Bench Dogs and 20mm Dog Holes: A Complete Guide to the 96mm Grid

Most woodworkers buy their first set of bench dogs without thinking much about the holes they drop into. Then something doesn't fit, or a setup that was square on Tuesday isn't square on Thursday, and the questions start. This guide covers bench dogs and 20mm dog holes from the ground up: what the 96mm grid actually is, why the spacing was chosen, what mounts in the holes and what doesn't, how to pick dog heights, and how to use the grid as a measuring system instead of just a place to stick pegs.

Rob Schumacher spent ten years working out the answers to these questions the hard way, first as a trim carpenter and cabinet installer fighting a bench that moved under him, then as the designer of the Dash-Board system. What follows is the practical version.

Quick Summary

• A 20mm dog hole is a 20-millimeter-diameter hole bored through a workbench top, used for dogs, stops, clamps, and mounting hardware.
• The 96mm grid means those holes are spaced 96 millimeters apart, center to center, in both directions. It is the spacing Festool used on the MFT and the pattern the whole multi-function table category standardized around.
• 96mm is about 3.78 inches, and it divides evenly by 2, 3, 4, 6, 8, 12, 16, 24, 32, and 48, which is why symmetrical layouts fall into place without arithmetic.
• On a Dash-Board or ShortCut bench, the 20mm grid lives on the benchtop and the dual clamp tracks run along the sides. They are two separate mounting systems and they are not interchangeable.
• Bench Dogs, SpiRail Dogs, Parallel Guides, Surface Mount Fences, and Universal Setup Blocks all register in 20mm holes. Guide Rail Brackets, Track Stars, and Outriggers mount in the side clamp tracks using T-bars or T-bolts.
• Dash-Board Bench Dogs come in three heights (1 inch Tall, ½ inch Medium, 3/16 inch Short) and are machined from Delrin so they will not dent your benchtop.
• Because the grid is a fixed, known dimension, counting holes is more reliable than measuring. A 3-4-5 squaring triangle lands exactly on hole centers at 3, 4, and 5 hole steps.
• Any bench with a true 20mm grid on 96mm centers takes the same accessories, including the Festool MFT3 and 1080, Kreg ACS, Benchdogs Ultra MFT, and shop-built tops.

What Is a 20mm Dog Hole?

A 20mm dog hole is a 20-millimeter-diameter hole bored vertically through a workbench top to accept bench dogs, stops, clamps, and accessory mounting hardware. The 20mm diameter is the standard across multi-function tables and their aftermarket ecosystem, which means a dog bought from one maker will drop into a compatible bench from another. The hole does two jobs at once: it holds the accessory down, and it locates it at a known position on the surface.

That second job is the one people underuse. A dog hole is not just an anchor point. It is a coordinate.

What Is the 96mm Grid?

The 96mm grid is the spacing pattern of 20mm dog holes on a multi-function workbench, with holes positioned 96 millimeters apart from center to center along both axes. Festool established the 96mm spacing on the MFT line, and because accessory makers designed around it, the pattern became the de facto standard for the category. Benches built to that standard share accessories freely.

Ninety-six millimeters works out to roughly 3.78 inches, with about 76mm of clear top surface between the edges of adjacent holes.

Why 96mm Divides So Well

The number itself is doing quiet work. 96 is divisible by 2, 3, 4, 6, 8, 12, 16, 24, 32, and 48. In practice that means you can halve a span, split it in thirds, or step it in quarters and still land on whole units of the grid.

It also means squaring math gets easy. A 3-4-5 right triangle, the oldest squaring check in the trades, maps directly onto the grid: three hole steps is 288mm, four is 384mm, five is 480mm. Drop dogs at those counts and you have a verified 90 degrees without touching a tape measure.

The Two Systems on a Dash-Board Bench

This is the single most common point of confusion for new owners, and it is worth getting straight before you buy anything.

A Dash-Board or ShortCut bench has two completely separate mounting systems:

1. The 20mm dog hole grid on the benchtop surface, spaced on 96mm centers.
2. Dual clamp tracks (T-tracks) running along both sides of the bench frame.

They do different things, they take different hardware, and confusing them leads to ordering the wrong accessory.

