Screen Cooler Tank

[raveney]

Hi,
I'm looking for help with designing and building a screen cooler tank for a 1/8 scale Nash 25 HP vertical engine. Documenting the build on this site. The only member that I have seen do something similar is Jason B and he executed it very well.

Various images from researching the topic below

questions

would 40 or 80 mesh copper screen scale well?

has anyone soldered their own tank or other vessel using copper sheet? what thickness?

copper pipe is horribly expensive in my opinion and I believe it would be 4" or larger to scale with my engine. The average ratio seems to be 44% to 63% of the flywheel diameter and the cone angle from 45 degrees to 70 degrees

any builders notes would be appreciated. Especially on the finish (cold galvanized or zinc plating?)

Happy new year and thank you

 

[Jasonb]

I've also done the R&V

https://www.modelenginemaker.com/index.php/topic,6884.msg192577.html#msg192577
I used a cut down 2.5lts paint tin as the tank with a brass band soldered around the top.

 

[Jasonb]

I had the 1/16" wall copper tube used for this fuel tank so no cost and another way to get the bead rolled effect

https://www.modelenginemaker.com/index.php/topic,11515.msg270623.html#msg270623

 

[raveney]

I've also done the R&V

https://www.modelenginemaker.com/index.php/topic,6884.msg192577.html#msg192577
I used a cut down 2.5lts paint tin as the tank with a brass band soldered around the top.

amazing to see such detail in a model. Truly inspiring workmanship. Thank you for the tips on how to fabricate the tank. I will give it a try later on using some spliced pipe or look for a can such as you did.

what size mesh?

thank you so much

 

[Jasonb]

I'll measure the mesh in the morning.

 

[raveney]

Some screen coolers that I took pictures of at the 2024 Florida Flywheelers show. The Root Van Dervoort was doing work churning ice cream so it was fairly hot. The Lauson was idling and not so much. The neat thing about the Cushman was that the cart curved to match the tank. I think the rivets on the tank look cool. They all appeared to use window screen size mesh, so I will scale down based on that. All were galvanized color also.

 

[raveney]

Just finished fabricating a small copper screen cooled tank for the Nash engine chronicled on this website elsewhere, but figured I would post a picture in this thread also.

build link

Made this tank from slitting open a piece of 2" type M copper pipe, annealing and splicing together to get the size I wanted. Silver brazed the seam and bottom plate in and used lower temperature silver solder for the other bits. The screen mesh is 20 size and is pure copper so seaming it was easy with electrical solder and rosin paste.

It took two tries for the dome and clamping ring as the mesh and thin metal burns through very easily. This design uses a clamping ring to secure the upper framework and the mesh to the tank. The brass "shower head" rests on top of the ring that will hopefully drizzle water down the outside of the screen cone transferring the heat to the air. The engine will have a belt driven water pump pulling suction off the bottom bung.

I plan to add two rings of 1mm x 4mm half round brass bands to simulate the stiffeners as Jason B referenced.

 

[Rdean33422]

Very impressive cooler.

Ray

 

[raveney]

Thank you Ray,
I'm building the water pump now so I can try out how well the water will spread across the screening. Might have to modify the upper dome or spray ring.

Added a band of brass half round to the tank to simulate the stamped sheet metal look. On the first attempt, I soft soldered two bands and it looked horrible because the bands did not come out parallel to each other. Removed them and fit a new single band and attached it using cyanoacrylate and then epoxy. Sanded and wiped with acetone before spraying a base coat of metallic silver. After that dried, I used a dry brush method to apply white and black splotches to give the appearance of a galvanized finish. I didn't think of it at the time but a small bit of sponge or 3M sanding pad instead of the brush might have worked better

 

[raveney]

I did have to remake the spray hood to get the water to trickle down the screening. I switched to aluminum to save weight so I could eliminate the brass tripod supports. The spray hood is made up of 7 parts including the #6-32 SHCS that secures it to the mesh cone. It is assembled using epoxy (JB Weld)



the inner part is drilled to distribute water somewhat equally around the circumference (12 holes). The outer part is very thin and allows a ring shaped hollow space for the water. The pipe stub is epoxied into a piece shaped like a saddle or what we call a weldolet in industrial piping applications. It just reinforces the epoxy joint. I let it cure overnight and then drilled very carefully through just the outer part and cleaned it up with a flat bottom bit.



To keep it on the screen I made a tapped plug and a washer that compresses onto the tip of the cone. I also ditched the lower clamp and cut a piece of thin wall 3" conduit to allow the base of the cone to be below the lip of the tank. It seems to work really well.

 

[Lloyd-ss]

Very nice work. I was not at all familiar with that "cooling tower" type of design for engines.
I know this is too late, but yours immediately reminded me of our stainless steel coffee drip cone. Extremely fine perforations.