[hst]

Gentlemen:

I am having trouble getting a solid to subtract from another solid. It should leave a cavity, but when told to subtract either one or the other of the solids disappears, or sometimes both.

The object is to create a bullet mold, creating a solid bullet and subtracting it from a rectangular solid to leave a cavity of one half of the bullet. The bullet solid is created by drawing the profile and using the revolve surface tool. It creates the solid, or at least it appears in all respects to be a solid. I have looked for flaws in the profile and the solid but can find none.

I have successfully done this before, using v28. I am now using v30. I am attempting to attach a screen capture of the contour I am using. Perhaps I am overlooking something obvious.

Thank you for your consideration and assistance.

Glenn

[jrmach]

Before u revolve are you sure you have clean geometry ? No Double lines

[hst]

jrmach:

Thanks for the response. I have looked at it most carefully, and run all three of the Cleanup/Optimize tools on it for good measure. I have tried making solids of just parts of the shape to see if I could isolate a problem, but so far no luck.

Glenn

[hst]

Here is the image I am looking at before pushing the subtract button and the weirdness starts.

[Third-Gen]

the revolve will make a shell most of the time, can you slice the bullet or subtract another 3d feature from the bullet to make sure its a solid and not a shell?

[hst]

Third-Gen:

It is possible that the solid is not a solid, as you suggest. Howsomever, I don't know how to find out. I tried to subtract another solid from part of it, but "Failed in Boolean Subtract". I tried the Split Solid tool as well and it would not work. " Measure One" shows volume, but I suppose it would do that with either a shell or solid.

I suspect you are correct about it being just a shell. Is there anyway to make such a shape into a solid?

Thanks for you help!

Glenn

[Third-Gen]

not sure on Bobcad, i do all my design work in Turbocad (where i can switch it in properties from a solid to shell with one click) and then just import it into bobcad for tooling. check properties in bobcad

[hst]

Third-Gen:

Thanks, I will have a look around for such a utility. I don't recall seeing such a thing before, but that doesn't mean it is not there.

In the meantime, I tried to revolve the cavity instead of the solid, and it worked. I cut the round solid in half and sure enough it was solid. I am sure there is some way for me to work with this.

Thanks again,

Glenn

[jrmach]

Revolve does fail a lot on me.The more sharp edges and stuff seems to help fail.Isolating in sections is what I done in past to figure it out.Also using the un-stitch/stitch commands to check things out.
Also,1 time I fought a job,,it ended up being the simple solid shape that was screwing it up.If I remember right I had extruded curves,,but something not good happened doing it,but I was convinced it was the more complicated shape,,,lol

You did try Intersect ?

[jrmach]

Also on your line geometry zoom in real close and make sure no boogers are there

window select your geometry and r-click entities summary,,,,see if what listed is what you drew,,,good way to find boogers

[BurrMan]

Can you show a screenshot of the bullet geometry you use to make the revolve?

In BobCad, you will want that to be "closed curve" geometry to get a proper solid.

So, in the screenshot of your bullet solid, you should have "half of a bullet geometry" with the bullet tip and center of the base "joined with a line" down the center of the revolve point.

1 single closed curve. 1 single shift click contour for revolve.

[BurrMan]

Can you show a screenshot of the bullet geometry you use to make the revolve?
.

Yup, i missed the first image you posted witg that screenshot in it.

There you have an "open curve"

Just join that open area along the x into a closed curve and revolve that....

When in the revolve command and you select geometry for it with a shift click, the start and end points of the contour preview arrow, should be the same place.

You wouldnt expect that, but it's the way BobCad works!

[BurrMan]

As an added note, with your cavity mold making....

With bobcads new split command, you may want to split your solid on the parting line, the just place the half surface splits whereever you want in the face. Then you can easily "planar" the surface edges with a stock outline to stich the cavity faces with the parting line surface...

Much less work and a much lighter file, than a bunch of booleans stacked in....

Unless your just doing 1....

[hst]

All:

Thank you very much for your help. I did manage to pummel the beast into submission. As was suggested, the problem was somewhere in the geometry I was trying to revolve. I located the area when I revolved the shape into a cavity rather than a solid. The shape failed to make a solid. When revolving a cavity, most of the shape worked, producing a cavity without the very tip of the nose. This indicated the vicinity of the problem. I tried without success to find the error, no matter how large I made the shape and no matter what I tried, I found no error. None the less I deleted the whole of the geometry in question and re-drew it. The new geometry worked.


BurrMan:

Thanks for the tip about needing a "closed curve" to create a solid. I was not aware of that. I had tried that in the course of trying everything but it did not help, but it wouldn't have of course because of the error in the geometry.


Thanks again for all your help.

Glenn