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Red_Stafford

Trying to Loft a hook

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Red_Stafford

Hi all I am trying to draw a hook but I am getting problems when using the LOFT command, I get the following error "MODELING FAILURE: A RAIL CURVE INTERSECTS A SECTION MORE THAN ONCE"

 

See my attached drawing

Top Hook_02.zip

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JD Mather

Go through these tutorials - especially MA13 and MA 105 http://home.pct.edu/~jmather/content/DSG322/inventor_surface_tutorials.htm

 

Your sketches are unconstrained and the rail connection points not projected to the cross-section profiles. You are doing way to much work with far far too many dimensions. Start using sketch constraints like = to replace duplicate dimensions. (Let me guess - you brought this in from AutoCAD and used the Autodimension?)

 

Use the origin and BORN techniques as described in the linked documents.

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Red_Stafford
Go through these tutorials - especially MA13 and MA 105 http://home.pct.edu/~jmather/content/DSG322/inventor_surface_tutorials.htm

 

Your sketches are unconstrained and the rail connection points not projected to the cross-section profiles. You are doing way to much work with far far too many dimensions. Start using sketch constraints like = to replace duplicate dimensions. (Let me guess - you brought this in from AutoCAD and used the Autodimension?)

 

Use the origin and BORN techniques as described in the linked documents.

 

Cheers, this was not imported from AutoCAD but I do have a AUtoCAD back ground, it was all done using Inventor 2008 but I did use auto dimension, you post kind of lost me but I will have a ready through that site.

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JD Mather
you post kind of lost me...

 

When you read those documents you will see that I suggest sketching one line, arc or polygon and dimension it immediately. Then as you add additional geometry dimension (preferably use sketch constraints like tangent, horizontal, vertical, coincident, colinear...) as you go.

When geometry is fully defined it will turn color.

Notice that my sketch (see attached) is much cleaner than yours and I needed far fewer dimensions.

 

I never ever use Autodimension.

 

Until you understand the techniques for building robust, fully constrained sketches I would work on easier parts than this one. Loft is an advanced function.

Dimensions.PNG

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Red_Stafford
When you read those documents you will see that I suggest sketching one line, arc or polygon and dimension it immediately. Then as you add additional geometry dimension (preferably use sketch constraints like tangent, horizontal, vertical, coincident, colinear...) as you go.

When geometry is fully defined it will turn color.

Notice that my sketch (see attached) is much cleaner than yours and I needed far fewer dimensions.

 

I never ever use Autodimension.

 

Until you understand the techniques for building robust, fully constrained sketches I would work on easier parts than this one. Loft is an advanced function.

 

The thing is I need to draw this for work, I have deleted all my dimensions and added the ones you have on your pic and it says i need 29 dimensions ?

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Aardvark

Use constraints. If you don't know what those are, read JD's tutorials and look it up in the help.

 

Then, I would practice on some simpler designs until you get the basic concepts down, and then try to tackle the loft.

 

Finally, when this project is finished, I would write an email or have a sit down discussion with your boss about getting some Inventor training. AutoCAD is not Inventor and vice versa.

 

Remember these words, "Forget everything you know about AutoCAD."

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Red_Stafford
Use constraints. If you don't know what those are, read JD's tutorials and look it up in the help.

 

Then, I would practice on some simpler designs until you get the basic concepts down, and then try to tackle the loft.

 

Finally, when this project is finished, I would write an email or have a sit down discussion with your boss about getting some Inventor training. AutoCAD is not Inventor and vice versa.

 

Remember these words, "Forget everything you know about AutoCAD."

I am doing a part time course but for know I need to get this hook sorted so all I can do is keep trying with your help

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JD Mather
...it says i need 29 dimensions ?

 

You must have missed the suggestion in the paper that says to sketch one entity and dimension/constrain immediately.

 

Here are the steps I would use

 

#1 Start over from scratch. (you can use the original for reference)

#2 Sketch arc and dimension constrain. look in lower right corner of screen if it says it needs any dimensions/constraints then attach the file here.

#3 Sketch next entity and repeat Step #2 as far as constraining/dimensioning and attaching here.

Entity by entity we can solve this problem, and yes, it will be faster to start over.

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shift1313

what were you given by your boss to draw this hook? Do you have a certain spec? Is this going to be produced?

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Red_Stafford
what were you given by your boss to draw this hook? Do you have a certain spec? Is this going to be produced?

