Now that AD is actually being maintained again, I am going to take a few minutes and document some problems I have with AD whenever I attempt to do geometry more complicated than rectangles and holes.
I have been working on a 1/43 slot car design, with the intent of 3D printing the majority of the car. Modelling the chassis is very straight forward, as it is just simple extrudes and cuts.
However, I'd like to model a body that has a few curves to it.
The game plan is to do 3 lofts, one for the front, one for the rear, and one for the cabin. Then shell them out. Front and rear "fascias" will be done as separate pieces.
Three sketches on 3 planes, all of which are done by drawing one half, then using the sketch "mirror" tool to make the symmetrical other half.
Here are the sketches:
Here are the results:
So, the result isn't symmetrical. One side has an odd bulge, and the other an odd twist. No combination of check boxes in the loft tool fixes this. I know better than to sketch half of the profiles and do the loft on just half, because the central plane will be warped so badly that mirroring the feature wont yield usable results.
Okay though, one half of this looks usable, so cut off the odd half and soldier onward.
Again, 3 sketches and a loft. This loft performs worse than the first loft. I already picked a side when I cut the first loft, I am stuck with a weird twist in the rear of the car that I don't want, but fine. Cut off half and move on.
Sketches:
results:
results:
By this point, I'm tired and am giving up. Instead of a 3rd loft, I just do an extrude with some draft to form the greenhouse. I doesn't look very good, but I've already spent twice the amount of time on this as I wanted to.
Lop off half of the greenhouse and move on.
Now it's time for the shell.
Right out of the gate, there is a problem. I'd like to select the bottom of the body as a face to remove, but for some reason when it solved the Loft, it didn't split this face into two pieces.
So, I'm stuck just picking the "interior" face and adding additional cuts later to knock out the bottom.
This is where AD always gets weird. For the first attempt, I go for the gusto and attempt a 2mm thick inward shell. AD grinds for a long time, then pops an error message that the operation has failed. No surprise. Then I turn the thickness down to 0.2 mm. AD Grinds again for a long time, and to my amazement succeeds! I see it rendered on the screen! Of course, an 0.2mm thick shell couldn't be more useless to me. I try to bump the thickness back up to 1 mm, and it fails. I turn it back down to 0.2mm and it fails. Wait a minute, why did it work the first time? I am never able to repeat that first success. Now, this isn't my first rodeo. I know that shelling outward is usually easier to solve, so I check the box and shell outward.
A 2mm shell fails. A 1.68mm shell fails, but a 1mm shell solves!
Not what I wanted, but I think I can do something with it.
Now for the easy stuff. I knock a couple of holes through the shell for the wheels. But what happened here???
Finally, I cut out the "bottom".
Okay, we are halfway there. Ideally, now I could just "mirror" all of these features and boom, I have a body shell. Of course, it can't solve that. I won't even bother with a screenshot. But, hope is not lost. I can use the Boolean Tools and insert two of these, mirror one, and "stick" them together!
Fire up a new part, do a few Boolean operations, and hey, I have an okay looking model, with one small issue.
Now, for the moment of truth, export an STL file and see if we can print something?
Here is how the STL looks when I import it into Simplify 3D:
More than half of the part is missing!
USELESS!
This little experience has played out probably a dozen times for me in the last few years. Basically, I just don't do projects that require anything other than rectangles and holes because I know Alibre simply can't handle it. It is so frustrating to be so limited! I have a hard time recommending people drop $1K or more on this software when I know it just chokes on anything slightly more complicated than plates with holes.
I don't expect to be able to model every swoop and curve of the latest Ferrari, but I do expect to be able to throw 3 lofts together and pop in a shell in a reasonable manner. I have experience with Pro/E and SolidWorks which leads me to believe that it absolutely can be done. I know, I know that AD costs less, and I know I know that it is a "great value" and that it does lots of things well. I'm also aware that there are lots of modelling techniques that "could be" used. At the end of the day though, I paid the price of the ticket for parametric 3D CAD software (in the economy class) and I expect the whole plane to fly all the way to its destination.
This turned into a bit of a rant and I apologize. The Loft feature has performed very poorly for me the entire 10 years or so I've owned this software. Is it going to get any better in the next 10?