What Mounts in the 20mm Holes

• Bench Dogs for positioning, registration, and workholding
• SpiRail Dogs for guide rail registration
• Universal Setup Blocks for repeatable rail placement
• Parallel Guides, which anchor with included ExpanDogs
• F2 and F1 Surface Mount Fences, which mount with sliding Fence Blocks
• Third-party 20mm workholding, clamps, and stops

What Mounts in the Side Clamp Tracks

• Guide Rail Bracket Set, via T-bar or T-bolt
• Track Stars, via T-bar or T-bolt
• Outriggers, via the same track hardware
• Bench connectors for joining multiple benches

Track Starslive in both worlds. They mount to the bench through the side clamp tracks, but they carry their own 20mm holes and slots on their surface. So a Track Star is a T-track accessory that then becomes a 20mm mounting platform out past the edge of the bench. That is how Parallel Guides and fences get positioned outboard for full sheet rips.

One more detail specific to Dash-Board tops: alongside the round 20mm holes, the benchtop includes slotted holes that accept SpiRail Dogs. Those are useful when you are working shorter pieces and want the rail registered closer in.

Choosing Bench Dog Height: Tall, Medium, or Short

Dash-Board Bench Dogs ship four to a set in three heights. The height refers to the portion that stands above the table surface, and that portion is 1 inch (25mm) in diameter regardless of which height you choose.

If you are only buying one set, buy Medium. It is the everyday height, it pairs naturally with the Setup Blocks, and it is the height that already ships with the Guide Rail Bracket Set. Most owners eventually keep two or three sets staged so they are not swapping dogs between setups.

Why Delrin Matters

Every Dash-Board Bench Dog is machined from Delrin, an engineering plastic, rather than steel or aluminum. The reason is practical rather than exotic. Metal dogs will dent and deform if dropped, but Delrin just bounces and keeps on truckin'. Delrin absorbs the hit without marking the bench and without breaking. Over a few years of daily use, that difference shows up on your benchtop.

How to Square a Crosscut Setup Using the 96mm Grid

Here is the sequence that turns the grid from a clamping surface into a measuring system.

1. Deploy your Guide Rail Brackets into the side clamp tracks and set your guide rail in place.
2. Drop a pair of Universal Setup Blocks into the grid with Bench Dogs inside them, so the rail registers against a fixed reference instead of a pencil mark.
3. Slide the rail against the Setup Blocks. The cut line now lands in the same place every time, which also means blade contact concentrates in one strip of your benchtop rather than spreading across it.
4. Mount your F2 Fence using its sliding Fence Blocks, dropping them into whichever 20mm holes give you the reach you need.
5. Lock the fence down with the all-metal knobs and add a Reversible Flip Stop for repeat lengths.

The advantage of steps 2 and 5 is that both use physical references rather than measurements. Physical references do not drift, and they do not care whether you are tired at the end of a long day.

Using the Grid for Repeatable Rips

Crosscutting gets most of the attention, but the grid earns its keep on rips.

Dash-Board Parallel Guides anchor into the benchtop's 20mm holes or into Track Stars rather than clamping to your guide rail. That is a meaningful difference. When your parallel guides reference the bench, the bench is the constant. When they reference the rail, you inherit whatever the rail clamps are doing.

Each guide carries two reference heights: a 6mm end that slips under the rail for narrow cuts, and a 29mm aluminum cap end that raises the reference for stacked or slightly warped material. Pair them with the Rip Gauge and you set both sides of the blade from a single kerf-corrected standard instead of calibrating two scales independently.

For rips wider than the bench, the guides move out to Track Stars, and the workflow stays identical.

Bench Dogs vs SpiRail Dogs vs ExpanDogs

Three different parts, three different jobs, and the names get mixed up constantly.

• Bench Dogs are Delrin pegs for positioning and backing up material. They sit proud of the surface and give your workpiece something to register against.
• SpiRail Dogs are anodized aluminum, 81mm long, with a machined spiral groove that gives you grip for fast tightening and release. Their job is registering your guide rail, not your workpiece. They slip into the bottom slot of any standard rail (Festool, Makita, Bosch, Mafell, DeWalt, Metabo, Powertec, Milwaukee, WEN, Grizzly) and then locate in a 20mm slotted hole on the bench top, a Track Star, a Guide Rail Bracket, or the Wingman.
• ExpanDogs are the expanding anchors that lock Parallel Guides and fences into the grid. Four ship with each set of guides.

