Five minutes from now, you will know two ways to recess a surface in SolidWorks. They won’t necessarily crush your skull, but they may expand it slightly by enriching your mind with the power of sketch, surface and split face features.
It seems like there should be one feature to recess a surface in SolidWorks. It’s simple on a flat surface, a cut with a draft. But for a curved surface? Now, that’s a whole other beast and requires much more than one feature to create. Fortunately, you have at least two methods. Let’s Rock.
More Than One Way To Skin a Skull
Last week Cris Rose, asked how to go about recessing a surface in SolidWorks. It’s a great question and also a chance to show some new features that are going to help you do it MUCH easier in SolidWorks 2010. We’ll be using the Hack-a-day logo to get this tutorial kicked of right.
As stated, we’ll look at two ways to do this. There are benefits to each and each show how the process could be improved. We’ll touch on that later, but for now here are the two three options available for recessing a surface in SolidWorks.
Option 1: Offset Surface
When all you have are surfaces, use this option to recess any type of odd shaped surface. Here are the steps:
- Project a Split Line of your sketch onto the surface (Insert, Curve, Split Line… Projection)
- Offset (Copy) the Split Faces the depth of your recess(Insert, Surface, Offset…)
- Delete the original split faces(Insert, Face, Delete…)
- Loft between profiles(Insert, Surface, Loft…) When Lofting use the SelectionManager (Right-click on profile edge, select Open Surface option)
- Knit your surface (Insert, Surface, Knit…)
Total Rebuild Time: 4.53 seconds
Download File: Surface-Recess-01.sldprt (SolidWorks 2010)
Option 2: Thicken-Cut Surface
Fewer Steps, faster rebuild. This option comes with much thanks to Charles Culp via the SolidWorks Forums. Whether you start with a solid or if you thicken a Surface half-way through your modeling process, the same process applies. This method will not work if all you have are surfaces.
- Project a Split Line of your sketch onto the surface (Insert, Curve, Split Line… Projection)
- Offset (Copy) the Split Faces a depth of zero (Insert, Surface, Offset…)
- Cut-Thicken each open profile (Insert, Cut, Thicken…)
Total Rebuild Time: 1.75 seconds
Download File: Surface-Recess-02.sldprt (SolidWorks 2010)
Option 3: 3D Sketch with Draft
Here is one more option courtesy of Mark Biasotti, Product Manager of New Product Concepts at SolidWorks. It takes a tad longer to rebuild, but if you really need those drafts in there, it’s absolutely the quickest way to go about doing it. Thanks Mark.
- Create single Spline curve feature in 2010
- Create a 3Dsketch and convert entities on all contour and extrude with 5 degree draft
- Reselect inner contours and extrude with draft up to body
Total Rebuild Time: 13.23 seconds
Download File: Surface-Recess-03.sldprt (SolidWorks 2010)
The ‘Pull’
About Draft
I realize this isn’t going to the first two options will not be suited for injection molding at this point. In the case of adding draft, use the third option. The first option works, but you need trim off a little bit of the profile before creating the lofts. In the second option, ideally you would be able to add draft to the Cut, but the Cut-Thicken options doesn’t have that functionality. For a shallow recess like these, you shouldn’t need much of a draft, maybe 0.5 -1.0 degree.
Better Ways to Recess a Surface?
The ideal way to create a recessed surface like the above examples, with a single feature, would simply be to allow the Wrap feature (emboss/deboss option) to function on a spherical/toroidal face. Oh, with multiple open profiles and the option to add draft. It seems to me that this functionality is already there with the features used above. They just need pushed into that single feature.
New Sketch, Split Line, Surface Features for SolidWorks 2010
These examples used new features available only in the 2010 version. Without them, you would either spend hours on workarounds or just not create a recessed surface. All together, these examples took 14 minutes to create and fiddle around with. Here are the 3 features in SolidWorks 2010 you’ll definitely love when it comes to working with curved faces.
Sketch Move/Resize
You may have noticed a box with handles around the sketch. When a sketch is undefined, this shows up when the sketch is selected. It allows you to quickly scale and move it. This is absolutely incredible for working with imported sketches.
Multiple Profiles for Split Lines
You may have also noticed the Hack-a-day logo has multiple profiles, but in the FeatureManager only one Split Line feature is shown. In SolidWorks 2010, you can now project multiple profiles onto a face.
New Surface Knit Tolerance
At the end of the first example, you knit all the surfaces together. In the past, this was a pain. It either worked or told you it couldn’t knit the surface. Now you have tolerances adjustment for gaps. Adjusting it slightly in this case, allowed the surface to resolve and the Knit feature to work extremely smooth.
A Better Way to Recess a Surface?
These are just two ways to go about recessing a surface for logos, text or simple indentations on complex faces. However, there could be other ways to do it. Any suggestions for a process that makes this easier? What if you wanted to make a gradual or sloped recess? Any ideas?
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Great post Josh. Although I have never had to do this type of feature, it is always interesting to read about it and bookmark it just in case. Adding this one to Google Reader for sure.
If you have solids, how about just extruding a cut up to an offset surface. You can do that with 1 feature, because you can offset the surface within the extruded cut. That is about as easy as it gets. I think that the surface has to be all one patch, but that seems to be what your example is showing.
AWESOME ecirwin. This is a great method too. It rebuilds a lot faster. Twice as fast as the last method. The only problems I've had are with getting a draft and the cut is always straight into the surface. Still, this is a super good method for very shallow recessed features. Thanks!
