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Thread: Table saw blade sharpening question

  1. #1
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    Table saw blade sharpening question

    I would like to hear from those that have had blades sharpened as to this question.

    We all know a sharp edge is the intersection of two straight faces to make that edge.

    Now when i look at the teeth of a table saw blade and see the small pieces of carbide welded on to form those teeth, my question is when they sharpen said teeth do they only grind the single face that is the front side of that tooth?

    Or do they do all sides ie two outer sides, top and front face?

    Reason i am asking is if a tooth has a chip then the face that corresponds with that chip surely needs to be ground too.

    Also how do any of the faces get to meet and hence form a sharp edge if only one face is ground on the tooth.

    The thing that has me going is that these blades are advertised as 6x sharpening etc . Implying that you can get numerous resharpenings done of the blade.

    But i am thinking that in the case of something like the thin kerf diablo freud blades, available here for $39 for a pretty good all round blade i dont see that its worth getting the blades resharpened if the returned result is going to be less than what the original was in the first place.

    A $100 plus woodworker full kerf etc i can understand but even then whats it like if only one face is "touched up" ?

    Then another observation i was making from reviewing a bunch of blades at the store was we often have comments made by various folk about how they like this or that blade and dont get this or that problem eg tearout or cutting ability etc.

    But no one seems to have commented on just how much carbide is used in those teeth.

    My point is, when i look at some of the real cheap blades around, if one takes a moment to put the glasses on and compare the more expensive with the cheap blades one will see the magnitude of the problem i am referring to. The cheap have what i would term a "token chip" of carbide as a tooth.

    Even taking this and comparing it side by side with a diablo from freud probably the lowest on the freud totem pole, one can see the substantial difference in the amount of carbide.

    Now subsequent to learning to take a good look at the carbide on a router bit ( and do this for yourself sometime, compare a Lee Valley router bit and some other private label) one can see the huge difference in thickness. When one considers that this bit of steel heats up rapidly when its working, then if its a small chip its going to battle to dissipate and distribute the heat away as it works.

    My question then is whats the real value of these blades if one were to lay out the coin to sharpen them given that a already relatively small chunk of carbide is being made even smaller.

    Its in these subtleties that i feel the manufacturers fail to educate the market to raise the value of the product such that the price does not become the lone arbiter of blade quality.

    My thanks go again to Carol the router lady for her book, if i recall correctly i got this insight of course related to router bits from her book. But its transferable know how.

    To me this is particularly relevant to hobby woodworking where cost is always considered and for the most part the majority of hobbyists probably have contractor saws not 3HP and 5Hp table saws.

    In my mind therefore a good compromise on cost is to use a reasonable quality thin kerf blade to make it easier for those smaller motors to push through hardwoods and then forget about re sharpening them and rather go for a new blade.

    Would love to hear thoughts and opinions on this point but also more intricate detail of the sharpening process used if anyone has knowledge of it.

    Thanks
    cheers

  2. #2
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    There are varying geometries used by different makers. The most common would be a flat face with three sides ground to meet it. Freud uses a double-side-grind which makes some of their blades cut with reduced feed effort and a great finish. Their Fusion blades use this IIRC. I think the idea is to grind a reasonable amount of side to support the face and then a second grind that bevel away from the kerf to allow ease of clearance. I'm sure their marketing glossy's can say it better than I do ;-)

    Other mid to high end blades have their own approach; some marketing fluff and some actual. Carbide formulations differ, plate coatings differ, etc. Carbide Processors have some blades that I have found to be without peer. I have had decent success with Forrest but, better success with Freud and Leitz. Snook's Saw out of Oregon has made me some blades that have become my go-to cutters. A few blades and router bits will be making the trip to the sharpener's after this pecan project is completed; man that stuff eats cutters.

    More info:

    http://blog.carbideprocessors.com/sa...st-saw-blades/

    http://www.freudtools.com/t-sharpen.aspx

    http://www.forrestblades.com/aboutsharpening.htm

    http://www.freudtools.com/t-blade_selector.aspx

    I used to toss blades that I got at a really good price once they were "done" . . . unless I got a $100 blade for $25. In that case I will sharpen it because then I got two $100 blades for $50 . . . . as you can see, I have a flexible rationalization engine ;-). At this point I have rip, general, specialty and crosscut blades of a sort that will take several sharpenings and will back fill them as they get near end of life.
    Last edited by glenn bradley; 07-26-2013 at 03:54 PM.
    Any sufficiently advanced technology is indistinguishable from magic.
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  3. #3
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    Quote Originally Posted by Rob Keeble View Post
    ...
    Reason i am asking is if a tooth has a chip then the face that corresponds with that chip surely needs to be ground too.
    ...
    If there is a significant chip in the carbide, the tooth can be replaced by any reputable sharpening service for a modest fee.

