We’ve updated our desktop frame-building jig.
New rear supports and MDF locking keys, in a simple flat-pack setup that holds your frame while you build. Watch the animated overview, then explore the drawings and assembly guide.
We’ve updated our desktop bicycle frame jig with revised rear supports and a simple MDF locking system. The original five-holder setup stays familiar; the changes are in the way the rear shelves are supported and the parts lock together.
The jig has a vital job during a build: it holds the frame’s separate tubes and fittings in position while you fit and join them. It gives you a set of reference points to work around and check.
Our approach keeps the setup simple and low-cost by design. The jig parts fit on two sheets of nominal 3 mm MDF. With a checked full-size frame drawing, tape and a suitable flat worktop, you can create a build space at home, in a classroom or in a workshop. The parts pack flat afterwards.
See the updated system in motion.
This 27-second animation shows the actual CAD: the new rear supports and locking keys, the frame locating points, and the flat MDF parts. The frame tubes are an illustrative example.
Open the short jig animation. The complete step-by-step assembly film and guide are below.
Why use a jig?
The position of each part contributes to the frame’s geometry. The head tube and seat tube need the intended angles. The rear axle needs the right position and spacing. The frame also needs to stay centred from side to side.
A jig helps keep these relationships in place while you work. It gives you something to measure against and frees your hands to fit the tubes. Setting up and checking the jig is still part of the job: it holds the geometry you give it.
How our MDF jig works.
Our original setup uses five separate holders: two for the head tube, one for the seat tube, one for the bottom bracket and one for the rear dropouts. The dropouts are the fittings that locate the rear wheel axle.
A checked, full-size frame drawing sets the positions and angles. You place the holders on that drawing, check their alignment and tape their bases to a flat worktop. The locating inserts and rear supports hold the frame parts at the required height above the drawing.
This makes the setup visible. You can follow the tube lines on the plan and see how each holder relates to the frame you are building. It is a useful way to explain frame geometry as well as hold the parts.
Why this can be a low-cost solution.
The construction keeps the material and hardware requirements modest:
- Two sheets of MDF. The current layout fits on two 600 × 300 mm sheets of nominal 3 mm MDF for our xTool P2S with slats.
- Flat parts, assembled into supports. The laser cuts profiles that slot together to form the holders.
- Wooden fixings. Slots, posts and locking keys hold the jig together without glue in its joints or metal jig fasteners.
- An existing work surface. A suitable flat worktop supports the holders, with tape securing their bases to the drawing positions.
These are the design choices behind the low-cost approach. The finished cost still depends on the board, laser access, cutting time and preparation; we are not quoting a fixed price here. The bicycle’s own metal dropouts and tube fittings remain part of the bicycle.
The benefit for a home build or teaching session is straightforward: a small set of flat parts can provide the locating points needed to understand and set up the frame. Accurate assembly, a flat surface and alignment checks remain essential.
What we have improved.
Our latest redevelopment keeps the original five-holder arrangement. It focuses on the details that make it easier to assemble, locate and check. Updated 19 October 2026: the drawings, guide and films show revision O4.
The rear holder has cross ribs with positive seats, revised shelf supports and wooden locks. These changes are intended to reduce unwanted movement. The assembly sequence keeps the lower fixings accessible: the posts, metal dropout parts and locking keys go in before the base.
The rear setup also shows why small details matter. Each 6 mm metal dropout plate sits flat against its 6 mm insert, making a 12 mm pair. Both inserts face into the wheel gap. For this configuration, the 135 mm spacing is measured between the inward insert faces where the hub makes contact; the MDF shelf pitch is 147 mm.
Locating the axle is only part of the setup. The toothed arms of the dropouts must also follow the chainstay and seatstay lines on the frame drawing.
The guide separates the locating-insert choices: 27.2 mm and 31.6 mm seat-tube bores, a 68 mm BSA bottom-bracket shell, and the different head-tube interfaces. A straight 44 mm bore and an integrated tapered bearing seat need different checks against the actual tube.
Retaining bridges keep pieces attached to the cutting sheets until release. The illustrated instructions are now eight pages, grouped by holder, with numbered drawings and direction arrows.
Inspect the technical drawings.
The two-page drawing sheet shows the rear holder from three directions, the 135 mm hub-contact gap, and the five holders on an example frame layout. The views come from the current CAD. Enlarge them to inspect the joints, supports and locating parts.
Download the two-page technical drawing sheet (PDF). This is an explanatory supplement to the assembly guide below, not a cutting file or a manufacturing release.
Read the illustrated assembly guide.
Follow the build with numbered line drawings, exploded views and direction arrows. The compact guide covers the rear holder, tube insert choices and placing the five holders on your frame plan.
Download the eight-page O4 assembly guide (PDF).
Watch the updated assembly film.
The complete illustrated walkthrough is below in two parts. It follows the O4 eight-page guide, from releasing the pieces through to placing the holders on a checked frame drawing. Pause whenever you need to inspect a step. The images are CAD illustrations of the setup.
Part 1 — preparation and the rear holder.
4 min 28 sec. Release and sort the pieces, build the rear support and fit the flat metal pairs.
Part 2 — tube holders and frame setup.
7 min 26 sec. Select the tube inserts, assemble the remaining holders and place the jig on the frame plan.
Simple construction, careful checking.
An earlier version has been tested and reported to work. The latest CAD has been checked with an illustrative frame, but the O4 rear parts still need a physical fit and loaded-alignment trial. Board thickness, laser kerf, joint grip and retaining-bridge release also need checking before a repeat production run.
The aim is an accessible jig that helps a builder understand where the frame parts belong and hold them there while working. The drawing establishes the geometry; the jig supports the build; the builder checks the result.
Explore our bamboo bicycle frame-building kits to see the wider home-build approach.
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