Do I need a Digital Micrometer?

Moore & Wright Micrometer

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

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.

Manual Micrometer

adjustment of manual micrometer

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.

Digital 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.

Conclusion

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.

References

About Nigel 384 Articles
I've been making models since I was around 7 years old and using a lathe from the age of 11, a self taught engineer with a passion for making model engines.

2 Comments

  1. I find I’m very slow at reading a mic and get very similar results using a digital caliper. I just find the markings a bit vauge. However I do persevere when its a critical part, even if I then back up my findings with the digital caliper!

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