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*Expert Elite*
JDMather
Posts: 26,166
Registered: ‎04-20-2006
Message 31 of 65 (367 Views)

Re: Posting a project for comments

05-04-2012 01:00 AM in reply to: donovandigital

donovandigital wrote:

Completed nut - did not seem to have posted last time


You missed a couple of steps and didn't even ask questions about them.

I specifically said to add a vertical constraint to one of the vertical lines - but you ignored this step.

I specifically said to drag the center point of the hex away from the origin and then back and note the color change of the sketch.  You ignored this step and didn't ask what I meant.  (this was an extra step that would not be required if you started from scratch and let Inventor do the work for you.)


Note that in the lower right corner of the screen that Inventor indicates that you still need dimensions (geomemetry constraints like vertical, horizontal or tangent can actually replace many dimensions).

 

constraining.pngWhen you follow my original instructions this will say Fully Constrained.  It might seem like extra work - but once you learn Inventor it will do most of this work for you and can save you a ton of work downstream.  I used to work out on the shop floor and I can tell you that missing dimensions are very expensive and the first thing a machinist does is fully constrain (dial in, indicate, zero......)  - changes on unconstrained geometry are unpredictable and costly.

Please mark this response as "Accept as Solution" if it answers your question.
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*Expert Elite*
JDMather
Posts: 26,166
Registered: ‎04-20-2006
Message 32 of 65 (366 Views)

Re: Posting a project for comments

05-04-2012 01:12 AM in reply to: JDMather

On to the board.ipt

 

Edit Sketch1

Right click and select Show All Constraints.

 

See all of those constraint glyphs?  Zoom in on them and investigate what they mean (you can click on them to highlight the geometry involved).

 

Ever written the steps to do something?

Imagine you are writting the program you will call "Inventor".

Write the steps (program) that should be followed to solve for each one of those geometry constraints.
Where should the program start?

What is priority?

You have 10 of the same constraint, now what is priority?

Hmmm, this is getting very complicated.....  file getting slow.  .... only one part out of many in an assembly.....  things start crashing.....  Inventor must be crap, I'll go use brand x SoftWare.   (you are going to see the same thing there as the logic involved in the problem is the same)

 

No!

 

Keep it simple.

 

Start with a rectangle centered at the origin as described here

http://home.pct.edu/~jmather/skillsusa%20university.pdf  (release 2013 makes this easier).

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*Expert Elite*
JDMather
Posts: 26,166
Registered: ‎04-20-2006
Message 33 of 65 (364 Views)

Re: Posting a project for comments

05-04-2012 01:18 AM in reply to: JDMather

So.

We see all of the constraints.
What about the dimensions (that you ignored).

 

Where did this number come from?

When something like this gets out to the shop floor you will lose all respect.
Use logical dimensions.

Use dimensions.

 

oddball.png

 

(at about this point - I can't help wondering what was taught in class.  Are you paying for this class?  Your parents?  The taxpayers (me)?)

Please mark this response as "Accept as Solution" if it answers your question.
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*Expert Elite*
JDMather
Posts: 26,166
Registered: ‎04-20-2006
Message 34 of 65 (361 Views)

Re: Posting a project for comments

05-04-2012 01:29 AM in reply to: JDMather

Let's start this part over from scratch.

 

As a beginner I recommend that you right click on the origin Center Point and make it Visible.

Use this for symmetry.  Most of the natural world is symmetrical.  You have two arms, two eyes....

Use logic.

 

Create a rectangle near the center point (in 2013 on the center point) and dimension as  shown.

Create diagonal construction line (do you know how to change linetype?).

 

rectangle.png  Add a coincident sketch constraint between the origin and the midpoint of the diagonal line. 
Question - what happened to the color of the lines when you did this?

Please mark this response as "Accept as Solution" if it answers your question.
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Valued Mentor
Mason-Paul
Posts: 296
Registered: ‎04-04-2012
Message 35 of 65 (357 Views)

Re: Posting a project for comments

05-04-2012 05:26 AM in reply to: Accudyne1

Here's how I draw my hex nut. The attached ipt is a 2.5 INCH BSW NUT and in IV 2012 ipt format for the BSW threads you will also need the other attached file Thred.xls copied to the default location in IV directory or the threads usually revert to ANSI Inch.

