New starrett problem

Nagel Precision · Nov 4, 2022

Hope this is in the right place.
I Recently bought a new 4/5 456.1 Starrett
.0001 resolution micrometer as I'm doing more and more tight tolerance finish work.
The mic is smooth until first contact.
Where it locks up before squaring up.
Messing with my touch.
If you pull up on the spindle locks up.
Thinking thread issue on body or spindle
It measures accurately against the company mic and standard.
Don't trust it yet.
Back grond have starret .001 resolution to 20 inch
1to 6 in .0001 resolution
All tge others are fine just this one...
30 years in the trade
Making turbine parts +/- .0004 tolerance
Any Ideas???

Conrad Hoffman · Nov 4, 2022

What's a 456? Can't find it in a search. You might check the parallelism of the anvils. It could have been dropped or something. We've got one Mitutoyo at work, out of several, that tends to lock up on parts. Not sure why, but it worked well when new, so something happened to it.

MCritchley · Nov 4, 2022

That is the wrong tool for sub thousandth work. Start with a dial snap gauge. You should also have a good way to check roundness that a two point measuring tool will not capture.

michiganbuck · Nov 4, 2022

I tend to feel-rub the part being measured, not trust the friction device that may or may not be exactly correct. I rarely trust a micrometer to be better than +- 0001.
Most seasoned guys feel they can read a .001 micrometer to .00025 but you can't ship a part on that reading alone.
But I do trust an indicating micrometer with a JoBlock and cotton gloves to .00005 and less.
Good chance a lock-up mic has a bug or miss-angle condition from a manufacturing error or an accident.

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michiganbuck · Nov 4, 2022

Actually seeing the price spread on eBay for a brand-new micrometer I suspect that there are counterfeit ones being made.

Kingbob · Nov 4, 2022

I recently bought a few new starrett tools and have not liked the feel of the threads. I took them down and cleaned and oiled them and it's a bit better, maybe just not "broke in" yet? I cleaned what looked like copper never seize out of them. I am sure you probably already did this just wanted to share so you knew it wasn't just you giving the hard eye to the new stuff.

michiganbuck · Nov 4, 2022

I have found when taking a Micrometer apart it is good to note the spool number where they come apart. Say they come apart on the nine, This is so you know where the thread end and start will be. So with knowing this one might set the thimble in at about 12 and know that at 9 the thread will engage.
This technique avoids accidentally jamming the thread.
I like to add a couple of drops of 3&1 oil.(20Wt spindle oil)

guythatbrews · Nov 4, 2022

Sounds like the anvils are not parallel or maybe not flat. Although I don't understand what you mean by "If you pull up on the spindle locks up."

If it's brand new I'd sure send it back.

michiganbuck · Nov 4, 2022

Another abuse is slamming the anvils at zero to test size..Much better to test with a JoBlock in the ballpark of where you intend to use it.

eKretz · Nov 11, 2022

When disassembling a mic I don't note the number where the spindle comes out, but I do use another method. When I go to place the spindle back in, I turn it in reverse until it jumps the first thread and drops into alignment with a small clunk. Then back forward again. That ensures a good start every time in my experience.

mjk · Dec 4, 2022

Aren't the threads single start thread?
They will only start in one place,unless you cross thread
Reverse until you feel the "drop"is a std mechanical assembly "trick"

eKretz · Dec 4, 2022

Micrometer threads are generally single start, but they are very fine pitch and easy to cross thread, especially with the split-nut approach that most manufacturers use. And you don't need to do much damage to make them almost unusable since they're so shallow.

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