Announcements
Attention for Customers without Multi-Factor Authentication or Single Sign-On - OTP Verification rolls out April 2025. Read all about it here.

3D Modeling Help Needed

ReachShaun
Enthusiast

3D Modeling Help Needed

ReachShaun
Enthusiast
Enthusiast

I have a thorn in my side and it's called a spoon cover. I had nothing but problems with this modeling project.
I have tried MANY different approaches to solve the problems but, to no prevail. Therefore, I am reaching out to you all for help. Please review the attached file named SPOON v1.5. As for the problems in the model, please refer to the six images below that locate and illustrate each problem. The uniform wall thickness of each cover should be no less than 1mm thick, and no more than 1.5mm thick-with 1mm being the preferred thickness. Please review the 3D model to determine if you can help me. I have started over from scratch multiple times only to arrive at the same problems. I have cut out the bad sections and patched in new pieces in an attempt to fix the problems but, it seems this has only ever made the problems worse. Yes, I have tried the G2 tangents and straights. Nothing seems to work. I had to delete faces and use very tricky approaches to simply add fillets to the sharp edges. Your help would be greatly appreciated. You should be able to see my vision and help me arrive at a workable model. Yes, the model tree is a mess. I am beyond frustrated with this mess. PLEASE help as soon as possible. Thank you.

 

Problem 1:

1A.jpg
Problem 2:

2A.jpg
Problem 3:

3A.jpg
Problem 4:

4A.jpg
Problem 5:

5A.jpg
Problem 6:
6A.jpg

0 Likes
Reply
923 Views
11 Replies
Replies (11)

S_May
Mentor
Mentor

Hi @ReachShaun 

 

How many years of experience do you have in Inventor?
Do you have a picture of the product?
0 Likes

andrewdroth
Advisor
Advisor

Wow, you have a lot of things going on in that part man.

 

What version of IV are you using?

 

Let's start with what you ultimately need. It looks like a two part plastic piece that clamps over the end of a spoon. What clearance should there be between the spoon and the plastic? What is the nominal thickness of the plastic?

What part were you referencing to make this part?

I think I'd try and model the whole plastic part as one piece then do a shell to hollow it out, and a split to make it two pieces. I just don't know how many things are governing it's geometry.


Andrew Roth
rothmech.com

YouTube IconLinkedIn Icon


IV2025 Pro
Apple IIe Workstation
65C02 1.023 MHz, 64 KB RAM
Apple DOS 3.3

ReachShaun
Enthusiast
Enthusiast

@S_May wrote:

Hi @ReachShaun 

 

How many years of experience do you have in Inventor?
Do you have a picture of the product?

I have one year of experience from school at ITT Tech and two years of professional experience from running my business as a freelancer. I have three years of school experience with AutoCAD and six years of professional experience. So, my Inventor experience has been on and off until these recent two years of experience using it in my business. I also use Fusion 360. I have modeled much more complicated and highly complex models than this spoon. I'm not sure why I am having so many issues with it.

There is no picture of the product because it does not yet exist. Also, the model is incomplete. All I want is to get the model in a workable state--up to its current progress. I will be modifying the model once the issues are fixed. I cannot reveal these modifications. I can say the modification cannot be executed because of the existing problems. What I will do is show everyone the end result once all work is completed and it's okay to share the information. I hope I answered your questions thoroughly. 

ReachShaun
Enthusiast
Enthusiast

@andrewdroth wrote:

Wow, you have a lot of things going on in that part man.

 

What version of IV are you using?

 

Let's start with what you ultimately need. It looks like a two part plastic piece that clamps over the end of a spoon. What clearance should there be between the spoon and the plastic? What is the nominal thickness of the plastic?

What part were you referencing to make this part?

I think I'd try and model the whole plastic part as one piece then do a shell to hollow it out, and a split to make it two pieces. I just don't know how many things are governing it's geometry.


There are a lot of things going on in the model because of all the attempts I've made to work around the issues, solve the issues and avoid the issues. I will break things done in an attempt to get us further along. 

I am using Inventor 2018. 

Some of your questions were answered in the original post. I will try to reiterate more explicitly. I have tendonitis so typing is quite painful for me. Let us begin.

You are correct--as per the current state of the model. You are looking at two plastic-like pieces that will clamp over the spoon. There are no features in the current model to accomplish the task of clamping the two parts because these are not critical elements to solve the issues. 

The spoon thickness fluctuates between 1mm and 1.3mm so, the void should be 1.3mm with 0.006 inches for expansion/contraction tolerance around the entire spoon area (top, bottom and around the outer edges). Therefore, the void should be 1.3mm + 0.006in tolerance around the entire spoon surface where the two plastic parts cover the spoon. The clearance is 0.006in between the plastic parts and the spoon. For the record, these will not be plastic--this is just a basis to allow us to continue moving through the motions.

The nominal thickness of the plastic parts is 1mm, no less. The thickness can increase to 1.5mm--no more--if necessary. I would much rather keep the thickness at 1mm if possible. 

I am not sure what you mean by asking what I am referencing to make this part. Please elaborate. The spoon is correct. The only thing I didn't do to the spoon was add the 0.006in tolerance (you referred to the tolerance as clearance) so the tolerance would be included when subtracting it from the two plastic parts to create the void/shelling effect. Which, leads to your next concern. 

