The design of a table saw runner, also known as a miter slot runner, is fairly straightforward - it’s a piece long, narrow cut of wood that is custom fit to your table saw’s miter slots. However, there are a few important things to remember when cutting these runners:
- Use a hardwood - oak, maple, and cherry are good choices
- Plan on cutting about 4 or 5 extra runners - you’ll need them now or later
- Take measurements with a caliper
- Cut the runners so the grain is vertical - this helps to mitigate side horizontal expansion
Measure the miter slot dimensions
We recommend using a digital caliper to get the most accurate measurements for your miter slots. You can find digital calipers at your local Harbor Freight for about $20 and even get them for less on Amazon.
You’ll want to find the width and depth of your miter slots at both the front and back of the table saw. If the measurements differ significantly, use the larger measurement.
Setup the table saw
You’ll want to use a zero-clearance insert in your table saw and a thin rip fence if available. Both are optional, but you may have trouble cutting the small stock without them.
Check to ensure your fence is square to the blade and lower the blade accordingly.
Square up your wood
Jointer / Planer the wood.
Orient your wood and plan your cuts
Cut the wood so that it is slightly larger than the measured dimensions. The goal is not to get the exact width of the miter slot on this cut, but to get close without cutting the stock too thin.
For each piece of wood, write on each side, which is the top and bottom. You want to make sure the wood is oriented with the grain running vertical. Cut a test piece, verify the fit (slightly larger than the miter slot), then repeat on the remaining runners.
Slowly remove material until the fit is snug
Slowly, you want to reach the exact miter slot width on the runners you've just cut.. These runners have to be very close to the exact miter slot width to perform correctly. You can always remove more material, but you can not add material back.
Re-adjust the table saw fence by just a bit - as in unlock the fence and tap it with your finger to move it. Make the cut, test the fit, and then repeat if needed.
For the test fit, slide the runner from front to back through the full length of the runner. The ideal fit should be snug - not too tight and not too loose. Error slightly on the tighter side as you can add wax later.
Mark and drill the necessary holes
For most table saws, you’ll want about 3 to 4 holes to connect each runner to the sled or jig. Avoid placing the holes too close to the ends or you’ll risk splitting the wood. Aim for at least 4” to 6” in from each edge.
Do not directly screw into the runners without pre-drilling. Due to the narrow width of the stock, these will split easily.
If you have trouble with the wood splitting when drilling a hole, start with a smaller drill bit and step your way up to the needed size.
We recommend using a drill press to do this because it’s important to drill these holes at as close to 90 degrees as possible. If you do not have a drill press, take extra time to ensure the drill bit is going into the wood at a 90-degree angle.
Finally, countersink the holes by using a countersink bit. This ensures the screw heads will not stick out and scrape the bottom of the miter slots. If you do not have a countersink bit, you can use a larger drill bit and drill part of the way into the smaller hole.
3 Best Table Saw Sled Runner Materials
While hardwoods are the preferred material for most woodworking projects, the table saw miter slot rails are not one of those projects.
Will they work?
Yes.
Are they the best performing option?
Not even close.
There are 3 materials that perform significantly better than wood does for little cost increase. Those materials are:
- Aluminum
- UHMW Plastic
- HDPE Plastic
More specifically, compared to any wood, these materials offer:
- Less thermal expansion and contraction
- Greater wear and abrasion resistance
- Greater resistance to water
- Greater resistance to chemicals or cleaning agents
Aluminum, UHMW (Ultra High Molecular Weight Polyethylene) plastic, and HDPE (High Density Polyethylene) plastic are widely available, used in a multitude of other applications, and are easy to purchase.
You can walk into your local Walmart and get a small sheet of HDPE for just a couple of dollars.
Hard to believe?
Head on over to the kitchen cookware aisle and find one of the hard, white, plastic cutting boards. More than likely, this is made of HDPE and will cost $3-$4.
Before you do that, there are some better options out there.
Aluminum Miter Slot Runners
Aluminum miter slot rails offer the most features as a pre-cut ready-to-use miter slot rail assembly. Higher end models offer adjustable, spring-loaded plungers which allow you to customize the fit of the sled or jig to different table saws.
These plungers have adjustable slots that make it easy to remove the ‘slop’, or lateral variation, on your table saw or reuse these same sled runners later if you decide to upgrade or modify your jig.
Holes on every model we’ve seen online offer pre-drilled holes and hardware that make it easy to align the runners to the jig quickly and accurately.
Lastly, if you like to match the colors of the tools in your shop, some offer different color options.
UHMW Plastic Miter Slot Runners
UHMW, or Ultra High Molecular Weight, Polyethylene is a common thermoplastic used primarily in manufacturing processes or other high-use/high-wear applications.
Since UHMW is built for an industrial application, you’ll find it will perform perfectly for home use.
There isn’t anything fancy about this material. You can find options online that are pre-cut to your needed dimensions, with pre-drilled holes, and with hardware included.
HDPE Plastic Miter Slot Runners
HDPE, or high-density polyethylene, is also a common thermoplastic and used in nearly everything - shampoo bottles, cutting boards, pipes, milk jugs, and more. Because of its high-use, supply is plentiful, and the price is usually low.
You won’t notice much of a difference between HDPE and UHMW. For the purposes outlined in this article, they’re essentially the same.
If you’re looking for an inexpensive option, head to Walmart, TJ Maxx, or your local HomeGoods store and find a cheap cutting board you can cut up to make some runners.
How to attach table saw sled runners
- Square up a sled’s base, getting as close to a perfect 90 on the corners as possible.
- Align the table saw fence to use as a guide to align the sled base
- Place coins or washers in the miter slot rails
- Place the runners on the coins or washers and check that the runners are slightly elevated above the table saw surface.
- Use double-sided tape or spray adhesive on the on the runners/base.
- Align the base on the fence and lay it down on the runners
- Allow the glue to cure or the tape to stick
- Mark the center of the holes in the runners on the base
- Remove the runners and drill holes in the hose
- Attach the runners with screws
- Test the fit, adjust if needed