If I remember correctly, if you have slop with the UHMW ones you can countersink a small screw and as it tightens the UHMW will expand a bit taking up the slop.
Contributor
If I remember correctly, if you have slop with the UHMW ones you can countersink a small screw and as it tightens the UHMW will expand a bit taking up the slop.
Contributor
Yes. That's just what I do.Originally Posted by Matt Day
Member
Yea I personally could never figure out why any one would want to use wood over UHMW for sled runners. I mean the stuff is slick as can be in its natural state, can easily be tweaked for a perfect fit, will last forever and you dont have to worry about it expanding or warping for any reason.
If at first you don't succeed, redefine success!
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One often uses what he has on hand. The runners on my sled are oak and have held up fine for decades. Never a problem with wood movement.
"Anything seems possible when you don't know what you're doing."
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Okay yes, that is a valid point.
If at first you don't succeed, redefine success!
Contributor
Pretty obvious someone here is not familiar with the properties of cast iron. One is not going to dent a slot in a cast iron table with a steel runner by "wiggling" it around.
Last edited by Keith Outten; 09-13-2017 at 10:17 AM.
Contributor
Can you explain why to use double runners? A single runner sled has EXACTLY the same number of guiding surfaces as a double runner sled, and is affected less by humidity and temperature.
Contributor
I think the general guideline is if it's a big sled, use two runners, if it's small use one.
I wouldn't use a large sled with one runner. I would think it could introduce too much stress on the runner and its fasteners.
Administrator
I use Dupont Corian for runners for the same reasons that Jim Becker mentioned plus Corian won't ever swell from moisture. You can sand it as easily as wood and cut it with any shop saw. Apply wax on the runners and they will slide like their on bearings. I have a truck load of scraps so the runners I make are free.
If you need some material to make Corian runners let me know the rough size, you pay the shipping. I have both 1/2" and 1/4" thick Corian.
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Last edited by Keith Outten; 09-10-2017 at 3:07 PM.
Contributor
Jack, lots of good (and some not so good) advice here on sled runners. I would like to make a case for using a single runner. Consider that the center to center spacing of two runners will not be EXACTLY the same as the spacing of the saw slots. The sled spacing will, of course, change with changes in humidity. Say the runner spacing is greater than the miter slot spacing. The sled will be guided by the outside edges of the two runners. The inside edges of the runners never make contact with the slots and thus these two edges have ZERO affect in guiding the motion of the sled. Similarly, if the runner spacing is less than the slot spacing the inside edges of the runners alone guide the sled. I have heard comments that a double runner sled is more accurate because there are twice the number of guiding surfaces. Is NOT true! A single runner also has one left and one right guiding edge as well. As a matter of fact, a single runner sled can be made more accurate for the amount of free play does not have to be large enough to accommodate the changes in the runner spacing with humidity change. An advantage of a single runner is you can use the runner in one slot for zero-clearance applications and that same runner in the other slot for dado and bevel use. And yes, that sled is easier to construct.
Contributor
Jack
Yep, you'll make more than one, that's a guarantee. You'll also find out what features are important to you.
I've made a lot of sleds, for various machines through the years. Some I've kept, some were tossed once that project was done. The nice thing is that they don't have to be expensive.
I just got done making a coping sled, and somehow or the other, it was dead on 90 degrees right off the bat. Not a single tweek required. I couldn't believe it. That'll never happen again.
"The first thing you need to know, will likely be the last thing you learn." (Unknown)
Contributor
Keith, say I wanted to rip Corian into pieces 3/4" wide by 24" long and use it on a sled -
* What sort of blade do you need to make such cuts? (Surely not my Forrest WW-II?)
* Can a normal contractor saw do that with the right blade or do you need a 3-5 HP saw?
* Does the Corian drill/tap/screw to the sled, or does it have to be glued?
Just curious as I never thought of Corian for this application (or anything else but counters).
Thanks,
Fred
Contributor
I'll do my best to help answer the corian questions.
-regular carbide blade. I use an older one, but wear a mask and get ready for a dust storm!
-No need for a 3-5hp saw, corian cuts easily.
-you can tap corian but it doesn't have much holding strength. I'd drill and countersink the corian and put screws in from the bottom but don't use a drill to put in the screws as corian cracks easily - screwdriver for that.
Corian also works good for router table tops. I've made a ZCI before but I don't think it's worth it, plywood is a lot cleaner and more forgiving.
Moderator
There's a lot of different runner material to chose from. I went with UHMW rails and have no regrets. It machines easily, is impervious to humidity, and very stable.
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Andy Rooney
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I previously had QS oak runners, but they would give me grief when the humidity would change. I moved to adjustable aluminum ones (can't remember if they're Incra or some other brand I found...) and love them.
Clark Harbaugh
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