Metric Specialty Threads

[nornrich]

All,

I am looking to find a chart of metric specialty threads. Our design challenge is that we have a thin wall (1.5mm) that we need a 3.5mm clearance home and then we are going to thread this hole to screw a retaining cap in place. If we back off the clear hole to 3.3mm we can then use a standard 4 x 0.7mm thread, but I would like to have a finer thread pitch. Is there anything out there like a 4mm fine pitch thread.

Regards,

Rich.....


Richard Nornhold, PE

http://www.ovenind.com

 

[ornerynorsk]

Have you tried working the numbers with an imperial thread size? 6-48 is the finest commonly available in that 4 mm range.

 

[CorBlimeyLimey]

http://www.tapdie.com/html/metric_taps_fine_or_taps_metri.html

http://www.newmantools.com/taps/tapsmetric.htm

 

[geoffthehammer]

Fine pitch for M4 is 0.5mm. Taps/dies should be readily available (but perhaps not if you are in the USA)

 

[nornrich]

Correction: The wall thickness is now reduced to 1.187mm. So I guess the question becomes what type of thread could we use that would get us a fine enough pitch to have 3+ threads of engagement.

Rich.....


Richard Nornhold, PE

http://www.ovenind.com

 

[CorBlimeyLimey]

http://www.thorlabs.com/navigation.cfm?Guide_ID=131

Pick a size ... most are available with taps to suit.

 

[KENAT]

You can still have 'specials' in metric just like you can have UNS for inch. Some are even available off the shelf from precision part suppliers like Thorlabs as CBL points out.

Assuming US take a look at ASME B1.13M-2001 section 7.6.

If it's important enough and/or you're making enough of them special threads are perfectly reasonable. We use them a lot for find adjustment, often parts from Thorlabs or sometimes we have our own made. In inch things like 80 TPI or even 100 TPI are readily available. Try finding the equivalent for metric, the link CBL gives may help.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[cpretty]

Maryland Metrics is a company in the US that supplies a large amount of free information on metric threads.

Check out there site

http://mdmetric.com/fastindx/indexmstr.htm

 

[juergenwt]

M4 x 0.2,x 0.25,x 0.35 are standard metric fine.
Look here:

http://www.infometall.de/index.html

clk on "Gewinde" and than "Feingewinde" on the left.
Or here:

http://www.pro-lite.co.uk/File/OWIS_FGS_Fine_Pitch_Screws_Datasheet.pdf

Taps here on Pg 66:

http://pdf.directindustry.com/pdf/hahnreiter/thread-cutting-gauges/33352-20819-_66.html

I looked in Europe and they are available. May be these people can help you:

http://mdmetric.com/