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My first ZCTP

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  • My first ZCTP

    Hello Gurus,

    Now that my saw is raising and lowering I am excited to build more accessories for my saw.

    Trying to make my first ZCTP and struggling to figure out the correct cutouts. Which holes do you guys use to secure the ZCTP. Do you guys use A & C or B & D in my photos?

    Also I am trying to understand what mpc has tried saying in this post -
    https://www.sawdustzone.org/forum/di...005#post832005

    I tried making one that sits on the lower tabs (like in photo 3) following the above post and ignoring the 0.1" lip. But that doesn't seem right. The drop of 0.1" or so seems big enough for the material being cut to get obstructed on the rear side. Clearly I haven't understood that post correctly.

    May I see some photos of ZCTPs you have built.

    Thanks a bunch in advance.

    NG

  • #2
    I threaded holes A and C in your pictures. My ZCTP fits inside the opening as you show in pics 3 and 4. However, my upper ZCTP surface is even with/flush with the top of the table saw. So only the small rectangular spaces (basically at holes B and D) have "drops" in them. The vast majority of the throat area is flush with the regular tabletop; having those small areas a tad lower hasn't been a problem for me.

    If those drops do concern you though, some options are:
    1: make your ZCTP blanks longer, cutting rabbets on each end to cover holes B and D. I'd still use screws in A and C though as the ZCTP material - assuming you make your ZCTPs out of wood or MDF - would be too thin to have any strength to hold screws.

    2: an easier approach might be to make the core ZCTP piece sit inside the opening (as your 3rd and 4th pics show) and be flush with the B and D surfaces instead of being flush with the main tabletop surface... and then glue on a thin veneer layer over the entire area - B, D, and the central ZCTP blank - to bring the final ZCTP flush with the main tabletop. The veneer would thus creat the rabbet joints. This would also be a lot easier method if you don't have a dado set yet compared to making the rabbets of option 1.

    mpc

    Comment


    • #3
      I use B & D. Even with rabbeted hardwood ZCTPs it works. There doesn't need to be much material thickness for the screws as they simply hold it in place. As mpc says make sure you are flush with the top of the table. Stytooner (LeeWay Workshop, SharkGuard, etc.) made or had them made from HDPE once deciding Lexan was not the best choice. I have a variety of sawblades and consider a ZCTP a wear item. When the slot becomes a bit too wide for best results it becomes a Dado ZCTP.

      Perhaps IMHO the most important tip is to make sure the blade clears the bottom and that you hold a board over the top by mechanical means while cutting the blade slot the first time, slowly lifting the blade.

      just another brick in the wall...

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      • #4
        Either A-C works or B-D
        I seem to recall the four holes you call A-C Does not come tapped (threaded) from the factory but its easy to run a 8-24 tap through it. I just checked mine and they are tapped I probably did it at some point. They may even come with self-tapping screws.

        Whichever you use should have the plate solidly sitting on the surface with the hole.so things don't flex and distort,
        I don't tighten the screws hard at all, because it distorts the plastic throat plates - the B-D holes are very thin there. There's no real forces on the plate requiring more than just snugging them.

        The screws they give you are 8-24 x 3/4" long which is way more than needed for B-D but probably right for A=C which are set deeper.

        TO me this is the key thing. The plate must be very flush with the surface of the saw,.say between -3 mils and 0 mils. That is from about flush to 3 mils below the table. Flush means you can slide a steel rule across the top of the plate and not catch it when moving from the table to the plate. My plates from Ryobi were never quite that good (I assume manufacturing tolerances) but I simply shimmed my plates up with some metalized address label stock that was about 3 mils thick, using as many as I needed.

        Why so tight? So small pieces won't catch as you are feeding them across the blade. And so that depth of cut settings for the blade hold for big pieces and small. Also I think you need to adjust your SMT so it is level with the main table.

        Anyway, if you are making a throat pate then you need to decide whether its going to register on B-D or A-C or maybe both.
        Youre going to have to cut rabbets on a any plate of adequate thickness. wider Rabbets can be made on a BT3 with multiple parallel passes.

        The BT3 FAQ has some specific advise on cutting a zero clearance slot... if the plate is too thick it may jam against a 10" blade and destroy your expensive and hard to get belts

        My honest evaluation of your picture says you have the top of your plate set way too low. 0.1" is way more than my -0.003" I would allow!

        I will measure my Ryobi accessory plastic ZCTP blank for you.





        Loring in Katy, TX USA
        If your only tool is a hammer, you tend to treat all problems as if they were nails.
        BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

        Comment


        • #5
          I posted pictures and the dimensions here https://www.sawdustzone.org/forum/di...ry-option-zctp

          Click image for larger version  Name:	ZCTP Dimensions.JPG Views:	0 Size:	69.1 KB ID:	843417

          Click image for larger version  Name:	P3190297.JPG Views:	0 Size:	124.9 KB ID:	843415

          Click image for larger version

Name:	ZCTP Outline drawing and hole location.jpg
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          Click image for larger version  Name:	P3190303.JPG Views:	0 Size:	153.6 KB ID:	843414
          Attached Files
          Last edited by LCHIEN; 03-19-2021, 10:52 PM.
          Loring in Katy, TX USA
          If your only tool is a hammer, you tend to treat all problems as if they were nails.
          BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

          Comment


          • nicer20
            nicer20 commented
            Editing a comment
            This is super helpul and thanks a million for all the help.

            - NG

        • #6
          Thank you mpc , Black walnut & @LCHIEN: All super helpful as usual. Can't thank you all enough for all the insights.

          @LCHIEN: Your honest evaluation is very much on the money. In fact that was my primary concern for the post. When I made mine, the way I have done, I started to see the problem it being too low. I had clearly misunderstood MPC's post. Of course, entirely my problem - not his as he was referring to some other gap. (So please please this is not at all a criticism of anyone or any post).

          mpc: I am now following some of your suggestions - trying to put another layer on top of that plate. But I don't have a planer so I am trying to use some other ideas.

          BTW I have a BT3100 and it seems all the holes are already tapped - don't know if the previous owner did it or factory did it.

          And I am going to follow the BT3 FAQ suggestion to use a 7 1/4" blade to create a relief first before using the 10" blade. Can' take chances with the belts as the saw has started to become more useful after overcoming the raising/lowering mechanism problem.

          Now to the shop to make the ZCTP.

          Thanks a million again,

          NG

          Comment


          • #7
            If you make one too thin you can always add aluminum tape to the bottom to build it up until it is level.
            just another brick in the wall...

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