DeWalt Router Sled
A slab wider than your planer has two routes to flat: a wide-belt sander you do not own, or a router on rails. This is the router on rails — two straight rails either side of the slab, a bridge that runs across them, and a DeWalt DWP611 taking the high spots off a couple of millimetres at a time until the whole face sits in one plane.
The part in this folder is the router’s half of it: a sub-base that copies the DWP611’s stock plate — same outline, same holes — and comes out at 6.35 mm instead of the 4.35 mm plate it replaces. That is the entire point of it. A router hanging off a bridge with a wide cutter loaded up spends the whole pass trying to flex its own base, and every bit of that flex ends up in the slab.
The plate
Everything on it is traced off the stock DWP611 sub-base, so the screws that come out of the stock plate go straight into the print.
| Feature | Size |
|---|---|
| Outline | 103.0 mm circle squared off at one end, 123.2 mm overall, 6.35 mm corner radii |
| Thickness | 6.35 mm (1/4 in) |
| Bit opening | 37.9 mm |
| Arc slots | 4 × 6.86 mm wide, on a 63.0 mm bolt circle, 30 degrees of arc each, one on each axis |
| Mounting holes | 4 × 6.35 mm on a 60.96 mm (2.4 in) square, counterbored 10.2 mm × 2 mm deep |
| Pockets | 4 × 9.45 mm dia, 2 mm deep |
| Rib | 66 × 4.5 mm, standing 1 mm proud |
The arc slots are the router’s sub-base screws — those hold the plate on the router, and the arc is what lets you rotate the plate before you tighten them. The four counterbored holes on the 2.4 in square are what you bolt the bridge through; the counterbores are there so the heads do not sit proud.
One face of the plate is dead flat with nothing on it but through-holes. Every other feature — counterbores, pockets, rib — is on the opposite side. The flat face is the one that faces the work.
Check the cutter diameter before you buy a bit. The opening in the plate is 37.9 mm. A cutter wider than that cannot pass through it in either direction, so you can never get the bit into the collet with the plate bolted on. A 1-1/4 in (31.75 mm) surfacing bit fits with room to spare. A 1-1/2 in (38.1 mm) one does not fit at all.
The DWP611 takes 1/4 in shank bits only, and most slab-flattening cutters are sold with a 1/2 in shank because most people run them in a big router. Buy the 1/4 in shank version. It is a smaller cutter and the passes take longer, which is the trade you make for a router light enough to hang off a bridge all afternoon.
Parts
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The router and the cutter:
- DeWalt DWP611 compact router — the router the plate is drawn around
- Slab-flattening / surfacing bit, 1/4 in shank — 1-1/4 in cutting diameter or less, see the caution above
- DeWalt DNP618 edge guide — optional, and it fits the same fixed base
The rails and the bridge:
- 2020 aluminium extrusion, 2 m — ×2 for the rails, plus a length for the bridge
- 2020 corner brackets — a 10-pack
- 2020 drop-in M5 T-nuts — the roll-in kind, so you can add one without dismantling the frame
- M5 button-head bolt and nut kit
- 1/4-20 bolts and washers — ×4, through the plate’s counterbored holes
- #8 × 1-5/8 in deck screws — for the timber base frame the rails sit on
Printing it:
- Carbon-fibre PLA filament or PETG — not plain PLA, see below
- Hardened 0.4 mm nozzle — only if you go carbon fibre; CF eats a brass nozzle
- Digital caliper — for checking the holes after printing
Dust, ears and lungs, because a surfacing bit throws an extraordinary amount of chip:
- Wet/dry vacuum
- Dust collection hose with reducers and the DeWalt DWV9000 universal connector
- 3M reusable respirator, OV/AG/P100
- Electronic earmuffs — a compact router at full speed for an hour is the loudest thing in the shop
- Safety glasses
Afterwards:
- Hot glue sticks — for locking the shims under the slab, and the best thing there is for it
- 5 in 8-hole sanding discs, 60–600 grit — the sled leaves ridges and sanding is how they go
- Rubio Monocoat Oil Plus 2C — one coat, no topcoat, and it does not sit on the surface like a film finish
Print settings
| Setting | Value |
|---|---|
| Layer height | 0.2 mm |
| Walls | 5 |
| Infill | 100% |
| Supports | None |
| Orientation | Flat face on the bed, features up |
| Material | PETG or carbon-fibre PLA |
| Footprint | 123 × 103 mm |
Every hole and slot runs straight through the Z axis, so there is nothing to support and nothing to bridge. Print it flat and it comes off the bed finished.
Do not print this in plain PLA. It is a structural plate under a motor that gets warm, holding a spinning carbide cutter, under sustained load for the whole length of a pass — and sustained load at slightly-warm is exactly where PLA creeps. PETG is the safe answer. Carbon-fibre PLA is stiffer and the better answer if you have a hardened nozzle in the drawer, and stiffness is what this part is for.
