Smart questions
Smart answers
Smart people
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Member Login




Remember Me
Forgot Password?
Join Us!

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips now!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

Join Eng-Tips
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Donate Today!

Do you enjoy these
technical forums?
Donate Today! Click Here

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.
Jobs from Indeed

Link To This Forum!

Partner Button
Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

proEdj (Mechanical) (OP)
5 Jul 05 11:58
What is the best way to call out a slot?  I have used basic dimension to reference the true center of the slot from 2 perpendicular datums.  Then I called out the width of the slot and the height (the length from one tangent line off the full radius to the other tangent line) using standard dimension with tolerances.  Then I called out the "2 X Full Radius" and also had a positioning block calling out diametric position of the center of the freature.  Does this sound correct?
Helpful Member!  ewh (Aerospace)
5 Jul 05 12:15
That is one of several correct methods.
ctopher (Mechanical)
5 Jul 05 12:29
I had to read it a few times, sounds OK.
Just a side note ... "2 X" should be "2X". I see this a lot.

Chris, Sr. Mechanical Designer, CAD
SolidWorks 05 SP3.1 / PDMWorks 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

Hydroformer (Automotive)
5 Jul 05 13:21
I like the automotive standard: Slot 8x14 (w/GD&T positioning)

regards,

Hydroformer

TheTick (Mechanical)
5 Jul 05 13:34
"2 X Full Radius" on a slot callot is straight from the Department of Redundancy Department.  Just say "slot".
ewh (Aerospace)
5 Jul 05 14:20
I never thought it would happen, but I must disagree with TheTick.  Y14.5 requires that "R" be called out, to ensure that it wasn't simply a mistake on the detailers part in missing a dimension.  You don't need the "FULL" in front of it, but it does no harm in having that also.  It really depends on what standard the drawing is done to (ASME Y14.5, industry or company).
drawoh (Mechanical)
5 Jul 05 14:27
ewh,

   I would say that the 2X R callout is correct, period, as noted in ASME Y14.5M-1994.  I am not sure what it means when you add the word FULL.

   All you are trying to say is that the ends of the slots are round, and their size controlled by the width of the slot.

                     JHG
ewh (Aerospace)
5 Jul 05 14:34
drawoh,

I agree with you.  I'm not sure where "FULL" originally came from, but I do remember having to use it years ago.  It is not technically correct per ASME Y14.5-1994.
ctopher (Mechanical)
5 Jul 05 14:40
I am not sure where it originated. I have been told by machinist's and inspectors that if you call out "2X R" on a slot, it can be technically any radius. If you call out "2X R FULL", it is a radius exactly the width of the slot (same tolerance).

Chris, Sr. Mechanical Designer, CAD
SolidWorks 05 SP3.1 / PDMWorks 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

ajack1 (Automotive)
5 Jul 05 14:42
I would agree with hydroformer, but maybe that is because I also am familiar with automotive standards. Failing that the slot size and two full radii, if you specify the length and width of the slot and the radii and start using limits you can end up with a flat or “short” radii on the ends, is that what you want?

I do however have no idea about American standards.
ewh (Aerospace)
5 Jul 05 14:46
According to Y14.5, hydroformer's method is close to being correct.  The standard omits the word "SLOT" from the callout, and states that the end radii are to be indicated but not dimensioned.
TheTick (Mechanical)
5 Jul 05 14:53
No arguing with the standards.  Seemed too obvious on the surface.  Star for ewh for actually looking this up.
tunalover (Mechanical)
5 Jul 05 15:55
ProEdj-
Don't you have a copy of Y14.5M-1004?

Tunalover

drawoh (Mechanical)
5 Jul 05 17:24
Tunalover,

    Don't you mean Y14.5M-2004?  I just looked at  http://www.asme.org.  The standard is still 1994, re-approved (re-affirmed?) 1999, unless their website is out of date.

                          JHG
Hydroformer (Automotive)
5 Jul 05 17:26
Dang, just pulled a drawing to check... The word "slot" isn't there. Just the length x width (and tolerances) above a feature control frame to define positional tolerancing.

