# From PTC Mathcad to the 3D Printer: Springs and Drillbits

#### by Ioana Dănilă | August 24, 2017 | Mathcad Blog

Calculations and scribbled notations are old friends to an engineer. Without these methods of memory and communication, we would lose countless brilliant ideas. Take Leonardo da Vinci, for example. His famous notebooks were recently digitized. Five centuries later, we’re still learning from him and sharing his engineering lessons.

PTC Mathcad is an engineering notebook too. But unlike a standard notebook that simply documents your ideas, you can also use PTC Mathcad to directly integrate calculations and engineering documentation with your CAD models. (Check out this blog post from Tim Bond for a good introduction.) That’s a significant upgrade from Da Vinci’s days.

So what does it look like in practice? Let’s compare a few common uses of helical patterns.

## An Optimized Spring

We used an example from Cosmin Negru to help design a helical curve in PTC Mathcad. This compression spring emerged from three inputs:  minimum deflection, allowable shear stress, and applied axial load.

Using a solve block in PTC Mathcad, you can optimize the calculations to create a spring that meets whatever you specifications. Then generate the part in the CAD application, and you’re all set!

Spring as it appears in Creo. With the PTC Mathcad integration acting as the engineering notebook, parameters changed in PTC Mathcad automatically change in the 3D CAD model.

Thanks to Alex Cazacu,  we took the design a step further to see how it would do on the office’s 3D printer.

View from Makerbot, with added supports

Printed spring

## Helical Drill Bit

The second example applies it to manufacturing. Using PTC Mathcad, we develop calculations and design a helical for a drill bit.

We then push those values into Creo and use them to design our model.

Drill bit modeled in Creo

And the finished product.

Printed model

Because the Creo model includes the PTC Mathcad worksheet with all its calculations and documentation, the full design intent is accessible by everyone who needs it. No time is wasted with phone calls, emails, or meetings asking questions about specifications, materials, and other details.

## Crankshaft

Okay, one more. The image below is a crankshaft and pistons from an internal combustion engine. The crankshaft rotates, moving the pistons up and down to compress air and fuel, resulting in the combustion that drives the engine. Oversimplified, but you get the idea.

Crankshaft designed in Creo (left) with an assist from PTC Mathcad (right)

The diameters of the piston heads, the crankshaft radius, and the allowable compression and displacement ranges are all shared between the PTC Mathcad worksheet and the top-level Creo model. The PTC Mathcad worksheet calculations reflect any changes made to the piston head diameter in the model.

This connection and feedback gives you nearly instant verification and validation of your designs. And that’s the beauty in the PTC Mathcad/Creo marriage. It all revolves around three specific use cases – as seen in the examples – that are most common to your work.

Analysis Driven Design: To create the helical compression spring, we performed necessary calculations to come up with parameters that drive Creo geometry.

Document Design Intent: Manufacturing a simple drill bit. Use PTC Mathcad as a partner to the CAD design; with the new integration, you can embed a PTC Mathcad worksheet within the Creo Model.

Verification & Validation – Making changes to the engine specs means bringing Creo dimensions into PTC Mathcad and using calculations to verify that the Creo part or assembly pass requirements.

Leonardo da Vinci used helical patterns, too. One of his more popular designs is the helical screw, or aerial screw. Some think of it as inspiration for modern helicopters. It’s too bad his notebooks didn’t enjoy the benefits of CAD and an integrated engineering notebook like PTC Mathcad. We can only imagine what the great inventor would have accomplished with PTC Mathcad, Creo, and a 3D printer!