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Thread: Crosscut sled, my version

  1. #1
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    Crosscut sled, my version

    I’ve learned almost all I know about woodworking from this forum, so I figured this might help someone getting into the hobby. My version of the crosscut sled. It’s 47” long, 24” wide, base is two layers of 1/2” Baltic birch, fence is 3/4” red oak doubled up and edge banded. I used the Kreg top track system and modified the rigid stop for my 4” fence. The runners are aluminum to minimize seasonal changes. There are replaceable zero clearance inserts on the base and fence that are fastened to the sled with 1/4-20 stove bolts. Made a couple attachments for stuff I commonly do. Squared it with the 5 cut method. It’s big, but honestly my incra sled was just too inaccurate for my usual work, and how I have ZCIs for bevel cuts, dados and even my custom ground 8 deg dovetail blade. The whole thing was sanded and I hit it a couple times with wipe on poly. So far my only impression is that I Waited entirely too long to make this. Feel free to ask any questions

    . 99E64C49-9F21-46A9-8747-0B2C4910C6CD.jpg9BB5EF21-B393-44AF-B0A5-DE451C0AE6D8.jpgAA9E0BB5-FDCB-4DB9-A5C4-70A7983D7540.jpg

  2. #2
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    Justin, That is very similar to the "big" sled I used. When I got tired of lifting it on and off the saw, I built a second smaller one that covered 75% of my needs. Now, they're both gone and I run a Short stroke slider instead. I think you'll really like your sled.

  3. #3
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    Very nice sled, I like the tracks and accessories. I'm sure you will get lots of use out of it.
    Lee Schierer
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  4. #4
    Quote Originally Posted by justin byers View Post
    I’ve learned almost all I know about woodworking from this forum, so I figured this might help someone getting into the hobby. My version of the crosscut sled. It’s 47” long, 24” wide, base is two layers of 1/2” Baltic birch, fence is 3/4” red oak doubled up and edge banded. I used the Kreg top track system and modified the rigid stop for my 4” fence. The runners are aluminum to minimize seasonal changes. There are replaceable zero clearance inserts on the base and fence that are fastened to the sled with 1/4-20 stove bolts. Made a couple attachments for stuff I commonly do. Squared it with the 5 cut method. It’s big, but honestly my incra sled was just too inaccurate for my usual work, and how I have ZCIs for bevel cuts, dados and even my custom ground 8 deg dovetail blade. The whole thing was sanded and I hit it a couple times with wipe on poly. So far my only impression is that I Waited entirely too long to make this. Feel free to ask any questions

    . 99E64C49-9F21-46A9-8747-0B2C4910C6CD.jpg9BB5EF21-B393-44AF-B0A5-DE451C0AE6D8.jpgAA9E0BB5-FDCB-4DB9-A5C4-70A7983D7540.jpg
    You used aluminum runners to minimize seasonal changes, but to use two runners maximizes seasonal changes. You have what is essentially one runner that is about 10 inches wide, and its width variations are determined by the growth/shrinkage of 10 inches of wood.

  5. #5
    Here's a miter bar runner design that creates a very snug, wobble free fit . It uses easily built wooden springs. I think you could use 2 of these, with the springs facing the same way on both, and it would address Dan's warnings about using 2 bars .


    https://www.youtube.com/watch?v=-_EPwn8GIhY

  6. #6
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    Quote Originally Posted by Dan Cameron View Post
    You used aluminum runners to minimize seasonal changes, but to use two runners maximizes seasonal changes. You have what is essentially one runner that is about 10 inches wide, and its width variations are determined by the growth/shrinkage of 10 inches of wood.
    Due to its alternating grain direction construction, plywood doesn't expand and contract much due to seasonal movement. Since the saw has cut the bottom board essentially in half and the remaining continuous wood is long grain the seasonal expansion/contraction between the rails is likely to be near zero*. Any movement in the plywood would likely close the saw gap, which would immediately be cleared on the next cut. I've had a plywood base sled using two runners for over 25 years and I have never had an issue with seasonal movement.

    * The longitudinal shrinkage (parallel to the grain) in most species is less then 0.2% from green to oven dry. If his 47" long pieces started out as freshly cut green wood, the total length change to kiln dried would be about 0.094 inches over the total length. Because the wood will never be that wet again there would be no significant length change in normal use.
    Last edited by Lee Schierer; 03-24-2022 at 9:26 AM.
    Lee Schierer
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    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

  7. #7
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    Nice job Justin. Just an observation. I tend to keep the front fence short. This allows longer stock being mitered to extend beyond the front to back dimension of the sled.

    Box Sled (17).jpg
    "A hen is only an egg's way of making another egg".


    – Samuel Butler

  8. #8
    Quote Originally Posted by Lee Schierer View Post
    Due to its alternating grain direction construction, plywood doesn't expand and contract much due to seasonal movement. Since the saw has cut the bottom board essentially in half and the remaining continuous wood is long grain the seasonal expansion/contraction between the rails is likely to be near zero*. Any movement in the plywood would likely close the saw gap, which would immediately be cleared on the next cut. I've had a plywood base sled using two runners for over 25 years and I have never had an issue with seasonal movement.

