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Thread: Tablesaw Crosscut sled

  1. #46
    Join Date
    Feb 2003
    Location
    Hayes, Virginia
    Posts
    12,280
    I cut Corian with any saw, type of blade or router bit in my shop. My preferred method is to cut it on my band saw with a one inch blade. The last runner I made was for my band saw slider, I machined it on my CNC Router because it wasn't a standard 3/4" by 3/8" slot and I wanted the fit to be very accurate for my one runner slider.

    I often drill and tap holes in Corian for joining parts then use epoxy on the threads when I screw them together which makes a very reliable connection.

    As mentioned earlier we all have a tendency to use the material we have on hand especially shop scraps when we can. UMHW is probably the best material for runners in my area because of our very high humidity but I have a truckload of scrap Corian so its my second best option. I did recently purchase some UMHW for a job so I will have some for the next set of runners I make. I have used King Color Core material in the past, its a close cousin to UMHW. Its my understanding that there isn't any adhesive that works with UMHW so that is a concern on some projects.

  2. #47
    Quote Originally Posted by Pat Barry View Post
    I've found that two runners work better than one - that was the reason for my earlier recommendation. I feel that the setup is much more stable with two runners. I can see how there is logic behind the idea that one runner will get the job done, but in my own use, I found my single runner sleds (more than a couple of them) to be a bit on the loose side. Perhaps this was to a deficiency in my manufacturing technique - so be it - the double runner eliminated the issues I had.

    One advantage of a single runner sled is that you could actually use both miter slots - dedicate one for normal square cuts, and setup the other for 45 degree cuts (for example). Can't do that with a double runner sled.
    Double runners make it much less likely you will be able to slightly twist the sled in relation to the runner, and thus bind up the sled. I have a small table saw miter sled I built using one runner, and it is possible to torque it radially and slightly skew if (not quite bind it) if you are not paying attention to how you are feeding.

    Cutting a synthetic polymer material is best done with a TCG blade, and generally one with zero or negative hook. Specify the tooth pitch to the thickness of the material being cut, for cutting runners and such, you will want a pretty high tooth count blade such as an 80T 10" blade as the stock will be at most 3/4" thick. A 100T blade may even be more appropriate for cutting the thin stuff.

    One thing nobody has mentioned is that there are other tools out there that are by design better equipped to do precision crosscuts than a tablesaw. A sliding tablesaw, good quality radial arm saw (not some Emerson-made Sears/Ryobi/Ridgid or a <=12" Black and Decker-made unit, but an old cast iron DeWalt or new Original Saw Company unit, or an OMGA saw), or even a decent SCMS would do better than a tablesaw for precision crosscuts. I have Grizzly's 10" 3 hp Unisaw clone, and it is a pretty decent 10" cabinet saw, but it is much easier and more precise to do crosscuts on my 61 year old 900 pound DeWalt GE radial arm saw than to do them on the cabinet saw. The Neanderthals among us would recommend a backsaw and a guide, and that can be very precise in the proper hands.

  3. #48
    Join Date
    Apr 2011
    Location
    Williamston, MI
    Posts
    420
    Quote Originally Posted by Frederick Skelly View Post
    I generally use UHMW plastic for runners, unless you want to spend the money for the adjustable metal ones. Lee Valley and other companies sell it. Link.
    You can make runners from inexpensive kitchen cutting boards.

  4. #49
    Quote Originally Posted by Roy Turbett View Post
    You can make runners from inexpensive kitchen cutting boards.
    Yup. I've done that too.

  5. #50
    Join Date
    Dec 2009
    Location
    El Dorado Hills, CA
    Posts
    1,214
    Quote Originally Posted by Roy Turbett View Post
    You can make runners from inexpensive kitchen cutting boards.
    My thoughts exactly. I recall paying under $10 for a large poly cutting board at Walmart. It had a juice groove that I cut away, but it still yielded over a dozen runners.

    Steve

  6. #51
    For all the talk about runners, I feel the back fence is a more important subject. It's important to use a stable material.

    If wood runners get tight and bind, you can always resolve it with a swipe of a hand plane or a little wax. If the back fence moves, even slightly, it's a bigger problem, and usually why I end up making a new sled. So you could say I've learned the hard way to use laminated baltic birch for the back fence. Any stable material will do.

    It's useful to have a one runner sled with a single square fence at the leading edge, for cutting larger panels square. Norm Abrams used to demonstrate one in some of his episodes.

  7. #52
    Join Date
    Jan 2005
    Location
    A suburb of Los Angeles California
    Posts
    589
    Quote Originally Posted by Matt Day View Post
    Do you own stock of one runner sleds Dan? This is the third time in this thread you've been adamant that one runner is the way to go.
    Dan is an amazing engineer and woodworker with no great need to hear himself talk. For more than a decade he and I belonged to the same WW club.
    It took me longer than it should have to learn to pay attention to what he says.
    AKA - "The human termite"

  8. #53
    For those saying 2 runners for large sleds and one for small sleds, have a look at this video.

    https://www.youtube.com/watch?v=4p0UTVUXh48

    I have a cross cut sled, panel sled, miter sled, bevel sled and even Incras miter express sled (my favourite) all made with one runner using Incras miter sliders.

