Just wondering what the difference is between thin kerf and regular kerf for table saws.
I bought a used table saw and replaced the blade, buy mistake I picked up a thin kerf dewalt blade. No markings on the blade itself. I found out when I installed a micro jig splitter from Lee Valley. I bought the one for a regular kerf and after I installed it of course the wood wouldn’t’t go through.
Now I don’t know if I should stay with the thin kerf or buy another regular kerf blade. I am not worried about the splitter.
thanks
James
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Replies
If you're feeling underpowered when ripping, then a thin-kerf will definitely help. Of course they are more susceptible to overheating problems than regular blades, and will more easily wander from the line if sideways pressure is present for any reason. We're always trading off one thing for another.
DR
Ditto to Ring re: the underpowered saw thing. If you're using a contractor saw (1.5HP or so) I think you'll find the thin-kerf to be of benefit. My Jet saw performs much better when ripping oak or maple with a TK blade than with a standard blade.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I am going to try describe an incident that I had with a Thin Kerf (TK) blade. I was ripping some 2x stock on a Makita bench top saw. I should emphasize that I am a contractor and I work with these tools every day. The technique that I am about to describe may not be "recommended", but I use it. I ripped the piece about half way and as is my practice, lifted the material off the blade, using the front edge of the saw as a fulcrum. Apparently, I was asking too much of the blade for as I removed the piece from the saw, the blade warped. Now, I'm not talking a minor warp, I mean that the blade was slapping around so much that it was taking chunks out of the insert. This no zero clearance insert. This is the factory aluminum job that has maybe 3/16" space. I can't tell you how much this freaked me out. 3600 RPMs and the blade had warped like it was made of aluminum. That was it for me and TKs. I use only full kerf blades. If my saw can't cut with a full blade then either the blade is dull, or I need a new saw.
John
I had a similar thing happen with a full thickness blade, 5hp unisaw factory insert, not zero clearance. Apparently a small oak offcut got afoul of the blade and insert, in the blink of an eye one side of the insert had bites taken out of it by the blade and the other side of the slot had about a 1 inch chunk broken out of it. Ruined the blade and needles to say the insert. Got my attention. I never assume the blade is going to stay in the same plane anymore.
Wow! I thought stuff like that only happened to me! I just sent an oak warning to a friend as well. I don't know why, but it does seem to cause havoc! Good lesson for all of us.John(Glad you were OK!)
If I am reading your "accident report" correctly, seems like if you'd had a near-zero-clearance insert, the accident would not have happened. I'l learned to not like inserts that leave too much space between it and the blade. forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I came to the same conclusion, I use the zero clearance for everything now. Bored holes to aid DC and made a cut out behind the teeth for the small offcuts to fall into.
Let me see if I am getting this right. Your are doing something with a potentially very dangerous tool; that you acknowledge is a dangerous practice; and you are blaming the saw blade? You can't choose to ignore the laws of physics.
Dear Hand,
Yeah, I'd say that you got it right. Mostly, with two exceptions:1) Blade: I don't think that my technique had anything to do with the event. I think that the blade was unsuitable for what I needed it to do. The blade had one purpose in life. That purpose was to rip wood, cleanly & safely, just like every other blade that I have used before and since. It failed at its one task. It is therefore useless to me. Those are my laws.2) Technique: My "potentially dangerous practice", of removing the piece from the spinning blade, had been developed for the following reasons. It keeps my hands off of the table, and therefore away from blades that can fail. There are other reasons, such as I always have the bulk of the material in two hands, therefore giving me a mechanical advantage over the saw. My main reason is keep my hands away from the blade. No, I don't have any guards, no splitters either. Just a nice, sharp full kerf blade.JohnPS. I run with scissors as well.
Edited 5/5/2006 7:59 pm ET by Jmartinsky
Hopeless.
Dear Hand,
Oh, I don't think that you are hopeless, perhaps out of arguments, but not hopeless. Peace,John
Next time you run with scissors your are going to get your mouth washed out with soap, young man! You're just plain sassy.