 

It for a colleague to take to one of our supppiers to see if they can supply something simillar this is just part of it I have drawn the rest no probs it's a pully and that hook goes on top

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Red_Stafford
When you read those documents you will see that I suggest sketching one line, arc or polygon and dimension it immediately. Then as you add additional geometry dimension (preferably use sketch constraints like tangent, horizontal, vertical, coincident, colinear...) as you go.

When geometry is fully defined it will turn color.

Notice that my sketch (see attached) is much cleaner than yours and I needed far fewer dimensions.

 

I never ever use Autodimension.

 

Until you understand the techniques for building robust, fully constrained sketches I would work on easier parts than this one. Loft is an advanced function.

 

How did you create your sketch did you do it using three point arcs around each of the lines coming from the centre like I have ? yours looks neater than mine and you dont even have anything in front of you to draw it from.

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Red_Stafford

ok I think I give up, I have been trying to do this hook since last week and I have not got a clue.

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shift1313

Red, the issue is you jumped into the deep end, you may be able to paddle around but you just dont have enough training to move around smoothly.

 

If you sit down and go through some of JDs tutorials he linked to I think it will all make a lot of sense. Once you get a feel for the proper way to dimension something and how to use constraints you will be much better off with trying to model this.

 

My copy of inventor at home hasnt worked for some time so unfortunately I cant help you out from here.

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JD Mather
ok I think I give up, I have been trying to do this hook since last week and I have not got a clue.

 

Why would you give up when I offered to walk you through this literally step-by-step?

 

Sketch a circle - attach the file.

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Red_Stafford
Why would you give up when I offered to walk you through this literally step-by-step?

 

Sketch a circle - attach the file.

 

Sorry dude just getting fustrated, ok I have sketched and dimensioned a circle see attached.

Hook.zip

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JD Mather
I have sketched and dimensioned a circle see attached.

 

I do not see any evidence that you read the documents I suggested earlier.

 

Pay particular attention to http://home.pct.edu/~jmather/AU2007/MA105-1L%20Mather.pdf

Tip #8 to turn on the visibility of the origin and Project Geometry the origin Center Point. You want this to be at a logical location in the part.

 

There is no point in continuing until that basic principal is understood. Out on the shop floor the first thing the mill or lathe operator does in setting up a job is determine 0,0 location.

 

I looked at your hook 4 - I never ever use Fixed constraint - use the origin. Also you need to use many many more tangent contstraints where appropriate and also = constraints. If you see dimensions repeating over and over again (like for fillets) there should be only one dimension with the rest replaced with = constraints.

Origin.png

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Red_Stafford

Ok, see attached circle I have turned the center point on.

35mm Cricle.zip

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JD Mather

Nope

 

See Tip #4 to Autoproject part origin on sketch create

 

and tip #10 for green "hard snap" placing coincindent constraint.

 

If you do not see this green dot then you need to Project Geometry the origin Center point yourself (rather than relying on automatic as decribed in #4. Project Geometry will be one of the most important concepts in creating the section profiles for this hook.

 

If you can drag your circle it isn't anchored. It didn't change color - so it isn't constrained.

 

Think of it like dropping a block of aluminum on the milling machine table and trying to make a cut. If you don't anchor it down all kinds of bad stuff is going to happen. No machinist could ever get away with work like this.

 

Of course because we are doing this step-by-step over the internet it will be far more frustrating and far less efficient than classroom training.

 

JD

Certified Machinist

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Red_Stafford
Nope

 

See Tip #4 to Autoproject part origin on sketch create

 

and tip #10 for green "hard snap" placing coincindent constraint.

 

If you do not see this green dot then you need to Project Geometry the origin Center point yourself (rather than relying on automatic as decribed in #4. Project Geometry will be one of the most important concepts in creating the section profiles for this hook.

 

If you can drag your circle it isn't anchored. It didn't change color - so it isn't constrained.

 

Think of it like dropping a block of aluminum on the milling machine table and trying to make a cut. If you don't anchor it down all kinds of bad stuff is going to happen. No machinist could ever get away with work like this.

 

Of course because we are doing this step-by-step over the internet it will be far more frustrating and far less efficient than classroom training.

 

JD

Certified Machinist

 

Ok cheers I have projected the centre point, see attached.

 

How do I get into the options screen that you have on your tutorial ?

Step_02.zip

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