    Also for those worried about fence squareness and not wanting to do the 5 cut method, have a look at this video

    https://www.youtube.com/watch?v=AdXTtTnJAvk&t=68s

    I have tried both methods of squaring fences and the dial indicator way is just as accurate, quicker and less mess. In fact the only cut is a test cut to see if its square. Dial indicators are not expensive and have other uses.

  9. #54
    Join Date
    May 2004
    Location
    N Illinois
    Posts
    4,105
    I like hardwood strips and wax them before use...Have had good success with them.
    Jerry

  10. #55
    Join Date
    May 2004
    Location
    N Illinois
    Posts
    4,105
    I also vote for TWO runners for stability..
    Jerry

  11. #56
    Quote Originally Posted by Roger Marty View Post
    But trying to nudge a fence into alignment with that whole screw method is just tortuous for me.
    You don't have to do nudging to get things the right way. I don't know what you mean by screw method (unless you mean just, the screw that holds the fence down to the base).

    What I'd recommend is doing the 5-cut method to find your angular error in inches per inch. Measure out as long of a distance from a known pivot point (i.e., one screw) as you can comfortably work with- ideally a couple inches from the opposite edge- and put a mark there. Multiply this distance by your error to get the amount that second point needs to shift. Get a stack of feeler gages that's equal to your error, then put that stack up on the mark you just made. Next, push a piece of scrap up against the feeler gage and clamp it down. Pull out the feeler gages and pivot your fence up to the scrap; you will now have moved it by exactly your error. Clamp the fence down then screw it into place.

    You can repeat it a couple of times if you want to get it really dialed in. I haven't done this to a crosscut sled yet but I used this method to square up my cheap Ryobi miter saw; took me around a half hour to do it the first time. I iterated a couple of times to get the error as small as I possibly could, and it's held well. It shouldn't be a pain to do.

    I haven't tried the dial indicator method, but as always there are many ways to skin a cat!

  12. #57
    I have experienced too much flex when using only one runner. Even with double stacked baltic birch.

  13. #58
    Join Date
    Mar 2005
    Location
    Spokane, Washington
    Posts
    4,015
    William NG has a great video explaining the five cut method and how to build a cutoff sled. I highly recommend watching this!

    In it he shows how to do the calculations necessary to determine exactly how far to move the sled's fence, in which direction, and from which point, and how to go about this with enough precision to get accuracy within .001" over the equivalent of a 96" cut. He does this in one try! The video is well worth watching, lots of great tips, what to watch out for, way too much information to relate here. I used it to set up the the fence on my Jessem sliding table, which is actually much more difficult to do than a sled, just because of the way it's constructed. My fifth cut was off by .001 over about 80" ( 22 x 18" rectangle). I think I can live with that

    5 Cuts To A “Perfect” Cross-Cut Sled – William Ng School Of Fine Woodworking

    First do a five cut, starting with a rectangle whose long dimension is at least 24", and whose width is great enough to be very stable resting against the sled fence. Measure the width of the fifth cut piece to the nearest thousandth of an inch, both top (A) and bottom (B), and the length of the cut (C) and record. Measure the distance from the pivot point of the fence to the opposite end where the adjustment will be made, and record that (D).

    Now here is the formula, spelled out because I don't have a "divided by" symbol on my keyboard : A minus B; divided by 4; divided by C; times D.

    Subtract the bottom measurement from the top, divide by 4 (number of cuts, which multiplies the error on the fifth piece), divide that result by the length of the last cut, multiply that by the distance from the pivot point of the fence to the point of adjustment. This tells you exactly how far to move the fence at the point of adjustment. With the pivot point on the right side of the fence, and adjusting on the left, if the result of the above calculation is a positive number, the fence needs to move down, away from the blade. If a negative number, then it needs to move up, toward the blade. In the video, he explains why each of these factors in the formula are important to the final result, and shows how to reliably move the fence by using a stop block and feeler gauges. It sounds complicated, but in reality it's very simple to do. A calculator is your friend. I was surprised to see that he had the same calculator that I bought over thirty years ago.

    Dan



    Eternity is an awfully long time, especially toward the end.

    -Woody Allen-

    Critiques on works posted are always welcome

  14. DF--I enjoyed watching that video. Thanks.
    "Anything seems possible when you don't know what you're doing."

  15. #60
    If you want a simpler, quicker and just as accurate method as the 5 cut method read post #10 above. If your bade has flex or its not parallel to the slots etc then the 5 cut method won't be as accurate. When adjusting fences on sleds and gauges its important to reference off the slots not the blade because those fences are moving via the slots. The dial indicator method is referencing off the slots. This video explains why you should do that ... https://www.youtube.com/watch?v=NrTeFQ0iQ5k

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