I would say that unless you are making this feature more than 1mm (.040″) deep, the draft is overkill. If you really need the draft, I don't see why a Parting Line draft wouldn't do the trick. We use this method all the time to put text on our parts.
Another thing you can do is to make the cut-extrude “from surface.” That way, you don't have to worry about offsetting surfaces to extrude to. However, this method doesn't let you add draft.
(Also, hi everyone! I've been reading this site for a while, but this is my first post here. I hope to join in more discussions in the future. Thanks!)
My method does not require you to create an offset surface. From within the Cut feature for the depth choose Offset from Surface.
I never create draft from within a Protrusion/Cut. It generally just leads to problems and the inability to find the draft to change it when I need to. Maybe it is old school CAD, but I try to create all my features, then create draft, then create rounds. Seems to create robust models most of the time.
For a sloped recess – offset a surface, then use a body copy/rotate and rotate the offset surface a small amount, then trim, loft and knit. Not sure about rebuild times, but you could always use trim with multiple contours in a sketch instead of split lining it?
Also, not sure about how well the rotate method for creating a sloped recess would work on surfaces with a high degree of curvature – my guess is you would need to copy the initial sketches and modify the geometry in these cases.
Hi Petr, thanks for the comment. looking forward to getting your input in the future too. That method definitely save on rebuild time.
It probably depends on the part and the manufacturer. I've been recommended draft from manufacturer. It's probably more of a catch-all, just-in-case type thing though – a general rule for the parts they mold.
While the draft probably isn't needed in most cases for shallow cuts like this, having the option would still be kinda nice.
Hi Kieran, I love it. that sounds like a great method. I haven't tried this yet, but I have a model coming up that I'll need to do this on. Your suggestion will be the first one I try
thanks!
The difference between Extrude To Surface (or extruded cut to surface), and an offset is a matter of the sides, and the curvature. Extrudes will create flat sides, and a linear extrusion. If you are looking ad embossing or debossing a logo into a plastic part, then it is definitely the way to go. You can then create draft, and it will be easy to make.
The reason to consider an offset surface is for more complex shapes. If you want it to cover a 90° bend, for example, it will have to be an offset, because you cannot extrude in both of the directions. Because the “curvy surface” used in this example is almost flat, this is not noticeable.
Also, if it is a plastic injection molded part, with the offset surface you will have to accommodate the draft with other solutions. Simply “applying draft” will probably not work, and that will all just depend on the model.
Josh,
Are you saying that you are unable to apply the draft at all? A “Parting Line” draft isn't working? Or is it that you have to add another feature to get the draft, and you just don't like that?
Eric
For those that are curious, I've updated the post with a method from Mark Biasotti of SolidWorks. It takes a little bit longer to rebuild, but it creates a draft recess with a couple features.
Hey Eric, I don't mind the extra feature so much if it works. Like in the second option. I couldn't get a draft on that one unless I convert the profile to sketch lines in 3D sketch, then add a cut with a draft, like in the 3rd option.
Still, I'm hoping this will be a single feature in the next release.
cool! never heard of Solid Works until now! 3d program?
Haha, I've never actually had to model this, so I'd definitely like to know how you get on.
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From the dead!
Gradual recesses are easy. Here is a method to do it with one tangent edge, so the recess blends into the original face.
1. Copy the face you want to contain the recess.
2. Trim out an area of the copied face that extends past the boundaries of the recess sketch. One of the edges of this area must cross thru your sketch, unless you don't want your tangent edge to crop your recess/deboss sketch. (but then it doesn't blend!)
3. Create a new surface tangent to one of the trimmed edges.
4. knit the two, and you have a gradual-slope extrude up to/boolean solid trim tool.
Sometimes it is hard to freehand a surface in space. If you are having trouble creating the tangent surface, you can split and copy in step 2 instead of trimming. Rotate the copied patch downward, then use a pair of bride curves to blend the converted edge of the patch to the desired tangent edge. That should give you enough info to create a tangent deboss/recess that looks like it was derived from the original surface.
These techniques can be varied to create all types of non-constant offset features, like vents, debosses, embosses, strap recesses, etc.
great method. I'll definitely try it out. are you using a boundary surface in step 3?
You can use boundary, loft, or fill surfaces. It depends on how you set up the curves that define the surface. I find fills are often the most reliable, but don't offer as much control as a loft or a boundary surface.
From the dead!
Gradual recesses are easy. Here is a method to do it with one tangent edge, so the recess blends into the original face.
1. Copy the face you want to contain the recess.
2. Trim out an area of the copied face that extends past the boundaries of the recess sketch. One of the edges of this area must cross thru your sketch, unless you don't want your tangent edge to crop your recess/deboss sketch. (but then it doesn't blend!)
3. Create a new surface tangent to one of the trimmed edges.
4. knit the two, and you have a gradual-slope extrude up to/boolean solid trim tool.
Sometimes it is hard to freehand a surface in space. If you are having trouble creating the tangent surface, you can split and copy in step 2 instead of trimming. Rotate the copied patch downward, then use a pair of bride curves to blend the converted edge of the patch to the desired tangent edge. That should give you enough info to create a tangent deboss/recess that looks like it was derived from the original surface.
These techniques can be varied to create all types of non-constant offset features, like vents, debosses, embosses, strap recesses, etc.
great method. I'll definitely try it out. are you using a boundary surface in step 3?
You can use boundary, loft, or fill surfaces. It depends on how you set up the curves that define the surface. I find fills are often the most reliable, but don't offer as much control as a loft or a boundary surface.
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