Keeping in mind that these drawings are 'pictorial representations' and CAD is the MASTER.

regards,

Hydroformer

tunalover (Mechanical)
5 Jul 05 17:33
Sorry-
I meant Y14.5M-1994.

Tunalover

drawoh (Mechanical)
5 Jul 05 18:17
ewh,

   I don't know where FULL comes from either, although I have seen it used.

   I just pulled out my Engineering Drawing Sixth Edition, by Thomas E. French (1941).  They draw the slot and show the ends round.  There is no radius specified, and no mention of FULL anything.  They dimension either to the centre or to the ends of the radii.  Tney do not show tolerances, even on the drawing that shows limit dimensioning all over the place.

                       JHG
tunalover (Mechanical)
5 Jul 05 19:46
Folks-
Why use drafting references from 1941?  If you use Y14.5M-1994 and Y14.100M (and the standards referenced within) and can't go wrong!  There's too much to worry about at work besides drafting and tolerancing practices. Why not go with the standards?

I work at a company where each designer and engineer does his own thing; beyond the format, a drawing from one guy looks completely different from a drawing from another guy.  As for me, I prefer to "go by the book" rather than rely on something that I may have seen or did ten years ago.



Tunalover

Heckler (Mechanical)
5 Jul 05 21:10
IAW ASME Y14.5M - 1994  a slot can be dimensioned as such listed on page 15 figure 1-35. The end radii are indicated but not dimensioned.  Also, refer to page 143 figure 5-47 for another example of a typical slot.
drawoh (Mechanical)
6 Jul 05 12:34
tunalover,

   I do not use a drafting reference from 1941, at least, not for drafting.  I collect old books, and I am curious about old engineering texts.  The 1941 text sits on my bookshelf next to a couple of books from 1835 and 1844, which do not describe how to dimension slots (drat!).

   We seemed to be discussing old drafting procedures.  I was not advocating the 1941 procedure.  I was describing it.  Somebody swiped my old drafting textbook which was based on ANSI Y14.5M-1976(?).  That might have been more interesting.

   I prefer to use ASME Y14.5M-1994 for drafting.  I only wish more people understood it.

                       JHG
ctopher (Mechanical)
6 Jul 05 13:30
In our dept, we each have a copy of ASME Y14.5M-1994, and follow it.

Chris, Sr. Mechanical Designer, CAD
SolidWorks 05 SP3.1 / PDMWorks 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

ewh (Aerospace)
6 Jul 05 15:39
drawoh,
It is interesting to read up on old practices, and perhaps understanding the evolution of standards.  The first drafting book I was taught from was by French and Verrick, and the section on descriptive geometry is as valid today as when it was written.  Fortunately, we don't have to sweat that anymore.
proEdj (Mechanical) (OP)
6 Jul 05 16:15
Everyone,

Thanks for all you comments.

ProEdj
RedPen (Mechanical)
6 Jul 05 16:24
All,
IMHO "FULL" when applied to radii appears to have come from sheet metal shop practices and, of course, typically means the ends of the radii are tangent to the parallel sides of the slot (diameter of punch equals width of slot) or "FULL WIDTH".  This allows production of the feature without having to make/buy the specific slot punch.  2 round holes connected by one or more square or rectangular punch hits produces the equivalent feature.

If the punch diameter were larger than slot width it produces a "dog bone".  If it is smaller, it produces a "hotdog".  Both leave sharp corners at the transitions.  "FULL R" eliminates these undesirable sharp corners.

tunalover (Mechanical)
8 Jul 05 19:50
drawoh-
I've got an oldie but goodie too:  FAN ENGINEERING, 1931, Buffalo Forge Co.  There's more knowledge of forced air cooling wrapped up in that one book than anywhere else!

Tunalover

Helpful Member!  SrGilberto (Mechanical)
11 Jul 05 18:03
A slot, by nature, would normally need different tolerances differing horizontal to vertical.  That's why in the standard you normally see composite feature control frames to specify the tolerance around the true position of a slot.
The orignial question by Proedj seemed to indicate that he wanted a diametrical tolerance zone.  I question that if one has a diametrical tolerance zone, why would someone place a slot there?  I think the proper way to specify a slot tolerance zone is with a rectangular tolerance zone prescribed by a composite feature control frame (IMHO).

