Salt vs Ice vs Air to Bend a Coil

[Azures]

3 short bits of 6mm copper tube bent around a 5/8" mandrel for the inner coil.

Left to Right

Salt
Least amount of flattening.
Hassle filling with salt on small bit of tube. Bit of shaking and overnight soaking and blowing to get it out.

Ice
little more flattening
Need freezer space.
easy to fill and easy to empty.
Ice turns back to water when compressed, but water don't compress much.
Ice melts and cold on your hands. needs re-freezing, gloves may interfere with work.

Air
Most Flattening
I have only made one coil (will document later) so my skill is very limited.
With practice maybe I can get better.

[Mud Mechanik]

Nice picture and explanation, I'll throw in my 2 cents. The flattening of the tubing in your picture will not hinder water flow, as long as it does not crimp and flattening is kept to minimum. The tube pictured on the far right will cool vapors just as good as the one on the left, I have made several coils without filling or freezing and flattening was not an issue.

I'm not criticizing you methods, just letting you know it can be done without lots of trouble, just take your time and bend slow with a steady pressure.

[Bushman]

I would think the flattening would be hard to get a good connection to your water supply. I use salt because it seems to work the best for me. The first time I tried the method used here at the forum with water. I had better luck using my compressor and air. I roll it between my hands and shake out as much as I can then I apply air and repeat the process. Takes me between 15-20 minutes to get the salt out. I then soak it in water and rinse to get rid of the salt residue

[myles]

6mm will bend just fine when empty, around a 1" / 28mm mandrel. You can always fill some of the inside space with a cold finger or scrubbers.

If you need a tighter coil then it can be done - I use salt because I have never had much success with water. Salt is an easier filling option with 8mm / 3/8" tube as opposed to the 6mm.

These two coils were salt filled and are in 8mm tube. The tighter one was wound on a 15mm / 1/2" mandrel, much tighter than the recomended minimum bend radius. They both work just fine - although it took some time to get the salt out.

[Azures]

The flattening of the tubing in your picture will not hinder water flow, as long as it does not crimp and flattening is kept to minimum. The tube pictured on the far right will cool vapors just as good as the one on the left, I have made several coils without filling or freezing and flattening was not an issue.

That fills me with relief, for my 1st condenser, a little flat on the inner coil.

Right now I am bending 2nd full coil with Ice

ONE DOWN SIDE!!!! i just noticed is you feel a little bit rushed to do as much as you can before putting it back in the freezer.

the result is I'm not taking my time and rushing slightly. As a result the coil is not as well spaced out and towards start of thawing it bends a little more easier than freshly frozen (Ice to water = less volume) which means you can over bend and flatten out a bit by accident.

So when I'm finished the inner coil I'll sort out the spacing and gently braze the few flat bits and pinch slightly with some snub nosed pilers to round out again.

I'll try and take pictures.

[rad14701]

Perhaps it's just me but it sounds like you're spending more time perfecting your crutch than perfecting your coil winding technique... With proper technique it is entirely possible to wind a coil without flattening and without filling the tubing... The technique has been covered... 1/4" tubing can be wound around a 3/4" mandrel without flattening and even around a 5/8" mandrel with only very minor flattening... Ditch the crutch and just wind the coil... Be at one with the copper, grasshopper...

[Azures]

crutch

Lost in translation.... over here "crutch" is the area between your legs that you don't wanna be kicked in.

My first coil I made was with just a mandrel. The 2nd Ice coil is less flattened, but if I blow through both of them there is no noticeable difference in resistance.

My Verdict:
Ice I get less flattening, but feel a bit more rushed with making.
but no real advantage is achieved.

I'll just continue with Air from now on.


Side note:
My inner coil would not fit inside my outer mandrel, so I had to "Bodge" one instead as a result the outer coil is ugly and not perfect.

Question:
Does it matter if my coil touches the side of the 2" Column a bit? I'm gonna have a slanted plate underneath with overflow to centre the reflux.


Test
I boiled 1.5 liters in kettle ran water through coil and cooled it down to gentle warm in 4mins

4.187KJ/Kg Heat capacity of water
x 1.5 Kg
= 6.285 KJ per degree C

100 - 40 = 60

6.285 x 60 = 376.84
/ 4 mins
= 94.2 kJ / min

since 1/3 was hanging out the kettle scale it up

( 94.2 / 2 ) * 3
= 141 kJ / min

energy removed per min (roughly) = 141 kJ / min

my maths is rusty possibly complete rubbish.

Picture:
Top coil Ice
Bottom coil Air

I heard Chuck Norris can just look at a copper pipe and it just coils itself out of fear!!!