If you are buying a Guide Rail Bracket Set, note that it already includes 4 Medium Bench Dogs, 2 Universal Setup Blocks, and 1 SpiRail Dog, so you may already own more of this than you think.

Will 20mm Dogs Fit My Bench?

Dash-Board dogs and grid accessories work on any bench with a true 20mm hole pattern, including:

• Dash-Board and ShortCut benches
• Festool MFT3 and MFT 1080
• Benchdogs Ultra MFT
• TrackTubes
• Shop-built MFT-style tops drilled to standard spec

One caution worth stating plainly: 20mm is not the same as 3/4 inch. Three-quarters of an inch is 19.05mm, so a 3/4-inch dog in a 20mm hole leaves nearly a millimeter of slop, and a 20mm dog will not enter a 3/4-inch hole at all. If you are buying dogs for a bench you did not drill yourself, confirm which standard it uses before ordering.

Building Your Own 96mm Grid Top

If you are drilling your own top, the grid is the easy part. The side tracks are where people get it wrong.

Dash-Board supplies both T-bars and T-bolts with Guide Rail Brackets and Track Stars. The T-bolts fit any track with at least a 7mm opening and 12mm interior width. The T-bars are 6mm thick and 12mm tall, need the same 7mm minimum opening, and require interior width over 12mm with depth to clear 6mm of material. Mini T-track will take the bolts but not the bars.

For mounting position on a wood-framed table with a 3/4-inch (18mm) top, center the track either 29mm or 39mm below the work surface. Those two dimensions correspond to the two sets of mounting holes on the Guide Rail Bracket and Track Star base plates. Either set it in a dado flush with the bench side, or surface mount it with a second piece below it separated by about 30mm so the base plates have vertical backing and cannot cantilever off a single point. Full details are on the FAQ page.

What the Grid Gives You Back

If you are starting from scratch, the practical path is a set of Medium Bench Dogs, a pair of Universal Setup Blocks, and the Guide Rail Bracket Set, which bundles both. Add Parallel Guides and Track Stars when you start ripping sheet goods. If you are upgrading an existing MFT-style bench rather than replacing it, the Core MFT Bundle covers the same ground.

See the full range on the shop page, watch the setup sequences on the videos page, or call Rob directly at (303) 376-5703 if you want a second opinion on what your bench actually needs.

Worth reading next: What Is an MFT Table, and Do You Actually Need One? and Setup Blocks 101.

Frequently Asked Questions

What size are the dog holes on an MFT table?

Dog holes on an MFT table are 20mm in diameter, which is the standard across the multi-function table category. Festool established the size on the MFT line and accessory makers designed around it, so a 20mm dog from one manufacturer fits a compatible bench from another. Note that 20mm is not equivalent to 3/4 inch, which measures 19.05mm and produces a loose, inaccurate fit.

What is the spacing between 20mm dog holes?

The spacing between 20mm dog holes on a standard MFT-style grid is 96mm from center to center, measured in both directions across the benchtop. That works out to roughly 3.78 inches, leaving about 76mm of clear surface between adjacent hole edges. The 96mm figure divides evenly by 2, 3, 4, 6, 8, 12, 16, 24, 32, and 48, which makes symmetrical layouts and squaring checks straightforward without arithmetic.

Which bench dog height should I buy first?

Buy the Medium (½ inch) Bench Dogs first if you are only purchasing one set. Medium is the general-purpose height, it pairs naturally with Universal Setup Blocks for guide rail registration, and it is the height already included with the Guide Rail Bracket Set. Add Tall (1 inch) dogs when you need vertical workholding or rail-back registration, and Short (3/16 inch) dogs for thin material and low-profile setups.

Do Dash-Board bench dogs fit a Festool MFT3?

Dash-Board Bench Dogs fit the Festool MFT3, the older MFT 1080, the Benchdogs Ultra MFT, and any shop-built bench drilled to the standard 20mm grid. They drop in without modification or proprietary hardware.

Can I mount Guide Rail Brackets in the 20mm dog holes?

Guide Rail Brackets do not mount in 20mm dog holes. They attach to the dual clamp tracks running along the sides of the bench using T-bars or T-bolts, both of which are included in the set. The 20mm grid on the benchtop and the side clamp tracks are two separate mounting systems. Track Stars and Outriggers also mount in the side tracks, then provide their own 20mm holes for accessories.