Regards,
SrGilberto
tunalover (Mechanical)
11 Jul 05 18:57
proEdj-
SrGilberto hit the nail on the head.  You need the ability to provide tighter control in one direction than in the other.  You certainly don't need to exert the equal control in all directions as with cylindrical tolerance zones.

If you consult ASME Y14.5M-1994, you'll see that the slot is used as an example on how to get geometric bilateral tolerancing using feature control frames.  Basically, the feature control frame looks just like one would normally use for hole patterns but the diameter symbol is omitted.

Bruce Wilson's book DIMENSIONING & TOLERANCING HANDBOOK has good examples and explanations too.


Tunalover

ewh (Aerospace)
12 Jul 05 8:32
A star for SrGilberto for catching that!  A diametral tolerance zone is usually overkill for a slot.
Hydroformer (Automotive)
12 Jul 05 9:54
Touche...

But, check the stack. The slot may be there to allow compliance of the mating component. The increased tolerance zone may take you outside the stack.

*Without data, you're just another person with an opinion.*

Hydroformer

templetonc (Aerospace)
4 Oct 05 14:01
Ok, there are three ways according to ASME standard to call out a slot hole. One of the ways is individual dimensioned length, widith and with a blank radii. In this type of call out where do you put the depth?
drawoh (Mechanical)
4 Oct 05 14:19
templetonc,

   My prefered depth specification would be applied to the side view that was projected right next to my slot dimensions.  This makes everything clear.

   I would reluctantly recognize and accept the ANSI depth symbol and a numerical value applied to the length or the width of the slot.  This saves you the extra view.  I would be curious about how your depth value got there.  Typed-in dimensions are bad practice in CAD, especially 3D CAD like SolidWorks.  There are ways to do it right.

   Once you have saved yourself the extra drawing view, it is possibly some machinists duty to call you up and waste a half hour of your time asking stupid questions about the drawing.

                      JHG
ewh (Aerospace)
4 Oct 05 15:23
drawoh,
When I have a dimension such as this type of depth, I dimension from a side view, turn off the dimension lines, extension lines and arrowheads, and locate the dimension with the slot callout.  It's associative and works great until the views get moved around.  I agree that manual dimensions are tools of the devil.
templetonc (Aerospace)
4 Oct 05 15:29
I am still learning. I was able to fit another view on the page and my checker was happy with it.
drawoh (Mechanical)
4 Oct 05 17:25
ewh,

   I have done what you describe, using AutoCAD.  This is one of the ways to do it right, although you are relying on co-workers to be observant, and as clever as you are.  I have been burned.

   In SolidWorks, you can write a note and attach dimensions by clicking on them.  Once the note is attached to the feature, everything is associative, and everything follows any drawing updates you do.  You have to hide the dimensions of course!

                         JHG
wgchere (Mechanical)
19 Oct 05 12:34
I remember when "FULL" was dropped. It was changed by ANSI Y14.5M-1982. It probably had to do with ISO standards and they dropped it. It was extraneous anyway, since the standard states that if a drawing appears to be tangent/right angle/etc. then it is if there is no notation to the contrary. Thus, if a slot doesn't show a sharp corner or a step between the radius and the straight edge it is by default interpretation, tangent and is also a "full" radius.

Boy! this standards stuff is better than Bible-bashing!
tunalover (Mechanical)
19 Oct 05 19:58
Folks-
Honestly I don't understand why all this dialog (and thread) is necessary.  The methods for dimensioning slots are clearly shown in Y14.5M.

Tunalover

ctopher (Mechanical)
20 Oct 05 9:41
I agree. I think all companies should have a set of ASME/ANSI stds for ref...and follow them.

