Woodworking Gap Gauge

This is a very useful and versatile woodworking tool. I use it for many gap-measuring applications such as measuring the width of a mortise and then using the other side to fine-tune the tenon. Same for dadoes and lots of other applications where you need to lock-in an inside/outside dimension and then compare it to the other mating piece(s), saw blade location, etc. This is a real time-saver for large-scale, repetitive operations where it's impractical to use the mating piece for test fits.
The accuracy is fairly good but not super-precise. As you can see in the photos I posted, I set it to one inch and locked it down tight. I then compared the inside and outside dimensions using a dial caliper. The outside dimension was .004" long, and the inside dimension was .004" short. So the two sides are "off" by .008 inches, even if I precisely set one side at exactly 1 inch, i.e. without using the arrow scale. Granted that's a small amount for some applications but still a little disappointing.
The tool is well made from what appears to be anodized aluminum. Everything is smooth and consistent. The sliding mechanism and lock screw work quite well, though I had to add a small amount of machine oil. It's scaled in both inches and millimeters. There are a few strange elements that I don't understand, like the two arms on the inside dimension side are different heights. There's also a 20mm groove on that side that doesn't serve any purpose that I can tell.
Overall, this is definitely a useful gadget to have around the workshop. It's well made and should be quite durable over time. I thought the accuracy was a slight disappointment. But with some extremely careful filing, I might be able to tune that in a little closer.

This is a bit challenging to review. When I received the gauge, I was not able to loosen the adjustment knob by hand. My initial guess was that the knob was just tightened too much during final assembly, so I used pliers to loosen and remove the knob. Then I could tell that the adjustment screw had been cross-threaded into the tool body during assembly.
I checked the thread pitch and used an M6/1.0 tap and tie to clean up the threads. It wasn’t a difficult fix, but the manufacturer should be more careful. Not everyone has a tap and die set handy.
For this review, I'll assume that the assembly defect with the one I got is not typical.
It was a bit difficult to determine from the ad exactly what this tool is used for. The tool consists of two body parts (anodized aluminum, I think) and a knob that will tighten the two parts together. The two body parts are "L" shaped, and the scale shows the distance between the outside edges of the feet. The distance on the scale is also the size of the gap between the body parts. So you can use this gauge to measure outside distance or inside distance, and you can use the tool to transfer an outside measurement to an inside measurement and vice versa.
One side is marked in 1/16" increments; the other side is marked in millimeters.
The markings are very accurate, and at a given setting, distance between the body parts and the outside of the "feet" is the same. (Measured with a caliper, no more than 1/128" variation.) The thickness of the feet establishes the lower limit of the tool's range. Measuring range is about 13/64" to 2".
As an example, you might use this gauge to capture the thickness of a board and compare that with the inside width of a dado.
A nice improvement would be to add a vernier scale.
In any case, this is a well-made, accurate, useful and reasonably priced tool. I deducted a point for the careless final assembly, but I like this tool quite a lot.

This measuring tool is solidly made of aluminum. The measurement scales appear to be printed on the surface and are visible. The maximum measurement possible using the slider is about 1 1/8th of an inch or about 27mm. The gauge can be tightened so as to retain the measurement obtained. It is a simple but useful measurement tool.

there is lots of these on the market which range in price greatly, like 4x
the value of this tool is, you can get a measurement from one end, either recessed or outside, see pix
and then transfer that measurement, i.e. without reading scales... the two sides are always the same..
the alum makes the tool durable, and repeatable...

This is a really well-thought out functional piece. It will work for my needs and I can see that using this will make my projects go a bit easier.
Like some other reviewers, the knob was very tight. I did finally get it loosened, and thankfully my threads were fine. After checking for damage or burrs, I was able to add some oil and get it nicely loosened up-- but I'm still able to tighten it now, and untighten smoothly.
Mine is accurate, as checked with a caliper. Recommended addition to the toolset.

DIYer has lots of devices for measuring when he does his many project including wood working. Each device has their own benefits depending on the where and how a measurement needs to be taken. He found this depth line ruler came in handy because it is compact, easy to use and required minimum fuss to set up. He found it great when he was making some cabinet drawers and doors. It is lightweight and had measurements it both inches and centimeters.

Sliding motion could be a little smoother. Itherwise, It’s a good buy for the price. Especially with the “name brand” items being 3-4 times as much money. Bought for the purpose of sizing mortise and tenon joints. Haven’t used it yet but looks good.