Is it valid on the profile tolerance callout? 1

[SeasonLee]

Hi all

I'm wondering if it is valid to apply the all around and between symbol at the same time on a profile tolerance callout,
or are there anything that I missed here? Please ref to the picture below.

Season

 

[drawoh]

SeasonLee,

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

--
JHG

 

[chez311]

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

 

[Sa-Ro]

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

 

[SeasonLee]

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

Season

 

[axym]

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

 

[cr7]

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

Catastrophe. Nice catch Evan.

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

 

[3DDave]

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.

 

[axym]

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

 

[SeasonLee]

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

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

 

[3DDave]

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

Who is the "author"?

 

[Tarator]

SeasonLee,

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

 

[3DDave]

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/

“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.

 

[SeasonLee]

@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