Wireless Doorbell Switch Mount


Solutions articles showcase ways 3D Printing can quickly solve unique problems. 

Intro

Don't you hate it when you rush home from the local Big Box store so you can enjoy the latest gadget, only to find that the installation procedure isn't 100% compatible with your desire to live a pain-free life? You're not alone - it happens to me all the time!

The usually tried-and-true doorbell to my house, which produces beautiful chimes when it works, recently stopped functioning. I investigated, but couldn't quickly determine the problem. No worries, I'll save it for another day -- but it's quite annoying not having a functioning doorbell. How will I know when someone is ready to spread the Good Word to me?

I set out to purchase a simple wireless doorbell kit - that way I wouldn't have to fiddle with running wires through walls or hooking up transformers to 120V AC lines. After getting the kit home, I realized the switch portion doesn't fit nicely where the old switch was mounted.

Measured and printed a small test-fit part

Measured and printed a small test-fit part

The builders of the house placed the original switch and cemented around it, creating a perfect hole for it. A perfect hole that isn't so perfect for my brand-new and larger wireless switch. I could chip away at the cement or I could take the civilized route and use the 3D printer.

Making the Part

I measured the original hole and printed a quick piece I could test fit. It was good on the first go, so I could move onto the next step, which was making a small extension part, and a body that the switch could press-fit in to.

Putting down some layers

Putting down some layers

I took some measurements of the switch and drew up the part in CAD. I had to adjust the tolerances a couple times to get a nice fit. I printed my test parts in white PETG, only because it was installed in the machine at the time of this project. 

Too small, too big, just right; Goldilocks would be so proud 

Too small, too big, just right; Goldilocks would be so proud 

Nicely press-fit into place. Easily removable to change the battery; snug enough to not fall out

Nicely press-fit into place. Easily removable to change the battery; snug enough to not fall out

Final Touch

I could have stopped here, installed the switch, and went on living. But a white plastic holder for a white/cream colored switch is just too ugly for me. I used this as an opportunity to try and find a nice color match by using the material swatches from the Architecture Color Kit. I selected a concrete looking color, which is actually a wood-filled filament!

I like the middle swatch the best!

I like the middle swatch the best!

The completed switch mount

The completed switch mount

Conclusion

After taking the part off the bed, I tried to press-fit the switch in, but it was just a little too tight. This clearly illustrates how the selected material and profile settings impacts the finished part. Easy problem to remedy though, as with just a little bit of light sanding, I was able to fit the switch into its new holder easily. Happy with the state of the mini-project, I removed the switch, grabbed some screws, and mounted the newly printed adapter where the old switch used to live. 

The final result: a nice looking mounting adapter!

The final result: a nice looking mounting adapter!

Overall, this was a fun and quick little project that took a couple hours on a Saturday afternoon. It's easy to create custom parts for your house and add nice finishing touches so that they look like they belong!

Push Plastic Amber Translucent PETG


Test Drive articles provide a 'sneak-peek' at upcoming filaments, 3D printing accessories, and helpful software.

Intro

The fine people at Push Plastic were recently offering samples of their new PETG filament. I had never used PETG before, so I figured it would be a good idea to grab some and experiment with it a bit.

PETG offers the printing ease of PLA (no warping or odor), with greater tensile and elongation strength than ABS! Also, PETG prints can be used in higher temperature situations, as it begins to soften around 80° C (176° F), compared to PLA's 60° C (140° F). 
Geek Sidebar: This "softening" temperature is called the "glass transition temperature"

PETG is still a relatively new filament on the market, so prices aren't as low as they could be, and color selection is pretty limited. You probably won't find "Neon Chartreuse" from your favorite supplier. Still, for basic colors and some very cool translucent ones, PETG definitely deserves an investigation.

First Look

The first thing you notice is that this filament has a rough texture. It isn't smooth like the PLA or ABS you might be used to. I've read on various blogs and from suppliers that this texture was implemented to give the extruder drive gear better grip, preventing the filament from slipping while extruding. Hey, that sounds plausible!

