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Thread: Finally, a better sled runner

  1. #1
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    Finally, a better sled runner

    I will be building a larger cabinet and needed a sled that could cross-cut 24" panels. I wanted a single-runner sled (cause my table saw only as one miter slot).

    Wish list: (1) A runner that had no seasonal movement. I've used wood. It expands, it shrinks. (2) A runner with no slop. I have used the Incra miter runners, but they are tricky to adjust. The 24" version has only three (I think) width adjustment points and no matter what I do, there is always a little bit of side-to-side play. Plus, the 24" Incra Runner (their longest) wasn't really long enough (my sled is 27" long and I wanted a runner at least 27" long to match).

    I decided to try UHMW plastic. I got a boatload of the stuff on sale from Peachtree Woodworking's sale. Included were two 48" long runners.

    The stuff is flexible, doesn't glue well, and it was about .003" shy of .75". Great!

    This is what I did: I routed a .75" groove in the bottom of my new sled (1/8" deep). I centered six 3/16" holes along this groove (at 6" intervals), and drilled some matching (but slightly larger at 1/4") holes in my UHMW runner.

    I inserted special prongless t-nuts into the UHMW plastic (I used my woodworking vise to just squeeze them in). These nuts, BTW, are sometimes referred to as Propell nuts, sometimes as Hurricane nuts, McMaster just sells them as t-nuts. I used the #10-24 size (they have a base that is 45/65" in diameter).

    Inserting the t-nuts into the runner made it "bulge" up to .752" around each nut.

    I screwed through the top of the sled, through the runner, and into the t-nut. Trying the sled in my miter slot it was a little tight. A couple licks with a cabinet scraper at the "bulges" and it slid perfectly, no play and slides like butter.

    The best thing is, I can actually tighten the screws from the top and the plastic bulges a little more (and the runner tightens in the slot). Loosen the screws and it slides like butter again. So, it is slightly adjustable.

    And I like the fact that the runner can be removed/replaced, too.

    You may wonder how to achieve this with a dual-runner sled (if you're one of the lucky ones with two miter slots). My suggestion is to make two single-runner sleds (one for left of blade, one for right). Then, with the sleds in their respective slots, attach the front and rear fences to join them together into a single unit.
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  2. #2
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    Great post! Thanks!
    Thread on "How do I pickup/move XXX Saw?" http://www.sawmillcreek.org/showthread.php?p=597898

    Compilation of "Which Band Saw to buy?" threads http://www.sawmillcreek.org/showthre...028#post692028

  3. #3
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    Nice job Phil. You post brings back good memories - I had a BT3K of some sort for about 20 years before I bought a Unisaw a couple of years ago.

    Mike

  4. #4
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    Quote Originally Posted by Mike Goetzke View Post
    Nice job Phil. You post brings back good memories - I had a BT3K of some sort for about 20 years before I bought a Unisaw a couple of years ago.

    Mike


    I still really like my BT3K. My dream saw is an Inca 10" cabinet saw (280/290 model). It was an Americanized (w/ 5/8" arbor) tilt-arbor cabinet saw with hard-anozied aluminum top. Very few of them got imported, you mostly run into tilt-top and 2100 cabinet saws.

  5. #5
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    Did you get the 90degree angle bracket at McMaster also?

  6. #6
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    Nice job! Is there any reason you didn't go with the Kreg fixture bar?

    http://www.toolmarts.com/kregkms7303.html

    They're 30" long and have 6 adjusters. I used two of them for my sled, which is also 27" long.

    -Brian

  7. #7
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    Quote Originally Posted by Michael Panis View Post
    Did you get the 90degree angle bracket at McMaster also?
    No, they only had it in 8' lengths and I didn't know what shipping would do to me. I picked it up at a hardware store.

  8. #8
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    You're quite the innovator, Phil! Glad to have you aboard and a nice job!
    Crown Molding: cut, cope, cuss, caulk, chill....

    Did you know SMC is user supported? Please help.

