Minimum thread depth
Minimum thread depth
(OP)
Can anyone point me in the right direction of a Minimum thread depth chart?. I am tapping a m2x0.4 hole into a piece of HE15 but am limited on depth what is the minimum length of thread neaded to have contact in the tapped hole?
Thanks
CDC02254
Thanks
CDC02254





RE: Minimum thread depth
RE: Minimum thread depth
the next question is how strong do you need it to be ?
the rule of thumb is three threads develop the full strength of the bolt.
if i was designing something with minimal thread engagment i'd either consider the effects of vibration VERY carefully, even if you don't think you'll have vibration, or consider the effects if this thread backs out, or add positive retention device (lock washer) ... but i doubt you've got room for this.
good luck
RE: Minimum thread depth
Dik
RE: Minimum thread depth
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Minimum thread depth
1. 5 full threads
2. one diameter of engagement--if the screw is 5mm then it needs 5mm of engagement
RE: Minimum thread depth
RE: Minimum thread depth
http://www.hexagon.de/dose/dose1e.htm
RE: Minimum thread depth
the thread in the aluminum is larger
than the thread of the bolt so you
have to examine two different sizes
for strength calculations. Heli-coils
generally come in lenght of 1 times
the diameter, 1.5 times the diameter
and 2.0 time the diameter without
being a special order or design.
RE: Minimum thread depth
Sometimes its better to use many small fasteners instead of one large fastener.
If you can't use three threads, then you usually have a problem. Remember you can always use fine threads.
Charlie
www.facsco.com
RE: Minimum thread depth
Wgchere is quite right, typically one diameter is full length of engagement. This is usually used in the thread programs when length of engagement is unspecified.
Otherwise you need to know the loads applied to the threading and determine length of thread based on shear. Since the internal thread profile has greater shear area than the external counterpart, and I mean always, you can base your calculation on the external threading alone.
The Machinist Handbook covers this fairly well for Acme and Stub Acme threads, not so great for Unified National and Metric edition. However, there are plenty of programs readily available to which you can apply the numbers specific to your case for a quick answer.
I'd concur with others and say one thread diameter.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: Minimum thread depth
RE: Minimum thread depth
RE: Minimum thread depth
Our corporate standard is 2X Diameter for anything smaller than M5...
RE: Minimum thread depth
Yeah, don't think a guy would want to stand the whole house over the M2 X 0.4. Thread shear value is good, but tensile load below the minor diameter of the pin (i.e. screw) would certainly lead to a failure.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada