ChgImposs 12" Adjustable Sliding Combination Square Ruler & Protractor Level Measure Measuring Set, Inch/Metric

First impressions and what’s in the set

This combination square set gives you a 12-inch stainless steel rule paired with three heads: a square head with a level and a self-storing scribe, a center head for finding pipe and round stock centers, and a protractor head with a double 0–180° scale. The rule is graduated in inch and metric, which is handy if you bounce between plans and suppliers. Out of the box, it’s clearly a budget-friendly kit: light cast heads, a laser-etched rule, and small knurled thumbscrews. Mine arrived without instructions or a case, so you’ll be relying on your own know-how and whatever storage solution you concoct.

That said, the set covers a lot of ground for layout work: checking 90° and 45°, setting saw blade heights and fence offsets, laying out mortises and tenons, transferring measurements, finding centers, and rough angle setting with the protractor. There are also horizontal and plumb vials across the heads if you need a quick bubble check.

Build and features

• Rule: The 12-inch stainless blade has inch graduations on one side and metric on the other. The inch side on my sample carries 1/8 and 1/16 divisions, but no 1/32s, which limits fine layout. The metric side is in millimeters. The etching is crisp enough, but contrast is low on certain lighting angles; blackening the graduations with a Sharpie and wiping the surface improves readability.

• Square head: The casting is straight and flat enough for woodworking duties. There’s a slot for the rule, a horizontal level vial, and a threaded hole that stores a small scribe. The scribe is an emergency-use accessory—fine for marking softwoods or sheet goods but not a replacement for a dedicated knife.

• Protractor head: The direct-reading, double 180° scale lets you measure and set acute and obtuse angles without flipping the head. The scale marks are very small. On bright benches or with aging eyes, a raking light and a fine mechanical pencil to highlight the setting line help. Lockup on mine required firm finger torque to prevent creep.

• Center head: Simple and useful for splitting round stock. For wood dowels, small pipes, and turning blanks, it does the job.

The locking screws are on the small side. If you have larger hands, expect to pinch harder than you’d like to keep things from sliding.

Setup and calibration

Before putting it to work, I did a quick tune:

1. Deburred the blade ends with a fine file to remove sharp edges and tiny burrs.
2. Wiped all sliding faces and the rule with mineral spirits to remove machining residue, then added a drop of light oil.
3. Performed a flip test on the square head: draw a line, flip the square, and draw again. Lines were essentially coincident, with only a hairline divergence over 10 inches—well within tolerance for general woodworking.
4. Checked the 45° using the same method with a verified triangle.
5. Verified the protractor’s 0° and 45° against a digital angle gauge. It was acceptably close at 0° and off by roughly half a degree at 45° until I learned how to properly tension the lock screw.

One quirk: if you fully remove the blade from a head, the spring and adjustment screw can drop out. Keep a shallow tray on the bench when reconfiguring heads, and consider threading the screw a turn or two into unused heads for safekeeping.

Accuracy and repeatability

For square and 45°, the set is accurate enough for cabinetry, home projects, and machine setup on table saws, miter saws, and drill presses. The square registered well across multiple flip tests after tuning. Repeatability is decent as long as the threads and the rule are kept clean and lightly oiled.

The protractor is the weak link. The scale is tiny, the pointer is not ultra-fine, and the lock needs a strong turn to minimize drift. For rough angle layout—say 30°, 45°, 60°—it’s fine. For precision joinery or machine setup where half a degree matters, I’d reach for a digital angle gauge or a higher-grade bevel protractor.

The bubble vials are “good enough.” They’re useful for quick checks, but I wouldn’t use them to set anything critical.

Day-to-day usability

In use, the rule slides with a little grit until you clean and oil it; after that it moves smoothly. The square head’s bearing on the rule is even, though you can feel some slop if you barely snug the screw—tighten properly and it holds. The scribe is convenient but small; I ended up continuing with my marking knife for fine lines.

On the metric side, I appreciated having millimeters for hardware spacing and Euro-style layouts. On the imperial side, the lack of 1/32 divisions slowed me a bit on detailed work. You can work around it, but if you routinely lay out to 1/32, this limitation is noticeable.

As a depth and height gauge, it works well. I used it to set a router bit height and a table saw blade to a repeatable 3/8 inch, and it held the setting when I rechecked. For fence offsets, the square head makes it easy to reference off the table and register an accurate distance.

Durability and materials

The rule is stainless and resists rust; mine shrugged off a week in a humid shop with only fingerprints to wipe away. The heads appear to be zinc alloy castings with painted or powder-coated finishes. They’ll survive normal use, but they’re not the kind of heavy, finely ground steel you get on premium sets.

Over a few weeks, the edges of the heads stayed true and the rule’s markings didn’t fade. The thumbscrews, however, are small and the threads feel a little coarse. Expect to snug them firmly for consistent lockup.

No case is provided. I built a simple plywood tray with slots for each head and a recess for the rule; it’s worth the 20-minute shop project to keep everything together and to avoid losing that spring and screw.

What it’s good for

• General woodworking layout: squaring edges, marking 45°, transferring measurements.
• Machine setup: checking blade tilt, setting fence offsets, verifying drill press table square.
• Centering on dowels and pipes with the center head.
• Light metal and 3D printing projects where you need quick measurements and angles but not machinist-level precision.
• Mixed-unit environments: having inch and metric on one tool is convenient.

Where it falls short

• Protractor readability and lockup leave something to be desired for fine angle work.
• Inch rule lacks 1/32 graduations.
• Locking hardware is small and requires firm torque.
• Components can fall out if you remove the blade completely; no storage case or instructions.

Tips to get the most from it

• Clean and lightly oil the rule and contact faces before first use.
• Deburr the rule ends to prevent scratches and improve seating.
• Blacken the graduations and protractor pointer line with a fine marker to boost contrast.
• Use a tray or DIY case to keep the spring/screw from wandering when swapping heads.
• For angles tighter than a degree, verify with a digital gauge or a higher-precision tool.

Alternatives

If you need tighter tolerances, heavier castings, and silky slides, there are professional-grade combination squares from the likes of Starrett and Mitutoyo that cost an order of magnitude more. Mid-tier options from iGaging and PEC offer a nice bump in quality without going all the way to premium prices. If you mainly need a square, a single high-quality 12-inch combo square may serve you better than a full three-head set at this price point.

Recommendation

I recommend this combination square set for beginners, casual woodworkers, and anyone who needs an affordable, all-in-one layout tool for general shop work. It covers the basics well—90°, 45°, depth/height gauging, and centering—and the stainless rule with inch/metric graduations is genuinely useful day to day. Expect to do a bit of setup, be mindful of the small hardware, and accept that the protractor is a coarse instrument here. If you need precise, repeatable angle settings, higher-contrast scales, and dead-solid lockup for constant professional use, step up to a mid-tier or premium set. For the price-conscious user who understands its limits, this one earns its keep.