# Modeling Chain

As the title suggests, how would you model a very basic chain loop to check for clearance issues. If it helps, it’s for a west coast drive. I want to model #25 chain but I am assuming the same concept can be applied to #35 chain whatever it is. I’m using Solidworks 2018.

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Draw an arc for one sprocket, an arc for the other, then draw two lines connecting them and make tangent. Then you can offset sketch and extrude.

Example using Onshape just because I don’t have solidworks ready. The same principles apply.

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thank you, is the arc the pitch diameter of the sprocket or the total diameter

You’ll want the outer arc to be the outer diameter of the chain wrap. Vex’s technical drawings include a list of these, but I’m pretty sure there’s also a way to calculate it from the sprocket teeth count and pitch. They also list the width of the link as 0.232", not the 0.125" I guessed.

The above suggestion will work perfectly fine. Even simpler of a drawing is doing a thin extrusion from the midline in solidworks of the correct width and height of the chain. Thin extrusions save me and my company a LOT of sketching time, and I do suggest becoming familiar with their usage.

What I typically do is draw the standard chain pitch line (which is not the correct length for C-C) and also the maximum corssectional profile of the chain and sweep along the pitch line. You can get a few more of the specific detailed dimensions when doing it this way, but it’s not necessary for FRC purposes. I use this at work as we often have tight clearance issues with parts.

I would recommend an easier path of doing this, Solidworks has a chain and belt mate tool that can create all of these sketches for you. However, this is within an assembly and in my example, used for elevator chain. It still good to know, so I will continue. Our design team has done this in the past and it has saved us a tremendous amount of time. Step 1: Insert your Sprockets, Then, Create One Mid-Plane in one of your sprockets. Step 3: In the drop down for Assembly Features, select “Belt/Chain”. Step 4: Select the Edges of the Sprockets in the Belt Members Section. Step 5: Select the Mid-Plane you created for the one sprocket and put it in the Belt Location Plane Section. Hit Done. If done correctly, it will look like this.

DISCLAIMER: Optional Steps Ahead. Step 6: If you then want to create the chain, In your Case 25, insert both link models into the assembly. Create Mid-Planes in both Links. Then go to the Drop Down Near Linear Component Pattern. Select “Chain Component Pattern” Step 7: Select “Connected Linkage” or the Third Option At The Top. Step 8: Select the Sketch within the Belt Mate Created Earlier. Then, Check the “Fill Path Option”. Step 9: Select One of Your Chain Links. Then proceed to select the cylindrical face. (If Inside Link, Then Select the Face in Which the Outside Link Goes Into. Vise Versa). Next, Select the Face Perpendicular to that. After that, Proceed to Select the Mid-Plane You Created Earlier for the “Path Alignment Plane”. Repeat for the Other Link. (If Dynamic is not Pre-Selected, Select It). Then, Click Done. After it Rebuilds, the Chain Should Be Fully Linked! I hope this helps!

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