Chris
Sr. Mechanical Designer, CAD
SolidWorks 05 SP3.1 / PDMWorks 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

smcadman (Mechanical)
22 Oct 05 12:40
What about slot depth callout?  I just had 200 ft of square tubing slotted with laser, but I didn't put THRU because THRU is assumed unless otherwise specified.  Only 1 face was slotted, and it has to be returned to have the far side slotted.  

For clarity in the future, I will put "NEAR SIDE ONLY" or "THRU", but is the assumed THRU for holes only and not for slots?

Flores
tunalover (Mechanical)
22 Oct 05 13:08
No.  THRU is by default for all features.  Your note should say NEAR SIDE but the words "THRU" or "ONLY" are are unnecessary.  If the feature were blind, you would have simply included the depth symbol (downward arrow).

Tunalover

ringman (Mechanical)
22 Oct 05 17:24
I believe a slot is a hole.  according to the Y14.5 if it is not clearly illustrated as a thru 'hole' it should be labeled as "THRU".
wgchere (Mechanical)
22 Oct 05 22:49
Just to be clear, in a case where there are two sides to go thru I say THRU, BOTH WALLS.

There is a stong possibility there will be a literalist interpreting it and feel that thru only applies to the wall indicated.
smcadman (Mechanical)
23 Oct 05 9:57
The slots were on a front view, and there was a top view because of a hole on the top view.  The slot lines on the front and back were clearly visible because hidden lines were shown (using Solidworks 2006).  If it was faxed to our vendor, then it would be possible that some clarity in the drawing could be lost, but since a PDF was sent, I know the hidden line were clearly visble BUT I guess it wasn't clearly notated.

Flores
microdesign (Mechanical)
25 Oct 05 19:02
Hello all!

I wish to GDT a continuous (looped) slot, below a surface, which does not need special (tight) control on its location, but mostly needs control of the width independent of location.

Is there a control for one wall of the slot relative to the other, when neither wall is a datum?

Can it be done independent of the location?

Do I have to use a basic dim. with a centerline and a control based on center?

Can I dim. one side of the slot and then have a GDT control on the slot width relative to the side wall location?

Thx,

Davin
ewh (Aerospace)
26 Oct 05 9:43
If location isn't that important, I would just control the width with a tight dimensional tolerance.
microdesign (Mechanical)
26 Oct 05 11:38
Yes, that was my thought also, but in the interest of using only GDT on the part, I wonder if there is a proper way to do it.

What if I DID wish to closely control the location of the slot feature?  Could I GDT it without using centerline?


drawoh (Mechanical)
26 Oct 05 13:41
microdesign,

   Dimensions with +/- tolerances are a part of GD&T, and are described explicitly in ASME Y14.5M-1994.  If that is what you want, that is what you should call up.

                        JHG
ringman (Mechanical)
26 Oct 05 13:57
drawoh,

What is the section of the std that describes +/-
tolerances?
ewh (Aerospace)
26 Oct 05 14:09
Most of section one and para 2.2a.
microdesign (Mechanical)
26 Oct 05 14:27

Quote drawoh

" Dimensions with +/- tolerances are a part of GD&T, and are described explicitly in ASME Y14.5M-1994.  If that is what you want, that is what you should call up."

True enough.  My issue with that  is that my drawing is dimensioned with basic ordinate dimensions.  If I were to place a direct dimension on the slot, I would also have to use non-basic dimensions all the way back to the datum.
drawoh (Mechanical)
27 Oct 05 14:06
microdesign,

   It depends on what you want to control.  You can apply GD&T controls _and_ +/- tolerances.  The part must conform to both specifications.

   How about you apply a profile tolerance of 1mm around both edges of the slot and a +/-0.1mm tolerance across the width?

   The inspector will verify that the slot lies within 0.5mm of nominal position with respect to your datums, and he will verify that each side of the slot is positioned to within 0.1mm with respect to the other side.  If this is what you want, the specification is correct.

   This works the other way too.  I can tolerance the top surface of a block to +/-.050", and apply a GD&T parallel tolerance of 0.005".  It gives me a sloppily located but very parallel surface, which could be exactly what I want.

