Thread: 355mm hand held circular saw

hi gerhard, you are still the man!
once again you have delivered in spades!

have you ever heard of an accident using these types of saws?
is kickback a common thing?
or does the parallel guide and the riving knife eliminate kickback?

i would be happy to be the man pulling, (no pun intended folks), but i would certainly not want to be standing behind that puppy!

keep up the great work gerhard.
regards, justin.

hi phil, with regards to your original question.

i would buy the Protool CSP 132 E. this model weighs ONLY 18kg!

model no. 638 480

it costs 1842 euros. thats AU$2975!

but if you need something this big, then obviously you are prepared to pay a premium for a high quality specialized power tool.

you should try calling your local festool dealer, for more info about this saw.

regards, justin.

Originally Posted by gerhard

Haha, thank you for the compliment, Herr Fledermaus! And yes, Ben, as long as they don't come too close to the magnetic field, their balls will be all right. As you see in the pic, it's no joke! A 640 mm blade and almost 5 hp!

Gerhard

This is what Triton should have used for their saw "system". Would have got a bit more interest I reckon.

Hi all,

Soth asked if the two guys in the pic were actually sawing. The pic indeed looks a bit engineered, with the clean shirts and showerfresh hair and whatnot, but in fact they are really sawing and this is indeed one of the ways how this thing should be used. No matter if an OH&S should flip over it, this machine is exported worldwide and gets the approval of many safety testing organisations. But then this is no tool for leymen, and especially in Germany the rules of practice are very strict when handling machines known to be dangerous. No apprentice is to touch this tool, without at least direct help and oversight of master carpenters on the same workfloor. When a firm lets any harm come to an apprentice or unqualified not-yet-trained person with a tool like this, they are in very big trouble and may have all their licenses and insurances revoked. So it's a serious self-regulating thing that has worked well over the decades, but the commercially hyped anxiety of the overobsessed Anglo-American lucrative safety bandwagon is also creeping in on Germany (much like the asbestos-astronauts and the HACCP-foodstuffpolice).

So the guys operating this thing know a bit about wood and tools and circ kickbacks. I've seen such a machine in action in a large workshop near Passau, making prefab roofing and ceiling units, much like the sort of workpiece that is being treated in the pic. In such shops the timber is cut and jointed to size, the readymade unit is flung on a truck, hoisted in place by a rented crane and adapted to exact size if necessary. This is common practice in Germany, where there is a a lot of woodframe housebuilding going on. They are even able to build all-wood high-rise constructions up to 7 stories and probably more than that.

The hazard is mostly in the ripping; experienced guys will be able to make any cross cut without a blink, even with such a large saw and even freehand. When selecting and judging the wood beams, they will first make a good study of the wood grain, to predict the hidden forces in the wood, which will make themselves known while the beam is ripped to size. If they suspect a risk that is too unpredictable, they don't use a saw like this but go for a vertical chainsaw instead. The wider cut of a chain means more loss of expensive wood, but less chance of accidents because of the narrower chain blade assembly, that will get stuck less likely and will merely leave a very rough cut finish instead.

This saw in action is an event to watch. The machine is used either freehand (which requires many years of practice) or is used with a guide rail. Mafell offers a standard 3 metre rail with 1.5 metre extension units, and all sorts of stands and clamps to keep the rail assembly at proper height and width. The two guys working the saw are a seasoned team, they discuss their plan and what they decide to do when things aren't going to plan, and then they just proceed. If necessary, they have other guys standing by with hardwood wedges or axes and sledges, to pry open the cut after the saw at the slighest hint that it should jam. The riving knife in this machine is big and relatively thick, but as an only measure it's not enough when forces in the wood pinch the cut together or skew it.

And then they start. These machines of course have a star/delta switch and spinning up the blade takes about two seconds. There is this sharp low pitched acceleration whirr that reverberates in the big blade and when the thing is up to speed, there is the sharp gnawing sound of the teeth in the wood, the loudest circ noise i ever heard. The standard blade choices have either 56 or 26 TC-teeth and at nominal load speed of 900 rpm that leaves a sharp sound pitch of 840 or 390 Hertz. 840 Hertz sounds about the same as the blade of a smaller handheld circular saw with a 16 teeth blade at 4000 rpm. So in spite of the low rpm, this machine doesn't sound much out of the ordinary with the 56 teeth blade and only sounds darker and more monstrous with the 26 teeth blade fitted. That darker sound resembles the sound of the man-high circ blades used on the Indonesian islands, with which they rip tropical forest trees roughtly to size, on site.

