T-Plug Caps


I love playing around with CNC based machines so it was only logical that I pick up a 3D printer. They have been around for a while and are starting to go mainstream as the technology is becoming more popular.  You can purchase a preassembled and tested machine for under $500 now and be printing free files shared on the internet from places like thingiverse.com without any knowledge of 3D modeling.  I recently picked up a PrintrBot Simple Maker kit to build with my sons.  It went together in about 5 hours over two evenings.  It was a great project to share with them as they learned about how CNC machines work.


I have been working with Sketchup for a few years now and I love that it’s simple yet accurate for design work.  Best of all it’s free unless you want to unlock the pro features.  There are thousands of plugins for it to expand it’s capabilities as well.  The ease of creating 3D objects in Sketchup make it a great tool for designing items for 3D printing.

While I was browsing the web I came across the idea of using battery end caps as charge status indicators.  A simple colored plug could tell you at a glance if your pack is charged or discharged.  With the many different plug styles out there I had hoped to find one for the popular T-Plugs that I use on my smaller models but I did not so off to Sketchup I went.  I just needed a few measurements from my calipers on a plug and about 30 min later I had the basic design. A quick export command from Sketchup and I had an STL file ready to be processed.

Screen Shot 2015-03-20 at 2.12.30 PM

The Printrbot guide recommends using Cura to take STL files and slice them into gcode for the printer.  There are a variety of settings you can choose from in the program that are going to be specific to your type of printer.  I opted for no brim for adhesion and about a 15% fill to save on material. Once the options were set I warmed up the printer and let it start the print.Screen Shot 2015-03-20 at 2.31.20 PM

3D printing is a slow process as it builds the part in small lines and layers.  Printing one plug at a time would take about 7 minutes on my printer but then I’d have to restart the job.  So I maximized my print area of 4″x4″ and setup 12 plugs in one job.  This took about 90 minutes to complete.


Here is a video of the printer in action printing out the 12 plug setup.



If you have a 3D printer and would like to print out these plugs for yourself I have included the STL file for download below.  I would just ask that you leave a comment below letting me know how it worked for you!

Click here to download the STL files for the TPlugCaps

One thought on “T-Plug Caps

  • August 2, 2015 at 9:09 pm

    I was looking up colored caps for T plugs and came across this page. Thank you for posting it! Just wanted to share a few ideas with you. I see a company is selling red and green and you have black and red. A lot of people are looking for protector caps that can distinguish charged or not. I’m currently going through balancing, then reducing to storage voltage so I’ve found I have 1)charged but not balanced 2)charged and balanced 3)not charged 4)charged to storage capacity. I’ve also seen caps that are imprinted with “full”. I wonder if there would be value in having more than two colors and/or imprinting 1, 2, 3, 4 etc?

    Also, I haven’t been able to find caps for the balance plugs. I see “protectors” so the wires are not pulled out when you disconnect the balance plug, but nothing to cover the terminals. Is that something you might consider making and selling?

    Thanks again for your website!


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