Another week is upon us, it’s time to knock those cobwebs out of your head and get ready to learn some more cool stuff. Last week, I went over a couple of fillet tricks that I hope you enjoyed and this week I am doing more of the same. One of my favorite fillet tricks is using Hold Lines with Face Fillets. Hold lines allow you to better control how you fillet your part by specifying the tangent lines for a fillet rather then the radius. Today, we’ll look at two ways hold lines can be used.

Creating a Hold Line

Using the same basic model we used last week, we are going to apply a radius to one edge of the part just to demonstrate how to use hold lines. Don’t be fooled by the simplicity of the part we are using. Using Hold lines can help you create some complex fillets and shapes but we are going to keep it real simple today.

The first thing you need to do is create a Split line if there is not another line available that be used as the Hold Line. You can specify any edge on a part as a hold line but we want to create our own to achieve a different kind of effect. On the top face of the part, we are just going to sketch a spline. Doesn’t matter what the shape is at this point, just have fun with it.

In the Mold Tools toolbar select Split Line or you can also click on Insert -> Curves -> Split Line.

In the Split Line PropertyManager, select Projection as the Type of Split. In the Sketch to Project field (pink) ensure that the phrase current sketch or the name of the sketch with the spline is shown. Then with the Face, to Split field (blue) active, select the top face of the part. Click the green arrow and the split line will be created for future use.

Create Face Fillet with Single Hold Line

With the split line created, click on the Fillet tool.

To use Hold Lines you must select Face fillet in the Fillet Type section of the Fillet PropertyManager.

In the Items to Fillet section, select the two faces. Notice that the Split Line has no effect on the fillet, in fact it is still a standard fillet with a radius of .100″. That is because we have not specified the Split line as the Hold Line yet.

In the Fillet Options section header of the Fillet PropertyManager, click the arrow to expand the section.

Click the Hold Line field…

…and select the Split Line we created earlier.

You will see from the preview how the nature of the Fillet has changed. No longer does the Fillet use a specified radius, in fact if you look in the Fillet PropertyManager the field to specify a radius has been removed. Instead the radius changes as the Hold Line drifts from the edge. As you can imagine, this could mean some really cool radii without having to use a Variable Radius but what if wanted the shape to be different on the second face?

Create Face Fillet with Two Hold Lines

Using the same process as with the first Split Line, create a second Split Line on the other face of the part. Once again the shape doesn’t matter on this one, just make sure it is different then the first Split Line. Then when creating the Face Fillet, select both Split Lines as Hold Lines in the Fillet Options section.

When using two Hold Lines, you must make sure that you have selected Curvature continuous in the Fillet options.

Click the green check mark to create the new fillet.

Ooo… So Pretty…

Can you see why I love using Hold Lines? I can get some great effects, when I am creating injection molded parts, without having to use the Variable Radius Fillet. The same warning I gave you last week still holds true, don’t get to crazy on your fillets if your parts are intended for machining, your machinist will thank you. Until next time..

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