Miniature Train help please!

[Anonymous]

In school, I've been assigned to assemble the Miniature Train from Project Lead the way but I'm having some trouble, particularly with the Axle Peg and the Cow Catcher.

With the Axle Peg, I planned on revolving it. I was able to do it but the total length dimension was off so I decided to redo it but forgot how I did the top, curved part of the peg. I remember I had to make one circle from the tip of the line that the revolution is around and from where the circle and a second vertical line crossed, I have to create a second circle that would be the curved part of the screw. What would the dimension be for the first circle?

Am I making any sense?

Is there a different way I can go about doing it?

I also noticed that the packet is missing the diameter measurement for the part that needs to be threaded. Would you guys know what dimension it is?

For the cow catcher, I offsetted the plane and lofted but now it won't let me 2-D sketch on 2 of the faces. One of my classmates said it had to do with the axis. Can someone explain? I saw a youtube video on a different approach for the cow catcher but I really want to know why my approach won't work.

the link is a web copy of the packet, courtesy of google search:

http://www.muhsd.k12.ca.us/188320624112056793/lib/188320624112056793/Engineering/Handouts/Quarter%20...

[Anonymous]

Here is my take on the Cow Catcher. In metric units as I am from the land down-under. Would be interested to hear comments/suggestions from any of the experts on this forum.

Regards. 

[Anonymous]

Hi there,

It would really help if you could attach examples of your work, even screenshots would make it easier to understand where you're having problems.

For the cow catcher, it sounds like the problem is with your loft... When you loft from one surface to another it's VERY easy to end up with surfaces that aren't flat, hence you won't be able to create a sketch on them. Without seeing what you've done, I can only guess this is the case.

Do a quick Google for cow catchers, and remember to model it the way someone would build it...

Cheers

[JDMather]

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@Anonymous wrote:

Here is my take on the Cow Catcher 

Regards. 

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Sketch1 & 2 are unconstrained and too much work.  Rather than repeating dimensions I would use equal = and symmetry constraints.

You might read this document http://home.pct.edu/~jmather/skillsusa%20university.pdf

[Anonymous]

Admittedly the first part was a little rushed. Here is a "Mach 2" version with constrained sketches and modelled around all three Origin Work Planes.

Regards.

[Anonymous]

Thanks for the tip JD. I thoroughly enjoy reading yours and others i.e. Dennis Jeffrey etc tips on this forum. 

Do you know of somewhere I can find a "Do's and Don'ts" literature? For example I remember reading in a post from Dennis once where he said he avoids projecting geometry whenever possible. A "dot form" of all these small but handy tips would be great reading...

Regards. 

[JDMather]

Here are the sketches I would use (not including the pockets.

(I think I would leave it up to the OP to attach a part before continued guidance.

[Anonymous]

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@Anonymous wrote:

For example I remember reading in a post from Dennis once where he said he avoids projecting geometry whenever possible. A "dot form" of all these small but handy tips would be great reading...

Regards. 

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Venturing off topic I know, but I wouldn't recommend following someone elses "do's & don'ts"... In my opinion, don't avoid any feature unless you have tried and failed yourself. Even then, it could be something you don't understand about the particular feature. Personally I love the project geometry tool, If you avoid projecting geometry, then you're missing out on a really handy feature. Having said that, you need to be aware of how it works, and the consequences of making changes when you rely on it too much. I'm a fan of tips or suggestions, not "do's and don'ts".

Just my 2cents... Back OT...

[Anonymous]

Fair point.

I have had all kinds of trouble in the past with projecting geometry - but I suspect the problem is between the seat and the keyboard. Having only 5 or so years experience in using Inventor I am well aware that I am still an amateur, particularly given the company I keep on this forum...

Regards.

[Anonymous]

Ditto....

[coreyparks]

I just take the do's as recommended do's and the don'ts as recommended don'ts. Projected geometry is a good thing in modeling.  However all good things should be  taken in small doses.  In other words you should project only what you need to get things accomplished and no more.  It keeps your model smaller and limits the number of issues you will have down the road debugging sketches.  Regardless a person should never project all geometry on sketch creation, unless he wants practice debugging problem sketches. 

[Anonymous]

I need help on the axle peg as well. If it's not too much trouble, can you make a youtube tutorial or another type of tutorial.

[JDMather]

Post the ipt of what you were able to complete for futher help - we cannot do this for you and need to see what might be causing difficulty.

[Anonymous]

Attached is my cow catcher...I can't seem to draw on the two diagnal faces and I don't know why...

I'll probably end up doing it a different way but I'd still like to know why my attempt failed.

As for the other suggestions, I really appreciate it. I learned a lot from them!

[JDMather]

See attached.

Your Sketch2 is not fully constrained.  Missing vertical and equal constraints for vertical lines.  Missing dimension.

Move the origin Center Point to the middle of the lines in Sketch1 and 2 to make use of the Symmetry constraint with a construction line from the origin.

Read this document http://home.pct.edu/~jmather/skillsusa%20university.pdf

The reason you can't sketch on those faces is because the sketches are mis-aligned causing the faces to be slightly twisted (not planar).

Looks like now you can make some real progress.  Hollar back if you run into trouble.

[Anonymous]

I am in the process of creating a metric train. I also need to create the part in metric for 3D printing. 

Step one  Create a new IPT in metric.

Step 2 when you are dimensioning the part you can enter the part in inches and Inventer will convert the part to metric. This would be a good time to intruduce the conversion to the student. let them do some rounding in the disign like adjusting the design from 1/4 in to 25mm instead of 25.4 mm. The student need to learn how document their project, let them build the instuction for the project.                             

step 3 check tolerences before printing. I also would assign different collors for each part. 

I plan on creating a metric lesson for drawing all the parts and exporting to STL files and printing the parts.