Matching threads

[napacaldog]

Hello,
I've been trying to figure out how to make the threads match on a male and female part. Using a tap size chart, I made a hole 31.5 mm in diameter. Then I added interior threads with a tap size M33 x1.5. How do I determine the diameter of the male part before adding threads? Would it also be 31.5 mm? I plan on 3d printing these parts, so I've also been using the thread modeler tool. Any help would be appreciated. I do not have experience with taps and dies. Thanks!

[Paul-Mason]

An M33 is a Metric Coarse Thread with a Pitch of 3.5mm Core Dia of 27.706mm Thread Depth 2.1470 Tapping Drill of 26.5mm Clearance of 33.5mm Not a Metric Fine as you seem to be indicating but even then there is is NOT a Metric Fine or Metric Standard thread of 33mm with the pitch of  1.5mm

The nearest M Fine is 30mm, Pitch 2mm Core 32.319mm Tapping Drill of 32.75mm

ALL size are taken From the UK issue of Zuse Data Charts, a copy of these data charts has been posted here https://skydrive.live.com/#cid=30A7361EF9C3AE77&id=30A7361EF9C3AE77%21496

[josh92brown]

Just answerthe stupuid question i have been trying to figure this out forever. We just want to know if an 8mm hole threaded with the reccomended metric thread will align with a 8mm rod with its own reccomended metric thread. Or if sizing of either holed needs to be adjusted for a proper fit. 

please

[JDMather]

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@josh92brown wrote:

...We just want to know if an 8mm hole... ...will align with a 8mm rod with its own reccomended metric thread. .

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An 8mm rod with pass through an 8mm hole - no thread engagement.

Can you attach your files here - I can demonstrate proper thread fit.

(indicate your manufacturing process)

[josh92brown]

Ok so the hole need to be smaller the the 8mm rod for "thread engagement"?
Ok i will attach my files. fyi the parts will be milled. 😉

I will leave the parts not threaded, but will leave the holes on the
"hanger" part. were the "axel" needs to fit. Please note that the axel
needs 10mm of thread length on each ends. The short end is where it fits
into the "hanger". They are long-board trucks

[IgorMir]

Hi Paul,

It is not exactly true. The standard fine pitch for the M33 thread goes for 3 mm, 2 mm, 1.5 mm 1 mm and 0.75 mm.

Here is a quick link to a table showing M33 x 1.5 thread definition. http://mdmetric.com/tech/thddat4.htm

If need be - I can spend some more time on the net and find a Standard which defines all of them.

Regards,

Igor.

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@Paul-Mason wrote:

An M33 is a Metric Coarse Thread with a Pitch of 3.5mm Core Dia of 27.706mm Thread Depth 2.1470 Tapping Drill of 26.5mm Clearance of 33.5mm Not a Metric Fine as you seem to be indicating but even then there is is NOT a Metric Fine or Metric Standard thread of 33mm with the pitch of  1.5mm

The nearest M Fine is 30mm, Pitch 2mm Core 32.319mm Tapping Drill of 32.75mm

ALL size are taken From the UK issue of Zuse Data Charts, a copy of these data charts has been posted here https://skydrive.live.com/#cid=30A7361EF9C3AE77&id=30A7361EF9C3AE77%21496

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[mcgyvr]

Typically one might look at a thread chart that shows a min and max diameter.

example...http://www.engineersedge.com/screw_threads_chart.htm

http://www.pencomsf.com/screws-categories/screw-design-guide/

[JDMather]

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@mcgyvr wrote:

Typically one might look at a thread chart ....

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Old-timers keep a Machinery's Handbook reference nearby.

The question arises though, if these are going to be milled (turned?) are modeled threads really needed.  I would normally use cosmetic threads and specify the nomenclature on the drawing.  The only time I model threads is when it is a particularly large part (not a standard fastener) or if I am going to 3D print.  3D printing involves special considerations - which is why I asked about the manufacturing process.

In any case, I don't see the promised part file attachments.

[mcgyvr]

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@Anonymous wrote:

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@mcgyvr wrote:

Typically one might look at a thread chart ....

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Old-timers keep a Machinery's Handbook reference nearby.

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I actually wrote that the Machinery's Handbook is a great reference to have on hand but then thought these youngsters would want a link to something on the internet.  I love that book and use it all the time.. Still using the 24th edition here.. 

[JDMather]

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@mcgyvr wrote:

@mcgyvr wrote:

....

...these youngsters would want a link to something on the internet.  I love that book ...

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Book? What is this artifact that you refer to as "book".

[mcgyvr]

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@Anonymous wrote:

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@mcgyvr wrote:

@mcgyvr wrote:

....

...these youngsters would want a link to something on the internet.  I love that book ...

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Book? What is this artifact that you refer to as "book".

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I've actually got the 11th edition too from 1942 in pristine condition.. I wonder if its worth anything..  (edit.. nope.. looks like its going for $10 to $65 or so on ebay)

[rdyson]

This might be of interest to some:

http://www.brokenbolt.com/images/starrett-inch-metric-tap-drill.pdf

[Paul-Mason]

DUH read the charts that I posted the link to

THEY TELL YOU WHAT YOU WANT TO KNOW.

Look for M8 in "METRIC COARSE THREADS" for the tapping drill this is 6.8mm OR on the page headed I.S.O and I.S.O METRIC FINE THREADS IN M.M where the M8 FINE tapping drill is 7mm then IF you bothered to look on  the page HEADED STANDARD DRILL SIZES AND DECIMAL EQUIVALENTS  17/64 inch nearest drill for M8 coarse and 9/32 nearest size drill for M8 fine

SIMPLES as Alexander Meercat would say

[mcgyvr]

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@Paul-Mason wrote:

DUH read the charts that I posted the link to

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yeah right after you create a microsoft account and sign in.. no thanks 🙂