Better Cooler Drain Plug (RubberMaid Cooler) with o-rings.

thingiverse

I lost the plug for this cooler a long time ago, and since then I've replaced it several times. One replacement was made out of duct tape! This time, I decided to design and 3D print a new one that would be better than any other plug available. That's exactly what I did, and now I'm confident that you can't find a better plug for your cooler anywhere. The hole on my cooler is precisely 9.7 mm in diameter, so this plug should fit perfectly on many coolers made by different manufacturers. However, I've included the design files, so you can adjust them to suit your needs. To ensure a watertight seal, I added grooves to hold two rubber o-rings. I purchased an assortment of o-rings from AliExpress for projects like this one, and the ones I plan to use are labeled 9 x 2 mm. I also filleted all the edges, which is effortless in FreeCad - my primary reason for using it, aside from its free cost and compatibility with Linux. Updates: I've printed this object a couple of times now. The first time was on a PrintrBot Simple Metal, where I used supports and a brim, and it took about an hour at the highest resolution. Then, I printed it on a Zortrax, which completed the job in just 33 minutes. I'm having a romance with the Zortrax printer now. The slots for the o-rings ended up being slightly too shallow. So, I've made them 0.4mm deeper and am printing the updated plug now. Without the o-rings, the plug fits snugly, but I might want to enlarge the handle to make it easier to put on and pull off. The files are now at revision 3. Update: I printed rev 3, and initially, it was too tight. However, after applying a little vaseline to the o-rings, they slid in perfectly tight. Now, I'm certain that vaseline isn't the right substance to put on o-rings (and mine are nitrile o-rings). But I was in a hurry and wanted to see if it needed just a little lubricant. And that was the solution. Now, I'm positive that what I should have used is silicone grease - which I have in my tackle box for fishing reels. UPDATE: Even with lubrication, it's still just a touch too tight. So, I've redesigned the slots for the o-rings to be a bit deeper and increased the size of the base so it's easier to grasp with my big hands. I'm reprinting it soon. This latest version is Rev 4. Rev 3 worked and will remain as a backup plug. But Rev 4 is the gold standard for now. Latest Revision: Rev 4 I've printed and tested Rev 4 on a Printrbot and a Zortrax at high resolution, using ABS. It fits like a dream. First, I coated the o-rings with the proper silicone grease - just a tiny amount will do. Then, when inserting it into the drain hole, it resists initially, but then snaps right in all the way in. I haven't filled the cooler with water yet to test for watertightness, but I'm confident it's going to work perfectly. Actually, this plug is better constructed than the original that came with the cooler and the replacements available online. I field-tested the Rev 4 this weekend, and not one drop leaked. So, I consider this a huge success and can finally put this project to rest. I took the cooler on a 3-day fishing trip last weekend and didn't have a single leak. The bottom of the cooler was as dry as a bone. I printed a second one to duct tape to the inside of the lid as a backup. Print Settings: Printer: Zortrax Rafts: Yes Supports: Yes Resolution: High Infill: 30 Post-Printing: Remove raft/brim and supports. This design uses two, 9 x 2 mm rubber o-rings. How I Designed This: I designed this in FreeCad using simple Geometric Primitives.