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thread depth callout
3

thread depth callout

thread depth callout

(OP)
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

RE: thread depth callout

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

RE: thread depth callout

(OP)
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.

RE: thread depth callout

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

RE: thread depth callout

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.

cheers

RE: thread depth callout

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

RE: thread depth callout

  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.

RE: thread depth callout

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

RE: thread depth callout

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".

cheers

RE: thread depth callout

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.

RE: thread depth callout

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)

RE: thread depth callout

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).

RE: thread depth callout

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)

RE: thread depth callout

Quote:

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.

cheers

RE: thread depth callout

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.  

RE: thread depth callout

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)

RE: thread depth callout

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

cheers

RE: thread depth callout

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

RE: thread depth callout

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.

RE: thread depth callout

CBL
lol
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)

RE: thread depth callout

I agree with what you just put Ctopher, if in doubt put a section and dimension it there.

However, I still stand by my interpretation of the OP and while I'd probably use the depth symbol rather than say 'deep' I would use pretty much the same callout if I needed to better control the length of thread than just saying 'min full thread'.

Perhaps I need more sections...

RE: thread depth callout

At risk of "kicking a dead horse here", a few remarks:

A.  I agree with the majority and yield to ASME Y14.5M-1994 which makes it clear that the full thread depth is .24.  What happens below that depends on the tap and the machinist's preferences.  That's why it's preferred to provide a section view of a blind hole.

B.  In most cases when you specify a through-hole the note "THRU" is not required.  Only in cases where the hole could produce multiple penetrations is this needed (and even then only when the dwg lacks a far side view).

C.  Metric thread standards (invoked with ASME Y14.100) permit a drawing to state only "M3" to call out the coarse M3 metric thread (M3X0.5-6H or 6g).  That is "M3" is shorthand for M3X0.5-6H as long as it's clear its internal.

D.  When using the shorthand callout "M3" it may be necessary to provide the thread gender (if it's not clear on the drawing) by amending the thread callout with "EXT THD" or "INT THD" or the spelled-out equivalents.

E.  Of course "DIA" and "DEEP" have been replaced with internationally standard symbols that we all know about.

Tunalover

RE: thread depth callout

tunalover

B.  I'm a fan of thru.  Mainly 'cause I'm the idiot that takes minutes trying to work out if it's a thru hole when it doesn't say thru.  I know you don't need to say it if other views make it clear but it's something I likesmile.

C I'd double check this.  We went through this a few months ago and looking at the actual ASME thread specs and it appeared that in the US you still have to say the thread pitch on metric threads even though in the rest of the world you can just say M3 and get the standard course pitch.  We did research this and looked closely at the standard, I don't have the standard to hand but I think you're wrong.

RE: thread depth callout

If a section view shows the thd or any hole going THRU, there is not a need to indicate "THRU".

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

RE: thread depth callout

Like I said, I like it due to my own failings.

RE: thread depth callout

Chris,

Just a quick note.

From dealing with many different machine shops , the clarification on holes which are THRU' is always appreciated (even though it is unnecessary if obvious). As most will know, machinists are a funny bunch, anything you do to hinder them is a disaster, but anything you do to help them can turn you into a God.

From my own point of view, when it comes to checking drawings, the THRU command is great

Kevin Hammond

Mechanical Design Engineer
Derbyshire, UK
 

RE: thread depth callout

prohammy-
There are many factors that try to influence the drawing and one of the biggest are machinists and other tradesmen.  The drawing is an engineering document emphasizing the end-item and its functionality and, as such, we should resist "dumbing it down" to suit those who may end up reading it (there are other documents like work instructions is for doing this).  

I've found that the assemblers, manufacturing engineers, and machinists always want to turn the drawing into a manufacturing document with all the "hot to's" spelled out in gut-wrenching detail using piles of notes and exploded views.  Tailoring a drawing set to the whims of ONE manufacturer only stifles OTHER manufacturers' creativity and know-how by telling them precisely what to do to get to the end-item.

