away with running the blade dry when you didn’t want bar oil all over your work. Sure, the chain and bar work out faster, but they were cheap enough, as was the saw itself.
Jesse
I haven’t seen this one from hf, but the prazi I had was a useless piece of junk. Mounted on an skil worm drive it pulled the chain fine, but no matter what I did I couldn’t get a square cut. Unless it’s been updated it had no oiling system either. The chainsaw I had been using was a much better option.
Ct451
You might as well get an electric chainsaw while you’re at it. Same quality of cuts.
Bill
You’re right about the quality of cut, but the precision of keeping it square left and right and forward back would be a challenge with a standard chainsaw.
Mopar
Not if you add a a guide or foot to it. There are some really simple $30 ones, all the way up to this: http://www.bigfootsaws.com/bigfootproduct/head-cutters/
Bill
Fair enough. The 12″ prazi is $179, 18″ $295 and the bigfoot $279. If you have both a chainsaw and a circ saw (like I do), I would choose the circ saw.
JoeM
I’ve seen these from other companies. I think Prazi and Stihl? One company has different models for the two kinds of Circular Saw, Central propelled, or Wormdrive. I believe they calibrate the gears to handle how much torque each type delivers from the moment of pulling the trigger. That way it doesn’t jerk the chain, or mess with any of the lubricants in any way that might hurt the saw itself. But I’m not sure.
I’ve been curious about these chainsaw accessories for a while. I don’t see myself needing one, but it is certainly one of those accessories that I’m glad exists, simply to show how versatile a tool can be on the job.
MFC
I have wanted one of those for a while but i’ve been unwilling to spend $150 for an occasional use attachment. On large beams I typically make the first pass with the 7 1/4 and then follow up with a recip saw for the additional depth. I cut stacks of I-joists with a chainsaw when they need to be batch cut, but they’re typically 14″ or larger so this wouldn’t work for that anyways. Yeah, even at $60 I probably still won’t get one, especially considering that the quality from HF is usually pretty bad…
Dominic S
chain beam cutter conversion kit is not high up on the list of items I would try from Harbor Freight. Can only imagine how that thing could maim me when it inevitably doesn’t work correctly.
Anthony B Hinsley
Yeah and it might, just maybe, do it twice.
Kinda doubtful though!
Blocky
My experience on one large project is that the 12â prazi drives like a very cheap jigsaw. For very deep and long cuts, a guide ends up working against you, as you have to ride the cut by hand and eye. Constant pressure to one side will skew the bar. Of course oiling and tensioning the chain is necessary and far more annoying than a purpose built saw.
I generally could achieve better cross-cuts freehand by marking and cutting with a standard chainsaw.
As others have said above, for almost any amount of use, corded is a must. We used the makita hypoid saw, which is more similar to a worm drive. The cuts were generally at 11.5â depth. The 18â prazi was not yet on the market nor was the Skil.
Harrison
Honestly, including a small oil reservoir makes it an improvement over the Prazi, regardless of price.
Quality wise, I donât think thereâs much to worry about. Itâs a few bolts, a bearing, cast metal bracket and commodity bar and chain- not really a whole lot to go wrong, especially as these tend not to be everyday tools.
Considering the Prazi isnât regarded as particularly accurate or fine-finish, this seems like an easy choice if you must have the circular-saw form factor, (vs a real chainsaw) and donât want to spend a lot of money.
For those who want a pro-solution, the Skil SPT-55-11 Carpenters Chainsaw kicks all these options out of the park.
-Large capacity oiler mounted on top of the saw.
-Enclosed housing with vacuum port
-Tip guard/bracket that clamps the bar and splitter together for actual straight cuts.
-Dedicated beam-saw chain with a tooth on every link for smoother surface finish and increased material removal at designed RPM.
https://www.protoolreviews.com/skilsaw-carpentry-chainsaw-sawsquatch-expands-worm-drive-reach
(All the other options use a standard skip-tooth gas saw chain that is designed for high RPM and no regard for surface finish. )
Jon Porter
At the end of the day, you’re still trying to make a clean cut with a not so clean tool. Chainsaws come with a wide kerf and bar that’s only 3in tall. That’s a lot of room for waiver when following a chalk line. Plus the extra kick you get bc of the size of the bite. It’s wrong to say the attachment makes a circular saw a beam saw. It makes it a chainsaw with a foot plate and the added capability of cutting angles. My beam saw is clean enough for joinery. This attachment, not so much.
Bill-L01
Interesting tool! I have been cutting lumbers of 4×6, 6×6, 6×8, and 8×10, and I just use my DeWalt miter saw, by cutting it once halfway, flipping the beam over and cutting it again from the other side, with precise cross cuts and smooth cutting edges. And for anything bigger such as 10×12 and 12×12, I use my Husqi chainsaw with a cheap guide attachment, screw a 4×6 wood onto the beam as a guide, and set the chainsaw guide on the 4×6 to make a straight cross cut. With my setup, I think I can pass this.
Charles
Back in the day I could see it. But why wouldn’t I use the m18 chainsaw instead these days?
Raymond Bailly
This gives you a table to aid in keeping cuts square.