Metric threads, uhggg

[DODGERFAN]

I am looking for some info for a  50 X 2 external thread. Oddball B.S.......

Ive found a few charts and they are all different. Master cam doesn't have that thread in the lathe file. Can someone please tell me what the minor diameter is?   

[Brian Pallas]

For oddball stuff, I always find a diameter close that has the same pitch, and then add or subtract the differences in the nominal size.

So I looked in Machinery's Handbook M42 x2 and added 8mm. So minor - 47.835mm-48.210mm

[jeff]

here ya go... warning the page will burn your retinas

http://mdmetric.com/tech/thddat4.htm

[Guest]

http://www.calcool.dk/metricthread.htm

 

 

[Guest]

http://www.engineersedge.com/hardware/metric-external-thread-sizes2.htm 

[Guest]

Service ... that's eMastercam for ya.  

Can't even get up and walk to your book shelf that fast.  

[DODGERFAN]

1 minute ago, jeff said:

here ya go... warning the page will burn your retinas

http://mdmetric.com/tech/thddat4.htm

This is one of the charts i was using. When i use the minor from this chart, mastercam tells me "less than 1 thread will be cut with the current thread lead".

My lead is.07874, what am i missing?

[DODGERFAN]

8 minutes ago, JParis said:

http://www.calcool.dk/metricthread.htm

 

 

This is cool. 🍺

[jeff]

10 minutes ago, DODGERFAN said:

This is one of the charts i was using. When i use the minor from this chart, mastercam tells me "less than 1 thread will be cut with the current thread lead".

My lead is.07874, what am i missing?

I'm not sure.. it sounds like you're telling it the thread length is less than .07874" long

[DODGERFAN]

4 minutes ago, jeff said:

I'm not sure.. it sounds like you're telling it the thread length is less than .07874" long

My start position is.225, end position is-1.225???   

[crazy^millman]

Give your start more room to enter the thread and see if that helps.

[DODGERFAN]

7 minutes ago, C^Millman said:

Give your start more room to enter the thread and see if that helps.

Same thing Ron.  I've never seen this before. 

[RLeuschen]

I tried and had my post output g76 correctly.

 

G00 X2.1685 Z.2154
G76 P010060 Q0 R0.
G76 X1.8833 Z-1. P426 Q165 R0. F.07874
G28 U0. V0.

When i used the compute feature, it errored out when i had the 2mm in the threads/inch...

 

New Microsoft Office Word Document.docx

T.mcam

[Thad]

On 5/18/2017 at 11:24 AM, JParis said:

http://www.calcool.dk/metricthread.htm

 

 

Bookmarked!

Thanks JP!

[mkd]

Hijack/ revival:

got an aerospace part calling out MJ threads per ANSI/ASME B1.21M. Since i can't seem to find the spec on the net, I'll ask the experts here.

With English UNJ aero threads the only thing different for (internal) thread is you make the minor smaller to account for the shaft root radius. Even the thread gauge remains the same.

So what is different with an MJ thread compared to M, other than root radius or internal minor dia????

 I borrowed a thread gauge from the customer that is labeled MJ and there is a section of the Carmex catolog that lists MJ threadmills.

:head scratch:

 

[mkd]

ok, just talked to the gage house that inscribed it with a "J". It's just to make ignorant people (like me and source inspectors) happy seeing the same spec on print as on the gage. There is no physical difference on a plug gage.

 still not sure why carmex lists MJ threadmills...

[3R!< W3NG3R]

J threads have a larger root radius to make the threads stronger.  On the bolt, this makes the minor dia a little bigger.

Other than that, they are the same thread.