Miniature hose clamps

[gbritnell]

For those of us that have built water cooled I.C. engines there's always that point of how to clamp the hose/tubing to it's respective fitting and not have to use something that detracts from the overall appearance.
I started making miniature hose clamps because I like others didn't like resorting to automotive clamps. Even the smallest ones don't fit the aesthetics of a miniature engine.
I am presenting a step by step of how to make the clamps. It's not really that hard to do and you will be pleased with the results.
First find the appropriate tubing to use on your engine. Some fellows use a clear plastic type tubing but I prefer to use a black Neoprene type. Slide the tubing onto a drill shank or rod of the needed size. I try to make it a snug fit so as to not stretch the tubing too much.
Now measure the tubing without compressing it.  Now squeeze your calipers moderately to get a 'compressed measurement'.
This compressed dimension will be the one used to drill the I.D. of the stainless rod. 
Drill the rod and turn the O.D. .050 larger (.025 wall thickness.
For this example I measured a full sized hose clamp and then used a scale of 1/3 for the miniature.

[gbritnell]

The band on the full size clamp measured .562 which came out to about .187.  I parted the ring off and cleaned up the edges and burrs. For this example I decided on a 2-56 screw thread so a bushing was made .187 O.D. x .25 long. I put a small groove into the O.D. at the mid point so I could use this as a centering guide when I silver soldered it together. The bushing was drilled and tapped for the 2-56 thread then relieved halfway with a .093 drill. This extra clearance allows the clamp to close without distorting it. A small flat was milled on the bushing before parting it off. This takes the overall height down and allows the bushing to sit square against the ring when soldering.

[gbritnell]

To solder the two parts together I flux them then set them on a solder pad. I use a couple of small pieces of steel to back the pieces up so they don't move when soldering. After soldering the part was boiled in water to remove the flux. The little bit of extra silver solder was cleaned up with small files and then smoothed with fine emery cloth. At this point if you want a shiny clamp it's best to buff it now because it's much easier to hold than after splitting.

[gbritnell]

The ring is now placed in the mill vise and the bushing squared up vertically. Leave just enough space between the bushing and the vise jaws to allow the slitting saw to pass through. For this clamp I used a .062 gap so I mounted 2-.032 saws on the mandrel. This is where the witness mark that was cut into the bushing helps to center the saw.
When cutting always conventional cut just to be sure the saw doesn't grab the part and ruin it. I take several cuts until I'm close to breaking through then move the table so the saw will make the finish cut all the way through.

[gbritnell]

With the clamp split I remove any burrs on the inside with a small triangular file. The clamp is then slid over the tubing. Usually it need to be opened a little to get it on to the tube. Remember we made the clamp to fit the compressed state of the tubing. For this demonstration I used a 2-56 socket head screw but if you wanted a little more realistic look you could make a slotted or even a hex headed screw.
The clamp will probably need to be squeezed a little to get the screw started.
I used 303 stainless for the clamp but brass could also be used.
gbritnell

[gbritnell]

I have found that sometimes a small leak will develop so the clamps need to be snugged up a little. Depending on the softness of the tubing you might run out of adjustment so the clamps can be removed and a little material can be removed from the inside faces of the bushing. More from the counterbored side than the threaded side but this all depends on how much material you have on the bushing. 

[crueby]

This is awesome. Even for steam there is a need for this. When running on air, clamping the hose is an issue, and twisted wire works but looks like moldy swarf. Gotta build some of these!


One possible change to help with the leak at the joint would be to extend the ring psst on one side. Not sure how yet, may need to fab on a strip the bend around... Hmmm...

[Roger B]

Splendid   

Most of what I do is functional experiments rather than aesthetics but I still have to connect cooling hoses. Recently I have been using  cotton braided neoprene fuel hose, as it doesn't collapse on bends when it gets hot, and wire clamps. I will have to try some of your design.

[Don1966]

Love it thanks George for showing us how it’s done...... 



Don

[Admiral_dk]

Great little article - thank you very much George 

Best wishes

Per

[kuhncw]

Thanks, George.

Chuck