 
PETG's interesting texture

PETG's interesting texture

 

When I get new filament, I'll take a couple diameter measurements, just for a sanity check. Of course, this doesn't guarantee there won't be something horribly wrong further down the line, but it puts the mind at ease for a little while. 

 
Quick sanity check shows filament is in spec - 1.75 +/-.05mm

Quick sanity check shows filament is in spec - 1.75 +/-.05mm

 

Observations

Since this was a brand new filament type to me, I mostly printed hollow cubes and towers with my sample. Pretty boring stuff, especially for pictures, but it's the best place to start. I am using a direct-drive style extruder with an E3D V6 hotend and .6mm nozzle, and a GeckoTek HT plate on top of Borosilicate glass for the bed surface.  

 
Machine with GeckoTek Plate

Machine with GeckoTek Plate

 

Settings

When it comes to surface quality, recommendations from various blog and forum posts were to play with the extrusion multiplier and slow down the print speed, compared to PLA. I didn't really have enough sample material to fully verify those claims, but here's what seemed to work well for me at the start:

Nozzle Diameter: .6 mm
Extrusion Width: .65 mm
Layer Height: .4 mm
Extruder Temperature: 240 °C
Bed Temperature: 60 °C (w/ GeckoTek Plate)
Print Speed: 35 mm/s

I didn't have a chance to fully investigate proper retraction settings, so I just used what I usually do for PLA.

I had no bed adhesion issues at all with the GeckoTek plate -- parts held in place very well and released easily once the bed had cooled.

Strength

The strength of printed parts is overall much more "solid" compared to PLA. I don't have any data to back that claim up quite yet, but eventually I hope to have a test in place to quantify various properties.

A single wall cylinder flexed, but did not snap, while a double wall cylinder was amazingly much stronger. Here, in an entirely un-scientific fashion, you can see the difference. I held a 500g weight on a cylinder that was placed on its side. 

 
500g weight on 1 wall cylinder

500g weight on 1 wall cylinder

500g weight on 2 wall cylinder

500g weight on 2 wall cylinder

 

The single wall cylinder has much more deflection. I was very impressed that just adding a 2nd wall made the cylinder that much stronger!

surface quality

I noticed that the temperature really impacts surface quality and clarity. Higher temperature makes the surface very cloudy. Layer-to-layer adhesion seemed very good as well, but again, I'm hoping to develop a test to quantify this in the future. 

Print temperature ranging from 235-255 °C

Print temperature ranging from 235-255 °C

Additionally, I've also just started to play with some Natural PETG from eSUN and one surprising discovery was that fast retractions cause the surface to become more pitted. If I turned retraction off, nearly all the pitting went away. I'm guessing maybe air gets into the nozzle or the material material itself on a retraction somehow, which then shows up in the print. I spent quite a bit of time trying to get Push Plastic's Amber to have a perfectly clear & smooth finish, but ran out of material before I made my discovery about retractions. 

Pitting on the surface of this print.  Push Plastic Amber PETG w/ 150 mm/s retraction

Pitting on the surface of this print. 
Push Plastic Amber PETG w/ 150 mm/s retraction

Might be hard to tell -- more uniform and clear. eSUN PETG w/ no retractions.

Might be hard to tell -- more uniform and clear.
eSUN PETG w/ no retractions.

Conclusion

After printing a bunch of test models, I had just enough filament left for one final model --better make it cool, right? In order to showcase the strength and flexibility of PETG, I decided to print this very cool carabiner model

The light shines nicely through Amber PETG. Model credit:  Charlie1982

The light shines nicely through Amber PETG.
Model credit: Charlie1982

The whole print feels extremely strong, although I did not want to destroy it by testing its maximum weight capacity, so I can't give a number for that. The 'give' of PETG works well for the flexible latch part of the model, giving it some nice springiness. It snaps right back into place, even after many repetitions. 

Overall, I'm very pleased with how this material prints. I am going to continue to investigate the properties of PETG, as it seems like a very promising material to work with. It should be more impact resistant and tougher than PLA, which makes it a good choice for more technical applications. 


PETG from Push Plastic is currently available in Natural and Translucent Blue, in 1.75mm and 2.85mm diameters. Cost is $29 for 750 grams. 

Please leave your comments or questions!