Original MIDI size 3D Assembly Square

£80.00

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Taxes included. Shipping calculated at checkout.

Material High Density Moisture Resistant MDF Dark Grey Valchromat

Free UK deliveryUsually sent within 5 working days, then 2 to 5 working days in the post. US delivery is free on bundles.
14 days to return itUnused and in its original packaging. You pay the return postage.
Manufactured in SheffieldCNC cut from 12 mm board in our own workshop, where we use them daily.

In the box: 1 Midi square, 203 mm high. Flat packed with screws and a postcard with QR code links to the assembly videos. Clamps are not included. You will need a drill and a 2.5 mm or 3 mm bit to pilot the screw holes after push fitting the parts together.

Make square assembly fast, accurate, and stress-free.

Designed and used daily in our professional furniture workshop, this British-made jig is a proven game-changer for building bookcases, cabinets, kitchen units and more.

IMPORTANT: After initial push-fit assembly, all screw holes must be piloted to the full depth of the screw using a 2.5mm or 3mm diameter drill bit (not included).

Why it works

Holds parts perfectly square in 3 dimensions for precise screw-fastening.
Eliminates marking out, dominos, Lamello, or complicated joint prep.
Saves time and increases accuracy whether you’re a DIYer or trade professional.
Unique corner design gives clear visibility for lining up edges and marking reference lines.
Works seamlessly with Festool, Makita-style rail clamps, and most Irwin clamps.

Latest Upgrades

Extra clamping slots for upside-down benchtop use.
Re-shaped mid braces for easier assembly.
Clean, flat side surfaces (no recessed logo).

Perfect for DIY & Trade

DIY: Makes tough jobs simple with minimal tools.

Trade: Boosts efficiency and profit both in the workshop and on-site.

Workshop-Tested

At Freebird Interiors, we've used this jig concept for many years before refining and improving it for CNC production and sale to you.

We still regularly use this jig in our 2600 sq ft Sheffield workshop, alongside CNC, Lamello, Festool and Mafell tool systems - because sometimes, this simple tool is still the most efficient solution.

Specifications

Materials: CNC-machined in 12 mm thick Grey Valchromat®, a high-performance, colour-throughout fibreboard; or the more traditional and similarly dense MR MDF. Both are stronger, denser, and more durable than typical MDF; smoother and flatter than birch plywood.

Dimensions: Height 203mm max (191mm under lip). Top lip overhang: 18 mm, Top plate width: 210 mm (both sides), Body width: 192 mm (fits between shelf gaps just under 200 mm).

Packaging: Delivered flat-pack with screws included. (Clamps not included.)

IMPORTANT: After initial push-fit assembly, all screw holes must be piloted to the full depth of the screw using a 2.5mm or 3mm diameter drill bit (not included).

Assembly and instructions

Your order includes a postcard with QR code links to the instructional videos. The same videos are linked below.

Instructional videos (assembly and full build guides) are included via the QR code provided with the product, or online:

Drilling straight through a clamped corner with a Midi square holding the joint — Clamp, pilot, then drive the screws straight through from the outside.

Clamps that fit

All common styles of rail clamp, including Festool, Makita and DeWalt, plus most Irwin clamps. The Mini square does not take the mini Irwin types. Clamps are not included.

A rack of different rail clamps that all work with the 3D Assembly Square — The clamp styles we use with the squares in our own workshop.

Material choice

Both are 12 mm boards, CNC cut, and denser than standard MDF. Grey Valchromat is coloured all the way through and is the material we recommend. Moisture resistant MDF costs less and holds square just as well.

Delivery and lead times

UK: free delivery on every square and bundle. 2 to 5 working days after dispatch. Highlands and islands can take longer.

USA: free delivery on all bundles. Single squares are $30 on orders below $130. 3 to 14 working days after dispatch.

Orders are usually processed within 5 working days, excluding weekends and public holidays. If your order has not arrived within 14 days, please contact us. Full details are in our Shipping policy.

Returns

Tell us within 14 days of delivery if you want to return an order. Items need to be unused and in their original packaging. You pay the return postage. If anything arrives damaged or wrong, send us a photo and we will put it right.

See our Refund policy for the full terms.

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