• Common T Slot Sizes Diagram
• Common T Slot Sizes List

Nominal key size b × h Applied shaft diameter d Key size Keyway size; b h c or r Standard size of b1 and b2 b1Tolerance （h9） b2 tolerance （E9） r1 and r2 t1 t2; Standard size Tolerance（h8） Standard size Tolerance(h10) Standard size Tolerance Standard size Tolerance; 4×4: 10 or more and 13 or below: 4: 0 -0.018: 4: 0 -0.048: 0.5: 4. Choose from our selection of T-slots, including T-slotted framing rails, T-slotted framing structural brackets, and more. In stock and ready to ship.

Many of the woodworking jigs and fixtures I make have at least one length of t-track built into them.

A t-slot aluminum extrusion provides an easy way to make jigs usable for different size workpieces as well as adding an adjustable clamping point for jig accessories such as stop blocks and toggle clamps.

This 1/4' t-slot track has a groove down the middle to keep the drill bit from wandering off center when drilling mounting holes.

These different sizes are measured in T-sizes. If you haven’t noticed it yet, you will see in the market these T-sizes whenever you are shopping for the perfect torx screws. It can see them in the exterior of the parts, but sometimes, they may be hard to find. Depending on the manufacturer, you can quickly identify the size of the screw. Standard metric T-slots and T-nuts Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! - search is the most efficient way to navigate the Engineering ToolBox! 40-4040 is a 40mm x 40mm metric 40 series square T-slot profile with four open T-slots, one on each 40mm face. The profile is smooth, which makes it resistant to dirt and debris buildup while also being easy to clean. The 40-4040 profile is compatible with all 40 series fasteners.

A t-slot extrusion can be used in other places besides jigs. Use a pair on a router table to make an adjustable fence. Or use one on the fence to hold a featherboard or two.

Use them whenever you need to clamp anything anywhere along a straight line.

The two most common t-slot sizes are 1/4' and 5/16'. These two sizes will cover most every woodworking application. In fact, I use 1/4' most of the time because it's cheaper and plenty strong for what I use it for.

These t nuts and t bolts make it easy to attach clamps and other accessories to the t-track.

It is best to use t-nuts and t-bolts when attaching accessories to the track. Regular nuts and bolts can wreck the slot if overtightened.

If you have to use a regular hex bolt, use a small washer to prevent the head of the bolt from digging into the soft aluminum.

I like to get my t-bolts extra long and cut them down to the length needed for each application. This way I only need to keep one length in each size on hand.

Mounting the t track

No matter what your application, you'll have to cut a dado with either a table saw or router to mount the track flush with it's neighboring surface.

A 3/4' x 3/8' deep dado is cut to keep this t track level with the top of the workpiece. I cut this dado with the table saw.

The 1/4' track that I use requires a dado that is 3/8' deep and 3/4' wide. The 5/16' track needs a dado 7/16' deep by 7/8' wide. I think these are fairly standard sizes, but always measure first before cutting.

Some t-track comes with pre-drilled mounting holes, but the version I like to use requires you to drill your own holes. They do however, provide a small groove in the center to help keep the drill bit from wandering.

Drilling your own holes takes a little extra time, but allows me to place them where it's convenient or necessary. I found with the other stuff, I was drilling extra holes where I needed them anyway.

Where to buy

I live in a small city of 35,000 people with only two major building supply centers. Trying to find stuff like this is maddening, so for years I've been ordering hard to find items online.

I get a lot of my jig parts from Lee Valley here in Canada. Look under hardware -- Jig & Fixture Parts. They have a very nice selection of top quality goodies, even if they are a bit pricey.

With the Canadian dollar hanging pretty close with the US dollar these days, I find myself hopping across the virtual border more often when I find great deals online. Online stores like Amazon carry a large assortment of t-track and related hardware.

Common T Slot Sizes Diagram

One of the advantages of living in a large city is selection and availability of products. For those of us that prefer to live in smaller centers, the internet has evened the playing field. We can often get things shipped to our door cheaply and quickly for the same price a guy in the city might pay for gas running around to collect the things he needs. No white knuckle driving or one finger salutes... I love it.

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Common T Slot Sizes List

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Standards for T-slots

T-slots come in standard sizes. Needless to say things designed to fit in the T-slots are designed to fit these standard sizes. Similarly, the cutters designed for cutting T-slot are designed to cut standard size T-slots.

fig outline of a T-slot

The key characteristic of a T-slot is its width. Of course this can be metric or imperial

Metric T-slots (all in millimeters)

A b B+ C C+ Hmin Hmax

6 11 +1.5 5 +1 13 11

8 14.5 +1.5 7 +1 18 15

10 16 +2 7 +1 21 17

12 19 +2 8 +1 25 20

Imperial T-slots (All in inches)

diam of bolt width of slot depth of throatmax

A

1/4 9/32 3/8 1/8 9/16 1/2 15/64 13/64

5/16 11/32 7/16 5/32 21/32 19/32

3/8 7/16

1/2 9/16

5/8 11/16