WOW! Nice to be called young man! I appreciate it! Sassy, hmmmm not sure about that one. I've been called worse. So, seriously, back up your argument. I preface my techniques as "not recommended", but they work for me and I have the track record to prove it. I have had that TS spit a grand total of one piece at me, which I detailed in a different thread, and had nothing to do with the technique that I described here. I have stated that for my purposes, I have found TK blades to be unsatisfactory. I woodwork commercially and if a tool doesn't function, it serves no purpose that I can understand. I'm sure that there are plenty of woodworkers on this forum that will disagree with me, but I simply share my experiences. Now, as for you, my friend, sassy or not, you have implied that I have done something................what.............reckless? Dangerous? What? When ripping long stock, I don't run my hand along the fence, next to the blade, in fact I never even get my hands over the table. My weight is back, what do you see as wrong? Just to prove that I am not completely over the top, I'll bet even money that you use a push stick from time to time to complete a cut on the TS. Now that may be fine for you, but I'm not that brave. If it's that small, I'll find another way. Oh, how about a 45 degree rip? I'll pass on that too. I'll find an alternative. So, let's hear it, back up your statement...................................or shall I forgive my elder?John
I've tried several high quality TK's and several high quality full kerfs. For my 1-3/4hp saw, I much prefer the feedrate of the TK's. They cut just as cleanly, are easier on the motor, and I've had zero issues with deflection. The quality level you choose is pretty important though. A $15 TK isn't likely to be all that stiff, but one of the better Freud's, a Forrest, better DeWalt, CMT, Ridge Carbide or comparable should work really well for you. Keep in mind that brands like Freud, Oldham, and DeWalt have multiple quality levels....study up before choosing just on brand alone.
Edited 5/4/2006 7:48 pm ET by scottwood
James,
I had a small cabinet maker's saw for some years that took 6.5 inch diameter, thin kerf blades. This TS was a mere 1.5 horsepower but cut very rapidly and cleanly indeed, especially with good quality blades.
This was a European saw (Emco Moritz) so it had a blade-following riving knife. The knife makes all the difference as you cannot then bend the thin blade using your plank as a lever - the riving knife is very stiff and forces the plank to stay on the fence.
The thin kerf width was 2.4 mm (as opposed to the normal 3.2mm). I could use a 2.0mm kerf blade and the riving knife would only just allow the this - it was also 2mm thick, the same thickness as the blade body of the 2.4mm kerfed blades. I once made the error of trying to use a 1.6mm kerf blade (out of a Makita portable circular saw) but the riving knife wouldn't allow such a narrow cut to pass.
In short, thin kerf blades are really meant for saws designed to use them. In most standard TS they will not do well, especially those with no riving knife, ie nearly every American saw. In saws sans riving knife, only the stiffness of the blade itself prevents it being deflected by a badly-handled plank.
Lataxe
"especially those with no riving knife, ie nearly every American saw." Or, an after-market splitter, e.g., Merlin or Biesemeyer??? They make thin-kerf versions.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
FG,
Of course you are right - although all the pics I've seen of splitters seem to have them well aft of the blade. Ideally, it should be impossible to rotate the plank into the back end of the blade because the splitter begins just behind the crown of the blade - a la riving knife.
Lataxe
Totally agree that riving knives are the best approach. Aftermarket splitters are our "compromise" I guess until the manufacturers give us what we need.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I think most people answered your question except for one thing. The rep from Forrest told me that thin kerf blades were developed to give people with underpowered saws good results when ripping, not to save wood on multiple cuts. They do not recommend using a thin kerf blade on heavy cabinet saws because of distortion of the blade on higher feed rates with all that power. I was not convinced so I tested it. He was right!
Not to belabor the point, but I was able to distort one with a Makita bench top. Now, perhaps I was a bit aggressive, but still, I should of stalled the motor before the blade gave. I don't use them, I'm sure that there are plenty of people that do, with good results. So, what happened?John
I think there is a reason that cabinet shops and professional furniture companies do not use thin kerf blades. If you push them they will fail and the results may be not to your liking. I pushed 2" hard maple to test my Forrest thin kerf and it distorted about 3/8" and that was under controlled conditions. Granted I have a 5 HP Laguna saw and should never have tried that , but I wanted to test the blade. Kinda scared me. Distorted so bad it grabbed the insert. You just can't push those blades on the rip or they will go wacky.
Yep, that would do it! Wow! 2" hard maple. I use a PM66 in the shop and the Makita on site. I use the "industrial" grade Freud blades on both saws. If the Makita can't cut with a full kerf blade, I will find a saw that will. If a saw is "underpowered, then I suggest someone gets a more powerful saw, or take multiple passes. I'm on board with you. I am curious, however, what do you consider "controlled conditions" and if the blade distorted that much (I don't doubt you) how did you avoid kick back?Best,John
I've had a similar experience, one of the scarier moments that I can recall. Fortunately, the board I was ripping was clamped down to the sliding carriage of the saw so there was no possibility of kickback. The TK blade overheated and started to deform - it was really wavy, screaming and smoking - before I could stop the saw. Damage only to the table insert and the board of course, but that was the end of TK blades for me. Nowadays our shop has a 7.5 HP table saw so there's really no need. No more power issues, even ripping 3" hardwoods.
Thin kerf still offers something for those with small HP saws. But one needs to be aware that things can go wrong in a split-second.
DR
THAT"S what I had happen as well! No minor deflection, but a major warp. I wish I could describe it properly. You did a better job than I did. I'm glad that you were OK, what type of slider do you have?John
I'm glad you guys have shared your experience. I have a 5 HP saw and no TK's, but who knows what I might have bought on a lark at a show or in a store. I think I'll cross TK off my list.
Thanks!My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Having used thin kerf blades (2.4mm) for some years on a smallish HP tablesaw, I was puzzled at first to hear these experiences of blade warping. I cut many a big lump of hard timber with mine - including 2 inch oak, rock maple, teak, iroko and others - without any warping or other mishaps.
Further though persuades me that a major factor is likely to be blade size. My small TS used blades of only 6.5 inches diameter, with a maximum cut depth of 2 1/8 inches.
Maybe there is an optimum ratio between kerf thickness and blade diameter (as well as HP)? You can imagine that any lateral forces generated on the blade whilst cutting would deflect the rim easier on a 10 inch than on a 6.5 inch blade of the same thickness. This would only be more likely with more HP driving the blade.
The evidence, posted in this thread, that a blade stiffener reduces the problem seems to chime with this possibility.
So, the conclusion must be - use a thin kerf blade in a TS or other saw designed for the job. High power saws using 10 inch or larger blades are not designed for TK blades. If this is so, why don't the manufacturers say so, one wonders? What saw or sawing operation IS designed to use a 10 inch TK blade?
I think we should be told, Mr Freud and Co.
Lataxe
John,
I've had an SCM (Italian) slider for a number of years already - 14" blade, the carriage travels just over 10'. (SCM is the industrial parent of Mini-Max.) At the point when my shop got really serious (more than just myself and a helper) it became a necessity to have an industrial machine. We also have a Powermatic 64 that we've used on jobsites so I haven't completely forgotten what an American tablesaw feels like. But there's no comparison really.
DR
I'm not feeling too sorry for you right now. I am feeling a bit sorry for me, however! Thanks for the input, I do like the Minimax slider that I worked on. Just night and day compared to my PM66. Someday.......(Sniff)John
I had featherboards on top and on the outside edge. My Laguna has a riving knife and I shoved the board pretty fast. My kerf didn't get wide until the end of a 8' cut. Heat had a lot to do with it. I am not the guy from Freud because I got the most distortion with a Freud blade, and the least with a Forrest. I use the Forrest 5" stiffener all the time now and all my cuts are improved. Ripping with the Forrest WWII special grind with the 5" stiffener is a dream. Only down side is it limits your depth of cut. Not a big deal most of the time.
