[tOfOloco]

Alright, I've got what I thought was a fairly straightforward project.. that is turning into a headache. I've attatched the file so that anyone can take a gander and offer up an idea.

What I've got is this wheel that I've modeled and I'm trying to sink it into a cavity to make an investment casting mold.. I've been trying to use the boolean subtract feature to accomplish this with no success. What I'm wondering is if the center of my spokes all overlapping each other (it looks pretty nasty) even though all of that is contained within the center hub if that's why my subtract feature is failing. I've repeatedly heard that bobcad only works with "good clean geometry" and I do not believe that there are any holes in my model (except the axle side, but even trying to do the closed side first still fails) so any ideas, workarounds, ANYTHING is welcome. even constructive criticism [perhaps you have a better way to draw it?]


appreciate any input on the matter, thanks

[Bob La Londe]

What format is the file inside the zip?

[tOfOloco]

What format is the file inside the zip?

...BBCD

[jrmach]

You need to cap the the end of your spokes.

[RAF.]

Looks like a fun project:
What I found is that maybe your solid isn't a complete solid what I have done is to just select the outer part of the wheel and made sure that I had all the surfaces made into to a solid and then did boolean subtract maybe by checking more individual groups of components and then subtract you can find where the problem is.

[jrmach]

His spokes are opened ended.What he needs to do is delete all but 1 of the spokes.New layer,xtract,planar the ends,stitch.Then copy/rotate to create all spokes.Then boolean all together again.Then do your boolean subtract.

[RAF.]

Jrmach is completely correct.
What would be a simple solution for the OP be to find where the problem lies?

[jrmach]

Easy,look at the model with transparency on.You can see the open ended spokes.When he originally made the model,he should of capped the cylinders(spokes).

[tOfOloco]

Alright, I changed the spokes to cylinders instead of shells for lack of different terminology. Anywho, I also stitched all of the spokes to a solid, then all remaining surfaces to solid and attempted Boolean subtract. Still doesn't work? I'm sort of thinking outloud here; I guess I will try Boolean 'add' each individual component instead of stitching surfaces to solid as someone suggested earlier. will report back when I get this drawing working how I want & will tell you guys what I had to go through to make it work. happy machin' weekenders!

[RAF.]

I thick the hub is still a shell

[jrmach]

I think we need aBURR


I can get some of it to work but not all.I think if I had to make this,I would start from scratch.

[RAF.]

Bottom Mold cav
Top Mold cav
I split molds at Z0

Ill post bobcad files if you would like

[dwood]

What you have will work just needs a little tlc, will be difficult to do as one solid

unstitch everything, seperate the outter rim , i call tire, stitch together ,put on a layer by its self, make sure it will subtract

as jr says take 1 spoke redo the center end cap, extract edge redo planar stitch together, then copy and rotate , then boolean together
at this point see if it will boolean subtract, put on layer by it's self

seperate the sphere on the end , put on layer by it's self , it is already a solid, it will subtract

your hub has a extra surface inside, that gives it a problem , take the outter 3 surfaces of the hub stitch together,
then extract the end edges and planar both ends , stitch together, have a solid now , make sure it will subtract at this time

for the axle bore take the inner surface and planar the ends , stitch together, boolean sub , should have axle bore

get all these things to work seperate, no reason to have all joined , then make 2 copys of each on different layers to boolean sub from both halves

i hope this clear
dw

i a slow typer raf's got it

[RAF.]

What you have will work just needs a little tlc, will be difficult to do as one solid

unstitch everything, seperate the outter rim , i call tire, stitch together ,put on a layer by its self, make sure it will subtract

as jr says take 1 spoke redo the center end cap, extract edge redo planar stitch together, then copy and rotate , then boolean together
at this point see if it will boolean subtract, put on layer by it's self

seperate the sphere on the end , put on layer by it's self , it is already a solid, it will subtract

your hub has a extra surface inside, that gives it a problem , take the outter 3 surfaces of the hub stitch together,
then extract the end edges and planar both ends , stitch together, have a solid now , make sure it will subtract at this time

for the axle bore take the inner surface and planar the ends , stitch together, boolean sub , should have axle bore

get all these things to work seperate, no reason to have all joined , then make 2 copys of each on different layers to boolean sub from both halves

i hope this clear
dw

i a slow typer raf's got it

In one of the spoke layer it is doubled I just don't have time to delete right now but here are the files if you would like to look at them use at your on discretion for machining. Good luck!

[BurrMan]

Alright, I've got what I thought was a fairly straightforward project.. that is turning into a headache. I've attatched the file so that anyone can take a gander and offer up an idea.

What I've got is this wheel that I've modeled and I'm trying to sink it into a cavity to make an investment casting mold.. I've been trying to use the boolean subtract feature to accomplish this with no success. What I'm wondering is if the center of my spokes all overlapping each other (it looks pretty nasty) even though all of that is contained within the center hub if that's why my subtract feature is failing. I've repeatedly heard that bobcad only works with "good clean geometry" and I do not believe that there are any holes in my model (except the axle side, but even trying to do the closed side first still fails) so any ideas, workarounds, ANYTHING is welcome. even constructive criticism [perhaps you have a better way to draw it?]


appreciate any input on the matter, thanks

I would say that where you went wrong is in a misconception of commands. "stitching" versus boolean operations. "stitching is for when you create all the surfaces with shared edges and you "stitch" or join them into a single surface. For a cube, you would make 6 flaty planar square surfaces that all share their edges and stitch them into a cube solid.

So like where you mentioned about your spokes meeting at the middle point. You had all solid spokes, but should have "boolean unioned" them into a single solid. This would created the nice trimmed middle, or, you would leave each spoke as a seperate solid. If you unioned all the spokes, then you would union them to the outer solid, then also to the hub. Then they would all be a single solid that you could boolean subtract from the block.

The problem arises because BobCad will "stitch" things together that really arent a true solid. More like a "group", but these groups wont operate like a solid, in a boolean operation. This is BobCad doing something it shouldnt do (The stitchiing of seperate solids together into a group) Joining solids together is done with boolean union.

[jrmach]

DWoood,I got as far as the last step you outlined,and had to give it a rest.Other stuff to do.Glad to know I was on the right track.Don't do solids much,,this a good exercise.

[dwood]

may have not been clear, you should subtract the hub first , then the outter band, then spokes, then sphere

[jrmach]

Clear to me.Like I said I got as far as the very last.Checked to make sure I could subtract every step of the way.
It's a project I don't think I would of had any problems start to finish ,,it's when it is all done then you got to go back and see why it ain't working,,it became a little time consuming.Good practice though.What do we got next ? ?lol

[tOfOloco]

wow I come back after a while and you guys have practically done my project for me. lol, not to say I didn't figure it out (like that other boolean subtract problem I was having) general consensus is use boolean add whenever possible NOT stiching to solid. anyway thanks for the help guys

[jrmach]

Have you cut the part yet ? Pics please.