changing from UNC to UNF torque & applied force difference - SET SCREW
changing from UNC to UNF torque & applied force difference - SET SCREW
(OP)
Hey guys,
I'm new here, so I hope this is in the correct area. I have a question about torque of a SET SCREW as it relates to force applied. Specifically in machine tool holders (endmill holders).
It has been decided to change from course thread to fine thread set screws on the holders, but the question remains is what to torque the set screws to?
set screws:
was 3/4-10 x 3/4" long 120ftlbs torque
is 3/4-16 x 3/4" long ? torque
Is there a formula that can determine what the conversion from course thread would be? I've done a search but havent found anything yet on set screws. Everything I have found is based on Bolts (with a head) or nuts.
Thanks,
Scott
I'm new here, so I hope this is in the correct area. I have a question about torque of a SET SCREW as it relates to force applied. Specifically in machine tool holders (endmill holders).
It has been decided to change from course thread to fine thread set screws on the holders, but the question remains is what to torque the set screws to?
set screws:
was 3/4-10 x 3/4" long 120ftlbs torque
is 3/4-16 x 3/4" long ? torque
Is there a formula that can determine what the conversion from course thread would be? I've done a search but havent found anything yet on set screws. Everything I have found is based on Bolts (with a head) or nuts.
Thanks,
Scott





RE: changing from UNC to UNF torque & applied force difference - SET SCREW
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
Thanks,
Scott
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
So the areas of the head or tip or whatever don't come into it do they?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
Thanks for the quick replys!
Scott
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
list 140 and 120. I would think
the same would apply to setscrews.
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
Regards,
Mike
PS - Ratio of root diameters x 120 = 140
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
Are you saying it will take 140ftlbs of torque on a fine thread screw to match the holding power of 120ftlbs of a course thread screw? It just seems backwards to me, I thought fine thread screws required LESS torque to obtain the same holding power.
Thanks again,
Scott
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
I have heard you can take the Ratio of TPI x torque to get the resulting torque of the fine thread fastener. Is this an accurate statement?
Thanks again,
Scott
RE: changing from UNC to UNF torque & applied force difference - SET SCREW
Have a look at this link:-
ht
under the sub heading "intial bolt tension" at the bottom of that section it as a formula for tightening screws taking the pitch of thread into account.
desertfox