I not loyal to any one blade company, just ones that cut well. I have Freud, Winchester Saw, Schmidt and Forrest. Like the Forrest WWII special grind the best right now. I guess they changed the grind on the new WWII blades or is just called special grind. I don't know,I got it at a show. Cuts like butter.
I'm with you an the blade selection. I had a Forrest WW2 that worked well, but the Freuds are more available here and they seem to work just as well. I have no loyalties beyond performance. If the Freuds ever stopped working for me, I would order a Forrest, Amana, or similar. I am curious, with feather-boards on the top and sides, how do you complete a cut? Do you have a helper? Those European saws are nice. I keep saying that I should switch to one or a Saw Stop. I like my PM, but it could be safer. I really like a slider a lot. I have a condition that limits the feeling in my right hand, so I am always very conscience of slippage. By the time I feel any, a lot can happen. Using a slider for sheet goods as well, just seems like the way to go. Do you have a slider or a straight TS?John
John,
I use those magnetic featherboards so I can put them just about anywhere. I had a PM66 for about 20 years and I rebuilt it (arbor bearings) then I bought the Laguna TS because I don't use sheets goods that much and where my saw is in my shop it would have blocked my path to about three tools. I tested the TSS at a tool show and it works quite well. In your situation I would buy the TSS over the Saw Stop. Just my opinion though.
Not to hijack the thread, but the only slider I ever used was a Mini Max, and it was very nice. I notice that the Laguna is much less expensive. There seems to be a quite high level of competition between the two companies. Have you ever compared the two?John
John,
I have not. When I bought my saw Mini-Max was just getting restarted in the US market. They were here great guns about 20 years ago and kind of let their dealer network fizzle. Now I think they are back to stay. I have always liked Mini-Max tools, the ones made in Italy, and they are very high quality. I bought my Laguna TS through a WW show in Detroit and the Mini-Max rep just blew me off so I bought a Laguna TS and a 18" HD bandsaw. Went to the show with a buddy who has a Mini-Max 16" bandsaw and that is all he talked about. He was even embarrassed how the rep treated us, and the rep knew I was there to buy two saws. I think they are good tools ,but maybe they need to work on the people who represent them.
I Think the Mini-max is a true European slider and the Laguna TSS is an adapted sawwith a great slider attachment. If you do mostly sheet goods I would look hard at the Mini-Max. I have no I dea how much they cost.
Well, if they treated you like that, I don't blame you! That was foolish! I am always amazed when "sales" people treat others poorly. Good for you! I'm glad to hear that you are pleased with your machines, I take it that you like the Laguna 18" BS as well?John
Some of the blade manufacturers may tell you that the big motors have too much power for a TK. I've used about 9 different TK's on 3 saws that were all under 2hp and have never had even minor deflection....not saying deflection doesn't or can't happen, just that it hasn't for me on my saws. TK's are all I use now... and I've put 8/4 hard maple across my WWII, and 10/4 hard maple across a Dewalt DW7124TK and a Leitz 24T TK. The rippers just plow throught it at a pretty respectable clip. No doubt when push comes to shove, the full kerf just has the stronger body, but so far, I much prefer the feel and feedrate of the TK's on my saw.Wonder if CharlesM from Freud has any input?
Edited 5/8/2006 6:27 pm ET by scottwood
The tk blades that were bent sound to me like isolated and unrelated incidents so I will leave them alone. TKs are not just for underpowered saws. In fact, one our most popular gang rip blades is also one of the thinnest kerf blades we offer and those are monstrously powerful saws. Using the correct thin kerf blade for the correct application should yield the same results as the full kerf variant but with less waste and less load on the saw (assuming blades of the same high quality grade). HTH
Charles M
Freud America, Inc.
Dear Charles,
I appreciate you jumping into all of this. I have a high opinion of most Freud products and in all fairness, the blade that gave up on me was not one of yours. You stated "Using the correct thin kerf blade for the correct application should yield the same results as the full kerf variant but with less waste and less load on the saw", which leads me to the question of "If TK's perform the same as Full Kerfs (FK) then why manufacture both?" If Freud can make a thin kerf blade that performs as well as a full kerf blade, why even note the difference? Thanks,John
John,In answer to "If TK's perform the same as Full Kerfs (FK) then why manufacture both?" I have one word - Marketing. If we only offer full kerf we lose the thin kerf market and vice versa. This thread illustrates the clear lines that divide the market and both sides are correct if they are satisfied with the results.
