Spare part for a salt-pepper grinder

[dejmail]

Hey everyone

Hope this post is in the right place.

Attached is the spare part I attempted to design for an expensive salt/pepper grinder. This is the first thing I've ever drawn in CAD (certainly not my background), so I would be most appreciative if anyone could offer comments on how I could improve it. I think it is a bit sketchy, but it was taking me so long I just submitted in the end. Basically I drew numerous sketches, padded them until it looked like it was right, and then converted to an obj file and requested a print. It is just a collection of individual parts, none of which are is joined/merged with each other as I just couldn't seem to get that to work (as you can see from the extra edges). Probably not the best strategy, but then I'm not entirely sure what I'm doing.

[NormandC]

Hello dejmail,

Welcome here. Your first post is to share your project: very good, most people ask for help in their first post!

Hope this post is in the right place.

It is.

It is just a collection of individual parts, none of which are is joined/merged with each other as I just couldn't seem to get that to work (as you can see from the extra edges).

I'm a little surprised your fabricator didn't report problems with your obj file. But hey, if it works.

The basic principle in the Part Design workbench is to map your sketch on the face of the latest solid feature (usually the one visible in the 3D view). Then, any new Part Design feature gets added or subtracted, depending on whether you're creating a pad (additive) or a pocket (subtractive). This is done quite easily: simply select a face on the solid before creating the sketch.

In this specific case, what I would have done is to build the bridge walls right after the Outer circle, by mapping a sketch on the bottom face of Outer_Circle_Pad. That would have given you the planar face to map the Bridge_Sketch on. Then you'd only have to map the InnerRingSketch to the bottom face of Bridge_Pad, and you'd have a single solid.

I recommend you read the Basic Part Design Tutorial, it's a good intro on the matter.

[cox]

Nice dejmail,

I love these projects, when FreeCAD and some kind of manufacturing deprives landfills from from their cravings.

Hoping to see some pictures when the part arrives.

[r-frank]

Hello.

Welcome to FreeCAD and the Forum.
Thanks for sharing your project, always nice to see what others do/experience.

Attached find "my" version of the cap.

I used a "fused" approach.
I also used constraints instead of dimensions.
And I combined two sketches ...

Roland

[PrzemoF]

dejmail, welcome to the forum! If that's the first thing you did in 3D CAD I have to say you did a great job!

Can you post photos of the part + dimensions?

[dejmail]

Hej Norman

Thanks for the suggestions.

The basic principle in the Part Design workbench is to map your sketch on the face of the latest solid feature (usually the one visible in the 3D view). Then, any new Part Design feature gets added or subtracted, depending on whether you're creating a pad (additive) or a pocket (subtractive). This is done quite easily: simply select a face on the solid before creating the sketch.

I think I watched a tutorial (among several) where the person made extensive use of Union, Intersection and Cuts under the Parts workbench. This seemed to work in the beginning, but the problem I ultimately faced was that eventually I couldn't achieve the shape I was after, it was always cutting or intersecting the the inverse of what I was wanting. Hence I went the direction I went.

In this specific case, what I would have done is to build the bridge walls right after the Outer circle, by mapping a sketch on the bottom face of Outer_Circle_Pad. That would have given you the planar face to map the Bridge_Sketch on. Then you'd only have to map the InnerRingSketch to the bottom face of Bridge_Pad, and you'd have a single solid.

Yes, mapping to a face. I did try that, but could never quite get it right. I seem to remember the program complaining that I needed to do something extra (I have forgotten now what it was) and so I gave up on that. I also think my graphics card makes this design process rather challenging. Normally the face is so strangely shaded that I don't really know what I am selecting.

I recommend you read the Basic Part Design Tutorial, it's a good intro on the matter.

Thanks, I will definitely have another look at the tutorial you suggested. I think multiple practise attempts is definitely the way to go with this.

[dejmail]

Hej Roland

Many thanks for your suggestions. Your technique sounds rather more sophisticated than my sticky-tape approach, so I will attempt a study of the file to see you did.

[dejmail]

Hi everyone

The parts arrived from Shapeways, and I am very impressed with the quality of the print (strong white flexible plastic). I think when the parts break again, I will put in another bridge perpendicular to the current one to spread the load a bit. The previous parts all broke at the connection between the bridge and the outer circle. Perhaps I can have it printed in steel for added strength.

I have attached a picture of what it looks like, and not only does it fit snuggly, but it works !