A better miter bar?

[al ladd]

I've been working on designs for cross cut sleds and then miter gauges for some time, and it's become somewhat of an obsession.

I think I have come up with a design for a miter gauge bar that has advantages over commercially available options, while being economical for a cottage industry scaled business like mine to make.

The commercial versions all work with an undersized bar with adjustable thingies, some spring loaded, some not. So between the nubs the bar is a bad fit. The nylon bits wear out and have to be readjusted and replaced. If spring loaded they introduce unwanted friction, and/or can be overcome for a wavy travel down the slot. The accuracy required for the best performance is intense. Even a .002 undersize is notably imperfect. All sorts of compromises in the woodworking industries solutions. (A large part of why sliders have become popular!)

I start with 3/8 x 5/8 steel bar. Then I adhere a strip of UHMW plastic that has had .03 thick VHB tape adhered to it after the plastic is flame treated for better adhesion. The resulting bar is oversized in width (about .8") and user trimmable, even by hand plane for a super slick finish to perfect width. Because the foam core of the tape has a little give there's some room for oversizing a tiny amount, at least for part of the bar, and it makes sense to slightly oversize the first 4-6" for wide cuts when only that much of the bar is engaged. The whole bar is very slightly springy in width. I could have purchasers measure their slots and I would provide them with a bar maybe .002" oversized for them to custom fit. I can even add a couple set screws at the first few inches that bear against the plastic (don't penetrate it) that remove the springiness there, and can be adjusted to very slightly bulge out the plastic for absolute perfect dimension at the bar's start.

The foam also helps with possible displacement from the occasional knock the plastic might receive, serving as an impact absorber. This tape is used architecturally for adhering non-structural components, lasting many years in hostile environments.

I'm interested in knowledgeable woodworkers response to this. Would you be distrustful of this?

On a related note, how wide is your saw's miter gauge groove?

[Cary Falk]

Unless I misread something, it sounds like a nightmare from a manufacturing standpoint. You are relying on a measurement taken by somebody else(measurement device unknown), to supply a part within .002", on a tool where the miter slot may vary along the length of travel. Not trying to rain on your parade but that was my first thought.

[Edward Weber]

The one thing I'll say is that the "standard" 3/8" x 3/4" slots are not all the same. The half doxen machines I have with miter slots are all different to a small degree that you can feel.
Most people wind up using a dedicated runner for each machine.
If yours is a compression fit via the foam backing, the amount of give needs to be enough to span from the smallest to the largest. It also has to have a memory and not take a set. If the foam backing collapes and does not expand, the fit could become sloppy. Temperature will also have an effect on this.
Any adjustments in a miter bar, for me, needs to be both directions, especially if the same accessory is to be used on more than one tool.
Simply trimming to fit adds no benefit for me. you might as well just use a hard wood runner.

[Lee Schierer]

My Kreg miter gauge came with adjustable plastic set screws. They didn't do a good job and wore out quickly. I have some .005 and .010 thick adhesive backed UHMW tape. I put one layer of the .005 tape on one side of my miter bar and it was precisely thick enough to eliminate all the side to side play in my miter bar. The tape is 1" wide so I applied it to the side of the miter bar then trimmed it flush with the top and bottom with a razor knife. So far that piece of tape has lasted over five years. I have plenty more if it comes loose or wears out. I just checked it again and I still have not side play and it slides easily.

[Dave Sabo]

Couple of things:

Hope your endeavor is successful.

Sliders are not popular because of your perceived compromises with available miter gauges. They are popular because they are a great tool to process large sheets of material quickly, accurately, and safely. I'll bet you can count on one hand the number of businesses that bought a slider to cross cut stick material or miter dimensional lumber. And on the other - the number of hobbyists that bought one 'cause their miter gauge sucked.

The market is always looking for a better mousetrap.

I've yet to run into or read about anyone's miter slot wearing out because of spring loaded ballbearing in their miter gauge. Is your saw in that boat ?


Cary is correct on your customers ruining your business with returns because they screwed up. They'll not be above blasting you in reviews and soc. media even if you have an iron clad no return policy.

Can you make these things profitably at much lower cost than all the established players ? If not , you're going to have a tough time creating a value proposition. I'm skeptical as repeatable precise manuf. costs money and you're not likely to have the volume to offset the initial costs. Guessing you're not going to be able to sell yours at a premium in any kind of volume either to offset the costs.

You may want to re-asses your notably imperfect criteria as it applies to woodworking. Most wood moves 2 thousandths during a project and certainly through changes of season. Whatever you or we are making doesn't require better precession. It's not a manned spacecraft or blueprinted racing engine that has to last running flat out for 24 of LeMans.

[Dan Cameron]

A while back I posted "A shop made zero play miter bar" on this forum. It got bumped to the shop made tools and machines forum. Take a look. I have since made a version which is adjustable from the top of a sled.

[Richard Coers]

No idea how many young woodworkers want to buy a premade sled, but they only one I bought was at a garage sale. For the previous 48 years of woodworking, I made all my own. Slightly wider hardwood runner scraped to the perfect fit.