Mitutoyo Threads

[Bryan]

Is it 0.75mm pitch? Still not sure.
Is it close enough? Yes.

If you're happy we're happy Stu. Most of us anyway. There does appear to be a slight error though, which is curious. Strange to think of Mitutoyo making a mistake like that. It's not like there would have been some apprentice single pointing these screws. They must have used an automatic machine in the Swiss style surely? Or maybe it's a chinese copy of a Mitutoyo? I've got a "Rolex" like that. It even worked for a while.... Seriously, did you rule out the imperial hypothesis?

[Stustoys]

Or maybe it's a chinese copy of a Mitutoyo?

Well I'd hope not.

did you rule out the imperial hypothesis?

Well I did earlier. but thats when I was happy that it was 0.75mm*.
I think 36TPI is so close to 0.7 that over 16 threads I'd be going to tell the difference.(about .088mm) and its certainly not 0.7mm



Stuart

* and I forgot to answer Si it seems. sorry

[MuellerNick]

Is it 0.75mm pitch? Still not sure.

The tap's pitch is a tad smaller.
Did you ever check the pitch of your lathe's leadscrew?

For the length of a nut (0.9 * D) it certainly is good enough.


Nick

[Stustoys]

Hi Nick

The tap's pitch is a tad smaller.

I'm getting the taps pitch as a tad longer?

For the length of a nut (0.9 * D) it certainly is good enough.

3.6? Sorry I'm not getting you.

Did you ever check the pitch of your lathe's leadscrew?

No, but it did occur to me that I have no idea how close threads are normally, and how close is "close enough" for normal use.

Stuart

[MuellerNick]

For the length of a nut (0.9 * D) it certainly is good enough.

3.6? Sorry I'm not getting you.

The height (length, thickness) of a nut (in metric ) is 0.9 times the nominal diameter. Similar, a well designed internal thread is of that length or up to 1.5 times the diameter. So a slight difference in pitch doesn't matter.
More general: The length an internal and external thread mesh in should be 0.9 to 1.5 times the diameter. There are exceptions.

I'm getting the taps pitch as a tad longer?

So I confused tap and bolt in that picture I meant (didn't quote the picture). Anyhow, we agree that there is a slight difference.


Nick

[SiJ]

Hi Stu

From photo it looks as if there is one pitch difference over about 16 threads, so 0.75/16 = 0.047, so would seem that your thread is something like 0.703mm pitch.

Nevertheless, as you say I'm sure that the metric thread will do over the length of thread engagement.

Cheers

Si

[Stustoys]

Hi Si,
I think you are referring to the picture in post 62?
That's a M4 x 0.7mm bolt and the mystery thread.
Sorry for the confusion.

Stuart

P.s. Got it now Nick, thank you.

[SiJ]

Ah, sorry, yep, understand now ...........

Cheers

Si

[simonl]

Is it 0.75mm pitch? Still not sure.
Is it close enough? Yes.
Here are some pictures. Make up your own mind
I drilled and tapped a holed in 14mm MS(as long as the thread is) and the thumb screw winds in nicely. So I'm calling it good.

Stuart

Bloody hell you come up with some great pics Stu!

Simon

[simonl]

Now there is a cunning plan. Wasn't my idea Simon.

Stuart

I only just read this today

I should have read every thread before the BBQ as homework so that I would be up with current affairs!

It's all history now!

[Stustoys]

lol thats ok Simon, Joe lent me a tap and dia at the BBQ.

All done. From a foot away they match

Thanks guys

Stuart

[Anorak Bob]

lol thats ok Simon, Joe lent me a tap and dia at the BBQ.

All done. From a foot away they match

Thanks guys

Stuart

Looks the part Stu. Now all you have to do is deal with the mess the bloke made trying to spell his name with metal stamps. Just mill the slot a bit deeper.

BT

[Steamwhisperer]

As usual Stuart, well thought out and discussed and nicely executed. Always interesting.

Phil

[Stustoys]

Thanks Phil

Not so easy Bob, its hardened. As its on the back it might have to stay there until I get some carbide cutters. I'm not sure how often it will be used anyway much more likely to have a dial gauge on it.

Now to hijack my own thread. I made this excel file to give me the minutes and seconds for the 65 divisions needed. Anyone got something better or should I download gwbasic and practice my for next loops?

Stuart

[Bryan]

Well there's this. Whether it's better for your purposes I don't know, since I'm struggling to understand your spreadsheet.