    * The longitudinal shrinkage (parallel to the grain) in most species is less then 0.2% from green to oven dry. If his 47" long pieces started out as freshly cut green wood, the total length change to kiln dried would be about 0.094 inches over the total length. Because the wood will never be that wet again there would be no significant length change in normal use.
    With due respect, Lee, I feel your comments above have considerable error. I had a two metal runner sled become unusable due to plywood size variations caused by humidity variations. For a variation of RH of 40% a typical size variation in plywood might be 0.1%. That could move the spacing between two miter bars about .01 inches .Depending on the bar with vs the slot width AND the bar separation vs the slot separation, there might or might not be a problem

    Some may feel that if one miter bar is good, two has got to be better because there are four edges doing the guiding. The miter bars are presumably made of hard material so that they compress a very tiny amount. If the spacing of the miter bars is greater (or less) than the slot spacing by more than that tiny amount, then the inside (or outside) edges of the bars will never contact the inside (or outside) edges of the slots

    Using two miter bars instead of one can be a way to reduce the amount of play if the bars are too narrow, by intentionally spacing the bars inward or outward, but I think its a poor way to do it. There is a component of free play (slop) that must be there do to humidity effects. And the desired spacing is not likely to be achieved by laying the bars in the slots and slapping the sled down on them!

  9. #9
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    You’re absolutely right about the shorter front fence. As for the stability of plywood, in Alberta here the humidity doesn’t fluctuate a whole bunch, and my shop is quite a bit lower than ambient, so I’m hopeful movement will be minimal.

  10. #10
    Quote Originally Posted by justin byers View Post
    You’re absolutely right about the shorter front fence. As for the stability of plywood, in Alberta here the humidity doesn’t fluctuate a whole bunch, and my shop is quite a bit lower than ambient, so I’m hopeful movement will be minimal.
    If your runners are mounted with the rigid sides facing outward, then you have zero tolerance for any increase in humidity but a decrease would be tolerable. On the other hand if the rigid sides were facing inward, a decrease in humidity would cause the sled to jam, but not an increase. Just remove one of the runners.

  11. #11
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    to be quite honest, I've built a few of these sleds, always with birch ply. They've all had dual aluminum runners, and over 3 seasons I've never had a jam, honestly they're still deadly square too. Until, I'm forced to change them I think I'll go ahead and stick with whats worked. If it ain't broke, don't go on fixin it. But, perhaps the humidity where you're at proves a different story.

  12. #12
    It would be interesting to hear if others have had the issue that Dan Cameron is talking about- sled runners binding from humidity changes.

    There have got to be thousands of sleds out there, almost all with two runners. I haven't heard any complaints.

  13. #13
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    Quote Originally Posted by Cameron Wood View Post
    It would be interesting to hear if others have had the issue that Dan Cameron is talking about- sled runners binding from humidity changes.

    There have got to be thousands of sleds out there, almost all with two runners. I haven't heard any complaints.

    I am lucky in regard to sled runners and live in a southern California desert basin where the humidity swings are negligible. I have built things for people in other states and just build accordingly. If I lived in Fairhope, Alabama I would use UHMW or metallic runners. Where I am I have used a variety of materials just to test them out. All work fine year round but, I have to put up with what California has become . .. so there's that . My point is that one should use what is appropriate for the situation. In SoCal some straight grained white oak is good for life; in Houston, TX I would look to synthetics.
    "A hen is only an egg's way of making another egg".


    – Samuel Butler

  14. #14
    I'll leave the runner issue alone, but one thing I would suggest is this.
    While the T-track is great for adding fixtures, I would add one much closer to the blade. This will allow you to safely hold small pieces securely with something like a toggle clamp or similar.
    Just a suggestion.

  15. #15
    Quote Originally Posted by glenn bradley View Post
    I am lucky in regard to sled runners and live in a southern California desert basin where the humidity swings are negligible. I have built things for people in other states and just build accordingly. If I lived in Fairhope, Alabama I would use UHMW or metallic runners. Where I am I have used a variety of materials just to test them out. All work fine year round but, I have to put up with what California has become . .. so there's that . My point is that one should use what is appropriate for the situation. In SoCal some straight grained white oak is good for life; in Houston, TX I would look to synthetics.
    Glenn, Cameron Wood's issue was one miter bar vs two, not bar material. If you have two miter bars there is typically 11 inches of plywood the size change of which affects how tight (or loose) the fit is. A wooden miter bar has only .75 inches over which to grow/shrink. Plywood changes size only 1/3 to 1/5 as much as solid, but there is nearly 15 times the span. The whole issue is moot if you're happy with lots of free play. I am not. My favorite setup these days is two aluminum bars in the same miter slot.

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