Clampwright Desk Clamp System: Headphone Hook, Cable Tray and Keyboard Cradle, No Supports

Clamp it on, bolt it up, swap it later. Clampwright is a printed C-clamp that grips the edge of your desk with no drilling. A bolted 20 mm hex key on the front of each clamp holds a headphone hook, a 200 mm cable tray or a keyboard cradle, and lets you turn the accessory in 60° steps. Free to download.

Physical test print pending: settings are from PrusaSlicer slices on the MK4; load ratings (hook ~2 kg, tray ~2 kg, cradle ~1.5 kg) are design estimates, not tested.

• Two clamp sizes: S for desks 11–35 mm, L for desks 36–60 mm.

• Three accessories: headphone hook (70 mm reach), 200 mm cable tray with cable notches and zip-tie slots, and a keyboard cradle (42 mm slot) that stores a full-size board on its edge under the desk.

• Designed for strength: clamps print on their side so the C shape is in the layer plane. A knurled knob on an M8 bolt does the clamping, by hand.

• No supports on any part. PrusaSlicer 3MFs with the settings applied are included.

• Includes all STLs, PrusaSlicer 3MFs, the OpenSCAD source and a fit coupon to check your printer's tolerance first.

• Remixes welcome, please credit PtDesigns and keep them non-commercial.

All measurements are in mm.

Parts

• Clamp S (desks 11–35 mm): print on its side, ribbed face up

• Clamp L (desks 36–60 mm): print on its side, ribbed face up

• Knob: knurled, 42 mm, presses onto the M8 bolt head. Print grip face down

• Pad: hex pad, presses onto the bolt tip. Print desk face down

• Hex key: 20 mm, one per accessory. Print standing on an end

• Headphone hook: 70 mm reach. Print on its side

• Cable tray 200: 200 mm long. Print upright with a 3 mm brim

• Keyboard cradle: 42 mm slot. Print upright with a 3 mm brim

• Fit coupon: clamp socket, accessory socket and key. Print as placed

The 3MF files are PrusaSlicer projects with the settings below already applied. The OpenSCAD source (clampwright.scad + lib.scad) is included if you want to change sizes.

Sliced and profiled for Prusa MK4

• Printer: Original Prusa MK4 (Input Shaper), 0.4 mm nozzle, PrusaSlicer 2.9.2

• Material: PETG. Profile 0.20mm STRUCTURAL (0.2 mm layers)

• Clamps (load parts): 5 perimeters, 6 top / 5 bottom layers, 40% gyroid

• Everything else: 4 perimeters, 5 top / 4 bottom layers, 25% gyroid

• Supports: none needed on any part

• Brim: 3 mm on the cable tray and keyboard cradle only

• Pad: best in TPU 95A (3 perimeters, 20%). In PETG, stick 1 mm felt on its face

Print time and filament (PETG, from PrusaSlicer)

• Clamp S 11–35: 5h 24m, 91.45 g

• Clamp L 36–60: 6h 19m, 106.66 g

• Knob: 1h 00m, 15.12 g

• Pad: 11m, 3.25 g

• Hex key: 13m, 3.68 g

• Headphone hook: 3h 25m, 61.66 g

• Cable tray 200: 7h 23m, 144.08 g

• Keyboard cradle: 7h 50m, 147.85 g

• Fit coupon: 1h 29m, 25.22 g

Full set as pictured (3 × clamp S, 3 knobs, 3 pads, 3 keys, hook, tray, cradle): about 39 h 04 m and 694 g. Times are without brim; the tray and cradle add about 0.4 g of brim each.

Hardware

• Per clamp: 1 × M8x50 hex bolt (ISO 4017 / DIN 933, fully threaded), head pressed into the knob, and 1 × M8 hex nut (ISO 4032) that slides into the lower jaw

• Per accessory: 1 × M6x30 socket head cap screw (ISO 4762) and 1 × M6 hex nut (ISO 4032) that slides into the side of the clamp spine

• Optional: 1 mm self-adhesive felt for the pad face and the underside of the top jaw; a drop of CA glue if the knob is loose on the bolt head

If the knob binds, or for more knob room, use a longer M8x55 bolt; the knob just sits a little lower.

The full set as pictured needs 3 × M8x50, 3 × M8 nuts, 3 × M6x30 and 3 × M6 nuts.

Which clamp size?

• Desk 11–35 mm thick: clamp S (throat 44 mm)

• Desk 36–60 mm thick: clamp L (throat 69 mm)

Assembly

1. Print the fit test first (fit coupon + 1 knob + 1 pad, about 2 h 40 m and 44 g). The key should slide into both coupon sockets by hand, and the M6 nut should slide into its slot.

2. Knob: press the M8x50 bolt head into the knob pocket. Use a vise or a firm push; add a drop of CA glue if it is loose.

3. Clamp nut: slide the M8 nut into the side slot in the lower jaw.

4. Screw: thread the bolt up through the lower jaw from below, then press the pad onto the bolt tip. The crush ribs lock it on, so the pad turns with the bolt (it is not a swivel). Add felt to its face, or print it in TPU, to protect the desk.

5. Accessory nut: slide the M6 nut into the side slot in the clamp spine.

6. Mount the accessory: put the hex key into the socket on the front of the clamp, push the accessory's back socket onto the key at the angle you want (60° steps), and drive the M6x30 from the front of the accessory into the nut until snug.

7. Clamp it on: hook the top jaw over the desk edge and tighten the knob by hand. Do not use a wrench.

Keyboard cradle: it hangs a full-size keyboard (up to 440 × 135 × 40 mm) on its long edge, about 165 mm below the desk top. Mount it on a side edge of the desk if it would hit your knees at the front.

Loads (design estimates, not tested)

• Headphone hook: about 2 kg at the tip

• Cable tray: about 2 kg spread out (keep heavy bricks near the back)

• Keyboard cradle: about 1.5 kg

These are design estimates, not test results. No part has been load-tested yet.

Customising

Open clampwright.scad in OpenSCAD. Desk range, tray length, keyboard slot and fit clearance (fit_clr, 0.25 mm per side) are at the top of the file. If the key is tight in the coupon, try fit_clr = 0.3; if it rattles, 0.2.

License

CC BY-NC 4.0, see LICENSE.txt. Remixes welcome; please credit PtDesigns and keep them non-commercial.