Drawing dimensioned using a tooling ball 2

[VasilyR]

Hello,

I'm a mechanical engineering that closely works with our manufacturing shop, and often have to make suggestions on how to properly locate and later inspection parts during manufacturing. Recently I came across a part holes on which need to be dimensioned with respect to another hole. The problem is that the holes that we want to use for locating is on an angle to my target hole, so I can't use the positional tolerance in a standard way. My one thought was to use a Tooling/Machinist Ball to define datums on the drawing. However, that implies that I would have to have instructions on the print explaining what dimension tooling ball to use and how to locate the part in the machine.

In my experience, I've never seen anything like what I'm describing. So does anyone have any input on whether my logic is solid, and perhaps a sample drawing that uses tooling ball for dimensioning?

thanks in advance for your time!

Best,
Vas

 

[MacGyverS2000]

The dimension to other holes is with respect to the center of the ball, so angle should not be an issue. I would think a simple note denoting ball size and collar height would be sufficient for anyone to repeat the measurements. But then again, I don't work with that stuff in my day to day...

See the diagram at the bottom of the page here for an example:

https://www.carrlane.com/catalog/in...006280B1713050245221E0107070F1A3C3B285356425D

Dan - Owner

http://www.Hi-TecDesigns.com

 

[JNieman]

It's extremely common practice to draw a certain diameter gage sphere or tooling ball and dimension to the center of it, or to the farthest point on its surface (or tangent point), whatever makes sense. Sometimes it's the only way to measure taper diameters precisely, or to check the depth of conically tapered features.

I don't know about telling someone to locate it a certain way in the machine. I think that just dimensioning to a tooling ball (or from, if it's a datum) will tell them enough to get it done, and they can figure out the rest.

It's also been pretty common practice to use a set of 3 tooling balls to create a complete datum reference frame. You might have 3 balls, the first origin ball being a cartesian coordinate 0,0,0 with the second ball establishing the X vector and the third ball establishing the Y vector, with all 3 establishing the X-Y plane and typically your primary datum for any holes.

Elaborate tooling might end up having many dozens of tooling balls which make up many datum reference frames.

Tooling balls are great to use whether it's a complicated tooling fixture or a pin/spindle/rod with a precision conical taper in it that you must gage appropriately.

 

[KENAT]

I suggest you post over in forum1103 rather than here, a sketch of what you're trying to do and some information on what drawing standards you work to may also help.

Posting guidelines faq731-376

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

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

 

[GregLocock]

From a practical point of view, having worked in an inspection lab, they are usually cluey enough to work it out for themselves, but would certainly appreciate the double check. I dare say modern CMMs come with standard spherical tips, I am talking old school, slip gages and surface tables.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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

 

[Jboggs]

I would also suggest you repost in that other forum. I would also say it a common thing in my experience to use datum balls for measurement of unusual geometry. I would STRONGLY suggest that you get your "customers" (those who have to use your drawings) involved. Ask them how to best communicate your intentions. This will tell them that you value their judgment. They will appreciate the opportunity to give input, and the end result is more likely to be successful. The real professionals on this forum will agree with this statement: I would place more value on what your customers say than anything I read in an online forum.

 

[MacGyverS2000]

Never even noticed this was in the wrong forum... guess I look at way too many.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[VasilyR]

Hello all,

Thanks for the input. My first time posting, so in the future I'll be more careful about where I post.

From your input, and from what I found in my research, I have enough info to continue. I didn't mention this in the beginning, but I am the "customer" who got the drawing. The client was asking for an input, and I was trying to be thorough when responding to them.

Thanks again!