Pattern Problems

[Anonymous]

OK, first let me say I've done this before but not that often. But I need to pattern a feature(s) at a specified distance apart and along a specified distance of length. As you can figure I want them equally spaced at "X" along the distance of "Y". Thus if "Y" changes the number of features will be adjusted. The problem I'm having is no matter what I select as a driving factor of the "X" or the "Y" from the pulldown menu, it doesn't calculate correctly. Any ideas? As I said, I've accomplished this before, just don't recall how.

[Anonymous]

JimO,

In the Rectangular Pattern dialog:
Use the "Spacing" option (not "Distance" or "Curve Length")
Set Count = (Y / X) + 0.5
Set Spacing = X

Tom Sturtevant
Inventor Part Modeling


"JimO" wrote in message
news:f18d725.-1@WebX.maYIadrTaRb...
OK, first let me say I've done this before but not that often. But I need to
pattern a feature(s) at a specified distance apart and along a specified
distance of length. As you can figure I want them equally spaced at "X"
along the distance of "Y". Thus if "Y" changes the number of features will
be adjusted. The problem I'm having is no matter what I select as a driving
factor of the "X" or the "Y" from the pulldown menu, it doesn't calculate
correctly. Any ideas? As I said, I've accomplished this before, just don't
recall how.

[Anonymous]

Change the distance (X) to be Y/(number of reps -
1)?

Rui

style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">

"JimO" <
href="mailto:joflaherty@fastindustries.com">joflaherty@fastindustries.com>
wrote in message
href="news:f18d725.-1@WebX.maYIadrTaRb">news:f18d725.-1@WebX.maYIadrTaRb...

OK,
first let me say I've done this before but not that often. But I need to
pattern a feature(s) at a specified distance apart and along a specified
distance of length. As you can figure I want them equally spaced at "X" along
the distance of "Y". Thus if "Y" changes the number of features will be
adjusted. The problem I'm having is no matter what I select as a driving
factor of the "X" or the "Y" from the pulldown menu, it doesn't calculate
correctly. Any ideas? As I said, I've accomplished this before, just don't
recall how.

[Anonymous]

Tom, maybe I'm missing something but what you suggests gives me way more instances than I need. Here's the specifics in hopes it'll clarify: I have a length of 45.50" ("Y"), I need the spacing of each feature to be 1.50" on center ("X") for the length of "Y" to where if "Y" changes the spacing of "X" stays but the number of instances will adjust to the change in "Y".

[Anonymous]

Ok, funny thing happened on the way to the theater....I did exactly as you described....I got about 3 times more than I needed. Tried the same specs but changed to "distance" and "Curve Length" those gave me very close to what I needed but wasn't exact (was off between .069 and .017 respectivly). Then just for #%$^ and giggles I selected Spacing again as you mentioned...never changed a spec whatsoever and BOOM!!!! PERFECT!!!!!!!! Rest assured, the next time I do this I will be sure to have my pen in my mouth, sitting on the edge of my chair and Grand Funk Railroad playing on the radio station....:) Thanks Tom.

[Anonymous]

Similar to
above

size=3> 

Set Count = (Y
/ X) + 1
Set Spacing = X

Making sure that Y is divisible by X

Y=4, X=2 then count =3

Y=20, X =2 then count = 11

Y=30, X=2 then count = 16

Kathy Johnson

[Anonymous]

Using Count = (Y / X) + 0.5 causes a "round down" when Y is not divisible
by X.

Y=5.5, X=1 Count = (Y / X) + 0.5 = 6; Count = (Y / X) + 1 = 7

Tom Sturtevant
Inventor Part Modeling

"KJohnson" wrote in message
news:B82B5F6679A989F071C3D66496FD87DF@in.WebX.maYIadrTaRb...
Similar to above

Set Count = (Y / X) + 1
Set Spacing = X
Making sure that Y is divisible by X
Y=4, X=2 then count =3
Y=20, X =2 then count = 11
Y=30, X=2 then count = 16

Kathy Johnson

[Anonymous]

Ahhh. Thanks for the clarification.

Kathy Johnson

[Anonymous]

I hate to be a pain but while this does work for this case, I now see it will not work if the length changes.
For example it is @45.5 now which requires the formula of (45.5/1.5) + 0.5 but if the length changes to say 46 then the formula would have to be changed to be (46/1.5) + 1 and so on. Am I correct? And then again if the length does change to something that is in fact divisible. Am I missing something here or has my original idea been over looked/misunderstood?

