I’ve been thinking about my machining accuracy and asking myself the question: “Do I need a Digital Micrometer?”. So I thought I would discuss it here and see whether I can logically work it through.
Why do I think I need a digital micrometer?
In my normal machining I use a digital caliper, actually I use around 3 digital calipers depending on where I’m sat and what I’m making. That might be a problem in it’s own right, but maybe for another day.
Digital calipers have a number of advantages:
- easy to use
- read in metric and imperial
- versatile measurements: inside, outside, depth
- happily measure from 0.01 to 150mm
However, the issue I have is when I’m machining an axle or crankshaft to fit a reamed hole it’s just about ok. Adding quite a bit of judgement to get a great fit.
I end up around +/-0.025mm, ok, but could do better.
A Moore and Wright manual metric micrometer from 1984 (this was an 18th birthday present from Mum and Dad). Still pristine as I’ve not used it that much.
This really is able to measure to 0.01mm and the divisions are such that you can actually read to +/-0.005mm.
This is a significant move on from the digital caliper and as such I’m wondering why it resides in a drawer.
The downside is you have to take your time reading it and you can read outside dimensions. I could rectify that and buy an inside micrometer.
Most digital micrometers can read down to 0.001mm, but the real benefit is they are easy to read. Does this help me? Sometimes what I actually need to do is take my time. A high accuracy digital micrometer will read 0.0001mm. This is probably beyond what I need for my model making and beyond what I can machine to.
I’m going to try my manual micrometer and see how this improves my ability to machine axles to the right size. Then I can decide if I really need a digital micrometer or just to take my time and measure parts correctly.
- RS A complete Guide to Micrometers – describes the different micrometers and introduces their use.