There is indeed the risk of kickback, but the operators are well aware of this and hear one coming by the blade sound. The front guy pulling the saw dictates the forward pace and actually does most of the work. You can see it in the pic, the front guy strains more at the saw than the hind guy does. Both guys watch the progress and the right direction together, but the hind guy is better able to steer than the front guy. So, between the bits of steering now and then, the hind guy can afford to bear down on the handle bar a bit and he can grip the saw tightly with both arms anyway, which is a big difference with mastering a large circ saw on your own with only one arm holding the rear. The arms of the guy behind this saw should preferably be stretched (unless there's a steering manoeuvre), whereas your pushing arm behind your own circular saw is often bent. Stretched arms can control sudden upward forces much better than bent arms can.

As for this machine, it's not so Neanderthal as many three phase machines are. Most induction motor driven machines keep going on until their thermal over-current cut-out trips, but this one has built-in electronics, which also offer a quick brake function. Besides, the torque curve of induction motors is different from series wound brush-motors, anyway. Induction motors have the best torque and efficiency close to their no-load rpm. At 50 Hz, the "field speed" is 1000 rpm for a 6-pole motor, and the rotor of this saw follows the field regime asynchronously at 940 rpm no-load. The saw's nominal load is 900 rpm, at 800 rpm and below the torque quickly collapses to a fraction of nominal. So as long as the load rpm stays steady and the blade noise pitch sounds the same within a few percents, the going is good. The torque is high at that moment, but without a sudden change in inertia, there is little chance of a kickback. When the rpm drops in spite of the same forward speed, there is a sudden higher friction, which could mean a stalling in the making, and a risk of kickback if the stalling occurs very sudden. Upon hearing the sound change, the front guy immediately relaxes and eases the saw at a slower pace. If the friction is overcome, the trouble was only local (resin inclusion or grown-in branch crossing). When the friction remains or increases, it's probably due to lateral forces in the cut and it's time for the guys standing by to jam in a wedge and split open the cut. At sudden stalling, the kickback with the approx. 18 kgs worth of blade and rotor mass, is of course bigger as usual . But the amount of static mass in both machine and workpiece are also big. It takes a lot of energy to suddenly lift a 66 kg machine. And the workpiece is also likely to be heavy, so it won't be launched in the worker's face as a plank will be, on top of a kicking saw table. It's often the circumstances that dictate the happening. Remember angle grinders; the heaviest are in the 2800 Watts range; that's almost 3 hp pulling at your wrists when the disc suddenly snags. Yet you don't hear much about angle grinder kickbacks, and when they occur, it's mostly because of ill advised reaching or poor foothold or some impossible working posture against better judgment.

The guy in the pic below, handling the 185 mm version on his own, is at slightly larger risk than the two guys with the 245 mm version. His single bent arm is all he has to keep the machine under control if it should jump up. Still, it's an original pic from Mafell itself, used in their advertisements and product presentations. You can rely on the machines genuinely being in use in pics like these, because German craftsmen hate fake set-ups and expect to see no less than real-life situations. They want to see machines in action, to judge their size and bulk and to judge how the guys in the pics go about using them. With that information they can judge how they would fare themselves and if this machine could be a worthwhile purchase. But they still won't buy yet, based on mere pictures, they will first visit forums and throroughly discuss the machine with users and they will visit fairs and colleague firms to see the things in actions or to try them out for themselves. There are many power tool forums in Germany and fairs always offer a lot of demonstrations and masterclasses, which attract huge amounts of serious visitors. After that, the product will be bought, often already at the fairs themselves, preferably at club member or discount prices. Festool by no means is alone in this, it may be a wordlwide well known brand for investing in customer relations, but in Germany this is the obliged and expected way to go. That's why serious tool brands like Mafell stay alive and keep enjoying good sales figures, in spite of crises and hefty price tags. With reputable machines customers often already know what they're going to get before they buy it, and they want to keep it that way.

Greetings from Holland!

gerhard

Little mistake in the post above. The guy singlehandedly managing the large saw, uses a FSG165K, which has 165 mm saw depth, and not 185 as mentioned above.