[Anonymous]

One more issue....although the stated formula does work...it's not perfect as far as my needs/wants...here's why. Although the spacing between features is now accurate, it is not over the length. At the start, it's perfect, but at the end, it's off...in other words, the last instance is not the correct or same distance from the end as the first instance is. In this case, both need to be .5" from the ends. Am I missing something? Chances are I am, but I can't get this right. One last time....the total length of the part is 46.5" I need the features 0.5" in from each end, giving me a total length of 45.5" for the pattern of these features at a distance from eachother on center at 1.5"......something that should be so simple is making my head hurt. Ugh!!!!

[Anonymous]

CURVE LENGTH!!!!!! CURVE LENGTH!!!!!! THAT'S THE TICKET!!!!!
Ok, pardon my excitement. You must select "curve length" as your option for the above to work, not "spacing" or "distance". Whoa!!! Glad we got to the bottom of this one....geez.....I think I'll be sending my resume to AutoDesk....;) (actually I'd love to if you could locate me in CT)...hint, hint.

[Anonymous]

JimO,

I think the basic problem you have is that 45.5" is not a multiple of 1.5".

With the "Curve Length" option, spacing is computed as length/count. When
the curve length changes the count will be fixed and the spacing will
change. To keep the spacing fixed you need to use the "Spacing" option, and
have Count be a function of Length and Spacing: Count = (Length / Spacing) +
0.5

Tom--
Inventor Part Modeling

"JimO" wrote in message
news:f18d725.9@WebX.maYIadrTaRb...
CURVE LENGTH!!!!!! CURVE LENGTH!!!!!! THAT'S THE TICKET!!!!!
Ok, pardon my excitement. You must select "curve length" as your option for
the above to work, not "spacing" or "distance". Whoa!!! Glad we got to the
bottom of this one....geez.....I think I'll be sending my resume to
AutoDesk....;) (actually I'd love to if you could locate me in CT)...hint,
hint.

[Anonymous]

Ugh!!! Tom.....I just thought I had this all fixed and then you throw a wrench in it and spoil my day.....Ok, not really. I think I see what you're telling me. I will give it all another try in the morning. Thanks.

[Anonymous]

Having read all of the responses to your original question, I think that there is only one way to get what you are after. The problem is that the pattern is fixed on the first instance- you can't keep the 1.5" spacing and have the two end features have the same distance to the end of the part, correct?

The only way I found around this was to work from the center of the part. Dimension your first hole as 1/2 the total distance of your pattern, and then create the pattern. That way your equally spaced pattern will always be centered on the part. Not very graceful, but I think it will do what you are asking.

[Anonymous]

Dan,
One caution on this approach. I've run across a number of parts where the
centered pattern is created as a single "rectangular" pattern with the 2nd
direction opposite to the first, resulting in a lot of overlapping
occurrences. Let's say you want a row of 19 Holes spaced 1" - the original
is modeled in the center position. If you create a rectangular pattern with
direction2 opposite to direction1, count1 = 10, spacing1 = 1", count2 = 10,
spacing2 = 1" the result will *look* correct, but Inventor has generated
100 holes most of them overlapping. To visualize this, set direction2 to be
not quite opposite direction1 (try 175 deg) - now you can see all 100
occurrences. They will still be there when direction2 is 180deg to
direction1. (You can also see them in the browser if you expand the Pattern
entry.) These extra pattern occurrences obviously degrade the performance
in the part.

One solution is to set count2 = 2, spacing2 = (count1 - 1) * spacing1. This
still leaves one occurrence overlapping on top of the original. Another
solution is to create two patterns.

Tom Sturtevant
Inventor Part Modeling

"dan_mayers" wrote in message
news:f18d725.12@WebX.maYIadrTaRb...
Having read all of the responses to your original question, I think that
there is only one way to get what you are after. The problem is that the
pattern is fixed on the first instance- you can't keep the 1.5" spacing and
have the two end features have the same distance to the end of the part,
correct?
The only way I found around this was to work from the center of the part.
Dimension your first hole as 1/2 the total distance of your pattern, and
then create the pattern. That way your equally spaced pattern will always be
centered on the part. Not very graceful, but I think it will do what you are
asking.

[Anonymous]

???
I think I didn't make myself clear. If you dimension your first feature from the center point, and set that dimension to 1/2 of your pattern distance (d34 or d(hole count)*d(hole spacing)or whatever), then you shouldn't have a problem. I have several parts that I use this technique on and it seems to be working quite well.

Ah, ok- not enough caffeine this morning- you were thinking that you put the first feature on the center and then array out in both directions? That won't work in general because it will fail if you have an even number of features. (You have seen people do this? Have to give them points for creative thinking...)