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  1. #1
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    Apr 2001
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    Default Sharpening bandsaw blades

    I was asked to explain how I go about sharpening my bandsaw blades, and finally got around to putting together a couple of photos.


    Let me say first that I did not invent this method. It is widely used. I learned it on YouTube, that font of all important wisdom


    The fixture is new, and really thrown together in about 20 minutes. Before this, for a number of years, I would simply freehand this process. That worked well. Eventually .. recently .. I decided a fixture would offer more reliable results and less hand fatigue. Well, I think that this is so.


    The main tool is a Dremel with a small diamond disk (the disks are available for pennies on eBay).


    The blade here is bimetal 3 tpi 10mm wide. These are easy to sharpen. I use these blades for most everything except re-sawing wide boards.


    I have also very successfully sharpened a 1.3 tpi 1" Lenox Woodmaster CT, which is a carbide tipped resaw blade.


    The set up ...





    This is made of two pieces of ply, at 90 degrees, the Dremel is wedged between the brackets at the desired angle, and held on with velcro straps ..





    The method ...


    Simply "touch" the back of the tooth and grind a teensy weensy flat. Damn these technical terms - not too complex I hope? The angle I choose is in line with the back, but it is not critical. What I believe that the fixture does (better than freehanding) is keep the height of the teeth the same. That ensures that all teeth are cutting.




    Step 1. Mark the start of the blade (blue tape).


    Step 2. Set the fixture against the bandsaw fence to keep it tracking square.


    Step 3. Simply push the wheel into the tooth.


    Below you can see (not too well, I'm afraid - the shiny spot looks the length of the tooth, which it is not) a tiny silver shine on the back of the teeth sharpened, and the absence of this on those unsharpened ... a better picture would resemble the sharpening of a backsaw ..





    The result ...


    The wood here is hard, dry Jarrah. The two sides are the result of cutting with a freshly sharpened blade.





    Regards from Perth


    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

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  3. #2
    Join Date
    Jul 2018
    Location
    Canberra
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    66
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    Default

    Just for added clarity (I hope)

    I sharpen the bandsaw blades at the ACT Wood Craft Guild.
    I use exactly the same method, and it has been very successful process

    The only difference in the Jig is that I use rubber bands to hold the dremel in place (because it is convenient) and it allows me to flex the setup to change the angle slightly...if I need to,not that I have ever needed to, but when I build the jig I thought I might.

    The way I would describe the grinding process is that I "polish" the back of the tooth with a diamond cutoff wheel. It's a light touch that is all that is required

    I also use the weld as the start/stop point

  4. #3
    Join Date
    Mar 2008
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    Hobart, Tas
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    1,198

    Default

    Quote Originally Posted by derekcohen View Post
    What I believe that the fixture does (better than freehanding) is keep the height of the teeth the same. That ensures that all teeth are cutting.
    Thanks for documenting your process Derek. I am interested in the fact that you dont appear to use any form of indexing, as far as I could ascertain from the photos. Is the jig only providing a consistent angle, with the amount of steel removed determined by how much you raise each tooth into cutting disk?

    If there is no indexing, do you sharpen your blades until end of life, or do you have them professionally sharpened at intervals to reset all teeth to the same height, akin to jointing a backsaw after several touch ups?

  5. #4
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    Perth
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    Lance, no indexing - this method is as basic as it can be without doing it freehand. It is better than freehand, as the angle is consistent.

    How long can it be done? I have used the freehand method for several years, and sharpened the 10mm bimetal blades (from Henry and Sons) about 5 times. Then I toss them. I would say that I have had my monies worth. The cut can get slightly smoother each time since there is fractionally less set with each sharpening.

    What limits how long you can re-sharpen is, firstly, the size of the gullet - too small and it cannot carry away sawdust, and then it loads up and affects tracking. The second factor is the stiffness of the blade. Carbide blades are stiffer as they are thicker. They eventually fracture, and this is more common among bandsaws with smaller wheels, such as 14 (more bending). My Hammer has a roughly 18 wheel, and my last 1 Lenox Woodmaster CT, a carbide re-saw blade, disintegrated. It had been sharpened about 5 times.

    The number of teeth come into the equation. Too many and it will take hours. The 10mm 3tpi bimetal blades take about 20-30 minutes. The 1.3 tpi 1 blades take about 10-15 minutes.

