Is it valid on the profile tolerance callout? 1

• Jun 9, 2020

• #2

drawoh

Mechanical

Oct 1, 2002

8,875

SeasonLee,

That makes no sense to me. Does the specification apply all around, or just between[ ]A and[ ]B? Pick one.

--
JHG

 

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• Jun 9, 2020

• #3

chez311

Automotive

Mar 24, 2015

1,426

I would say not. It either applies all-around or between the points specified. It cannot be both - your designer needs to change that, judging by the bottom specification C<->D with the same 0.05 (and with the correct notation ie: no all-around symbol) this is a drawing mistake. Additionally a 0.05 to |A|B(M)| all-around specification would render the other three profile controls redundant.

Looks like you've got there a drawing of a razor blade, don't cut yourself

 

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• Jun 9, 2020

• #4

Sa-Ro

Industrial

Jul 15, 2019

273

Does that all around (without A<->B) over ride, other profile tolerance????

 

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• Jun 9, 2020

• Thread starter
• #5

SeasonLee

Mechanical

Sep 15, 2008

909

Thank you all, I think they need more proof reading.

Season

 

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• Jun 9, 2020

• #6

axym

Industrial

Apr 28, 2003

1,043

Hi All,

I agree, it looks like the all-around symbol was left in by mistake.

I'm sure that the inspectors are going to have fun lining up on datum feature B ;^).

Evan Janeshewski

Axymetrix Quality Engineering Inc.

http://www.axymetrix.ca

 

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• Jun 9, 2020

• #7

cr7

Automotive

Dec 21, 2019

65

axym said:

I'm sure that the inspectors are going to have fun lining up on datum feature B ;^).

Click to expand...

Catastrophe. Nice catch Evan.

@SeasonLee try to push to solve that B also if you only can.

 

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• Jun 9, 2020

• #8

3DDave

Aerospace

May 23, 2013

10,679

Datum Feature B is exactly what positions the item in the next assembly. Pretty easy to do with an optical comparator. For the end user it takes less than one second.

 

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• Jun 10, 2020

• #9

axym

Industrial

Apr 28, 2003

1,043

3DDave,

I agree that it would be straightforward with an optical comparator, if the template had the profile zones and an MMB boundary for datum feature B.

If they are using a CMM, especially one with basic software, then they are going to have some challenges lining up on B in a reproducible way.

Evan Janeshewski

Axymetrix Quality Engineering Inc.

http://www.axymetrix.ca

 

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• Jun 11, 2020

• Thread starter
• #10

SeasonLee

Mechanical

Sep 15, 2008

909

Evan said:

I'm sure that the inspectors are going to have fun lining up on datum feature B ;^).

Click to expand...

You hit the nail on the head.

The author recommend to use the same shape of the mating feature (the single bar in the middle) on the razor handle as datum feature B simulator with a profile tolerance all-around ensures a close fit with all shaver configurations, the picture shown below is the one I searched from internet to reflect the author's concept---how to use complex irregular FOS as a datum feature.

Season

 

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• Jun 11, 2020

• #11

3DDave

Aerospace

May 23, 2013

10,679

As I said, it takes the user a second to line it up.

Who is the "author"?

 

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• Jun 11, 2020

1
• #12

Tarator

Automotive

Sep 20, 2013

176

SeasonLee,

If the entire opening is not used (a bar is used instead), wouldn't the following more appropriate for datum feature selection?

 

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• Jun 11, 2020

• #13

3DDave

Aerospace

May 23, 2013

10,679

The chances they designed a very complicated profile in that opening if the only feature they interface with is a bar is really small. My guess it that there are more designs out there, but I never shaved with replaceable blades so my knowledge of handle variations is limited - however design patents are likely to be held by blade makers to stifle competition and changing the opening is a pretty good deterrent. I see this in the arms race for handheld oscillating cutting tool blades or that goofy thing that D***** dreamed up to increase cutt-off wheel costs.

Interesting article:

https://www.marketplace.org/2015/03/16/why-are-razor-blades-so-expensive/

Tracey Samuelson at marketplace said:

“Razor blades are really, really difficult to make,” says Jeff Raider, the co-founder of Harry’s, a start-up that sells shaving products directly to customers through its website.

Raider says before he started Harry’s, he had no idea how complicated razor production would be or that there’s only a few companies in the world producing blades. He wound up purchasing a German factory in order to get the blades and quality he wanted.

Click to expand...

 

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• Jun 11, 2020

• Thread starter
• #14

SeasonLee

Mechanical

Sep 15, 2008

909

@3DDave & Tarator

As we know, the interior profile of the razor blade is comprised of a series of curved and straight tangential surfaces defined as theoretically perfect in a CAD model, to create an irregular FOS. No matter a regular or an irregular FOS, the datum feature selection will be primarily based on function and assembly consideration, so the single bar picture posted is an idea/concepts sharing only, you may also find out different razor handle with different mating features design from the market.

You may think the single bar as an extension application of <CF>, I will not make a separate <CF> callout.
I like this GD&T forum for the knowledge and concepts sharing, the author is less important.

Season

 

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