novel cross cut sled runner design

[al ladd]

I've been working on the side for a few months of a redesign of the defunct Jointech Smart miter cross cut sled, probably the best cross cut sled ever made. It had the nifty feature of maintaining zero clearance to the blade at any angle setting, so you could set a stop to cross cut a board at 90 degrees, and then set to 45 and cut to the same length. Pivot travels in a slot and quadrant is cut eccentrically to compensate. A challenging CAD project for me; a simple trig problem for fellow Creeker Ed Aumiller. (PM me for Ed's program to calculate the curve).

I've been planning to sell a kit with hardware, some of it custom CNC milled by me, a modified piece of 80/20 extrusion, and a dxf file for those with CNC capabilities, or an MDF template for those with merely a handheld router with a template guide, allowing woodworkers to make their own version of this very useful tool any size they want. Today, via a Fine Woodworking Magazine newsletter, I learned that Wood Peckers beat me to the punch. Sort of. They're not planning on shipping until August 31. The price: $500. https://www.youtube.com/watch?v=t4hOuqY5rN0&t=8s

Remarkably, I learned they also designed a new miter bar with nylon leaf springs, ($69) that works similarly to the bar I designed to go with my sled. I just posted a video on my miter bar. It's a piece of 3/8" baltic birch or other high quality plywood, about 24" long and 19/32" wide, with (6) 1-1/4" long, 1/32" thick cherry spacers gluing on a piece of 1/8" thick cherry on one edge. Make the sandwich about .015" thicker than the width of your miter slot. Then, using plunge cuts on a carefully set router table against a fence, relieve the thickness at the spacers and just beyond them to just shy of the miter slot width. Now the unrelieved sections of cherry will act like springs, making for a smooth, low friction slide in the slot, perfect for a wobble free cross cut sled, with way more than enough "give" to compensate for the couple 1/1000" the bar will change dimension in some climates.

The problem with designs like the one used by Incra, with little discs that expand to take up miter bar slop, is that they're point-contact only and quickly wear out. For a busy one man shop like mine, they need readjustment or replacement for best work every few weeks. When I mentioned this to Incra they did send me a pile of free nylon discs. I'd imagine the same is true of designs like Rockler's and Kreg's, using little adjustable plastic plugs, whether spring loaded or not. Even this novel Woodpeckers' design, with a "nylon leaf spring" presents just the small arc of a small diameter tip of the spring. I bet it would wear out rather quickly with heavy use. My design presents 2" long wood "springs" that I doubt would ever wear out. This design will work especially well for imperfect miter slots, like the ones on job site saws.

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

[Steve Eure]

Not to start a fight, but the Dubby Sled is similar and has been out for years. I will admit that my Dubby, to me, is the best sled I've ever used. There are a few things I would do to modify mine to make it better, but it is a great sled.
BTW, I'm not knocking your design by no means, just saying that Dubby beat everyone to the punch years ago. Of course, your's possibly has some added features that I have missed.
Good luck with your endeavors.

[Larry Frank]

Always glad to see people trying to improve things.

[Ed Aumiller]

Steve, I have the Dubby sleds also.. the difference is that if you set up the stop on the fence at one angle for a certain length then change angles, you have to readjust the stop to get the same length.
The original Smart miter fence eliminated that. Appears the new Woodpecker fence does also. This is what Al is doing also.
Ed A.

[Dan Bundy]

Where can one find your video of the sled runner?

[Bruce Wrenn]

Not to start a fight, but the Dubby Sled is similar and has been out for years. I will admit that my Dubby, to me, is the best sled I've ever used. There are a few things I would do to modify mine to make it better, but it is a great sled.
BTW, I'm not knocking your design by no means, just saying that Dubby beat everyone to the punch years ago. Of course, your's possibly has some added features that I have missed.
Good luck with your endeavors.

+1 on everything you said. Only regret with my Dubby is I waited so long to buy one.

[Edward Weber]

"
The problem with designs like the one used by Incra, with little discs that expand to take up miter bar slop, is that they're point-contact only and quickly wear out. For a busy one man shop like mine, they need readjustment or replacement for best work every few weeks"

I've been using Incra miter gauges for years and have not had this issue of flat spotting or having to routinely (every couple of weeks) tighten the adjusters. I find this curious.

[al ladd]

"
"The problem with designs like the one used by Incra, with little discs that expand to take up miter bar slop, is that they're point-contact only and quickly wear out. For a busy one man shop like mine, they need readjustment or replacement for best work every few weeks"

I've been using Incra miter gauges for years and have not had this issue of flat spotting or having to routinely (every couple of weeks) tighten the adjusters. I find this curious.

