Tool Cool inside mics

I've never seen inside mics like this. Can't vouch for them, but wondering what others think.

6-100mm High-Precision Electronic Digital Display Three-Claw Three-Point Inner Diameter Micrometer Bearing Inner Hole Measuring - AliExpress 1420

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[Bandit]

Not sure what to think of that style. It appears from the picture that all 3 claws/feet are the same length. I don't think they will measure a dip/dent or other problem in a bore as the foot will bridge over it. The bore gages I have used in the past while having 3 feet, have the movable one much smaller, so it can at least not ride over most scores/dents etc.
They would likely be better then a nail and a wedge though. Mind you the nail and wedge does not need batteries.

 

[Susquatch]

I don't think they will measure a dip/dent or other problem in a bore as the foot will bridge over it.

I think they are mainly for nominal measurements and it would be difficult to use them to identify and measure anomalies.

 

[TorontoBuilder]

very pricey for my budget.

I see analog old school used mics of same or similar style for a lot less at auction frequently. I keep meaning to buy a set because 3 points of contact is better than two.

 

[Susquatch]

I see analog old school used mics of same or similar style for a lot less at auction frequently.

I've never even seen them before. I have and I use the 2 point type. But I'd rather have 3 point.

 

[Chip Maker]

A cylindrical grinder operator I worked with used them (analog type) in one shop I worked at to measure the bore holes for guide pins and bushings in die sets that we manufactured. Worked great for that application.

 

[OliverTO]

They work well for their intended purpose. The downside is cost, they are very expensive and have a small diameter range, therefore you need to have many different ones to cover a wide range of hole sizes. If you are doing production jobs where you are measuring one hole size all day the cost could be justified.

 

[Mcgyver]

I've a bunch of Tesas like that, analogue not digital. We all know to read mics, but the digital would be nice as you could calibrate to a close to size setting ring for super accurate work. All three legs move and you engage a lot of the bore. If you goal is detecting irregularities, stick with a dial bore gauge. The Tesa's are very accurate and nice to use. You need a lot though as each has a small measuring range.

I've also a bunch the Mitutoyo digital ones, borematics (name always reminded me of Dan Akryods old SNL skit, the Bass-o-matic). Uber expensive and quite accurate, all three legs move out radially. They are spring loaded with a lever to actuate (vs a micrometer barrel) so are kind of fool proof. Don't use them as much as I'd like as I'm missing a few setting rings. Short of a high end CMM, they are nicest way to measure a bore imo.

 

[Susquatch]

reminded me of Dan Akryods old SNL skit, the Bass-o-matic

That was super funny and worth the watch. You are a bad influence!