14 tips for designing prototypes for 3D printing

Matt Donley 3D Printing, News, Tips & Tricks 1 Comment

3D printing is an excellent technology for creating prototypes. In this article, I’ll share my tips for creating a 3D printed clip for my audio recorder. These tips will help you design your own objects that interact with your phone, remote, camera, or any other object you’d like to design an accessory for.

When you own a 3D printer, (or have access to one through a service like 3dhubs), you start thinking about all the awesome things you can design for the various gadgets you own. In my most recent project, I wanted to design a clip that would allow me to mount my audio recorder to my belt, or to a tripod.

As I finished up the model, I thought it would be helpful to share a list of tips I use in my workflow that you can apply to your own 3D printing project. Most of these tips can be used with any 3D modeling software, not just SketchUp. They will help you save time, model more accurately, create a stronger model, and reduce warping. Let me know if you have any additional tips in the comments below.

Designing 3D printed Clip

1. Research existing models

thingiverseThe first step I took when designing a clip for my Zoom H4n, was to do some research to find out if anyone else had already designed one. Although it’s not nearly as much fun to print out someone else’s design, if someone has already spent the time to do it, why waste your time reinventing the wheel?

In addition, the other purpose of searching for existing models is so you can reverse engineer it, and integrate their features into your own design. Try looking at Thingiverse.com and YouMagine.com for 3D printable models. If you’re searching for models related to a specific camera or phone for example, just search for the camera model number at first. Narrow your search from there. For instance, I simply searched for “H4n” and only found a handful of models. If I had been more specific, my search may have come up empty.

I found one model, printed it out, and found a number of things I wanted to improve:

  • The belt clip was a little too wide, leaving it feeling loose on my belt.
  • The clip itself was too loose, so it wouldn’t hold the Zoom H4n securely in place without using a bolt. I felt that I could design something that actually “clipped” in place, without having to use hardware.
  • The clip covered up important buttons on the device, something I wanted to avoid.
  • I wanted my clip to be able to mount to my tripod, using a standard mount called an “arca-swiss” mount. This model didn’t include this feature.

I wasn’t able to find any features I liked about this model, but I did discover an ingenious trick used in the model to help prevent warping while printing. See tip #13.

Existing model

2. Start with one profile

Instead of trying to model your entire part all at once, identify critical profiles that you expect will need multiple iterations. In the case of my audio recorder clip, I knew that the part that grabs the recorder will be really tricky because it needs to have enough grip to hold the recorder, but needs to be flexible enough to take on and off easily.

profiles

By isolating profiles like this, you can speed up your prototyping time by only printing that small part until it’s correct. Once it’s perfect, you can then integrate it into the larger design, knowing that the profile is correct and won’t need to be fiddled with again.

3. Calipers are required

In order to take accurate measurements of the object, you’re going to need calipers. I have a set of vernier calipers, but you can find digital calipers for sale too these days. This measuring tool will allow you to take interior, exterior, and depth measurements very precisely. Here are a few calipers I recommend on Amazon. The iGaging IP54 Electronic Digital Caliper  is a digital caliper, that will display the measurement on an LCD screen. If you’re looking for a vernier caliper like the one I have, check out the Fowler 52-058-016 Stainless Steel Fine Adjustment Vernier Caliper (These are affiliate links. If you decide to purchase through these links, I’ll earn a small commission at no additional cost to you.)

I find it easier to model in metric units when designing small objects like this in SketchUp. You can change the display units by going to Window -> Model Info -> Units.

calipers

4. Using paper to model profiles

When you’re designing something that is going to interface with a real life object (like an audio recorder), it’s really important to get an accurate model of the recorder into SketchUp so you can reference its shape when designing your 3D model. One way to do this is to use a heavy paper, like a manila folder.

paper scribe

Use a set of calipers to measure the device, then use a razor knife to cut the shape out of paper. Fit the paper on the device where your 3D printed clip is going to attach to the device. You’re not going to get a perfect fit on the first try. Use a pencil to scribe the paper against the device and trim it for a perfect fit. This is much faster than trying to model the profile in SketchUp, printing it out, checking for fit, and trying again.

Once you’ve gotten your profile trimmed perfectly, scan it into your computer, (avoid using a camera if possible in order to eliminate lens warp.) and import it into SketchUp as a JPEG. Once it’s in SketchUp, use the Tape Measure tool to scale it to size. You can now use this JPEG to trace over when creating your model.

If you’re not able to scribe properly because you are wrapping around an object, like in my case, you can use the offset tool to offset your pencil lines inside SketchUp.