  9. #9
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    Quote Originally Posted by Brian D Anderson View Post
    Nice job! Is there any reason you didn't go with the Kreg fixture bar?

    http://www.toolmarts.com/kregkms7303.html

    They're 30" long and have 6 adjusters. I used two of them for my sled, which is also 27" long.

    -Brian
    The main reason is that my miter slot is a shop-made fixture itself, using an Incra miter channel. Many of the miter bars out there are hard enough that I worry that they will wear the aluminum extrusion prematurely.

    I guess whenever I post I should remind people that my table saw is only a Ryobi BT3000. Many of the issues that I'm confronted with probably are non-issues for you guys. Don't get me wrong, I like my saw and I've modified it pretty extensively. But a saw that doesn't come with miter slots? Get outa here!

    If I had a cabinet saw w/ cast iron top, I'd absolutely look at something like the Kreg. The additional adjusters look like they'd allow for better adjustment than the Incra runners allow.

  10. #10
    I've also mounted UHMW with flat head screws and counter sunk holes up from the botom into the sled. You can also drill and tap UHMW with machine screw threads. Just be careful when tightening not to over tighten as the threads will strip out.

    UHMW can be worked with woodworking tools without much problem. The shavings are a bit of a pain to clean up.

    This is O.T. but I used UHMW to make sacrificial runners for my snowblower and they have already lasted longer than the steel runners that came on the snowblower. I wore through 1/8" steel in one winter. I put on 1/8" UHMW over a new set of steel runners and they look like they will easily last several more years as they are still almost 1/8" thick after one winter.
    Last edited by Lee Schierer; 04-24-2008 at 11:54 AM.
    Lee Schierer - McKean, PA

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  11. #11
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    Quote Originally Posted by Lee Schierer View Post
    I've also mounted UHMW with flat head screws and counter sunk holes up from the botom into the sled.
    I was gonna do that but when confronted with a choice, I always go for the non-obvious solution.

    When I first examined a piece of this thin plastic I noticed its flexibility. That is why I wanted the groove (to keep it straight). But the groove would further reduce the thickness of my sled, so less holding power for the screws. One thing led to another and I ended up with the solution above.

    But now I'm wondering whether, in the future, I'd be better off with a machine screw from underneath into a t-nut from the top of the sled. Perhaps this would give me a wider adjustment range. I don't know why that would be important, but maybe something to play with.

  12. #12
    If you don't have a bunch of UHMW plastic hanging around, Lee Valley sell these runners.

    http://www.leevalley.com/hardware/pa...=3,43576,43581

    2 foot and 4 foot lengths available. I like the "T" nuts!

  13. #13
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    In general I don't like UHMW runners, but they are the only way to go if you have an aluminum miter slot. Steel or cast iron and aluminum don't mix very well as far as friction goes. I never liked the aluminum miter slot on my router table.

    As far as miter bars for cast iron tables- I use 3/4" X 3/8" cold rolled steel bar. It is hard, smooth and a few years ago cost only about $5 for 20' of the stuff. I drill and tap it so it can be screwed in from the top of my sled. If you want a really snug fit, you just need to hit is with a center punch or peen it in a few spots.

  14. #14
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    I dont think all the UHMW runners are within .003. The ones I bought (from lee valley) were terrible, so I sent them back.

    Brad

  15. #15
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    Quote Originally Posted by Brad Shipton View Post
    I dont think all the UHMW runners are within .003. The ones I bought (from lee valley) were terrible, so I sent them back.

    Brad
    I do know Peachtree offers runners they claim are .75", and other runners designed for Craftsman slots that are .744". The .75" runners I got are a little shy of .75", though. It would be interesting to know the actual size of the Lee Valley units you returned.

    I do know that a year or so ago I tried some .75" UHMW plastic at Rockler in a chunk of the miter channel from Incra that I had. At that time I felt they were a poor match, the UHMW plastic had too much play.

    Knowing what I do now, I think it would have worked fine had I either used the prongless t-nuts or used the screws from the bottom like others have suggested. The little bulge in the UHMW plastic is really all it takes to firm the fit up.

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