The safest approach is to emphasize the the end-item and its functionality while keeping the drawing as simple and straightforward as possible.  Machinists are trained and paid to read drawings so don't let them make changes that clutter the drawing and defeat its purposes.

It takes a lot more money for the engineer or designer to draft (and check, and redraft, and recheck...) a manufacturing-friendly drawing than it takes for the machines to read and understand the drawing.

Maybe I'm a bit too sensitive on this subject but let's concentrate on OUR jobs and avoid doing OTHERS jobs for them!



Tunalover

RE: thread depth callout

Tunalover,

I beg to differ. The point of an Engineering Drawing (99% of the time) is to get a part made to suit a design that I as an engineer has produced. It is about dissemination of information. I can produce many and glorified drawings that detail the end-item, but if I am not clear in my specification (which you so politely call 'dumbing-it-down'), then I have failed the basic functionality of an engineering drawing. Adding 'THRU' to a dimension clarifies and distinctly specified (beyond doubt) what I require from the specific feature. The fact that it makes someone else's job easier is my goal, NOT pandering to the whims of others outside an engineering departmant.

One other point of view worth considering is the financial implications of unclear drawings. Many organisations now count the cost of clarity on a drawing (minimisation of rework, greater repeatability etc) towards the overall performance of an Engineering Dept.

Kevin Hammond

Mechanical Design Engineer
Derbyshire, UK
 

RE: thread depth callout

In principle I agree with tunalover but sometimes you can be slightly pragmatic without selling your soul and on the issue of Thru I don't think it's really turning it into a work instruction, it's just clarifying/condensing all the information you need into a single callout.

Drawing defines the finished part, at least this is my understanding of common practice and the standards I've looked at.  It is effectively the 'requirement' of the part.

Most of the time, how that requirement is met doesn't matter.  Trying to detail how to meet it on the drawing can lead to problems in is certainly agains ASME standards in most cases.

If I have a section showing the hole I probably wont add THRU.  If I don't then even if I have views showing both sides of the hole, and hence arguably making it clear that it's thru, I'll typically add THRU for clarity.

Tuna you are perhaps being over sensitive but having worked in my current place for over a year I can understand why so wouldn't beat yourself up over it.  You let little things slide and then it's an avalanche!

RE: thread depth callout

Regarding manufacturing friendly drawings vs. end product drawings, I go with tunalover and concur most of his points, and feel that maybe Prohammy has been brainwashed by manufacturing like the engineers and designers at my present job. Here, I have been battling to turn a bunch of miserable work instruction drawings, full of clutter, dumb, obvious notes and bad exploded views, with often no picture of the end product except maybe a pasted in photograph into a respectable engineering drawing package IAW ASME Y14.100, et al. I too use "THRU" a lot, admittedly by force of habit, but not on sheet metal parts where it's obvious. The worst is "THRU NEXT, or THRU ALL", which CAD jockeys took from their hole generating menus.

RE: thread depth callout

I concur with tunalover as well.  There is no place for processes on the drawing.  If there is a need to detail an extremely rare process which is not covered by standard practices, then the place for the description of that process in on a work instructions document.  In fact, there's even rules against addressing processes on drawings.  One does not say "MACHINED JUNCTION BOX" in the title.  One simply says "JUNCTION BOX".

That said, the original discussion regarding "THRU" or not doesn't really matter that much because the drafter should simply use it where clarity is necessary.  It's not a description of the process, but a requirement of the end-item.

Bottom line, engineering drawings should not address processes because drawings are not work instructions.

Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
http://sw.fcsuper.com/index.php

RE: thread depth callout

AMEN! I love to quote ASME Y14.5 ΒΆ1.4(c)and(e) to engineers at my place, whenever I get step by step assembly notes on drawings, or drill, ream, tap drill, or the like.

RE: thread depth callout

I also concur with tunalover.
If the machine shop or anyone else needs to understand the dwg, take classes.

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

RE: thread depth callout

I also agree with tunalover.  The pupose of a drawing is to define the part as concisely as possible, NOT how to achieve the finished product (with the exception of special engineer required methods, which should be kept to a minimum).

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