5. Plan the orientation of your model

The orientation of your model is critical. You should have a rough idea of the shape of your model before you begin, so you know which part of the model will be touching the printer bed. There are a few things to think about when orienting your model:

  1. The surface that is facing down needs to be flat, and needs to have enough surface area to support the model, stay adhered to the bed, and prevent warping.
  2. The direction of the “grain” is really important depending upon the type of stress being placed on the model. In my example, I am designing a clip, so there will be forces on the belt clip and the clip holding the audio recorder. I need to orient the model so that each layer follows the profile of the clip. You don’t want to depend upon the adhesion between layers for stress points.
  3. You need to make sure you don’t have any parts of your model in excessive overhangs, or else you’ll need to print with support material. You want to try to avoid support material when possible to produce a cleaner print, save time, and save filament.

goodorientation

badorientation

6. Use taller layers to save time

With these early prototypes, use a larger layer height when printing in order to print faster. (Larger layers means you’ll reduce the number of total layers in your print because each layer is taller. This makes it print faster.) You can change the layer height in your slicing software. Once you get to your final prototypes, you can decrease the layer height in order to have a smoother surface on your print.

slicer layer height

For those new to 3D printing, the general software workflow looks like this: Design your model in a 3D modeling program like SketchUp, and export it as an STL file. Then, import the STL into a slicing program. The slicing software allows you to set all the parameters like layer height, infill, print speed, etc. The slicing software then “slices” the model and generates a file called GCode, which are the actual instructions for the printer to print the model. Finally, you use a printer interface software to connect to the printer and send the Gcode instructions to it. Some printers have their own all-in-one software, which includes slicing, and there are many free open source software packages for 3D printing.

7. Use straight lines when possible

It is much harder to make changes to curved surfaces in SketchUp. If possible, use straight lines, aligned to an axis when possible. Once you’ve finalized your design, you can review it and add curves and rounded corners if desired.

8. Save copies of your model at different stages

At different phases of your design, create a copy of your component, right click, and select “Make Unique.” This will leave you with a record of your design process, and will help you when you need to go back and make changes to your design. And don’t forget to save your file too.

keepcopies

9. Create a rough model of the object you’re attaching to

It’s a good idea to include at least a rough model of the object you’re going to be attaching to. In the case of the audio recorder, There were buttons that I needed to have access to, and there was a speaker on the back that I wanted to keep exposed, so I created a rough model of the audio recorder in order to reference the position and orientation of the things right inside SketchUp.

I used a simple circle to represent the speaker, just so I had a visual cue reminding me to stay clear of it.

zoomh4n

10. Integrate other models in your project

arcaswiss plateOne of the features I wanted to integrate into my model was the ability to attach it to my tripod, using a special mounting device called an “arca-swiss” mount. Instead of modeling the plate from scratch, I went on thingiverse and found a model of an arca-swiss plate that I used to base mine off of.

Sometimes you can import the model and join it to your existing model. But other times, you might find it easier to just use it as reference. For example, maybe you want to include a hinge in your model. You can find many hinges and integrate them into your design.

11. Test your prototype

Once you’ve printed out a prototype, test it thoroughly. Once you find something you want to change, don’t stop. Check for print quality, strength, fit, clearances, overhang quality, ergonomics, etc. Keep searching for other things you want to change and make a list of them if needed. You want to try to find as much as you can in each prototype so you can make multiple changes in each iteration.

In my first prototype of my audio recorder clip I wanted to make these changes:

  • I wanted to orient the arca-swiss mount 90° the other way, so it would be stronger, and the entire clip could be the same height.
  • It was difficult to unclip it from the audio recorder, so I thought I’d add a finger tab to give me more grip.
  • The belt clip was too loose, so I thought of adding some ridges inside to provide more friction.

clipimprove

Sometimes, if you make too many changes at once to the same area, you get into trouble. For instance, the clip profile needed to be very specific in order to have the right feel, so I only changed one surface at a time until I got it right.

Before you begin to make changes, make sure you save a backup copy of your SketchUp file so you can go back to the currently printed version if necessary.

12. Round corners on final prototype

Once you have a prototype close to the final design, round the corners of your model that you’d like to smooth out. Eliminating sharp corners puts less wear and tear on your printer and makes a stronger print. I use the RoundCorner plugin, which you can read about in my 3D printing plugins article.

When designing small objects for 3D printing, remember that you don’t need a lot of segments in your circles and arcs. 6 segments is usually enough for rounded corners. Sometimes it’s easy to forget how small the object really is when you’re modeling while zoomed in.

roundcorners

13. Add breaks on the bottom layers to reduce warping

One of the challenges of 3D printing is warping. It occurs naturally as the bottom layers of the print cool faster than the ones above them. That’s why you hear a lot about active cooling, heated beds, and printer enclosures. It’s all to regulate temperature. Aside from trying to prevent warping on the printer side of things, you can also incorporate some tricks into your model that will help prevent warping.

breaks

Add physical breaks in your model every 15mm or so, about 1.5mm high.

reliefs

largewarp

alternate holes

Doing this will cool the layers more evenly, allow for a small amount of contraction, and prevent pulling on the edges of the print, reducing the chances of warping. You might find it’s not necessary to do this if your printer can print your model without warping. I’m using a MendelMax 3 with a heated bed, so it really wasn’t necessary for me to do this.

14. For large surface areas on the build plate add reliefs in the middle

If you have a model with a large surface area on the bed, try raising a few areas up a few millimeters in order to reduce the amount of filament on the first few layers. It will make your model stronger, promote even cooling, and prevent warping. You’ll also save yourself some filament.cooling reliefs

Let me know if you have any additional tips below, and check out some of my other 3D printing articles, like:

8 Tips for 3D printing
Design considerations for 3D printing
Best 3D Printing Plugins for Sketchup
Working with STL files in SketchUp for 3D printing

 

Comments 1

  1. Thanks, a good mix of things I already do (nice to know I’m doing things right), with some new tidbits (warp relief gaps?!?! Who knew!!).

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