Questions on connector cut out 2

[KENAT]

I’m looking at a bracket that has a couple of mating pairs of D type connectors that mount to it. The location of the cut outs in the bracket isn’t too important but the size/shape of the cut-outs, and the holes associated to the cut-outs are more critical. See attached sketch.

I’m thinking this is an ideal case for composite profile like ASME Y14.5M-1994 fig 6-25 for the cut-out. However, I’m not over confident on then relating my holes to follow the cut-out. I found a similar example in some training material from Gary Whitmire but my cut out is a lot more complex and I don’t fully understand the datum structure regarding use of D-E rather than D|E.

Q1: Which of the hole feature control frames in my sketch makes more sense or is there another better way.

Q2: Where symmetrical I’ve given overall dimensions for the cutout, like you would for a simple slot. However some of the examples around here that my previous checker did have additional dimensions to relate the overalls to the ‘center’, e.g. a .656 dimension from the center to one of the holes and similar for the width and height of the slot. Are these extra dimensions really needed?

(Please note I haven't properly calculated the values of the positional tolerances yet, I probably should have made them the same for the sketch.)

Thanks.


KENAT, probably the least qualified checker you'll ever meet...

 

[TheTick]

Sorry. I see you had to write it twice. Didn't read slow enough the first time.

 

[KENAT]

OK, I got caught up on other emergencies and now am back to this.

I've looked at the spec, the links and tried to incorporate what various ones have said.

I also found another more recent drawing which appears to use nominally the same connector cut out but has slightly different dimensions so I've adjusted my drawing to be closer to that. (Connector is on vendor cable who aren't currently in contact with - don't ask - so going back to the source would be time consuming).

So what say you all, it's a bit over the top by some reckoning but I've used it as a learning experience as well as trying to be thorough.

So, marks out of 10?

KENAT, probably the least qualified checker you'll ever meet...

 

[Xplicator]

Kenat,
Here are my comments on the latest rev.

Change 4X to 2X on the mounting hole pattern

Drop the tertiary "A" on the surface profile since it is already covered with "D"

I am bit torn on the added notes, may I suggest substituting what you have written next to the datum and FCF for "2X SEPARATE REQUIREMENT" under Detail A.

Ultimately, however I believe the cleanest most unambiguous method would be to just specify using position and profile on the second cutout and holes wrt to datum "C"& "D". You may gain something in the way of a stack, but I truthfully don't see where that will functionally get you.

 

[MadMango]

I have a problem with the basic 2X 3.500 being called out from the bent flange in the lower RH view. You'll get less rejection if the d-sub cut-outs are dimensioned from the part edge. There must be dims that already locate the tab these features are being placed in.

"Art without engineering is dreaming; Engineering without art is calculating."

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[KENAT]

I think you're correct that putting the number of holes in in the detail view like I did is unclear.

Is the Tertiary A not still needed for orientation?

The added notes are straight out of the standard, sort of. In 14.5 I believe it only talks about using this for C'bores like in fig 5-39 however the link Powerhound gave suggests my use is legit..

I wondered about referencing the 'left hand' holes to the datum hole. Last night I decided against it but now I'm wondering again.

Maybe this is one of those cases where there isn't a 'one size fits all' solution that the majority of people can agree on.

KENAT, probably the least qualified checker you'll ever meet...

 

[ringman]

Kenat,

One thing that I might question is the use of a 4 place basic dim to locate the centerline when a 3 place to one of the holes would seem more appropriate.

 

[Xplicator]

Kenat take a look at the markup I attached. This makes the most sense to me.

 

[KENAT]

Mad, functionally that face is the datum, I'd hope they can hit +-.05 on the position of the cutouts, and overalls are +-.03. In fact from a function point of view it should perhaps be -A- but as a concession to inspection I made it -B-.

ringman, I'm not a fan of that 4dp either especially as dimension and tol dp should match. Comes from a dimension scheme designed to be centered on the middle of the cutout, not from one of the holes. In reality .0005 either way probably isn't gonna matter but I hate just rounding and not actually drawing/modelling it like that.

KENAT, probably the least qualified checker you'll ever meet...

 

[Xplicator]

Kenat, I would additionally tighten the tolerance to a capable range to be used on the subsquent connector cutout/hole features again wrt C|D

 

[KENAT]

Mad, sorry I just noticed I don't have anything near +-.05, not sure what I was thinking. I've loosened the tol to dia .085 which is about +-.03.

Xplicator thanks for the redlines, I've looked them over. I'm still keeping the tolerance scheme based on 5-39 in the standard and this link

http://www.tec-ease.com/tips/march-01.htm

but incorporated some of your other points. Datum C in the lower half of the composite FCF was meant to be C, not sure what went on there.

Everytime I look at it I doubt myself or have another idea, and almost every post above has variations on how best to handle it so, having mulled it over I've arrived at the attatched. I had my boss look at it but he just got back from an unscheduled dentist appnt so isn't on top form.

I guess the proof of the pudding will be if the vendor has any concerns/crazy pricing.




KENAT, probably the least qualified checker you'll ever meet...

 

[powerhound]

KENAT,
Sorry, I just scanned over this thread again and noticed I hadn't answered your question about whether or not I was sure about my contention that the profile of your cutout would be pretty jagged.
Looking at Fig 6-25 you will notice the 0,1 wide tolerance zone located within the 0,8 tolerance zone. Without orienting the profile to datums B or C that 0,1 wide tolerance zone can float anywhere within the 0,8 tolerance zone and still be good. That applies to every linear element, so while the view shows the profile that is perp to datum A a little closer to the bottom than the top, if you move 1mm further along the profile, the 0,1 tolerance zone can be completely up at the top of the 0,8 zone and as long as the perp is still within the 0,1 zone it will still be good. Move another 1mm along the profile and the 0,1 zone can be totally shifted to the bottom and as long as the profile is within the 0,1 zone it's still good.
If you look closely at Fig 6-25 you'll notice that the 0,1 tolerance zone is not centered within the 0,8 zone, it's actually all over the place just to show that the only profile that's oriented is the 0,8 true profile zone, the 0,1 zone can float anywhere within it at any point and the only thing the 0,1 zone is controlling in this example is the perpendicularity.

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[KENAT]

Thanks Powerhound.

KENAT, probably the least qualified checker you'll ever meet...