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Thread: Chasing my tail - xcut sled

  1. #1
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    Chasing my tail - xcut sled

    Hi all
    I'm at a total loss and know I must be doing something wrong.

    I am building a xcut sled using the William ng method. I've spent at least 6 hours trying to tune it to the . 001 he claims. I've watched the video again again and again. Ran the math numbers multiple times, but cannot get a consistent reading. I'll adjust up then down. Then down again then back up. Multiple times I've cut at the same setting and still cannot get a consistent reading. I've tried averaging the multiple readings and still nothing. I'm not sure if I have any wood left from all the screw test holes...

    I would like to run down my setup and hope you all can point out some type of flaws.
    Materials:
    1/2" mdf base
    1/2" BB ply (laminated 3 layers for the fences)
    Runners - red oak
    Built sled per his video

    Got into rough square using combo square. Made 5 cuts. Measured top cut and subtracted bottom, divide by 4, divide again by length of cut. Take that number then times it by the length of the pivot point you want to use or rounds to feeler gauge. If the number is a positive fence needs to move back, if negative move forward. So if it's a positive .005, set a block tight against fence, unscrew one pivot screw. Move fence backwards, insert appropriate feeler gauge, move fence forward to touch feeler gauge. Clamp fence, check feeler gauge, screw another screw back in.

    Make 5 more cuts and measure deviation...rinse and repeat.

    Can anyone comment on if all that sounds correct. If so what am I doing wrong?

    Not that it matters but I checked my blade alignment with a crude jig I made and found the rear of the blade was off by about 1.5 thou.

    The fence appears to have a very slight bump at the very far left end of it,which I tried getting out but couldn't. I will try lapping the fence flat with sandpaper on float glass.

    Anything glaringly wrong I am doing?

    Thanks
    Michael

  2. #2
    My first guess, which you’ve confirmed, is that the fence isn’t flat. I just went through this with a miter saw. I was trying to short cut the set up and ended up taking the scenic route 😬. In my case the fence was out of flat by width of a piece of paper across a 2’ fence, and two pieces of paper in one spot. I could not see this error and needed the feelers to find it.

    Making matters worse, I used a four cut method and found a .001 difference, which would have been great had I not then switched to the other side of the blade where the fence was off. Setup has to start with a flat fence, tight runners and yes a blade at 90 degrees. In other words don’t proceed to the test piece until the other variables are sorted.

  3. #3
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    Sounds right, although I always have to sketch out the positive/negative direction thing. Someone else here recently had a similar issue and turned out he was turning the test board the wrong direction after each cut. After each cut you turn the test board so the fresh cut is against the fence for the next cut. So, clockwise if you are to left of blade, CCW if you are to right of blade.

    Could that be your issue?
    --I had my patience tested. I'm negative--

  4. #4
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    Sounds like your method is correct. The bump in your fence can be throwing your numbers off, as can the blade not being parallel to the miter slots. Double check that there is no play when you're pushing the sled forward. If it shifts as you advance it all bets are off.

  5. #5
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    No help, but I feel your pain. Bottom of my fence looks like a woodpecker attacked it. Finally got it dialed in right using the same method you are using, but concluded that I would figure out a better way to adjust the pivot pin next time I made a sled, maybe some kind of micro adjustment device?

  6. #6
    Having built two sleds using this method I have a feeling either your fence isn’t flat or your runners aren’t tight enough in the miter slots. I assume you avoided cutting the base board material all the way in half until the very end where you’ve done the final securing of your fence?

    My first sled was like yours. Looked like a woodpecker with all the screws and I kept chasing my tail for perfection. My second sled I did differently.... first sled I stacked plywood as my fence and used screws to keep repositioning and dialing in the fence location. Second sled made my own fence out of hardwood and milled it dead flat on the jointer. Second sled I also made the fence and baseboard material extend PAST the end of the table saw table so instead of the woodpecker screw action I could simply clamp the fence into position and adjust as many times as I needed. I had far better success with my second method and was able to dial my sled in to be extremely accurate.

    Good luck!

  7. #7
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    Some more details would help.

    1. What saw are you using this on?

    2. When was the last time you checked the alignment of the blade to the miter slot?

    3. How much free play is there between your runner(s) and the miter slot.

    4. What blade are you using and is it sharp?
    Lee Schierer
    USNA '71
    Go Navy!

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  8. #8
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    While I appreciate the elegance and attention to detail in William Ng's method as a kind of performance art, as a matter of practical woodworking, it's a complete waste. If you want a dialed-in crosscut fence, success will come from:

    1. Getting the basics of your saw dialed-in first. That means in particular, a) having miter slots that are machined straight and parallel, and which are aligned parallel to the blade, and b) having a true 90o stop for the blade angle.

    2. Getting miter slot runners on your sled that run true with no slop in the miter slots. (My preference for this is to use UHMW runners that I can adjust through expansion with conical shoulder mounting screws, but others have different methods. Point is to get to parallel and zero slop).