I did attempt to model this as one solid model followed by a shell and split command. However, Inventor would not perform the task. So, I copied the spoon to create a duplicate solid of the spoon that was to be used with the combine command to subtract the copied spoon from the solid plastic cover. After successfully accomplishing this task, I attempted to split the single solid plastic part in an attempt to convert it into two parts. 

Lastly, let's discuss what governs the geometry. Everything discussed above governs the geometry. The first sketch in the model tree named SPOON _ORIGINAL SKETCH acts as the base for the "split sketches" (left and right sides of the oval from the preceding sketch) which created the loft for the spoon surface. The split sketches are located in the model tree under the lofts named LoftSrf_SPOON and LoftSrf_HANDLE. The thicken command was used to convert the spoon surface into a solid model and is located in the model tree named Thicken39. Directly below Thicken39 is Thicken50--which was used to begin modeling the plastic parts. I then thickened the outer faces to widen the Thicken50 result in order to make the plastic parts wide enough to adequately cover the spoon at the appropriate thickness. Everything below Thicken50 is me attempting to work my way through the plethora of problems that surfaced throughout the modeling process. I also created new sketches at the appropriate dimensions to create the plastic parts. I used the same approach as I did to create the spoon. However, the same problems resulted. I also lofted the neck of the plastic parts to an offset work plane that was tangent to oval shape of the plastic parts--same result. There is no need to send all the various models that ended as failed attempts and similar results. This is just a waste of everyone's time. I believe the best approach is for someone to use the dimensional information and written information within the provided model and this thread to successfully develop the plastic parts as suggested. I can then assess the successful model to see what I did wrong and/or what I could have done differently. I know this is a challenge, maybe not for everyone, but for many. I do hope we can ban together to solve the issues. I look forward to your responses. Thank you all in advance. 

S_May
Mentor
Mentor
Creating the model is not the problem, but you have to sit next to them and talk, it will not work on the Forum.
 
0 Likes

ReachShaun
Enthusiast
Enthusiast

@S_May wrote:
Creating the model is not the problem, but you have to sit next to them and talk, it will not work on the Forum.
 

Well, creating the model is 'my' problem. Also, I don't believe sitting down with anyone is an option at this point. I understand if you cannot or do not want to help. However, someone here will be able to. I am quite intelligent and capable. I believe this will be an easy task for someone who can figure out what's going on. I will be able to comprehend the correct approach once I see it. Thank you for your contributions so far.

0 Likes

johnsonshiue
Community Manager
Community Manager

Hi Shaun,

 

Many thanks for sharing the beautiful model! Just based on how the part was created, I can tell you do know a lot about surface modeling. You are an expert. You know what you are doing and talking about. In general, I don't see any issue in terms of how you model it. I would pretty much do the same with a little less features. I would probably use more trimmed surface edges than sketches in Loft. But, it does not really matter much in your case.

The limitation here is in Inventor itself, not the way you approach the design. I took a few snapshots in Zebra analysis to show the problematic areas. As you can see from the following images, the red circles highlight the areas with curvature discontinuity. Inventor does not have enough surface modeling tools to deal with the conditions. Each piece of surface is precise but the intersection may not be desirable. Freeform may help here but forcing Freeform face to conform can also be a pain.

Inventor was not designed to tackle this kind of model. It is because it weighs on geometric precision over curvature 

continuity. In surface modeling, the tolerance is usually low. You used 0.03mm tolerance in Stitching, which is way too big for solids (Inventor is accurate up to 0.00001mm). This is why most users may use surface modeling tool like Alias and its competitors to create the surfaces. Then import them to Inventor to create solids.

 

Exhibit3.png

Exhibit2.png

Exhibit1.png

 

I am sorry that I don't have much else to offer at the moment since this is not the strong area in Inventor. Nor do I see a quick fix. I will work with our project team to see if there is room for improvement.

Thanks again!

 

 



Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer

ReachShaun
Enthusiast
Enthusiast



Thank you for your kind words. I did try lowering the tolerance but, it only led to more holes, dips, kinks and failed stitching/patching/solid edits. I also found the same issues while using the zebra analysis feature inside Inventor. I have attempted countless times to solve the issues to no resolve. Do you think you could possibly attempt to model this from scratch (minus the spoon) using the provided information to see if you arrive at the same result? I would greatly appreciate it if you can as buying another program is not feasible at this time. Thank you kindly!

0 Likes

johnsonshiue
Community Manager
Community Manager

Hi Shaun,

 

I took a look at the model and played around with it a bit. I don't think I could remodel the whole thing. I think I would hit the same roadblock as you did anyway. I did have different modeling approaches to share. Like I mentioned before, I would use model edges more than sketches. It is because it offers better tangency control in Loft and Boundary Patch. Also, I would keep the Stitch tolerance as tight as possible. Please take a look at attached part.

Many thanks!



Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer
0 Likes

ReachShaun
Enthusiast
Enthusiast

@johnsonshiue wrote:

I would use model edges more than sketches. 


Thank you for your efforts. However, this method doesn't seem to solve anything but, rather cause 'other' errors that will result in the need for other workarounds. Please see red circle in below image. SPOON v1.5_simple.jpg

 

0 Likes

johnsonshiue
Community Manager
Community Manager

Hi! Indeed, there isn't a magic button to click to make it work easily. Modeling stylish objects in Inventor has always been a struggle. Like I mentioned earlier, this is why some users are using Alias or other surface modeling tools to create stylish surfaces and then import to Inventor for solid body operations.

Many thanks!



Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer