Minimum Spacing Between Threaded Holes Specification? 1

[rcpolk97]

Hi everyone,

Apologies if this has already been asked, but does anyone know if there is a specification for minimum distance between threaded holes in a plate? I've searched my Machinery's Handbook and the web and can't find anything.

For my specific situation, I have a 3/16" thk. steel plate and I have two different 1/4"-20 bolt patterns for mounting two different transformers (one is an alternate, so only one of the two would be mounted). As I currently have it drawn, two of the 1/4"-20 holes are only .38" apart C-to-C, so only ~1/8" material between the two. Does that sound reasonable? Like I said, this is to accommodate an alternate transformer, so only one of these two threaded holes will ever be populated at any given time. Also, the plate is parallel with the ground with the transformer sitting on top, so there are no significant shear considerations (application is an electrical cabinet on casters).

 

[3DDave]

Tear-out and pull-out are the main concerns and if thread-forming is used it can deform the neighboring hole - not a problem with thread cutting.

I would not expect a problem with the holes that would not first damage whatever is secured with them. Does the transformer weigh less than about 10-20 pounds? I would not worry until it got to 200-500 pounds.

 

[rcpolk97]

Thank you for the input - very helpful. It's a light weight transformer. Should be less than 8 lbs.

 

[DraftingMan]

rcpolk97,

I would suggest shifting one of the hole patterns, either rotationally or laterally, so as to create more space between holes.

IMHO



JHD