I used this occasion to present a further pic of heavy duty machines as used in Germany. The beam planers, for instance, have 300 and 320 mms width capacity!

gerhard

Wonderful report, Gerhard. Thank you.

soth

Thanks!

Just found a pic of an Indonesian saw mill, and this is just a medium sized and reasonably well maintained one. The blade is driven by a 6 cylinder diesel engine by means of a drive belt and an angled gear box. The logs are pulled up and led along the saw blade by a hydraulic motor winch, the controls of which are seen in the foreground (valve handle and pressure hoses).
I've seen a far bigger one in action on TV. A big log bounced through the saw, the blade wobbled wildly and i could swear i saw people running for a safe distance until the situation appeared sound enough again for them to immediately return and process another log. Talk about an OH&S flipping, now there was a spectacle that really made me cringe! I still can't look at one of those pieces of Asian teak furniture without picturing people with limbs missing.

gerhard

Jesus I can't get over how big that 640mm sucker is. I like the look of the Protocol but $4K in Oz is a bit out of my league. I'm mounting it on an adapter for my slabmaster so I'll miss out on building up killer guns by handling 18kg of power tool. I'll have to settle for something that cuts about 130mm so that I can dock 250 x 250 posts.

I'll mount this on my slabmaster

Originally Posted by Kyle

What about this.

Spear & Jackson Predator 22" Laser Guided Saw #SJ-B98LASER

It's got 550mm depth of cut, under $50 and you'll have arms like Schwarzenegger if you use it enough.

Plus it's 'laser guided'

Seriously is there anything tool makers won't fit a laser to these days?

Hi Phil,

a 120 mm saw needn't cost 1800 Euros or 2900 Aus Dollars. The link below shows one of the offers that can frequently be found in Europe. The suggested 600-something price is not even fixed, it's negotiable. Okay, it's Ebay and in this case it's Germany, so shipment to Oz would cost an extra arm and leg, but -with Hitachi's home country Japan being even closer to Austriala than it is to Europe- offers like these should be possible in your part of the globe as well. Especially because the influence of other competing Asian products (notably Chinese) must be even intenser over there than it is over here.

As for Hass + Hatje, it's one of the good German dealers also selling through Ebay, from which i regularly buy stuff. Depending on the weight, i have the goods shipped to my doorstep near Amsterdam for 20 to 30 Euros. They're professional people, they pack the items well. There must be firms like these in Oz or NZ, i guess. You even have stuff like Festool over there, so there is sense of quality and probably some degree of competition like there is over here, especially in these times of recession and slow sales!

Hitachi 128 mm Zimmerei - Handkreissäge C13U neu+ovp bei eBay.de: Sägen (endet 15.11.09 21:51:17 MEZ)

Success!

gerhard

Originally Posted by gerhard

so shipment to Oz would cost an extra arm and leg

And there should be a few of those lying around after the use of the machines shown in this thread.

So if you have a spare $4k you can go for the Protool saw. Why are the hitachi and mikita big saws not available in OZ? I could buy a 16 and 5/16" (401mm) Makita but could any one tell me if it well work over here since the USA electricity grid distributes at 120v instead of 240v. If I could run it here that would be great since the Makita is less than $700US which given the $AU at momment would be less than a 1/4 of the cost of protool saw.

Hi Weaver,

yes, with a "step-up transformer" you could perfectly well run a 240 Volts machine on a 120 Volts mains grid. For a 2200 Watts machine be sure that the transformer can handle a net output of 3000 Watts. Which means it is a big and heavy item that may even have a set of wheels attached. With the cost of such a large transformer added, it remains to be seen if the whole undertaking is still profitable. A used transformer will be much cheaper, but be sure the channels through which you purchase it, are trustworthy and willing to provide some sot of warranty.

Success

gerhard

Hi, Weaver, me again,

i read your post too quickly. Happens to me more often.I reread it and you didn't live in the USA, but you wanted to import a 120 Volts machine from the States and use it on 240 in Oz, right? In that case the transformer story still goes, but you need a "step-down transformer" from 240 to 120, which are easier to obtain but still expensive. The 3000 Watts net output spec remains unchanged.

regards

gerhard

PS; Strange that the Hitachi C13U and the Makita 5143R are not available over there. Probably something to do with these models not complying to a few of your safety standards. We have that in Europe as well, especially France is very nitpickerish about imported tools which do not comply to French wishes within a distinct molecular exactitude. Just protectionism, if you ask me.