Simple outline with problems...

[stevespo]

I am using BobCAD v20, and I have a fairly simple 2d shape that I am having problems with. It started out as a series of 2d points where Z=0. After connecting the dots with a spline, and then tweaking some of the curves manually with arcs, I can no longer use the shape to generate an offset - even though I can still chain select it.

My belief is that there are some Z values that are very small and that it's probably a general accuracy/chain gap type of problem - but I've been unable to fix it. Sometimes I can correct this by using the 3d->More->Move to Z function, but in this case it actually seems to make things worse.

Also, "cleanup and reorganize" and "make arcs tangent" don't seem to help either. There must be some other options to fix this up quickly and easily. These types of problems with BobCAD are driving me crazy. If I'm working in 2d mode, why are the spline/arc functions creating line segments where Z != 0? It boggles my mind.

Can someone please take a look at this file and give me some advice? I just want to be able to generate an offset from the line data. It seems so simple, but...

Thanks!

Steve

[Kiwi]

stevespo
Looked at your drawing and the only way I could offset your 2D shape was offset in small blocks.
You may need to touchup the offset line.
Not only BCC objects to doing offsets.

[The One]

The problem in your file is due to 3 arcs that were 3D arcs. I have highlighted them in this file. You will need to fix theese entities, but I have identified them for you.

Regards

[stevespo]

Thanks very much for the help. I appreciate it.

theOne, can you explain how you located those 3d arc segments? Is it just manually going around the outline and inspecting each segment? Is there a way to highlight everything where z != 0? I know there is 3d->Cut above z=0, so you can cut above, then flip everything and cut again.

Last night, I started over with my point data and regenerated the outline successfully - so I have what I need. My real reason for creating this topic is I'm trying to understand why these things happen from time to time.

If I'm working in 2d mode, why do I occasionally end up with 3d arcs?
How do you quickly locate and fix them when it happens?
Has this been fixed/improved in v21 and v2007?

Thanks again,

Steve

[The One]

I can't say specifically how they were generated, except that the end points of the 3 segments were not on Z0.

What I typically do is select everything that I am working with.
Then Click on Special/NC-CAM and the Verify option.
I then look at the Z bounds. If the numbers have a different sign on them I know that there is something amiss.
That is when I try the Move to Z function. Smoetimes this handles it, sometimes it doesn't. With Arcs, this function only moves the center not the end points.
Then Verify again. If they match great, if not I increase my dialog digits in the environment window. Then I just use the Tooltip to verify the beginning, end and center(if present) of the entity. If they are OK I blank them out. If not I leave them alone and fix them after I know all of the good segments are hidden.

V21 will give you the same results for the most part.

In 2008 you won't necessarily be ale to do the offset this way, because it isn't 2D, but if all you need to do is run a profile cut on the part, you can use the Profile Feature. The Profile Feature, as well as the other 2D Features, automatically flatten the geometry as it is passed to the CAM Tree, so you don't have to worry about the position in Z.

As a side note, if you are getting point data and using functions inside of BoCAD to connect the points. Use the Move to Z function before you start creating the arcs and such, this will make sure that they do not creep up on you.

Regards

[j-radkemachine]

Hey The One. I've Seen Several Of Your Posts On Here & I'd Like To Know How You Got So Good W/ Bobcad? How Long Have You Been Doin Cad? I'm Just Not Picking Up On It Very Well & Beginning To Get Discouraged.
I'll Put It This Way: Been Around Cnc's All My Life ( Dad Owns A Shop ) I Have Been Able To Learn To Program The Old Way W/ A Calculator , Pencil , Paper , & A Manual A Whole Lot Quicker Than By Using Bobcad ... Although I Can Import A Drwg. That Has Arcs , Holes , & Such .... I'll Click On The Arcs & Go To Machine All & ....... There It Is ( G-code ) W/out Having To Do All The Math... It Just Looks So Easy
I Just Cant Get The Whole Process Down.
Thanks For Any Help ! ! !

[stevespo]

TheOne, once again - thanks so much for the help. You've confirmed my suspicions and provided a sanity check. I begin to think that I'm the only user who experiences these things, but obviously I'm not.

I am careful about making sure my points start out as z=0, but as I work on a part, sometimes I generate new points by using the "point on entity" and if the arc isn't completely z=0, then I now have points that aren't either. So I can see how these things might creep into a drawing. I'm going to be more careful, verify more often and try and figure out what exactly is causing this behavior.

j-radkemachine, as another beginner/intermediate with BobCAD, I would suggest buying the training CDs and working through all the examples. It will be a big help. Once you have had a few successes, your knowledge will grow. I have had very good luck with most of my work - including complex 3d parts - but occasionally run into these "simple" problems and am grateful that people here are willing to share their expertise.

Steve

[The One]

j-radkemachine,

I have been working with BobCAD for about 4 years now. Just so that you are aware, I do work for BobCAD. When you work with a program for 8+ hours a day, you tend to pick up on some things here and there.

The biggest thing that I can suggest is to find something that you would have interest in designing outside of work. Through my years working with BoCAD users, I have found that the users who figure it out the fastest are normally those that are designing a part just for the heck of it.

Let's face it: If you are under the gun on a project and you are trying to get a product to your customer, you are under a lot of stress and in a hurry. When I am in a hurry I commonly forget the minor details, like including the attachment with an email, or tying the other shoe before I walk out the door. If you are working on something that is not a priority, you will be ale to take your time and find the nuances in whatever program you are using, so just "play" when you can.

Don't get discouraged though. It will come to you, you just need to take your time.

Regards