thread depth callout 3

[learman3]

I have a drawing with the following callout:

DIA.10 THRU
M3X0.5-6H .24 DEEP

Would you interupt the thread depth to mean full thread?

thanks
lear

 

[aardvarkdw]

No, I would interpret this to mean a .1 diameter hole thru the part with an M3 tapped hole .24 deep. If your part is less than .24 thick then yes, but you don't specify how thick your part is.

David

 

[learman3]

David,

I don't understand why the thickness of the part matters. If the part was less than .24 thick then you would be tapping all the way through the part. You would only need to specify a depth when not tapping all the way through.

 

[aardvarkdw]

That is true. What program was the drawing produced with? Many CAD programs create thread notes based on the parameters given regardless of material thickness. In Inventor you can create a hole either thru or with a distance. The program defaults to distance. When you specify a distance the program creates a hole note with a depth callout, regardless of the material thickness (there are ways to correct this or to bypass it).

Another reason you may have a depth that is larger than the material thickness is if your hole ends at another hole or similar cylindrical feature. You want the hole thru the material but you may not want it to go thru the other side of the hole. In this case you can either say thru to bore (there is a whole series of threads about the validity of this note) or you can give a depth that is larger than the material thickness and this ensures that the machinist drills deep enough to get through the material but stops short of cutting into the other side.

David

 

[CorBlimeyLimey]

I would interpret the .24 DEEP to refer to full thread depth. Anything else would be pointless because the tap type (plug, taper or bottoming) is not being specified.

 

[aardvarkdw]

CBL,

What if you don't care what the tap is? You have specified a tap drill size thru and you have specified a tap with a depth, what else do you need? Anything else would be telling the machinist how to do their job.

David

 

[ewh]

This is much ado about nothing. The note says "DIA .10 THRU" - meaning exactly what it says. It goes on to state "M3X0.5-6H .24 DEEP" - again, meaning exactly what it says.
".24 DEEP" is a full thread requirement. If it were not full thread, it would not meet "M3X0.5-6H" at the bottom of the depth callout.

 

[aardvarkdw]

I think I am interpreting the question differently than everyone else, sorry. I am interpreting the question to mean, "is the thread full length of the .10 hole" and my answer is no the thread depth is .24, and everyone else is interpreting it to to mean is the threaded hole threaded the full .24 length.

David

 

[CorBlimeyLimey]

aardvarkdw ... The question is; Does the .24" dimension refer to the overall length of threading (regardless of thread form) or the length of thread which has the full thread form.

I think you are misinterpreting the "full thread depth" to refer to the length of thread down the hole instead of "full-thread depth" across the hole for a depth of .24".

 

[KENAT]

Yes I'd interperate the .24 to be full thread (e.g. full thread form to deptho of .24 from the relevant surface), although whatever the drawing tolerance block for .xx dimensions would apply.

e.g. if the tolerance for 2 decimal places is +-.01 then the full thread depth could be anywhere from .23 to .25.

 

[ctopher]

I would call out the depth and let the machine shop determine if it's full thd or not.

Chris
SolidWorks 06 5.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 02-10-07)

 

[KENAT]

What if you need the full thread all the way down to ".24" because of the length of screw you are using?

To me if you specify the length of thread then the length specificed (with its tolerance) is full thread form (allowing for lead in etc).

 

[ctopher]

Call out more depth so the screw will fit.

Chris
SolidWorks 06 5.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 02-10-07)

 

[CorBlimeyLimey]

I would call out the depth and let the machine shop determine if it's full thd or not.

Sorry Chris ... I definitely have to call you on that one. As ewh stated ... ".24 DEEP" is a full thread requirement. If it were not full thread, it would not meet "M3X0.5-6H" at the bottom of the depth callout."

If you let the machine shop determine the length of full-thread engagement, then why bother specifying a depth? The whole point of specifying a depth is to ensure the correct amount of thread is available for a mating screw.

 

[KENAT]

Ctopher,

We use 'min full thread depth' when we need a minimum length of thread to accomodate a fastener but don't mind if the thread goes a bit deeper.

That is not what the callout in the OP says. It just says .24 Deep.

Hence to me you are saying you need .24 (+- whatever drawing tol) of full thread form.

 

[ctopher]

If I want to meet a certain thd reqt, I have always called out "min full thd". Adding a dim can cause confusion with some machinists and inspectors. Adding a dim depth is possible you can be out of spec.

Chris
SolidWorks 06 5.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 02-10-07)

 

[CorBlimeyLimey]

Never thought I would 'hear' you advocate against ASME/ANSI standard

 

[KENAT]

Rules are for the obediance of fools and the guidance of wise men!

 

[MintJulep]

Do we assume that the metric thread is metric and all the other units are inch?

Otherwise you are calling for less than 1/2 a thread.

But yes, the depth call-out specifies the distance down from the surface that the specified thread form must be maintained, subject to drawing tolerances.

 

[ctopher]

CBL

I'm never against ASME/ANSI standards.
Also, If a dim for thd depth is needed, show the dim (w/tol)instead of a callout. If there is a Cbore or some other feature above the thd, having a callout would confuse a machinst where to start.

Chris
SolidWorks 06 5.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 02-10-07)