slot call out 2

[proEdj]

What is the best way to call out a slot? I have used basic dimension to reference the true center of the slot from 2 perpendicular datums. Then I called out the width of the slot and the height (the length from one tangent line off the full radius to the other tangent line) using standard dimension with tolerances. Then I called out the "2 X Full Radius" and also had a positioning block calling out diametric position of the center of the freature. Does this sound correct?

 

[ctopher]

In our dept, we each have a copy of ASME Y14.5M-1994, and follow it.

Chris, Sr. Mechanical Designer, CAD
SolidWorks 05 SP3.1 / PDMWorks 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716
FAQ1010-1130

 

[ewh]

drawoh,
It is interesting to read up on old practices, and perhaps understanding the evolution of standards. The first drafting book I was taught from was by French and Verrick, and the section on descriptive geometry is as valid today as when it was written. Fortunately, we don't have to sweat that anymore.

 

[proEdj]

Everyone,

Thanks for all you comments.

ProEdj

 

[RedPen]

All,
IMHO "FULL" when applied to radii appears to have come from sheet metal shop practices and, of course, typically means the ends of the radii are tangent to the parallel sides of the slot (diameter of punch equals width of slot) or "FULL WIDTH". This allows production of the feature without having to make/buy the specific slot punch. 2 round holes connected by one or more square or rectangular punch hits produces the equivalent feature.

If the punch diameter were larger than slot width it produces a "dog bone". If it is smaller, it produces a "hotdog". Both leave sharp corners at the transitions. "FULL R" eliminates these undesirable sharp corners.

 

[Tunalover]

drawoh-
I've got an oldie but goodie too: FAN ENGINEERING, 1931, Buffalo Forge Co. There's more knowledge of forced air cooling wrapped up in that one book than anywhere else!



Tunalover

 

[SrGilberto]

A slot, by nature, would normally need different tolerances differing horizontal to vertical. That's why in the standard you normally see composite feature control frames to specify the tolerance around the true position of a slot.
The orignial question by Proedj seemed to indicate that he wanted a diametrical tolerance zone. I question that if one has a diametrical tolerance zone, why would someone place a slot there? I think the proper way to specify a slot tolerance zone is with a rectangular tolerance zone prescribed by a composite feature control frame (IMHO).

Regards,
SrGilberto

 

[Tunalover]

proEdj-
SrGilberto hit the nail on the head. You need the ability to provide tighter control in one direction than in the other. You certainly don't need to exert the equal control in all directions as with cylindrical tolerance zones.

If you consult ASME Y14.5M-1994, you'll see that the slot is used as an example on how to get geometric bilateral tolerancing using feature control frames. Basically, the feature control frame looks just like one would normally use for hole patterns but the diameter symbol is omitted.

Bruce Wilson's book DIMENSIONING & TOLERANCING HANDBOOK has good examples and explanations too.




Tunalover

 

[ewh]

A star for SrGilberto for catching that! A diametral tolerance zone is usually overkill for a slot.

 

[Hydroformer]

Touche...

But, check the stack. The slot may be there to allow compliance of the mating component. The increased tolerance zone may take you outside the stack.

*Without data, you're just another person with an opinion.*

Hydroformer

 

[templetonc]

Ok, there are three ways according to ASME standard to call out a slot hole. One of the ways is individual dimensioned length, widith and with a blank radii. In this type of call out where do you put the depth?

 

[drawoh]

templetonc,

My prefered depth specification would be applied to the side view that was projected right next to my slot dimensions. This makes everything clear.

I would reluctantly recognize and accept the ANSI depth symbol and a numerical value applied to the length or the width of the slot. This saves you the extra view. I would be curious about how your depth value got there. Typed-in dimensions are bad practice in CAD, especially 3D CAD like SolidWorks. There are ways to do it right.

Once you have saved yourself the extra drawing view, it is possibly some machinists duty to call you up and waste a half hour of your time asking stupid questions about the drawing.

JHG

 

[ewh]

drawoh,
When I have a dimension such as this type of depth, I dimension from a side view, turn off the dimension lines, extension lines and arrowheads, and locate the dimension with the slot callout. It's associative and works great until the views get moved around. I agree that manual dimensions are tools of the devil.

 

[templetonc]

I am still learning. I was able to fit another view on the page and my checker was happy with it.

 

[drawoh]

ewh,

I have done what you describe, using AutoCAD. This is one of the ways to do it right, although you are relying on co-workers to be observant, and as clever as you are. I have been burned.

In SolidWorks, you can write a note and attach dimensions by clicking on them. Once the note is attached to the feature, everything is associative, and everything follows any drawing updates you do. You have to hide the dimensions of course!

JHG

 

[wgchere]

I remember when "FULL" was dropped. It was changed by ANSI Y14.5M-1982. It probably had to do with ISO standards and they dropped it. It was extraneous anyway, since the standard states that if a drawing appears to be tangent/right angle/etc. then it is if there is no notation to the contrary. Thus, if a slot doesn't show a sharp corner or a step between the radius and the straight edge it is by default interpretation, tangent and is also a "full" radius.

Boy! this standards stuff is better than Bible-bashing!

 

[Tunalover]

Folks-
Honestly I don't understand why all this dialog (and thread) is necessary. The methods for dimensioning slots are clearly shown in Y14.5M.


Tunalover

 

[ctopher]

I agree. I think all companies should have a set of ASME/ANSI stds for ref...and follow them.

Chris
Sr. Mechanical Designer, CAD
SolidWorks 05 SP3.1 / PDMWorks 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

 

[smcadman]

What about slot depth callout? I just had 200 ft of square tubing slotted with laser, but I didn't put THRU because THRU is assumed unless otherwise specified. Only 1 face was slotted, and it has to be returned to have the far side slotted.

For clarity in the future, I will put "NEAR SIDE ONLY" or "THRU", but is the assumed THRU for holes only and not for slots?

Flores

 

[Tunalover]

No. THRU is by default for all features. Your note should say NEAR SIDE but the words "THRU" or "ONLY" are are unnecessary. If the feature were blind, you would have simply included the depth symbol (downward arrow).


Tunalover

 

[ringman]

I believe a slot is a hole. according to the Y14.5 if it is not clearly illustrated as a thru 'hole' it should be labeled as "THRU".