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  1. #1
    Join Date
    Jan 2017
    Location
    Sunshine Coast
    Age
    60
    Posts
    196

    Lightbulb Trial sharpen tablesaw blade, with a tablesaw...

    G'day all

    I'm sure someone else has done similar...

    But i got Jack of 'it costs more to have a circular blade sharpened, than buy a new one'.

    I am in the need of 2 more sharp 10" circular blades, and was disheartened to add another 2 circular blades to the blunt pile.

    I thought I should at least try and figure out a way to sharpen them.

    I know how circular blades are sharpened. Pass a circular fine abrasive past the front of the carbide to reface it.

    Proof of concept idea...

    So, I bought a 9" diamond blade to fit to my table saw.
    I made a sled.
    I gave it a try.
    I checked the sharpened teeth with 20x magnifying glasses. The teeth are now sharp, although the sharpened face is much coarser than new ie cut marks from the diamond saw.
    IMG_2976.jpg

    IMG_2981.jpg

    IMG_2984.jpg

    Blade sitting on top of acrylic sit to clear teeth.
    IMG_2985.jpg

    IMG_2990.jpg

    Diamond saw in action. Bring carbide tooth gently to the side of the continuous diamond surface.
    IMG_2989.jpg

    Sharpened teeth
    IMG_2994.jpg

    Proof of concept validated. Clean edge sawing melamine.
    IMG_2993.jpg

    I reckon, if I buy a much higher quality diamond blade I should get even better results. The trial blade i bought was a tile cutting blade.

    This is the moment you tell me that I have wasted an afternoon and some money, coz you know where I can get my circular blades sharpened cheaply on the Sunshine Coast!?

    That would be OK
    Oh, and I don't know how to rotate images

  2. #2
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    29
    Posts
    4,991

    Default

    I don't think a more expensive blade will give you a better finish. Saw blades are designed to cut, not polish, and they need to be pretty coarse to do that effectively

  3. #3
    Join Date
    Jun 2005
    Location
    Helensburgh
    Posts
    6,081

    Default

    Well done, why buy another diamond disc, you can't fix what ain't broke. The only thing I can think of is changing the pivot relationship to the diamond disc to allow for different rake angles that blades can be bought with. This or a similar jig could also be used to change the top profile of the teeth is needed.
    CHRIS

  4. #4
    Join Date
    Jan 2017
    Location
    Sunshine Coast
    Age
    60
    Posts
    196

    Default

    Thanks

    The diamond blade I chose can chip the TC teeth if I go too hard/too fast.

    When looking via 20x magnification the grind is very coarse compared to original.
    A finer diamond blade may reduce the chance of chipping the edge of the TC teeth.
    But, so does talking your time

    Fortunately, the rake on most of my blades is constant, even though the number of teeth isn't.

    Good point though.

  5. #5
    Join Date
    Apr 2014
    Location
    Little River
    Age
    73
    Posts
    872

    Default

    Why not just get a proper diamond sharpening wheel?

  6. #6
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    29
    Posts
    4,991

    Default

    Quote Originally Posted by Bohdan View Post
    Why not just get a proper diamond sharpening wheel?
    Cos one big enough to use in a table saw will likely cost a fortune, if you can even find one. They're usually only 4-6" diameter.

  7. #7
    Join Date
    Dec 2010
    Location
    Mornington Peninsula
    Posts
    2,387

    Default

    Well done.

  8. #8
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    23,404

    Default

    Quote Originally Posted by graham.murfett View Post
    I reckon, if I buy a much higher quality diamond blade I should get even better results. The trial blade i bought was a tile cutting blade.
    I don't think it's a quality issue but more of a grit issue because it sounds like you are using a cutting wheel which has a very coarse grit.

    What you need is a grinding wheel that comes in a very wide variety of sizes (4" to 12") and finer grits and they don't cost a bomb.

    SWMBO uses a wide range of diamond grit wheels (from about 60 grit to 1200 Grit) for her lapidary work so I managed to sneak a few 180grit wheels onto her order.
    We get her diamond wheels from thk.hk

    I have one of the 180g diamond wheels mounted on an bench grinder to shape TC bits for my MW lathe and router bits.
    I would easily be possible set it up for TS CT tipsharpening but a larger table would need to be setup to hold the blade.

    Speed is another issue to consider

    From Ukam.com.
    The best speeds for diamond wheels for grinding carbide is between 5,000 to 6,000 surface feet perminute. Slightly higher are not detrimenta.l, particulary if a flood of coolant is applied and grindingpressure minimized. Table traverse rates of 100" to 500" per minute with cros feeds of .030 to .060may be used. The diamond wheel may be used with down feeds of .125" when hand fed across thework. For general surface grinding operations, down feeds should not exceed .001 per pass, forrougher grits and .00025 should be used for used for finish grinding or with fine grit wheels.
    Note how little TC should be removed per pass, if you push too hard the diamond will wear/break off

    If your TS saw is running the blade arbor at 3000 rpm then the surface speed on the outer edge of 9" wheel will be ~7100 FPM.
    Many TS run higher than 3000 rpm at the arbor, with some running as high as 4200 rpm this would mean a surface speed of nearly 10k FPM which will be too high.

    If you were to get a larger wheel bear in mind that this will increase the FPM.

  9. #9
    Join Date
    Nov 2011
    Location
    Sutherland Shire, Sydney
    Age
    66
    Posts
    1,187

    Default Great idea

    I have often pondered ways of DIY circular saw sharpening, never thought about doing it your way. If I were to duplicate your system I would incorporate a maggy lamp type of magnifying lamp attached to the table saw top so that the geometry of the teeth could be matched to the diamond blade. My eyesight isn't what I would like it to be!

    Good luck with your experiments.

    Alan...

  10. #10
    Join Date
    Apr 2011
    Location
    McBride BC Canada
    Posts
    3,370

    Default

    Very clever trick. Very clever. That diamond blade doesn't owe you a penny.

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