 

Where AF = 1.5D and thickness/high =D the values in the formula may also vary for different Country standards, these same method may be used for metric and others standards threads

 

In particular note

1) The plain that the nut is drawn on

2) The way the hexagonal sketch is constrained

3) The extrusion option used for the body of the nut

3) The FACE used for the construction sketch (a 3 point tangent circle)

4) The Circle in 3 is PROJECTED GEOMETRY on to the Plain use to sketch the chamfer (a rotated cut)

5) The Plain used to mirror the chamfer created in step 4

6) The face and option used to create the tapped hole, using one of the arcs created by the rotated cut in 4

This is one of those every day parts that I'd safely say there will be/are as many ways of doing the same part as there are posters on this site the method I use is just one example.

 

I hope it is of some help to you.

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Active Contributor
donovandigital
Posts: 49
Registered: ‎02-16-2012
Message 36 of 65 (320 Views)

Re: Posting a project for comments

05-04-2012 05:08 PM in reply to: JDMather

I rebuilt this again, from scratch, and got the same result as yesterday. Unless I delete all predefined constraints, center point will not move. As for vertical, autodesk says it adready did that.

 

Sorry I did not mention this

 

Joe

Active Contributor
donovandigital
Posts: 49
Registered: ‎02-16-2012
Message 37 of 65 (318 Views)

Re: Posting a project for comments

05-04-2012 05:10 PM in reply to: JDMather

And no, I have no idea why it was not fully constrained.  It says it needs 2 constraints, but anything I try returns the "overconstrained sketch": error. Sorry about that too.

Active Contributor
donovandigital
Posts: 49
Registered: ‎02-16-2012
Message 38 of 65 (311 Views)

Re: Posting a project for comments

05-04-2012 06:08 PM in reply to: JDMather

Board and fixed nut. I repeated the procedure of drawing the centerline for the nut and it became fully constrained (I'm assuming that's what you meant by lines changing color, from black to blue). In my defense, you did not have me do that for the nut.

 

Re general poor quality, some explanation

 

A) Instructor (at community college) has 10+ years experience with acad and next to none with inventor. He has not used half the features. Primary reason I posted this in this state is I have no idea what bad habits I picked up. Secondary reason being...

 

B)I was, and still am, under some time pressure. I want to actually build this thing in the next 2 weeks, but I would prefer that the design be completely straightened out first.

 

That said, C) Most of the screwups are mine. I made a good-faith effort to constrain everything, and had no idea I could, for example, change preexisting dimensions by adding constraints. Was I paying enough attention? No. However, as I say, I had no clue such things were possible so I was not on the lookout for them.

 

All that aside, what is the generalized solution to the problem I am having with having an under-constrained sketch which complains about being over-constrained for every constraint I attempt to add? Are you saying this centerline/origin business is the only path to consistent accuracy? Also, why do you say that the rectangle must be drawn near the midpoint in wo12 and around the midpoint for 2013?

 

Thanks again for the help

 

Joe

*Expert Elite*
JDMather
Posts: 26,166
Registered: ‎04-20-2006
Message 39 of 65 (280 Views)

Re: Posting a project for comments

05-05-2012 07:05 AM in reply to: donovandigital

donovandigital wrote:

 Also, why do you say that the rectangle must be drawn near the midpoint in wo12 and around the midpoint for 2013?


 

2013 has a centerpoint rectangle tool (finally)

 

Assuming you have Inventor Fusion installed you can see how a centerpoint rectangle works.

Saves you some steps - been in Fusion for a while and should been in Inventor years ago.

 

Please mark this response as "Accept as Solution" if it answers your question.
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Active Contributor
donovandigital
Posts: 49
Registered: ‎02-16-2012
Message 40 of 65 (221 Views)

Re: Posting a project for comments

05-08-2012 07:08 AM in reply to: JDMather

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