I'm sorry, I was assuming (one should never assume)that most members of this forum knew that the 2008 draft was available by reading the November 7th thread. I have just received the new ASME Y14.5M-2008 dimensioning and tolerancing draft ($85) from ASME. I was hoping someone would know the answer to my question who may have been attending the ASME meetings or who would just know the answer.
Thanks vigildesign - For those who do not have a copy of the Y14.5 draft, the illustration 1-35 in the present standard has been removed from the 2008 draft. This is OK, we will still have figure 1-27, 1-28, and 5-47 shown in the present standard for dimensioning sloted shaped features. What we will not have is dimensioning to the center of the slot with a ± tolerance for punching sheetmetal.
Interesting, just a few weeks ago I was looking at these illustrations trying to decide if the standard contradicted itself between para 1.8.4 & figure 1-35a.
KENAT, probably the least qualified checker you'll ever meet...
Kenat:
You just addressed what I think is one of the anomolies of the standard. Why talk about fully rounded ends when it duplicates the slot callout of Fig.1-35? Personally I champion use of Fig. 1-35(c) (and Fig 1-27) as the best way to dimension slots for end product and inspection. Fig. 1-35(a) is basically "in-process", and should only show up on manufacturing planning and routings.
I know I'll get disagreement on that one.
WhitmireGT is right in that Fig 1-35(b) is centered to accomodate slot punching, and should be kept for that reason. Off thread topic, I know.
Ron, that's pretty much my thinking, except I'd say why have a section talking about slotted holes when it just duplicates what you've said about generic round end features, or am I missing something?.
I think 1.8.4 covers it and matches figures 1-27, 1-35b & 1-35c. Fig 1-35a doesn't match para 1.8.4.
To me, based on what it says at 1.4 then when there appears to be a conflict between a figure and the text, I go with the text, so I discourage schemes like 1-35a.
Our of interest in the draft does the equivalent of 1.8.10 just refer to 1-27 or is there no illustration or is the whole para removed?
KENAT, probably the least qualified checker you'll ever meet...
The 2008 Y14.5 draft is screw up on the subject of slots.
Figure 1.8.10 is replaced by 1.8.4 Rounded End and Slotted
holes states: ..."using one of the methods shown in Fig. 1-29..." Figure 29 has only one example (was 1-27). Figure 1-29 should have been the same as 1-35 in the Y14.5-1994 standard. The bottom line is the text and figures are all mixed up.
So Gary, out of interest do you think that fig 1-35(a) (current standard) is a good way to go with for slots?
I'd be concerned about possible tolerance build up on the length and I'd think that it doesn't support inspection as well as the other 2 methods in fig 1-35. However I'd love to have my error explained to me.
KENAT, probably the least qualified checker you'll ever meet...
Kenat - My gut feel that the Figure 1-35(1994) will be removed, and the text will be corrected. If we want to position a slot, we will need two position callouts using the word "BOUNDARY" as shown in Figure 5-47(1994). If Figure 1-35 is reinstated and the middle illustration dimensioning the center of the slot with ± dimensioning, then we will know how to locate the center of a "D" shaped hole in sheetmetal without using position boundary and profile as stated in Figure 6-19(1994)which is an overkill. A "D" shaped hole will a detail view to dimension the shape and center.
Kenat - My gut feel that the Figure 1-35(1994) will be removed, and the text will be corrected. If we want to position a slot, we will need two position callouts using the word "BOUNDARY" as shown in Figure 5-47(1994). If Figure 1-35 is reinstated and the middle illustration dimensioning the center of the slot with ± dimensioning, then we will know how to locate the center of a "D" shaped hole in sheetmetal without using position boundary and profile as stated in Figure 6-19(1994)which is an overkill. A "D" shaped hole will need a detail view to dimension the shape and center.
WhitmireGT: You didn't answer KENAT's question regarding
"a good way to go for Fig 1-35a?" (were talking current 1994 std, not the new draft).
I only use Fig 5-47 for full slots and sometimes Fig 1-35c for open ended (U-shaped) slots, breaking out into the end of a part. I get a lot of resistance from Design who get mad because it forces them to model and dimension slots differently.
Yeah, to my mind 1-27, 1-35c & 5-47 are essentially the same dimensioning technique for the features themselves. 5-47 just extrapolates it to use with positional & boundary. 1-35b is also more or less the same though it does show the center lines.
1-35a however just seems like bad practice. The tolerance on the width is a factor of 2 dimension tolerances, the distance of centers and the width of the slot so to closely control the length you may end up with excessively tight width & centers. Also it doesn't support inspection as well.
KENAT, probably the least qualified checker you'll ever meet...
Sorry KENAT and CheckerRon, my brain was on the 2008 standard. I also don't like 35a because inspection needs to find the center of two radii and determine if the centers fall within the 14 length/tolerance. The other two examples of Figure 35 are a much better choice of the three if one can rely on good workmanship. A workmanship guide may be in order for all non-GDT dimensioning. A workmanship guide will provide rules for making parts that looks like the drawing for orientation, rule #1, and implied relationship of one feature to another, to list a few. A workmanship guide is prepared by a group of manufacturing and engineering personal. One reason to use dimensioning per Figure 5-47 is the use of a functional gage to measure the position and orientation of the slot. Functional gages do not measure MMC size unless zero position is stated.
I have mixed feelings in dimensioning slots on a bracket using general dimensioning and using position with the boundary callout. My primary concern is supplier bid cost.