I have been working on a 1/43 slot car design, with the intent of 3D printing the majority of the car. Modelling the chassis is very straight forward, as it is just simple extrudes and cuts.
However, I'd like to model a body that has a few curves to it.
The game plan is to do 3 lofts, one for the front, one for the rear, and one for the cabin. Then shell them out. Front and rear "fascias" will be done as separate pieces.
Three sketches on 3 planes, all of which are done by drawing one half, then using the sketch "mirror" tool to make the symmetrical other half.
Here are the sketches:
Here are the results:
So, the result isn't symmetrical. One side has an odd bulge, and the other an odd twist. No combination of check boxes in the loft tool fixes this. I know better than to sketch half of the profiles and do the loft on just half, because the central plane will be warped so badly that mirroring the feature wont yield usable results.
Okay though, one half of this looks usable, so cut off the odd half and soldier onward.
Again, 3 sketches and a loft. This loft performs worse than the first loft. I already picked a side when I cut the first loft, I am stuck with a weird twist in the rear of the car that I don't want, but fine. Cut off half and move on.
Sketches:
results:
results:
By this point, I'm tired and am giving up. Instead of a 3rd loft, I just do an extrude with some draft to form the greenhouse. I doesn't look very good, but I've already spent twice the amount of time on this as I wanted to.
Lop off half of the greenhouse and move on.
Now it's time for the shell.
Right out of the gate, there is a problem. I'd like to select the bottom of the body as a face to remove, but for some reason when it solved the Loft, it didn't split this face into two pieces.
So, I'm stuck just picking the "interior" face and adding additional cuts later to knock out the bottom.
This is where AD always gets weird. For the first attempt, I go for the gusto and attempt a 2mm thick inward shell. AD grinds for a long time, then pops an error message that the operation has failed. No surprise. Then I turn the thickness down to 0.2 mm. AD Grinds again for a long time, and to my amazement succeeds! I see it rendered on the screen! Of course, an 0.2mm thick shell couldn't be more useless to me. I try to bump the thickness back up to 1 mm, and it fails. I turn it back down to 0.2mm and it fails. Wait a minute, why did it work the first time? I am never able to repeat that first success. Now, this isn't my first rodeo. I know that shelling outward is usually easier to solve, so I check the box and shell outward.
A 2mm shell fails. A 1.68mm shell fails, but a 1mm shell solves!
Not what I wanted, but I think I can do something with it.
Now for the easy stuff. I knock a couple of holes through the shell for the wheels. But what happened here???
Finally, I cut out the "bottom".
Okay, we are halfway there. Ideally, now I could just "mirror" all of these features and boom, I have a body shell. Of course, it can't solve that. I won't even bother with a screenshot. But, hope is not lost. I can use the Boolean Tools and insert two of these, mirror one, and "stick" them together!
Fire up a new part, do a few Boolean operations, and hey, I have an okay looking model, with one small issue.
Now, for the moment of truth, export an STL file and see if we can print something?
Here is how the STL looks when I import it into Simplify 3D:
More than half of the part is missing!
USELESS!
This little experience has played out probably a dozen times for me in the last few years. Basically, I just don't do projects that require anything other than rectangles and holes because I know Alibre simply can't handle it. It is so frustrating to be so limited! I have a hard time recommending people drop $1K or more on this software when I know it just chokes on anything slightly more complicated than plates with holes.
I don't expect to be able to model every swoop and curve of the latest Ferrari, but I do expect to be able to throw 3 lofts together and pop in a shell in a reasonable manner. I have experience with Pro/E and SolidWorks which leads me to believe that it absolutely can be done. I know, I know that AD costs less, and I know I know that it is a "great value" and that it does lots of things well. I'm also aware that there are lots of modelling techniques that "could be" used. At the end of the day though, I paid the price of the ticket for parametric 3D CAD software (in the economy class) and I expect the whole plane to fly all the way to its destination.
This turned into a bit of a rant and I apologize. The Loft feature has performed very poorly for me the entire 10 years or so I've owned this software. Is it going to get any better in the next 10?
