What is "No Chamfer" 3

[PeteratPSP]

We are a contract manufacturer and I run into the same issue over and over.
What is the minimum chamfer allowance on a drawing callout for (No Chamfer)
Is there a measurable and or standard?

 

[KENAT]

If 'no chamfer' is called out then any chamfer present would have to be within the tolerance of the relevant surfaces, if fact even if it doesn't explicitly say 'no chamfer' this is the case.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[PeteratPSP]

Thanks
Is this information based on any standard and if so what standard.

 

[KENAT]

ASME Y14.5M-1994, however, what matters is what standard the drawing references.

For ISO it might be different as envelope principal does not apply - one to ponder on.

Note, it doesn't explicitly say what the definition of 'No Chamfer' is or similar. I'm simply extrapolating from ASME Y14.5M-1994 para 2.7.1

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[MikeHalloran]

"I", speaking as your customer, am the standard.

No particular callout, uos, means I don't want a chamfer or edge break, and I don't want a burr, either. If I want a chamfer or a burr, I will put them on the drawing, with a dimension and a detail drawing if appropriate.

The callout "no chamfer", means that I am damn sick and tired of the apes in your factory "knocking off the edges" with a 60 grit snag grinder, and I am not going to buy any more product like that.


Mike Halloran
Pembroke Pines, FL, USA

 

[KENAT]

Mike brings up a good point, sometimes it might mean they want a sharp edge - though almost certainly not a burr.

When the definition of something on a drawing isn't clearly defined by a referenced standard or similar then you should probably ask your customer.

Now, don't get me wrong, you may have a legally defensible stance using what I say above, but it may not do much for your customers opinion of you.

Alternatively, you could put in your quote what you take "NO CHAMFER" to mean. However, again while legally it may hold, it may not do much for customer service.

The whole area of edge breaks is one that's surprisingly poorly addressed in any standard I'm aware of. I had someone asking me questions about it today. There are devices that will test if something is a 'sharp edge' they're basically some kind of tape roll you run along the edge and if it cuts the tape then it's a 'sharp edge'.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[CheckerHater]

ISO 13715 makes attempt to regulate workpiece edges.
It provides terminology, examples, graphical symbols, and recommended tolerances.

Generally, having more material then shown on the drawing is called “burr”, less material “undercut”.
According to the standard, if no state of the edges is specified, part may be delivered “as is” directly from the machine, without any edge treatment.

Burr size of +0.02…+0.05, and undercut size of -0.02…-0.05 are considered “sharp edge”.

Unfortunately all of the above is based on textbook rather than real standard.
Anybody from ISO background, especially in the possession of standard book, please confirm or disprove.

 

[pmarc]

Here is the content of introduction to ISO 13715:2000 dircetly from the standard:

"In technical drawings, the ideal geometric shape is represented without any deviation and, in general, without consideration of the states of the edges. Nevertheless, for many purposes (the functioning of a part, or out of safety considerations, for example) particular states of edges need to be indicated. Such states include those of external edges free from burr, sharp edges or those with a burr of limited size, and internal edges with a passing. In principle, all the edges of a part should be produced in their requisite states. In practice, unless those states are specified in the technical drawing or related documentation, the part will be delivered direct from the machine without the required treatment.

This International Standard is aimed at enabling this situation to be avoided, through specification of guidelines for the indication and graphic representation of the states of edges in technical drawings."

 

[MintJulep]

What it means is that you have quoted to an ambiguous drawing.

Call the customer. Tell them that you want to give them what they want, if they could only explain exactly what they want is.

Don't talk to the buyer. Talk to the responsible engineer or designer.

 

[ewh]

Is there a general note covering edge breaks on the drawing?
It seems to me that the customer is wanting sharp corners, though I don't understand why it isn't being specified as such. I agree with the others; ask the customer to elaborate.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[ptruitt]

Rather than saying "NO CHAMFER", why not use gd&t form call-outs on the intersecting surfaces?

Peter Truitt
Minnesota

 

[dgallup]

We always have a default maximum edge break on a drawing & if I want something different I'll explicitly call it out. When I put no edge break on a corner I expect NO EDGE BREAK. Usually this is on a surface that requires special processing such as lapping to produce it with out a burr. We generally inspect such parts under a microscope at 20x magnification. It's always specified explicitly in the notes. Anything less and you have an ambiguous drawing. Call the customer.

 

[powerhound]

I don't read anything ambiguous about "No chamfer." To me, it means just what it says. There is to be no chamfer.

Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[fcsuper]

It may also be another way of saying "do not break edges". I agree with Power. I do not find the term ambiguous either.

Matt Lorono, CSWP
Lorono's SolidWorks Resources & SolidWorks Legion
Follow me on Twitter

 

[MintJulep]

Specifying what you don't want is not the same as specifying what you want.

Me: "What would you like for dinner?"

Wife: "Not Italian food."

 

[looslib]

In your context, you are right.
When a drawing says 'No Chamfer', it means just that. Most drawings have a general note saying that no burrs are allowed or break all sharp edges .005 max. The concept 'No Chamfer' doesn't bother me, especially if it is pointing to a specific edge.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[ptruitt]

Rather than saying "NO CHAMFER", why not use gd&t form call-outs on the intersecting surfaces?

Peter Truitt
Minnesota

 

[KENAT]

I'm not sure GD&T would do a better job, what are you going to do apply a ridiculously tight composite profile tolerance around the corner?.

I was wondering if there's a difference between 'do not break sharp edges' and 'no chamfer'.

I'm definitely second guessing my initial response, but I'm just not 100% sure that 'no chamfer' over rides the variation allowed by the tolerance of the surfaces.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[ptruitt]

Kenat,

I think this situation is handled well by ASME GD&T. After all, the posting is here because there is an 'issue' and there are quite a few varied opinions. I hear that ASME and ISO are different when it comes to the transition of two form control boundaries. It might be handled as simple as flatness intersecting perpendicularity or as explicit complex as non-linear profile boundary lines. We should ask: What is the design intent?

Peter Truitt
Minnesota

 

[MikeHalloran]

Appearance of a "NO CHAMFER" notation on a drawing, in my experience, ALWAYS implies that the customer already tried not specifying a chamfer, and some idiot "did them a favor" by "just knocking off the edge", completely ruining the part (or a large lot of expensive parts) for the intended application.

It further suggests that they are wits' end, and if you send them one more chamfered part, not only will you not be paid for it, but they will also send in a squad of very intimidating "Quality Control" people who will comb every square inch of your plant and kill anyone in possession of a chamfering tool.

It is, in other words, your last warning.


Mike Halloran
Pembroke Pines, FL, USA