Perfect 90° Joints Without the Readjusting
Keep corners square, joints tight, and pieces exactly where you want them for boxes, drawers, cabinets, and frames.
Precision Clamping Squares
One-piece CNC billet aluminium · 90.00° verified per unit to ±0.025° · Takes stock up to 2"
In stock — ships within 24H
FREE SHIPPING OVER $50
60-DAY WORKSHOP TRIAL
2-YEAR WARRANTY
Precision Clamping Squares
The Principle
Your 90° Reference
A true 90° starts with a reference you can trust. Place the square against your workpiece to instantly establish a right angle — whether you’re checking a corner, positioning a panel, or setting up your next cut.
And when it’s time to assemble, that same 90° reference becomes your clamping guide, holding both pieces square while you glue, drill, or fasten.
Workflow
Three moves. One hand.
Set the corner, tighten the grip knob, and the square holds both pieces securely at 90°. Now your hands are free to drill and fasten without holding the panels in position yourself.
- 01 Position the square against both pieces to establish a 90° corner
- 02 Insert the hook and hand-tighten the grip knob to lock everything in place
- 03 Drill or drive your fasteners while the square holds the joint for you
Applications
Anywhere two panels meet at 90°
Comparison
Against what's already on your bench
An honest look. Every one of these will get you to square eventually. The question is how many hands it takes, and whether you find out too late.
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| Criteria | TURSTEIN CS90 | Plastic corner clamps | Framing square + bar clamps | Shop-made ply jig |
|---|---|---|---|---|
| Solid Machined Construction | One-piece CNC billet | Moulded plastic, flexes | Stamped steel | Plywood — as square as the saw that cut it |
| True 90° Reference | ±0.025°, every unit | Not specified | Square only while nothing moves | Only on the day you made it |
| Hands-Free While Fastening | Yes — hands-free | Yes | Slips under load | Yes, on inside corners |
| Inside + Outside Clamping | Both | Outside only | Depends on reach | Inside, realistically |
On shop-made jigs: they work, and we make them too. Inside a corner you've got a long diagonal and room for a gusset, and a plywood jig does the job well. Outside is where it falls down — the jig has to be massive not to flex, cutting a true 90° into ply is harder than it looks, and correcting one later is harder still. That's the gap the CS90 fills.
90.00°
Squareness — verified per unit
±0.025°
Max. deviation, one-piece CNC
2inch
Panel capacity
1hand
To place, square and clamp
Why it's true
Accuracy you can hang a cabinet on
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01 — ONE PIECE
Milled, not assembled
Each square is CNC-machined from a single billet. No welds, no rivets, no joints that work loose. The 90° is cut into the metal itself, not set by an assembly step that can drift.
02 — MEASURED
Every unit, before it ships
Before anodising, every square goes onto a granite surface plate and is measured against a certified master. Outside ±0.025° and it goes back to the mill, not into a box. Over a 120mm leg, that tolerance is about five hundredths of a millimetre at the tip — ten times finer than a pencil line.
03 — HOOKS
No play in the slot
The hooks seat in machined slots with no wiggle. Nothing to shim, nothing to take up, nothing that shifts when you lean on the work.
ENGINEERED FOR PRECISION
Machined to Stay True
Each square is precision-machined from solid aluminum to create a rigid 90° reference you can rely on build after build.
The anodized finish adds a hard, wear-resistant surface made for real workshop use — while Turstein red makes the square easy to spot on a crowded bench.
100%
Units measured
HV 400
Anodised surface hardness
2 yr
Warranty, no receipts needed
Reviews
4.8
5★
319
4★
33
3★
9
2★
4
1★
2
Swipe for more reviews
★★★★★
Dead-on square, big cabinet, no helper
Assembled a large pantry cabinet solo yesterday. Four squares held the carcass while I drove screws — checked the diagonals afterwards and they matched to the millimetre.
James D.— Austin, TX
Project: pantry cabinet, birch ply
Verified purchase
Project: pantry cabinet, birch ply
Verified purchase
★★★★★
Checked them against my engineer's square
Put them against a certified reference out of habit — no light gap I could detect. The hooks are the real trick: drop, twist, done, one hand the whole time.
Maria K.— Denver, CO
Project: drawer banks, oak
Verified purchase
Project: drawer banks, oak
Verified purchase
★★★★★
Great on wood, good on steel too
Bought them for casework, ended up using them to tack-weld a bracket frame — the anodising shrugged off the spatter.
Ryan H.— Portland, OR
Project: welded frame + casework
Verified purchase
Project: welded frame + casework
Verified purchase
The Turstein Standard
Put It to Work. If It’s Not for You, Send It Back
Don’t judge it on the workbench — judge it on your next build. Use it for boxes, drawers, cabinets, and glue-ups. If it doesn’t make assembly easier, you’re covered
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Trial
60-day workshop trial
Use it on real projects, not just out of the box. If it hasn’t earned a permanent place in your shop within 60 days, send it back.
Warranty
2-year warranty
Built for repeated shop use and backed for two years. If something goes wrong with the tool under normal use, we’ll make it right.
Questions
Before you buy.
Every square is machined to 90.00° and measured before it ships, on a granite surface plate against a certified master. Maximum permitted deviation is ±0.025° — about five hundredths of a millimetre at the tip of a 120mm leg, roughly ten times finer than a pencil line. Anything outside that goes back to the mill.
Anything up to 2" (50mm). Below that, seat the hook in whichever slot gives you the most reach — the two furthest apart give the longest reference and the firmest hold.
The square itself is one piece and doesn't. On long stock, use the two outermost slots for the longest reference, and put a square at each end rather than one in the middle. Over about a metre, two squares will always beat one.
Yes — weld tables, box section, light fabrication. The anodised surface doesn't react with flux or glue. Keep them clear of direct weld heat; sustained heat will take the edge off any precision tool.
No. The squares and hooks are in the box and everything hand-tightens. No bar clamps to add, and no framing square to double-check with afterwards.
No. Hard anodising isn't paint — it's an oxide layer grown into the aluminium at around HV 400. It can't chip, flake or transfer, and it doesn't react with PVA or polyurethane.
Both. There's a relief cut at the inside corner so it won't bind on stock that's slightly out of square — it seats clean either way round.
Yes. Every kit uses the same CS90 held to the same ±0.025°. Buy one set now and add more later; they'll reference to each other.
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