    3. Having a fence that is well and truly straight and flat, and stiff enough to stay that way when you adjust it.

    If you have those things right, then aligning the fence is simple:

    1. Cut the zero clearance slot in the sled to within about 10" of the fence.

    2. Mount the fence firmly but not overly tight with a screw in a round hole at one end, so you can still rotate it.

    3. Mount the fence fairly firmly on the other end with a countersunk, washer headed screw in a slightly elongated mounting hole. This is easily and neatly made with a router, but if you haven't got one, use a larger than necessary forstner bit for the countersink, and you can easily make the elongated screw hole with a hand drill and twist bit.

    4. Screw the fence down but not so tight as to be immovable, as close to square, as you can get, by aligning with a square to the zero clearance slot.

    5. Make yourself a true parallel test piece out of some clean cutting material. 1/8" masonite is perfect.

    6. Using single test cuts through the parallel, determine your squareness and adjust the fence with gentle taps at the slotted end appropriately. You can use feeler gauges and math if you want, but it's a real waste of time. Just eyeballing it is faster and easier, and you can easily get it right in a couple of adjustments.

    7. When you've achieved what you want, back the sled out off the table until the fence overhangs free space, clamp the fence carefully, and then tighten the end screws and screw it down in a couple more places.

    There are lots of words here, but they almost take longer to write than to do, if the first steps (saw alignment and fence flatness and mounting) are well done, the actual adjustment will take a couple of minutes.
    Last edited by Steve Demuth; 11-24-2020 at 9:49 AM.

  9. #9
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    Quote Originally Posted by Lee Schierer View Post
    Some more details would help.

    1. What saw are you using this on?

    2. When was the last time you checked the alignment of the blade to the miter slot?

    3. How much free play is there between your runner(s) and the miter slot.

    4. What blade are you using and is it sharp?
    70s craftsman 113

    Just did using a crude jig I built our of red oak. Found the rear of the blade was positive about 1.5 thou. I zeroed the dial out at the front. Like I said it is a crude jig from scraps but I couldn't notice the runners or anything flexing much.

    Some play. My crappy craftsman fence doesn't lock perfectly square, so the runners have a slight tape to them. But I cut them out of extra long material and then cut off the thin end of the taper to negate as much as I could .

    60t finish home depot amana blade. I am mostly a neander so my only other blade was a 24t frued rip.

    This whole thing is for a sheet goods project.

  10. #10
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    Quote Originally Posted by Michael J Evans View Post
    70s craftsman 113

    Just did using a crude jig I built our of red oak. Found the rear of the blade was positive about 1.5 thou. I zeroed the dial out at the front. Like I said it is a crude jig from scraps but I couldn't notice the runners or anything flexing much.

    Some play. My crappy craftsman fence doesn't lock perfectly square, so the runners have a slight tape to them. But I cut them out of extra long material and then cut off the thin end of the taper to negate as much as I could .

    60t finish home depot amana blade. I am mostly a neander so my only other blade was a 24t frued rip.

    This whole thing is for a sheet goods project.
    I have the same saw except I upgraded to a Biesmeyer fence years ago for the exact reason you cite about your fence. Last time I checked mine it was within .001 of being parallel, the same with the fence. I would suggest attaching a dial indicator to your sled against the blade and then wiggle your sled back and forth and see how much side play you are getting. As a Neander you should be able to tune a slightly oversize runner to eliminate the taper for a snug fit.
    Lee Schierer
    USNA '71
    Go Navy!

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  11. #11
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    Quote Originally Posted by Lee Schierer View Post
    I have the same saw except I upgraded to a Biesmeyer fence years ago for the exact reason you cite about your fence. Last time I checked mine it was within .001 of being parallel, the same with the fence. I would suggest attaching a dial indicator to your sled against the blade and then wiggle your sled back and forth and see how much side play you are getting. As a Neander you should be able to tune a slightly oversize runner to eliminate the taper for a snug fit.
    Lee the dial indicator to the sled is a good idea, I am going to try that. The runners don't feel like they have any play, but that would for sure tell me.

    And yes, when I cut the runners, I almost brought out the marking gauge and planed them to fit. But I decided since there was two runners running parallel I really shouldn't be getting any slop, since the fitment was already tight.

  12. #12
    Why are you chasing down a thousandth?

  13. #13
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    Hi John
    The goal as always is to be as accurate as I possibly can. In reality I don't think I've ever been accurate to . 001 , but one can strive for it.

    But that is not really the reason for this post. The reason I wrote this is because of my inconsistent readings I am getting.

  14. #14
    I too was chasing my tail. I finally realized I was pushing too hard against the feeler gauge. Once I stopped doing that I got my sled to 0.0008. This link to a 5 cut method calculator was very useful: https://www.windridgewoodcrafts.com/topics/five_cut/

  15. #15
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    Thank you for that link. When I'm feeling brave enough, I'll be giving it another go. For now it is sitting in a corner of the shop.

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