I believe a lot of the concern over flex in TK blades is carried over from the days when all blades were stamped and milder steel was used. The new laser cut blades are a lot stiffer.
Charles M
Freud America, Inc.
I had a suspicion that would be your answer. At least as far as the marketing goes, I don't know enough about your business to comment. There are companies that offer TKs that don't advertise them as such, "Matsus*ita" comes to mind. Good quality, but I've had them deflect as well. I suppose we can let it go at that. Overall I have been very pleased with Freud's products, and although I don't see me buying any "thin kerf" blades anytime soon, I appreciate your input.Thanks,John
Charles,
Hmmmm. So "marketing" is an acceptable answer to why we should all buy TK as well as a normal blades, is it? Not as far as this consumer is concerned; how about some engineering reasons, the only legitimate ones as far as my money and me are concerned.
In an earlier post to this thread you said,
"Using the correct thin kerf blade for the correct application should yield the same results as the full kerf variant but with less waste and less load on the saw (assuming blades of the same high quality grade)".
Presumably, then, TK blades are for those who have underpowered saws and/or for those who are resawing a lot and don't want to waste timber? But if the TK blades are otherwise identical in performance to a full kerf blade, why should we buy a full kerf blade ever again, from Freud or anyone else?
Of course, a TK blade will not cut a kerf wide enough for those of us with a normal kerf riving knife in our saw, but this to the side.
Were not full kerf blades originally made that width for a good engineering reason? Are not 12 -16 inch blades 4mm or even thicker in kerf? One wonders what the engineering, rather than the marketing, reasons are for those normal blade widths........?
Lataxe
I don't think Charles is saying you should buy TK's or FK's or anything. He was pointing out that regardless of the engineering soundness of today's TK's, there are people who won't buy 'em due to established prejudices. Thus, they have to produce full kerf blades for marketing reasons.
Myself, I'd rather not buy TK. Maybe it's just unreasonable fear, but the horror stories about TK's warping and tearing into inserts etc. are at least a plausible thing that could happen... and my 5 HP saw has no trouble pushing a full-kerf blade. I don't resaw much with the TS, so the kerf loss almost never matters to me.
Charles' position is pretty clear, that the new TK blades are dependable and could be their only product... if it weren't for fearful fuddy-duddies like me. :)My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
Three days ago, my Jet 10" TS decided to stop working. I do all my ripping on it with an Everlast thin kerf with freud stabilizer disks. I had to resort to using my SCMI slider with a Forrest WWII FK 12" blade (combo teeth spacing) to rip a fair amount of maple that couldn't wait. It was the longest day and a half of my woodworking life. I finally figured out that my Jet 10" had a bum plug (pardon my french), so a new one turned the trick, and I have my beloved 3 HP TK 10" blade singing effortlessly thru the rest of that hard maple. Amazing how 3HP will so totally outclass 6.6HP by simply thinning down the blade a bit. A good thin kerf blade with a proper stabilizer is the only way to go when ripping. By the same token, I wouldn't waste my time crosscutting with anything but a full kerf cutter; TK's seem to flex too much for a really clean cut, especially on miters.
I use a Forrest WWII full kerf 10" blade, 1/8", on maple, on a 5 HP Unisaw. I've never had it bog, never had it slow down. It pushes that blade through maple as fast as I could think of sending it through. But then I don't do a lot of ripping with it, I use a rip blade for that if I'm doing more than a board or two.
I simply can't believe that a 6.6 HP table saw is so hindered by a full kerf blade that it bogs down for that reason. Your experiment changed too many things at once to be considered a decent test of thin kerf versus regular kerf.
You went from a combination blade to a rip blade. Good idea for ripping, as the blade geometry is optimized to the task. Heck, I can get a better edge on ply with a $5 plywood blade in my crappy circular saw, than with the wrong (even expensive and sharp) blade on my table saw.
