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Thread: Repeat cross cuts on long plywood sheets

  1. #1
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    Repeat cross cuts on long plywood sheets

    I'm struggling with making some repeat cross cuts on 70" long sheets of ply for a couple large cabinets and am looking for some ideas based on the tools I have. I initially measured, struck my lines and then did my cross cuts with the track saw but this isn't accurately repeatable and I'm off by almost 2mm on one of my panels which is obviously unacceptable for cabinets. I have a tracksaw, mft table, parallel guides and a table saw but am racking my brain on the right approach. The parallel guides for the track saw don't go to 70" and even if they did I'd be a bit concerned with some wobble at that length. The MFT would be great but my panel is way longer than fence and stop block for repeat cuts. My cabinets are also a bit wider than what is practical to cut on there. I've done it, but I can't latch the track down since my wood is wider than the table and I have to manually square and clamp the track each cut. I watched a video where Peter Millard has a table behind his MFT where he basically temporarily pin nails a stop block to the correct distance and then uses the MFT and track saw to make the repeat cuts. This is probably my most realistic bet though I'd need to make a temporary second table with some saw horses, clamp it all together and hope for no wobble and still fiddle with not being able to latch down the track right.

    Hoping for some ideas on a better solution for this. Thanks as always!

  2. #2
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    I have a MFT and Sawstop, but when I'm trying to crosscut a long length, I revert to my homemade MFT table that just lays on my mobile bench. It could just as easily rest on a couple of 2x4's on saw horses.

    This is just a 3/4" sheet of MDF with bench dog holes drilled in using the Parf II system. This gives me positive stops and perfect 90 degree crosscutting.







  3. #3
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    Quote Originally Posted by ChrisA Edwards View Post
    I have a MFT and Sawstop, but when I'm trying to crosscut a long length, I revert to my homemade MFT table that just lays on my mobile bench. It could just as easily rest on a couple of 2x4's on saw horses.

    This is just a 3/4" sheet of MDF with bench dog holes drilled in using the Parf II system. This gives me positive stops and perfect 90 degree crosscutting.
    That's pretty sweet, do you have a CNC or were you able to get someone to make the top for you?

  4. #4
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    The holes were drilled using the (Peter ) Parf System Mark II


    https://tsoproducts.com/accessories/...ystem-mark-ii/


    This is the original system, but it's pretty much the same.
    Last edited by ChrisA Edwards; 08-27-2020 at 3:34 PM.

  5. #5
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    Rough cut with the tracksaw, finish cut on your TS. Pretty common. Do your finish crosscuts with a sled tuned to 90 degrees.
    NOW you tell me...

  6. #6
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    Quote Originally Posted by Ole Anderson View Post
    Rough cut with the tracksaw, finish cut on your TS. Pretty common. Do your finish crosscuts with a sled tuned to 90 degrees.
    I thought about a sled, but I'd need a pretty massive one to cross cut a panel that is over 70".

  7. #7
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    Story Stick is what I use. Every measurement is on the stick(s).
    Regards,

    Tom

  8. #8
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    I've made quick and dirty purpose built parallel guides when I need to do multiples with the track saw:

    Here's the idea, you make two of these (of whatever length you need):

    DSC_0311.jpg

    And here's how I use them to set the track (pic just shows one, but I use one at each end of the track). Once the track is positioned, you can clamp if you want to be really sure it doesn't move.

    DSC_0310.jpg

    I have the double sided dewalt track, so I make sure to register off the metal part of the track, not the rubber strip. It's no issue with other brands of track.
    --I had my patience tested. I'm negative--

  9. #9
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    Help me out here as I'm apparently missing something in my brain...how wide is the crosscut for those 70" long panels? 48"? 36"? Are they wider than your MFT can support for cross cutting with the MFT setup? If so, you can create a measuring stick with a tee (like a story stick with a stop) to index to end of the panel that you then can use for marking the dimensions you need to lay down the line for your track since you mention that this is a repetitive action. That should be accurate if the panels are square and is much better than using a tape. No way should you be getting up to a 2mm deviation.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  10. #10
    I think Paul Franklin has the right idea- obviously you have to square up one end of the panel first. Two story poles gauging from the squared end to the back of the saw track. I'm glad I have a sliding table saw.

  11. #11
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    Quote Originally Posted by Jim Becker View Post
    Help me out here as I'm apparently missing something in my brain...how wide is the crosscut for those 70" long panels? 48"? 36"? Are they wider than your MFT can support for cross cutting with the MFT setup? If so, you can create a measuring stick with a tee (like a story stick with a stop) to index to end of the panel that you then can use for marking the dimensions you need to lay down the line for your track since you mention that this is a repetitive action. That should be accurate if the panels are square and is much better than using a tape. No way should you be getting up to a 2mm deviation.
    They're 27" wide so I'm not able to close the track on the latch if that makes sense. On my initial cuts I put the track down on the plywood with it still being connected in the back and used a triangle to square the track to the fence and then locked the track down with a clamp underneath. Really not an ideal setup and probably contributing to the error. I think even if i get a good line across the board it's still going to be tricky for me to line up because of the track locking issue and fiddling with squaring vs the fence. Might be better for me to take the fence off the MFT all together and do it like you suggested.

  12. #12
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    Quote Originally Posted by Paul F Franklin View Post
    I've made quick and dirty purpose built parallel guides when I need to do multiples with the track saw:

    Here's the idea, you make two of these (of whatever length you need):

    DSC_0311.jpg

    And here's how I use them to set the track (pic just shows one, but I use one at each end of the track). Once the track is positioned, you can clamp if you want to be really sure it doesn't move.

    DSC_0310.jpg

    I have the double sided dewalt track, so I make sure to register off the metal part of the track, not the rubber strip. It's no issue with other brands of track.
    This is a great idea!

  13. #13
    Quote Originally Posted by Paul F Franklin View Post
    I've made quick and dirty purpose built parallel guides when I need to do multiples with the track saw:

    Here's the idea, you make two of these (of whatever length you need):

    DSC_0311.jpg

    And here's how I use them to set the track (pic just shows one, but I use one at each end of the track). Once the track is positioned, you can clamp if you want to be really sure it doesn't move.

    DSC_0310.jpg

    I have the double sided dewalt track, so I make sure to register off the metal part of the track, not the rubber strip. It's no issue with other brands of track.

    Make the one guide, then rip it in half length wise, then you have two that are the exact same length. I use a shop made cutting guide for circular saw, but it's only eight feet long. When ripping down 9 or 10' melamine sheets, I use the guide sticks to advance the cutting guide. No measuring, or guessing, after initial set up.

  14. #14
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    Quote Originally Posted by Paul F Franklin View Post
    I've made quick and dirty purpose built parallel guides when I need to do multiples with the track saw:


    DSC_0311.jpg



    DSC_0310.jpg
    That's clever.

    Kudos

  15. #15
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    Any time that repeatability is essential, some kind of physical stop or fixed measuring device (combined in the photos for the previous few post) is the way to do. Whether it physically holds the track or just provides the line, the results should be "pretty darn accurate".
    --

    The most expensive tool is the one you buy "cheaply" and often...

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