   The whole principal here is that you should be specifying the exact controls that you need.  If you do not need to locate your slots accurately, don't. Just get the width right.

                       JHG
microdesign (Mechanical)
27 Oct 05 16:56
Thanks drawoh,

Can I use a single positional for the slot such as in figs. 5-14, or 5-43 of ANSI 1994, or is that only usable in ref. to a centerline?  

Can the GDT parallel symbol be used for one side rel. to the other without a datum ref?

or

Can flatness be used for one side rel. to the other side?

I don't suppose a composite is appropriate, as the features are not identical and are coaxial.

Ideally, I would like to use one control for one side of the slot, and then another to base one side of the slot on the other.






ewh (Aerospace)
27 Oct 05 17:15
You can't use flatness relative to another surface.  Flatness is a "stand alone" control.  I suggest using flatness for one side of the slot, and control the other side with parallelism or profile relative to the first side.  You can also add a flatness control to the second side if it is critical (you just can't make it relative to another feature).
drawoh (Mechanical)
27 Oct 05 17:38
microdesign,

   My assumption about positional tolerances is that you are locating the feature itself, and calling up everything about its form, elsewhere.  The positional tolerance works from whatever datums you specified.  The centrelines are only relevant to the specific examples in the standard.

   The GD&T parallel symbol requires a datum.  That datum need not be one of the datums used to fixture your part.  You can define one side of your slot as a fourth datum.

   If you apply a tight +/- tolerance to your slot, this controls parallelism.  A parallel tolerance is a strategy for controlling parallelism, while tolerating a sloppy width.

                      JHG
microdesign (Mechanical)
28 Oct 05 13:58
Thanks ewh and drawoh.

My "problem" is that my continuous slot is in a way, 2 separate features.

Imagine a plane with a rectangular projection.  Now imagine a rectangular slot around the base of the projection.  That is what I have, a radiused rectangular slot.  As it is continuous, it has 2 separate surfaces.

If I place a direct dimension on it, I would have to do it for all segments seperately, wouldn't I?

If I place a +/- tolerance on it, It connot be dimensioned with basic dimensions, can it?




ewh (Aerospace)
28 Oct 05 14:20
If the dimension is the same for all segments, you only have to dimension it once and note how many instances.
You can use basic dimensions to locate it and +/- to define
the slot, or visa-versa.  You can't use +/- on a basic dimension.
drawoh (Mechanical)
28 Oct 05 15:05
microdesign,

   Use basic dimensions to call up the sides of your projection.  Apply a profile tolerance to the outline.  How about .020?

   Pick the slot on one side and apply a dimension something like...

   4X .500+.005/-.000.

   The outline of your raised surface is controlled with respect to your primary datums.  The width of each of your four slots is controlled with respect to sides of your raised surface.  The outside edge of the slot winds up where it winds up.  If you did not care about this, everything is fine.

   One of the main ideas of good drafting is that you do not control features that do not matter.  

                         JHG
microdesign (Mechanical)
28 Oct 05 15:53
Thanks again,

drawoh,

That is the conclusion I had come to also, but still some issues.  The slot is radiused also, so I guess I should do 4x the straight segment, and 4x the raduises, or should I say all around, or can I use an "all around" circle on a dimension?
wgchere (Mechanical)
28 Oct 05 17:56
It would have to be 4X, because you have 4 separate radii.

I'm glad you finally described the feature you were talking about. Personally, I would call that a groove. A slot, in my mind, is a thru-hole with two parallel sides and a full radius at either end. A pocket would be a slot that isn't through. Before this explanation I was wracking my brain to try to visualize this slot you were describing.

Instead of a profile tolerance, I would use a linear true position tolerance on the length and the width of the rectangular projection (unless there are corner radii to control), than use a regular ± tolerance on the groove width, assuming its inside edge is contiguous with the rectangular projection. I would only use position because it seems to be understood by more people than profile is.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

  • Eng-Tips ForumsTalk To Other Members
  • Notification Of Responses To Questions
  • Favorite Forums One Click Access
  • Keyword Search Of All Posts, And More...

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close