Solid infill is not optional either. A 20% part feels fine in your hand and still bows under the cutter.
There is a STEP file in the folder next to the STL. If you would rather have the real thing, that file goes straight to a waterjet or a CNC — 1/4 in polycarbonate is what a bought sub-base is made of, and it will outlast any print.
Printed holes come out undersize. Check the four mounting holes with a caliper before you go looking for a bolt, and ream them rather than forcing anything: a 1/4 in bolt driven into a 6.1 mm hole splits a printed plate along its layer lines.
The file is named dewalt_router_sled_cookie_sheet_divider_v2 — an old Fusion
design name that came along for the ride. There is one part in it and it is the
base plate.
Fitting the plate
-
Take the stock sub-base off the router and keep the screws. Lay it on the print and look through every hole. They should line up; if one does not, you have a different base, and that is much better to find out now.
-
Ream the mounting holes to whatever bolt you are using, and take the flash off the flat face. The flat face has to stay flat — it is the reference surface for the whole operation.
-
Bolt the plate to the router through the arc slots, finger tight.
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Centre it on the collet. Drop a straight bit in, sight the shank against the edge of the bit opening, nudge the plate along its slots until the gap is even the whole way round, then tighten. The arc slots exist for this and it takes two minutes.
Building the sled
The rails are the whole job. Everything else is carpentry.
-
Build a base frame for the slab to sit in — a rectangle of timber, screwed together, longer and wider than the slab and stiff enough not to twist when you lean on it.
-
Run the two rails along the long sides. Two lengths of 2020 extrusion, parallel, and — the part that matters — coplanar. Any twist between the two rails is copied straight into the slab, and you will not see it until you put a straightedge across the finished face.
-
Check them against each other, not against the floor. Bridge the rails with a straight offcut, slide it end to end, and shim until it sits flat everywhere along the run. A bench that is out of level is fine. Rails out of plane are not.
-
Make the bridge. Another length of extrusion, or a stiff piece of timber, spanning the rails and free to slide along them. Cut a clearance hole in the middle big enough for the cutter and for the sub-base screw heads, and bolt the plate to it through the four counterbored holes.
-
Bed the slab. It must not rock, at all. Shim under the corners until it sits dead still, then run a bead of hot glue down each shim to lock it. A slab that rocks under the cutter comes out with a rocker in it.
-
Set the first cut. Slide the bridge over the highest point of the slab and drop the router until the cutter just kisses it. That is your zero. Every pass after that goes deeper.
Flattening
Take 2 mm a pass, no more, and let the router do it in its own time. A compact router driving a 1-1/4 in cutter through hardwood is working near the top of what it has; if the motor note drops you are pushing too fast or cutting too deep, and you will hear that long before you see it.
Move the bridge along the rails in steps of roughly half the cutter width so each pass overlaps the last. Full-width steps leave a ridge on every boundary, and those ridges are what you will be sanding out afterwards. Keep the router moving whenever the cutter is down — dwelling in one spot burns a dish into the face that later passes cannot remove, because later passes take the whole face down with it.
When the last high spot disappears, flip the slab, re-bed it, and do the second face. The first face is now your flat reference, so the second one only needs enough passes to clean up.
Then sand. The sled leaves a corduroy of shallow scallops across the grain; 80 grit on a random-orbit sander takes them out and everything after that is ordinary finishing.
Troubleshooting
The finished face has a twist in it. The rails were not coplanar. Nothing at the router end fixes this — go back and shim the rails with a straightedge bridged across them.
A shallow dish down the middle of the slab. The bridge is flexing. It is spanning too far for its section, or the plate is bolted to a thin spot in it. Stiffen the bridge or shorten the span.
Regular ridges you cannot sand out. The step between passes is too big, or the plate is not sitting square to the rails, so the cutter is tilted and cutting on one edge. Loosen the arc slots and reseat it.
Burn marks and a hot cutter. Feeding too slowly with too small a bite. Take a deeper cut and move faster; a surfacing bit wants to be cutting, not rubbing.
The plate cracked around a bolt. Printed, then forced onto an undersized hole. Ream to size, and print the replacement at 100% infill in PETG.
Files & downloads
Printable parts
CAD source
The design itself, if you want to change it rather than print it. A STEP file is exact geometry and opens in almost anything; a Fusion 360 archive keeps the modelling history, so you can go back and edit the sketch that made the part.
- dewalt_router_sled_cookie_sheet_divider_v2.f3d Fusion 360 archive — the editable design, with its history
- dewalt_router_sled_cookie_sheet_divider_v2.step STEP — opens in Fusion 360, FreeCAD, Onshape, SolidWorks