Concentric Holes

Is there an easy way to add a hole concentric with a boss or another
hole?
Also, how do I add a line form the center of a hole, can I snap to the
center?
Using W3.
Thank you
Reply to
COM
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The hole type you are talking about is coaxial. Your boss should have an iternal axis as an extruded, circular feature. You may need to turn on an axis layer to see it. To place a coaxial hole, go to the Type dropdown list and select Coaxial as the type, then pick the axis first, go to secondary references, click in the box to activate selection and pick the start surface for the hole; fill in diameter, depth, etc. and you're done. In fact, you could have picked the axis first, selected the Hole icon and had the coaxial type and axis selected to start.
When setting up sketcher references, use the selection filter (bottom right), set it to axes and pick the boss axis. Your line will snap to this. Even if you do not have this set as a reference to start, you can always use the Constraints palette, pick 'On entity', then the axis and line. Snapping should occur.
Reply to
David Janes
May have to set the config option show_axes_for_extr_arcs if it hasn't been done already. Default is No.
If I may tack on a question: If a feature is created with the option set No is there an axis to show or is it necessary to manually create one?
Reply to
Jeff Howard
This option doesn't change the creation/appearance of arc for extruded, sketched circle. I get this no matter which way the option is set
I did a little investigation, results apply toWF2, not sure about WF3. However, let's start with what this option DOES govern, namely, the creation/appearance of axes on sketched, extruded fillets. The option name is misleading ~ if set to yes, the fillet is created with an axis, if no then no axis is created and would, if needed, have be done manually. It doesn't 'turn' the axes on and off and changing the setting has no effect on existing features, only ones created after the setting is changed. I would guess, though, that most people are happy not seeing axes on sketched fillets. My option was set to yes but I can't recall ever seeing axes on fillets, maybe because I use sketched ones so rarely. I've developed an allergy to them over the years as I've watched other rounds fail on existing, sketched rounds or I've gotten thrown into the dreaded "Resolve Mode" because I accidentally changed a dimension of the rectangular extruded feature to something too small to support the sketched fillets. The worst thing, though, is people who dimension to arc centers instead of to the edge of the actual feature and the reason they do it: they think they are making it easy for the machinist. I had a guy tell me this when I was working in the Motorola Model Shop after I finally asked him why he used that goofy dimensioning scheme. His somewhat huffy answer (as if I should have been thanking him instead of calling him out) was, "Well I'm giving you the centerline of the tool's cut path. It's got a quarter inch corner radius, so you just get a half inch cutter and bump it into the corners." Naturally, I thanked him for the machining lesson. I said I didn't use those manual machining tricks even when I was a manual machinist, but most definitely they were worthless for programming VMCs. I think we finally got settled that he would give me prints with completely defined features and I'd worry about how to do the programming. I guess my point is that I've seen a lot of bad uses (and fewer good ones) for sketched fillets and the axes they produce.
Reply to
David Janes
Thanks, David. I don't disagree. My train of thought ran toward having axes for concentric holes in other than cylindrical boss type features.
Reply to
Jeff Howard
So, sketched fillets so you can use the axis to put a hole concentric with the corner maybe? I'm not sure what else you might be thinking of. While this is handy and I've used it before, it got me in unnecessary trouble by making a fillet far more significant than it ought to have been, and in ways that were unintended, by tying a hole pattern to radius size. Change the radius size and the holes shift. In my case, this wasn't discovered until the parts were made and the screws holding on the cover didn't line up with the the holes on the box. Ooops. And all I was trying to do was make the radius a conventional size.
Reply to
David Janes
A boss with integral rib (text / verbal communication sucks sometimes)? A rectangle or trapezoid where one side is replace with a full rad tan arc. If that was the OP's "boss" (and maybe I'm confused, is that feature a "boss"?) and didn't have an axis to show he'd / she'd be shedding hair on the keyboard so I offered the show_axes... opt setting suggestion. I'm a believer in creating rounds as features, too, but they don't create / show axes either do they?.
Reply to
Jeff Howard
Yup, one of these days, someone's gotta turn this into a binary NG, so no one has an qualms about including pictures or attachments which has been the standard for this type of transient communication for a decade now (in the civilized world that made it past the 80s, at least)
Sounds like a typical slot with rounded ends. .... and
This is where you lost me. Is this a dimensioning problem? It's definitely not a feature creation problem as I just created the feature in two ways: sketch with three point fillet and round feature as surface to surface full round. The former could produce axes, the later, as you point out, not. Pulling hair, I definitely don't get. For quite a while and according to ANSI/ISO, I've dimensioned the width, length and "2X R FULL" of slot: feature completely defined (oh, yeah, and depth, location, etc.). But the length was dimensioned tangent to rounds at widest part. Semicircular round center axes were unneeded and unwelcomed and NOT dimensioned. I can't see anything that you want to do that requires these axes or that would benefit from them or the abscence of which would cause consternation (and yeah, once again, we do really need da PITCHERS!!!)
Reply to
David Janes
Me neither, but
snipped-for-privacy@COM.COM did wrote: "Is there an easy way to add a hole concentric with a boss or another hole?"
Just trying to oblige.
Would be nice but I guess this is good for the verbal communication skills. ';^)
Reply to
Jeff Howard

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