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  1. #1
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    Default A couple of table saw questions...

    A mostly Newbie woodworker here

    Was attempting to cut some Blackwood into 1/8 and 1/4 strips for making some box dividers, but am getting significant burn marks.

    Is this wood especially bad for burn marks? Found it in my grab bag, havenít used it before. Havenít noticed issue on pine or tas oak.

    Saw blade wrong or too dull? Itís a 40t combo blade that came with my saw (second hand). Need a dedicated rip blade, or just one thatís not so dull? I assume Jet branded combo blade is low end?

    Whatís good? 5/8 arbor, rather not deal with adapters if possible. Amazon has Freud, otherwise timbecon (Freud, sawstop, torquata) or carbatec has cmt. Iím not cheap but donít want to waste $

    The only other blades in my stack are dado, box cut, fine cutoff, and melamine/chipboard blades - which appear unsuitable.

    Or could blade be dirty?

    Saw is 1.75hp Jet. Underpowered?

    How would I ďfeelĒ appropriate feed rate?

    Tx, Simon

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  3. #2
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    Default

    What depth of cut?

  4. #3
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    Default

    About 2Ē

  5. #4
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    So much sanding required :/

  6. #5
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    Default

    Simon, forgive me if I ask the obvious but you are using a rip blade?
    It may also be that the fence may not be parallel to the blade?

    Cheers,
    Yvan

  7. #6
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    Default

    Blackwood is notorious for burn marks. Yes your blade has to be sharp and a rip blade is advisable. BUT the methodology says that after ripping the next step is to plane the surfaces then sand. By planing the faces any burn marks will be illiminated. You may even find that a newly sharpened blade will give you some burn marks too. One tip is to push the stock through with an even pressure and try not to stop the forward motion when changing your hand positions.

    Another tip....Blackwood will give you a sore throat and bunged up nose. It is a real allogin
    Just do it!

    Kind regards Rod

  8. #7
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    Default

    @yvan it's a 40t combo blade (branded as Jet), per the original post. Probably a bit old.

    I asked here for some blade recommendations, but nobody has replied yet - maybe it's one of those never-ending "arguments"?

    I ordered a few blades kindof at Random in the meantime:
    - Freud 50t combo blade Server Busy
    - Freud 40t thin kerf combo blade Server Busy
    - Freud 30t thin kerf rip blade Server Busy

    Google tells me the thin kerf might be a little easier on the saw, if 1.75hp is a little underpowered?

  9. #8
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    I tried to push it evenly, but looking at the marks, maybe not even enough.

    I switched to the bandsaw, which cut without burning, but has a pretty rubbish wavey finish, so needs sanding anyway. (new blade, maybe not well setup).

    I ripped some random bit of wood in my shed the other day, it was dark brown and very lightweight - almost balsa light. And it stank! My shed smelt for a couple of days!

  10. #9
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    Default

    If you fit a thin kerf then you need a thinner riving knife to suit.
    also you need to have the blade fully up for ripping 2Ē thick stock, the saw wonít be working as hard as there is less tooth contact with the timber.

  11. #10
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    Hand planing is the way to go after ripping.
    Especially with Blackwood, the dust generated by sanding you will regret sooner or later.
    Mate developed such a bad allergy he just had to walk into his shed and his tongue would swell up.
    H.
    Jimcracks for the rich and/or wealthy. (aka GKB '88)

  12. #11
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    Default

    With underpowered saws like yours (and mine ) a dedicated ripping blade is mandatory for quality results. Combination blades are rubbish for ripping hard timbers. riverbuilder is on the money with his advice concerning the height of the blade, if you're using a 10" blade to rip 2" stock the blade should be at full height. This allows the teeth to cut down into the timber and reduces the tendency of the blade to push back and lift the stock off the table that's a problem at lower blade extensions. Feeding the stock to the saw accurately and consistently also makes a huge difference in the quality of the resulting cut - use featherboards to ensure accurate feeding.

    Freud make an excellent dedicated ripping blade in the 10" size with 5/8" arbour hole - Freud 10 In. 24 Tooth Heavy Duty Rip Blade with 5/8 In. Arbor and Silver Ice Coating (LM72M010): Amazon.com.au: Home Improvement - it doesn't matter whether it has the silver ice or the more common red finish. I wouldn't be going thin kerf for heavy ripping. 24 teeth for a 10" full kerf ripping blade will maximise the abilities of your saw.

  13. #12
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    As others have said, dedicated rip blade, sharpened and set, right size riving knife, gullets clearing top surface. One more thing - a bit of parafin wax on the saw table and fence will make feeding much easier.

  14. #13
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    Thanks for the tips on blade height! I had it just above the top of the timber.


    And the riving knife for the thin-kerf blades! I might not have noticed that. Any idea where to get one? Saw is a Jet Proshop, and google isn't helping.


    I've never used a plane in my knife - don't know where to start with piece clamping and technique, let along buying a plane or sharpening the old ones I have lying around.


    Thanks for the tip on wax. I think mine is OK there, used some wax already.

  15. #14
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    Just buy blades that are slightly thicker than your riving knife, it will be easier than trying to buy another riving knife. A rip blade, in 300 diameter, should be around 24 teeth maximum. Set it as high as it will go, as high as the saw will wind it up. Use a push stick when the timber is near the end of the cut, push the piece thats against the fence.

  16. #15
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    Hi mate

    wrong blade for the job, especially if the timber is prone to burning easy.

    If you only have full kerf riving knife/splitter the a Freud 10 In. 24 Tooth Heavy Duty Rip Blade with 5/8 In. Arbor and Silver Ice Coating (LM72M010) would be my turn to for this.

    I have a 30t Glue line rip in full kerf and it can slow down at that depth of cut on really hardwood, i'd expect no issues on the 24t.

    The 1.75HP should be fine, just slow down a little

    This brings me to the setup. The issue with looking at the photos is we can't tell if the burning is coming from the right or left side of the blade or the front or trailing edge. Both will tell were the setup error is if there is one.

    It's often said and done to toe the fence out a bit at the back but if it is too far then you end up with the wood not traveling parallel to the blade and excess pressure applied by the blade to the cut edges leading to overheating. If you combine that with some dullness, wrong blade and timber prone to burning ... then you get a perfect storm.

    As others have said raise the height some more might help as well as it gives the teeth less time in the wood.

    Cheers
    Phil

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