Harbor Freight Digital Micrometer

[Charley Davidson]

I think we are talking about different numbers. The micrometers we bought measure only to 4 decimal points not five but probably still okay for what we plan to do.

I went back and looked at the earlier posts that Charley and I made and Charley got the decimal pont in the wrong place in his number and I have a error in the second standard I listed. That standard should be 0.250 not 0.0250. I will edit my post to correct my error if system allows. Charley's number should be 0.0001 not .00001, don't think I can change his.


Sorry for the confusion.
Benny

Benny, check again, they do go to 5 decimal points. Now you have to edit your edit and retract your retraction:lmao:

 

[Charley Davidson]

To avoid confusing me how about going metric and there should be 3 digits after the decimal point if it is the accurate micrometer I think it is

It should read in 0.001mm. or 1µm (which is the same).

It does

3 digits past the . in metric 5 in inches have it in my hand right now

 

[jgedde]

Very likely both those micrometers are far more than adequately accurate for anything that might come along. If all you guys saw was a 0.00001 difference, that's outstanding and nothing to worry about. Plus point is well taken about reading the basic markings, much less the vernier scale. I'm all with you on that.

I think the right n mber was 0.0001 not 0.00001. The latter has to be a mistype. The HF mic only reads (resolves) to 0.00005... In other words, 4 1/2 digits. For 10 millionths I agree with your statements on temperature, but not for 0.0001 unless the temps are dramatically different then what the instruments were calibrated at.

John

 

[jgedde]

Quite impressive for the money, I think Benny's checked out dead nuts & mine was dead nuts to .00001 :thumbzup:

I had decided to pass on this deal last night after Benny said he didn't think he was gonna go along, But at 8:AM sharp my phone rings and it's Benny saying he want's to go get one of these so I reluctantly agreed to go along and do a sympathy buy to keep him from feeling all alone in this. Tomorrows a new day.

He clearly meant 0.0001. The mic doesn't read to 0.00001...

John

 

[Tony Wells]

Per the manual for the instrument:

7. This Micrometer measures items in hundred thousandths of an Inch.

That statement should be taken to mean "able to read in 10 millionths increments", not the typical half-tenths (50 millionths) you get with a 4 1/2 digit readout. Of course, it may well be that the instrument is truly a 4 1/2 digit display. I would guess that it is just that. Otherwise, my concern about accuracy stands.

John, I would tend to agree that under normal ambient conditions, a micrometer and a standard or gage block would need to be several degrees apart to cause any issues in the +/- 0.0001 range. The materials of choice for those items are chosen partially for their temperature stability over the normal range seen during use. The CoE is quite similar. I was only giving the guys something to think about, perhaps for next time and for their edification.

 

[Tony Wells]

42 i hope you don't take this as too personal or negative but you remind me of those that taught metrology back when I knew a lot less than I do now. You manage to express and turn what are in fact non complicated issues into a paper fit for a master's degree.

This is after all a forum for those working with machines and checking/measuring what they make from a hobbyist's perspective. From what I read the vast majority are both knowlegable at what they do and have the common sense to do what is right.

Well, it is a remark of a personal nature, isn't it? However, I am not insulted or bothered in the least by it. It is simply my style to strive for technical accuracy when I write something on the Internet (or elsewhere) that may be read by those perhaps less informed or experienced than I. I am also aware that the majority of the members here are knowledgeable, and yet at the same time, many are beginners.

And the drivel I write here most certainly would not pass for a Masters thesis, but thanks anyway.

A suggestion. Why not start a thread with the title "the theoretical side of Metrology". It would prove interesting (at least to me) as there are a couple of things you have written that I don't agree with. The only reason I haven't stated what they are in a current thread is so as not to off track the thread/theards in question completely.

I will not do a thread on this forum that addresses the Theoretical Metrology for the same reason you stated as the reason I shouldn't write the way I do: This is a Hobby Machinist Forum. I'm sure it would bore most of the members anyway, and fail to be pertinent to their machining activities.

It almost certanly isn't your intention but I feel that I'm being spoken down to when I read much of what you write.

Gordon

Gordon, that is absolutely the last thing I want to do, or even give the impression of doing to you or anyone else. I have respect for my fellow man. Especially so for those who would take up machining for a pastime. Most people who do it for a living too, for that matter. There is so much talent on this forum, and many others, that I that look up to my fellow members, never down. I sincerely apologize if you feel slighted or insulted. It is not intended at all.

Re your first sentence - does the micrometer really come with a manual? Stating what you write after 7. then I can only say that any manual having something like that in it would be a first for me.

It may not come with a printed manual, but the website HF markets the instrument on has a download of it, and I was merely quoting from it. I did not feel it necessary to paste in the entire section I quoted. Like so many things though, I have my doubts about the veracity of the statement.

 

[Tony Wells]

Not to worry, Gordon old bean.....I did not take it too personally!

 

[AR1911]

I got one of these for Father's Day. Sat down and fiddled with it last night.
Mine will not change to inches, it's stuck on metric.
So I'll be exchanging it pretty soon.

 

[Video_man]

I got one of these for Father's Day. Sat down and fiddled with it last night.
Mine will not change to inches, it's stuck on metric.
So I'll be exchanging it pretty soon.

Mine requires holding the inch/metric button for about 5 seconds before it makes the change, which is probably a feature and not a defect. Same for the zero setting. On/off = quick push, zero = long push, abs/inc=short push, inch/metric = long push....hope it's working for you, I really like this mike...

 

[AR1911]

That was probably the only combination I did not try.
thanks for the tip