Broken Dia and callout?

[RyanCR]

There seems to be some confusion here as to the correct callout for a broken diameter. We have a round plate with a ID diameter going through the center. This ID diameter is broken by 4 slots.

Is it correct to show the dimensions as "4X Ø5.00" or if its a radius as "4X R2.25"? Or can you just show the dimension without the "4X" and it is assumed the same diameter and feature?

Thanks

 

[wgchere]

The dia will probably be machined as one feature and then the slots added, or machined as one feature after the slots are added, or machined as one feature at the same time as the slots. In any case, it makes most sense to dimension as 1 diameter. Tolerance is tighter and if the slots leave more than 180° of the diameter, you can use positional GD&T

 

[ctopher]

Yes, depends on how it will be machined. Mahcine one diameter, or 4 radii?
I would dim as one dia.

Chris
Systems Analyst, I.S.
SolidWorks/PDMWorks 05
AutoCAD 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

 

[dingy2]

You have 4 features that are coaxial. They should be shown a 4X and then the diameter. It really doesn't make any difference that the processing may only one operation (drilling as an example), one would still end up with four (4) coaxial holes.

To show that they share the same center (if you wish), reflect them in a positional tolerance using MMC but without a datum. This would reflect 4 holes in alignment.

If you wish to have the pattern of 4 holes relative to a datum(s), you could reflect them in positional to the datums.

Hope this helps.

DD

 

[ctopher]

I disagree, but maybe I'm not invisioning the part correctly?
RyanCR, can you show us a pic of the part?

Chris
Systems Analyst, I.S.
SolidWorks/PDMWorks 05
AutoCAD 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

 

[dingy2]

Please look up ASME Y14.5M - 94, top of page 148, reflecting exactly what I understand as the situation. In this case we have a composite feature control frame with 4 coaxial holes referencing datums A & B. The holes are shown 4X and then the tolerance.

If one does not want the 4 features in the pattern to A & B (bottom section of the feature control frame),look at the top of page 149 showing the 2 holes (different sizes here) relative to each other without a reference datum.

DD

 

[Heckler]

How it's going to be manufactured doesn't drive design intent.....it's the other way around. It's design intent that dictates the manufacturing process. I think it would be safe to say that this feature(s) could be dimensioned either 4R.xxx or 4Dia.xxx. The main thing is does it meet the overall design intent and is the dimension scheme clear.

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NVIDIA Quadro FX 1400
o
_`\(,_
(_)/ (_)

"Coming together is a beginning, staying together is progress, and working together is success." - Henry Ford

 

[wgchere]

I interpreted the initial question as a hole broken by 4 slots that were parrallel to and intersecting the centerline of the hole. It was the radius comment and that 4 slots left 4 radii or pieces of the hole that threw me in that direction. If the slots intersect the hole perpendicular to or at an angle to the hole they would create 5 pieces of the hole.

So now i'm confused. Which is it RyanCR? I think we really need some kind of a picture here.

 

[ctopher]

Agree, a pic will help.

Chris
Systems Analyst, I.S.
SolidWorks/PDMWorks 05
AutoCAD 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

 

[RyanCR]

wgchere is correct.

Image a washer, with 4 evenly spaced ID slots, which break the ID diameter into 4 equal segments (The segments don't need to be equal).

I believe that the ID diameter needs to have a "4X" associated to it, but a coworker does not.

I do disagree that the way the part is manufactured should have anything to do with the dimension call-out. Two different shops may create the part in different ways. It seems to me that there should be a standard on how this callout is shown. I always believed that if the dia or radius was broken, that a number went in front of the dimension.

Thanks,

 

[ctopher]

Can you please show us a pic??
See FAQ on how to do it.

Chris
Systems Analyst, I.S.
SolidWorks/PDMWorks 05
AutoCAD 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

 

[RyanCR]

See the file at the attached link for an example (TIF file).

http://multiterra.mooload.com/file.php?file=files/070306/1141746393/WASHER.tif

 

[ctopher]

Assuming you have a shaft of some sort running thru it, dim it as one dia. Dim as 6X R.XXX can give you a part that can interfere with the other because of tol. I am almost 99% sure it will be machined (or whatever process) as one dia. I agree with don't dim how it is made, but the dim has to be practical so to be made any way possible and turn out the same every time.

Chris
Systems Analyst, I.S.
SolidWorks/PDMWorks 05
AutoCAD 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

 

[wgchere]

I would definitely call it out as Ø4.714. There is only one dia there, so you wouldn't call it out as multiple diameters. You could call it out as 6 radii, but then you couldn't control it with GD&T and each segment would be individually toleranced and located, as ctopher pointed out. One diameter controls all six radii as a whole.

 

[RyanCR]

I completely understand what you are saying and agree. However, I was just wondering if ASME spoke to this and there was a standard that stated it should be called out with the "6X" and then a positional tolerance? If a standard says I need to put a "6X", then thats what I want to do...if not, great.

thanks,

 

[ewh]

I agree with Chris and wgchere on this, but I think it is much ado about nothing. It is one diameter, period. It will be made as one diameter. It will be inspected as one diameter. If you really want to get a**l about, yes it is 4 (or 6 in the example pic) separate radii. It is NOT 4 separate diameters.
The purpose of a drawing is to CONCISELY define a part. A single diameter dimension (with extension segments through the slots, if they aren't too small) will define this clearly, more so than 4X R, and will be easier to control with GD&T.

 

[wgchere]

I found only 2 illustrations that had any bearing on your problem. ASME Y14.5-1994, Fig 5-43, shows a diametral callout for the cylindrical surface of 11 tabs as well as a diametral callout for the cylindrical surface at the bas of the tabs. This is the opposite of your problem with tabs instead of slots, but the diameter callouts are similar. Of course, the std warns us of reading more into the illustrations than they are meant to illustrate and this figure is meant to illustrate positional tolerancing of tabs, not diameter callouts.

This is all I could find.

 

[wgchere]

Oops!

The second example is Fig 5-18. The diameter is not complete, being broken by the tab, but it is still called out as a diameter, although it is technically a radius.

 

[RyanCR]

Thanks for all the input. I was not trying to ruffle feathers with the question, but to understand if there was an actual standard that defined how this callout should be handled.

It is similar to the ID and OD of a part similar to a washer. You don't always see control frames controlling there relationship to one another. If there are no control frames, then technically the two diameters do not have to be concentric. Many people I have talked to seem to think there is a default positional relationship, but there isn't. I just wanted to know if the diameter/radius are assumed one, if not otherwise specified.

Thanks again for the responses

 

[ctopher]

There isn't really a standard on how to dim your parts. It depends on the design. The ASME standards are guides to help you with the design. If the design somehow requires you to dim the part with 6X R vs one dia, then that's the way it is. From the pic I see, I would dim per dia only.
I agree with ewh.

Chris
Systems Analyst, I.S.
SolidWorks/PDMWorks 05
AutoCAD 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716