    I leave the blade on the bandsaw - some like to do this task freehand on a bench grinder, and remove the blade to do so. Leaving the blade on the bandsaw makes it easier to keep the angle consistent ... and yet the bench grinder method still works well, which says that the sharpening is quite accomodating to angles. I do release some of the tension from the bandsaw, and work with the blade moving down. This is less tiring.

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  6. #5
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    Feb 2006
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    Perth
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    If you're game and your BS blade is bimetallic after touching up you can always add some set to the teeth using a conventional saw setter. The amount of set recommended varies and depends on type of wood being cut. The sort of figures I have seen bandied around are between 20 to 30% of the thickness of the blade. I just measure my somewhat used 3 TPI blade and it has a 21% set.

    If the tips are only very lightly touched up it's probably only worth applying more set after about every 3rd touch up. On the bandsaw mill (1 TPI - 210 teeth) I set the teeth after every touch up because a) the touch ups are not what would be called light and b) we have a semi automated setter.

    For Home use, just like touch up sharpening, whether you decide to do this may depends on the number of teeth on your bands and it may simply not be worth doing this on a high TPI blade.

  7. #6
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    Bob, I am not sure what your experience is, but much of the time these smaller blades can have too much set. Sharpening removes a smidgeon, and it is not until 5+ sharpenings that I have noticed any lack of set, which is apparent as binding, and even then it is slight. Less set equals a smoother cut.

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  8. #7
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    Do I take it that the diamond disc is perpendicular to the blade and not angled to suit the alternating set in each tooth?
    Dallas

  9. #8
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    Quote Originally Posted by Treecycle View Post
    Do I take it that the diamond disc is perpendicular to the blade and not angled to suit the alternating set in each tooth?
    Perpendicular.

    This is a simple process. The aim is to remove the wear at the back of the tooth. A small flat. No need to make it complicated.

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  10. #9
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    Jun 2005
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    Quote Originally Posted by derekcohen View Post
    Perpendicular.

    This is a simple process. The aim is to remove the wear at the back of the tooth. A small flat. No need to make it complicated.

    Regards from Perth

    Derek
    I have often wondered about this as when you get a new blade the face of the left and right teeth are at an angle to the blade. I had some of mine "professionally" sharpened by a reputable saw doctor and when they came back the new angle on the face of the teeth was at a right angle to the blade?
    They cut alright, but it had me thinking.
    Rgds,
    Crocy.

  11. #10
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    Quote Originally Posted by Old Croc View Post
    I have often wondered about this as when you get a new blade the face of the left and right teeth are at an angle to the blade. I had some of mine "professionally" sharpened by a reputable saw doctor and when they came back the new angle on the face of the teeth was at a right angle to the blade?
    It depends on the type, and capability of the sharpening machine and the operator Some auto sharpeners can file at an angle and some can't. What ever angle is used it has to be spot on or the blade will wander in the cut.

  12. #11
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    Quote Originally Posted by Old Croc View Post
    I have often wondered about this as when you get a new blade the face of the left and right teeth are at an angle to the blade. I had some of mine "professionally" sharpened by a reputable saw doctor and when they came back the new angle on the face of the teeth was at a right angle to the blade?
    They cut alright, but it had me thinking.
    Rgds,
    Crocy.
    To change the way a hand plane cuts, you alter the cutting angle - back bevel on a BD plane or higher bevel angle on a BU plane.

    Similarly, low rake teeth on a hand saw will perform differently from high rake teeth.

    If you alter the rake of the teeth on a bandsaw blade, you change the way it cuts. Sharpening needs to preserve the cutting angle, which comes from the rake. Sharpening the back of the tooth preserves the rake.

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  13. #12
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    Default

    How do the little Dremil discs stand up to the TCT? I have two of those 1" 1.3tpi both blunt, do I need to buy a box of discs? Thanks Phil.

  14. #13
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    Phil, diamond dulls eventually. Fortunately the disks are very cheap. Diamond is the only abrasive to cut TCT.

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  15. #14
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  16. #15
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    The problem with Dremel diamond wheels is their small size so there's not much diamond on those wheels to begin with.

    The trick with CT on diamond is very light touches.

    I have two 6" diamond wheels on a 1HP bench grinder that I use to sharpen TC tips for a TIG welder and TC tips for metal working.
    The oldest wheel has been in use for about 6 years amg is still working fine.

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