Max Screw Size Relative to Width 2

[bl79]

So I wasn't sure where to post this. Is there a machining forum? If there is I must have missed it.

Anyway, I've found lots of info on the minimum thickness of a material to be tapped but I haven't found anything regarding how wide the material should be.

In other words, how much material should be present on any side of the hole as a basic guideline? Like a 10-32 Screw in .25" material seems a bit sketchy. Thoughts?

 

[MiketheEngineer]

Yes - Machine and Machining Engineering Forum.

Most bolts, screws, etc have minimum "edge/end distances" and "spacing" dimensions. That would be your answer.

Check w/ supplier.

 

[bl79]

D'oh, I thought that forum was for machines, not machining.

Anyway, after poking around on McMaster for a bit(where most of our orders come from) there doesn't seem to be much advice on edge/end or spacing distances. Even google has failed me. Are there any rules of thumb I should know about?

Thanks!

 

[hydtools]

I generally use 1.0 to 2.0 times nominal bolt diameter, center to edge.

Ted

 

[Spoonful]

I guess it has to do with ligament efficiency? Once your adjacent holes are too close, the strength of the material are weakened.

 

[chicopee]

Ligament efficiency.. that's tube sheet hole spacing, isn't? I agree with Hydtools as it all depends on the material.

 

[FACS]

It depends on what you are doing wih the fastener.
How many are there?
Is it a compressive load?
Is it mostly shear or is it cantilevered?
Is it plastic, aluminum, steel, brass?

Is it tapped deep? is it tapped straight?

Is it holding on a plate, a cover or is it hanging a load?

There are no rules for this, you have to do an analysis on the principles

Charlie

http://www.facsco.com

 

[MiketheEngineer]

In wood or concrete - it can be up to 10 x Diameter to achieve 100%

 

[Cockroach]

This is a very basic machining question.

A 10-32 UNC-2B thread is drilled 5/32 and tapped to depth. You get 5/32 drill diameter by noting the nominal thread size of a #10 male thread is 0.19 inches and subtracting 1/32 off and rounding to the nearest 1/64th inch. Hence 5/32 drill diameter.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[desertfox]

Hi bl79

Bolts or screws should be placed at least 1.5 to 2 times bolt or screw diameter to avoid failure by tearout see this link-

http://www.acronymchile.com/noteshtml/3rd_Prodn_Design/joints_lecture1/joints01_handout.pdf

look at chapter 10

regards

desertfox

 

[osoloco]

If you can find "Analysis and Design of Flight Structures", possibly scanned by Google, I would expect that you can find out how to analyze the problem. I remember that they had good chapter on rivets & bolts.
Most machine design texts will address this quite well...
usually 2 diameters work, check bearing stresses, tensile rupture, and shear tear-out.