You went from 12" to 10"; it takes more power to spin a 12" blade than a 10". But then again, your 6.6 HP saw is plenty capable.
Who knows if the blades are both equally sharp and flat, both saws set up equally well, etc.
My point is just that you don't get better than 6.6 HP of performance on 3 HP by "slimming down a bit." The FK blades are only 33% thicker than a TK, so the most performance boost you could really see would be 33%, making a 3 HP "seem" like a 4 HP.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
John D,
Okay, so you want specifics. 10" Everlast blade is 24 tooth, .104" actual tooth thickness, and 1.303" spacing from tip-to-tip. 12" WWII is 40 tooth @ .120" actual tooth thickness, .925" spacing tip-to-tip. Both blades just back from my sharpener a few weeks ago, both razor sharp. I was actually surprised that they were this close in thickness because the Everlast rips so much easier than the Forrest. But remember, this particular Everlast is a pure industrial ripping blade, intended only for that purpose, and the Forrest is intended for a broader scope of uses. The WWII has more cutting angle to the teeth when viewed edge-on, and did not have stabilizer discs.
I was not intending to disparage my WWII, because it is a very fine blade. I simply wanted to illustrate how nicely a true thin-kerf ripping blade can do the job. And believe me or try it yourself; there is that big a difference between the two blades when ripping maple. I wouldn't make up something like that.
My point was primarily that a ripping blade is going to rip better than even a good combination blade, and that it's hard to say whether thin kerf has anything to do with it at all.
If you're providing evidence backing up CharlesM's point that TK blades can kick butt with the best of 'em, I've no dispute whatsoever. My only issue was your statement that thinning the blade is what gave you the great performance -- I would assert that the blade geometry is the reason for the good performance (and acknowledge your point that the TK didn't cause any problems).My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
"My point was primarily that a ripping blade is going to rip better than even a good combination blade, and that it's hard to say whether thin kerf has anything to do with it at all."I've experienced benefits from both of the variables mentioned in that statement. My first real ripping blade was a full kerf Freud LM72R010 used on a GI contractor saw. It was a big improvement over my full kerf LU84 50T combo when ripping 2" hard maple. I later got a TK 40T WWII as a gift, and the LM72 still ripped more efficiently than the 40T TK. The LM72 is a very good high quality purebred ripper used and respected by alot of people, but on my saw, 8/4" to 10/4" hard maple still bogged the motor more than I liked. I ran into a deal on a DeWalt DW 7124TK 24T ripper that had a very similar tooth configuration to the LM72 (Flat top grind, ~ 20d hook) but was available in a thin kerf. On my contractor saw, the DW was able to run through the same stock much easier. The same was true when I got a similar Leitz ripper as a backup. These are both very good rippers, but I doubt either of them are made quite to the same standard as the LM72, but on the smaller saw they really free up the motor more in the heavy stuff.My saw has since changed from the GI to a Craftgsman 22124 hybrid with a 1-3/4hp motor, and the same blades show the same tendencies on the motor when cutting similar thick materials. When push comes to shove, the smaller motors seem to really benefit from the thinner blade. Bigger motors may not b/c they're less likely to get "pushed" as much.
Edited 5/12/2006 2:23 pm ET by scottwood
Charles also pointed out the technical improvements to the stiffness of modern TK's, and that much of the prejudice orginitated with earlier versions.
Yes, full kerf blades were made that size for sound engineering reasons and the larger the blade the thicker the kerf should be (of course we are more concerned with plate than kerf when thinking in terms of blade stiffness). The changes in the types of steel used now allows for thinner blades with much the same properties as the older, thicker versions. I think John D interpreted my intent pretty well and I, like most in the industry, tend to recommend thin kerf for lower powered saws and thicker kerf for the stronger saws and we do it more because of tradition and market expectations than from necessity.
Charles M
Freud America, Inc.
Charles
You are probaly right. Ripping with a TK blade should be strictly a rip blade and not a combo blade.
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