That is curious Ed. I wonder if they've made the discs out of harder stuff lately?...it's been probably 15 years since they sent me that pile of discs, and I'm just about out of them. These used ones show the problem I have. I can tighten them 2-3 times, then rotate and get another 2-3 tightenings. Then they're trash. In fact just this morning I tightened the discs in place on the bar for a tighter fit. A couple were already tightened as far as they'd go. It's a pretty tiny socket head on the screws, so there's only so much torque you can get without risking stripping them. I might have exaggerated when i say they need adjustment "every few weeks", but often enough that when I do critical work, I often feel the need to tighten them first.

P1030096.jpg

[Edward Weber]

I would almost wonder if there is something in the miter track that is filing them down prematurely.
I would inspect the track and "carefully" feel for a hot spot or burr that could be doing this. Many times the underside (corner) of the 3/4 part is quite rough from the machining. A light file or sanding can smooth it out without enlarging the width of the track.
just a suggestion

[al ladd]

I would almost wonder if there is something in the miter track that is filing them down prematurely.
I would inspect the track and "carefully" feel for a hot spot or burr that could be doing this. Many times the underside (corner) of the 3/4 part is quite rough from the machining. A light file or sanding can smooth it out without enlarging the width of the track.
just a suggestion

Edward, thanks, great suggestion. I checked with my finger, and nothing was noticeable, but hearing as you've had years of use with no such issues, I ran a coarse diamond stone down the sliding surface, and it did improve the feel of the gauge sliding in the track. So maybe that will cut down on my adjustment needs. As primarily a box maker, making 100's of small parts, it does get sent up and down the track a lot, but it's wear speed has annoyed me.

[al ladd]

This evaluation of Woodpeckers 90 degree miter gauge using a bar like the one in their new "Autoscale" sled shows the miter bar mechanism that's analogous to mine: (@5:50) https://www.youtube.com/watch?v=JGFfAe9qk7A

As Ed Aumiller said: "the difference (between the Dubby or Rocklers adjustable sled) is that if you set up the stop on the fence at one angle for a certain length then change angles, you have to readjust the stop to get the same length.
The original Smart miter fence eliminated that. Appears the new Woodpecker fence does also."

The other advantage of the Smart Miter was that the quadrant allowed for both +45 degrees all the way to -45 degrees (it actually goes to 50 degrees). This allows for cutting the required angles on picture frame stock that's molded in such a way as it can't simply be flipped over. It also allows for cutting compound miters. To get that functionality from a Dubby requires two of them, a left side and right side. I was surprised that the proposed Woodpecker version has just a Dubby-like angle range, perhaps because they calculated they'd sell more pairs of sleds (like Dubby they offer both a right version and left version) to those who need that functionality than they would lose sales to those who need both angles but aren't prepared to spend $999 on the pair....

The Woodpecker sled also gears itself towards panel cutting, with a 24" cross cut capacity ("on most saws") . It places its fence at the rear of the sled, addressing what many described as a shortcoming of the Smart Miter, which placed the fence in the middle of the sled, greatly limiting cross cut capacity. This choice isn't so straightforward. Although the Smart Miter seemed like its design needlessly limited cross cut capacity, there's a shortcoming with any cross cut sled that has its fence to the rear of the sled: it has limited runner engagement at the end of the cut, unless the sled has a stiff runner that goes a few inches further than the sled extent .

My proposed sled (still waiting to catch up on my other work before finishing my prototype) will look more like the Smart Miter than like Woodpeckers. (by the way, I checked and Jointech never received a patent that I could find for this, but it would likely be up anyway by now. Jointech's owner died in 2007 and the company failed soon thereafter). My offering will have the fence in the middle for cutting any angle from +45 to -45. But the fence will be able to be quickly relocated to the back of the sled for square cuts. Builders will be able to make the kit any size they want, allowing at least a 24" cross cut, but also allowing it to be made small enough for job site saws, on which larger commercial sleds present a safety hazard. My design will also do what many better quality DIY sleds offer: allow for easily changed zero clearance inserts both at end of fence, (which Dubby does well) and floor of sled (which Dubby, WP, and Jointech all ignore)..

I've spent way too much time thinking about all these things, trying to design what so many have claimed: the "ultimate cross cut sled". I know most serious woodworkers solve the problem by making several sleds for different purposes. But wouldn't it be nice to have one that "did everything"? Reading through threads on this forum, with so many serious, smart, knowledgeable woodworkers, is a great source of information and inspiration.