    Quote Originally Posted by Rob Keeble View Post
    ...
    Also how do any of the faces get to meet and hence form a sharp edge if only one face is ground on the tooth.
    ...
    I do not know the sharpening technology, but I have assumed that two sides were sharpened back enough to meet a flat surface on the other side. In my experience, after sharpening the diameter of the blade is slightly different, but the kerf has not changed.
    Charlie Plesums, Austin Texas
    (Retired early to become a custom furnituremaker)
    Lots of my free advice at www.solowoodworker.com

  4. #4
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    I use the same blades as you, Rob, and I found my last Diablo combination blade (the one that is especially good for crosscuts) was still delivering good smooth cuts with 5 missing teeth and 6 damaged ones. I checked the prices of the repair with the local suplly company, and it was much cheaper to buy a new blade.
    Cheers,
    Roger


    The other member of Mensa, but not the NRA

    Everyone is a self-made person.

    "The thing about quotes on the internet is that you cannot confirm their veracity" -Abraham Lincoln

  5. #5
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    Thanks Glenn that freud link you posted was great info i had not seen before about their blades. The range they make causes me more confusion than anything else.

    Thanks Charlie thats what i was wondering about.

    Roger what are you doing to your blades to have them loose teeth? I have been through three of these diablo blades and cut all sorts and not had a tooth lost. I even took the plunge and bought a real junky cheap blade from home depot more as an experiment than anything else to experience just what it was like and i thought for sure this thing is going to loose some of those tiny chips of carbide and when i say tiny i mean real excuse for carbide and they did not lose a tooth even on ripping and cutting loads of rough hard wood and throwing in some pine and wet pressure treated stuff.

    Have you been hitting nails in wood or something?
    cheers

  6. #6
    I do an average amount of hobbyist building, an occasional addition to my house, a deck or two or three, all the furniture for three houses, plus my kids' homes, etc. I've had a really good combination Systematic blade for nearly thirty years, and it gets resharpened at a cost of maybe $15 every other year. In between, it delivers superb service. The good sharpeners do both the top bevel and the face. Occasionally it has needed teeth replaced. Throughout it all, I've loved the consistency of the cut. It's time for it to be replaced, and. I won't be going with a cheapie.

  7. #7
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    Rob, I really don't know the answer to your question. I had done a lot of ripping with that blade in hardwoods, primarily ash. I used it for a couple of years. As the wood I used was all new wood from the Wood Shed, I wouldn't expect to have hit any nails. I know that sometimes nails are concealed in lumber, but I never saw any evidence of metal in any of my wood. So, I don't know why I was so tough on the blade.

    I do think the Diablo blades are just dandy, and a very good value.
    Cheers,
    Roger


    The other member of Mensa, but not the NRA

    Everyone is a self-made person.

    "The thing about quotes on the internet is that you cannot confirm their veracity" -Abraham Lincoln

  8. #8
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    Roger i hope you are no longer using the blade with teeth missing. Have you had this problem with teeth missing repeated since its first occurrence? For safety sake i would recommend that you either get the blade repaired and checked out which if its a diablo i would not bother with for the cost/risk benefit. Bear in mind these are intended for the contractor market so dont expect too much for the price point.

    This was my whole point, these blades sell in Canada at the depot for around $39 plus tax of 13%. So i dont see it being worth the "CLAIMED" 6x sharpening for a blade like this.

    Especially not when i consider

    a) Its think kerf already so there aint much carbide in that tooth to start with
    b) You now sharpen one face and have even less.
    c) The whole point of my post which i really did not get clear in my rambling, was that there are three cutting edges to each tooth as far as i make out on a table saw blade.
    So my point of debate is dressing one face does not ensure that all edges are sharp.

    If this was the case, why do we flatten the rear of a plane blade or for that matter a jointer blade.

    Charlie makes the point that they sometimes do the top of the tooth which may get a chip or that the tooth can be replaced if it has a chip.

    My point is that the blade to start had better be as Glenn points out, worth it to do and have the carbide resources to make it still substantially a good blade after sharpening.

    I have no experience with a sharpened blade, would love to see a reasonably scientifically done review and comparison of a good blade performance both before and after sharpening once then twice then three times and see to what degree the performance deteriorates.

    There is also the question of balance and if they did touch up the sides then the thickness of kerf it cuts being altered.

    Sooooooo this kinda takes me full circle as to the merits of buying a high end blade for a hobbyist (note not a Pro that makes a living from his woodworking and the quality of said woodworking) versus buying a lower cost blade but doing so more frequently.

    Add to this whole point, how many hobbyists have 3hp and up table saws.

    Therefore the think kerf good quality but not super high end blade makes more sense to me. But i am open to having my thoughts changed.
    cheers

  9. #9
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    Rob, I think you may be overthinking this whole thing.

    I have two primary blades that I use. A crosscut and a rip. Both are mid-level Freud Industrials and both are thin kerf. I actually have three that I use, because I bought a replacement for the rip blade on sale a few years ago, but I still use both rip blades. (One for non-critical stuff and the other for more important stuff.) At their sub-$70 price points for either style of blade, I'm not gonna worry about tooth geometry or how many sharpenings they can take or which faces get honed in the process or whether the sharpening process is the same as that for a plane blade or a chisel. I'll just use the blades until they aren't giving me a satisfactory cut, then either send them somewhere for sharpening or replace them. The older of the rip blades has been in use since about 2005. The other two blades are at least 5 or 6 years old, and showing no signs of needing to be replaced. (Granted, I'm not using my tablesaw a lot these days, but when I was making a lot of cutting boards, it was getting a lot of use...with these same blades.)
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