DIY Concrete Sprinkler Donuts

Please bear with me this is my first Instructable.

So after replacing multiple of my sprinkler heads due to me damaging them with the mower, the trimmer or my dog chewing on them I decided I needed to find a way to protect them. I found several solutions online but none fit my needs or desires. They were either to small, to thin or made out of plastic. So at that point I came to the conclusion that the only way I was going to get what I wanted was for me to make my own, but how was the problem. I know I wanted them to be out of concrete but I needed a good shape that would suit my needs and still be good enough to protect the sprinkler heads and be aesthetically pleasing (those of you married men will understand that part). So I would need to find a good mold that was sturdy enough for multiple castings and it had to be larger for what I felt would be real protection.

So I went to Google and looked for ideas, after several searches I was not really satisfied with anything I was seeing. I saw some people where suggesting to use bunt cake pans but that was not really what I wanted, it was too big for my needs and I was not convinced on its shape. I kept thinking about the concept that the bunt pans offered but it would be a lot of work to get the right form and shape I needed. So while brainstorming trying to figure out a simple solution it came to me, use a 4” to 2” PVC reducer. So off to Lowes it was to get my reducer and find a way to get the inside part where the actual sprinkler head would be. I tried multiple fittings and ways to fill the inside but nothing was really working out, when the Boss AKA the Wife came to hurry me up and she then said “Just use this pipe in the inside.” It was a two-foot section of two inch PVC pipe, boy was I shocked and felt pretty dumb after I spent a good half an hour of looking for a solution when it took the wife less than 30 seconds of being there with me to do that, good ole over engineering I guess. So I bought a bag of Quickrete ready mix, the reducer and the pipe and went home.

Once home I had to gather my tools and get my mold ready I mixed approximately 16 oz of Quickrete mix. I put the pipe in the reducer and mixed the ready mix with water and poured the mixture into the mold. That did not come out at all the way I was expecting to. I realized I rushed the process to get results. The pipe was stuck inside the concrete and there was no way of taking out the product from the mold. I had to break it to get it out so I broke the concrete and re-evaluated the process.

I used a new procedure to get this done. I got my materials and tools together.

Tools:

1. Hack Saw

2. Digital Calipers

3. Ruler

4. Measuring tape

5. Dremel

6. Dremel sanding drum

7. Channel Locks

8. Drill

9. Extension Cord

10. Two half inch socket extensions

Materials:

1. Mold – four inch to two-inch reducer

2. Two-foot section of two inch Pipe

3. Adjustable Hose Clamps

4. Concrete Mix (Quickrete Ready Mix)

5. Vegetable Oil cooking spray

6. Bucket

7. Mixing Pan

8. Something to mix and stir

9. Cup

I fist used the Dremel with the sanding drum to remove the lip inside the reducer in order to allow the pipe to go through all of the way. Next I cut the mold in half as close as I could to the center, I actually had to do this twice the first cut went way sideways and I had to stop because that would have ruined my mold. So if you look close enough you see 4 cuts. Once the mold was split I used the adjustable hose clamps to bring them together to form the mold. I then grinded down the pipe approximately 5 inches from the top, I took off about 1/8” in order to allow the mold to go all of the way through it once done. It would be less friction so easier to pull out. I drilled a hole through the bottom part large enough for the socket extensions to go through so I could step on them to be able to pull out the mold.

I used the mixture of approximately 16 oz of Quickrete and 4 oz of water. I made several molds using that mixture but I was not really happy with it because of the amount of rocks in the mix, it did not give it a good texture I was pleased with I understand it will not be visible but not one to do things unless I like the results. I sprayed the vegetable oil on the pipe and the inside of the mold as a release agent. I remember from my days in construction we used to use diesel but I know that is now frowned upon for the sake of the environment and besides at the cost it would not be worth the expense of using diesel and the added smell would not be very welcoming.

I did some more research and found a better mixture option and I needed to use more cement to change the mixture ratio of the rocks and added sand. The mixture ratio I found online was 1-part cement and 1 ½ sand. That’s where the Portland cement comes into play. I use 1 part Quickrete Mix, 1 part Portland and 3 parts sand. That mixture ratio gave me the best results for my need. For the water mixture I used approximately 20 oz of my cement mixture with 8 oz of water, I try to use a thicker mixture due to the cuts I made when I messed up and if it is to watery it will leak out. This mixture is not the strongest but since I will not be putting a large load on it beyond my weight when I step on them I am not too concerned with the mixture ratio and I also chose not do this for the same reason but if you put any type of wire in the concrete will also give it more strength. If that will be a concern for you then reduce the amount of sand and use some type of wire inside the mold.

Once the mixture is ready I poured it into the mold already setup with the adjustable hose clamp. Once it is all poured in you try to mix it with your spatula or whatever you use to mix it, you also want to lightly tap the top of the cement mix to bring the water up to the surface that gives you a smoother surface for your final product.

I attempted several different times for drying. I tried to remove from the mold at 4 hours and it came apart on me. I tried 8 hours and that was somewhat successful, so eventually settled on 12 hours to sit in the mold and then once it is taken out I let it fully dry and cure for a week before I put it to use.

To remove the mold, I first loosened the hose clamps and placed the extensions so I could step on the mold. I pulled the mold up while twisting side to side, once out I put the mold upside down on my work bench and I loosened the hose clamps and removed the mold. After the first few donuts one half of the mold broke due to the bad cut I made. I was tapping the mold on the wall to loosen any leftover material and it broke off so that’s why there is three pieces now. Using the vegetable oil makes it easier to take the mold apart so don’t be worried about being too liberal with it.

This last part is really beyond the scope of my Instructable but I will briefly explain how I placed them just to complete the story/process. I first dug out a hole and then I put it in, that was not the best choice for me since it left to much dirt around the donut for my liking and would have to back fill the hole until it was just right. I adjusted my method and I now just move the grass out of the way and use a gardening shovel to soften the dirt enough to move it out of the way just enough to put the donut in. I keep softening the dirt until I am able to put the donut at the level of the dirt or a half inch above the sprinkler head.

I started this to make the donuts for my forty five sprinkler heads only, the thought has crossed my mind to make these on the side for more people but unsure if people would pay me for this. But that’s just a thought since I am a full time student, have a full time job and a full time family.

But the ability to mass produce these is possible. If you have twelve reducers, you can make four at a time three times a day. You can put in the first set of four on and then after eight hours of cure time with the pipe you remove them from the pipe putting aside to cure in the mold and put four more on leaving the second batch to cure for eight hours. By that time the first batch has been curing in their mold sixteen hours. You repeat that process for the third batch and when those have cured their eight hours the second batch will have sixteen hours in their mold and the first batch have been curing twenty-four hours in their mold before you remove the mold from them and each set will have also been curing for twenty-four hours before you remove the mold. So you could theoretically make up to twelve a day on one two-foot section of pipe and 12 molds. So there is a possibility to make larger quantities but for my needs the slower two a day will do. The boss will not authorize the added expense for more molds since this is technically only for my forty-five donuts.

I hope you enjoyed my first Instructable and are able to make some on your own or maybe modify my idea/design and be able to improve this.