[myles]

There are two sides to the question of the coil touching the side wall - well possibly 3 or more

1. It creates a vapour trap that forces the vapour to travel a spiral path between the coils. This is good in my book.
2. It transfers cold into the side wall, creating another condensation surface. Again good in my book.
3. It is possible to transfer 'cold' down the side walls to the take off port area (thinking VM) - potentially bad news but easily solved by inserting a heads column - or just a bit of space between the coil and take off zone.

That is enough for now.

[brodywx]

Cool to see more people trying the ice technique. Even though others say it can be done without filler, I've never been able to do it without ice no matter how slow and carefully I try, but that's a problem with my own skill I guess. As long as you have the cooling capacity, it makes coiling fairly risk free.

I've come across one major problem with it though. The ice does expand the tubing very slightly, and compression fittings will not fit over the ends (if you trim after coiling). I had to sand some ends of tubing down a bit so I could attach compression fittings.

The expansion only occurs towards the middle a tube length, since not enough pressure will build up at the ends to expand the tubing. For this reason it's only an issue if you freeze a section of tube, and then cut off a piece from the end.

[Samohon]

Its all in the working of annealed copper... No need to fill the tube, just work the copper correctly...

Ive rolled ¼" coils for a few people, just keeps gettin better...

Have a Look Here...

Just my 2 cents...

[rad14701]

Lost in translation.... over here "crutch" is the area between your legs that you don't wanna be kicked in.

No, a "crutch" is something you use to help you walk when you have a bad leg...

A "crotch" is that place between your legs where your private parts reside... Or the place where a tree limb meets the trunk of a tree...

So if you get kicked in the "crutch" you will just lose your balance and fall down, but if you get kicked in the "crotch" you will fall down and hold your private parts soothingly while gasping for breath...


Class dismissed...

[Samohon]

[Azures]

actually laughed out loudly.

[Azures]

Its all in the working of annealed copper... No need to fill the tube, just work the copper correctly...
Ive rolled ¼" coils for a few people, just keeps gettin better...
Have a Look Here...
Just my 2 cents...

This is what I used for my first attempt (bottom coil in the picture above) came out well for my first attempt, thanks.

For my second attempt the mandrel for the outer coil didn't fit so i had to adjust one. It really screwed things up which is why the ICE one looks ugly. I could of done it allot better if i had the correct mandrel, but I couldn't wait to go buy one.

Anyways I've ordered more 6mm copper its on the way so I'll be making some more.

I think I'm done using ICE. I'll see how my next empty coil turning goes.


What coil is better, what shall I make next?
Another Double Coil (and improve upon the old ones above)
or
Single or Double helix to Cold Finger?

[Azures]

I've come across one major problem with it though. The ice does expand the tubing very slightly, and compression fittings will not fit over the ends (if you trim after coiling). I had to sand some ends of tubing down a bit so I could attach compression fittings.

Yes I have found the same problem my 6mm tube is now 6.5mm and the capillary will not fit.

I'm gonna stick with air.

[Barney Fife]

I can bend 1/4" tubing without aids, but my pump struggled with the restrictive flow, so I had to go up to 3/8" tubing, and found I couldn't get it wound to fit inside a 2' column without salt. Salt works, salt works well, and salt is proven to work well. Why mess with a known method? Air compresses, so that will never work. Ice(and water) contains dissolved air, so it, too, can compress and allow a kink when you least want one.

You're really working much harder to avoid a using simple solution...

[Usge]

I'm no expert...just did my first couple a few months back with a lot of help/guidance from members here. From that experience using no salt, etc...I found that a 1" or larger mandrel ..you can bend 1/4 od soft copper coil pretty easily without too much flattening if you take it slow. Under 1"..things get harder (with more flattening) the further you go. The inner coil flattened quite a bit..and I "thought" it was ruined. But, it actually flowed fine. I ended up just keeping the outer coil, and making a cold finger. I think the lesson I walked away from that was..it can actually flatten quite a bit and still have enough flow rate to function perfectly...so long as it's not kinked up. And to Barney's point above...I guess it does kinda also depend on the pressure of your water source as well. But the ultimate test to that is not how it looks...but how it flows water.

I'm surprised no one has yet mentioned "sugar". I've not used it...but I've seen a few posts from people here who have and suggested it packs just like salt...but is much easier to get out after the fact because it melts/dissolves easier than salt. I can't confirm this ...but it seems to make sense. Maybe put the coil in some boiling water...or put a tube down the input with hot water. Should just dissolve it right out? However, having to straighten the coil out first to pack it...seems counter productive to me...given it will harden the annealing in the first place making it harder to work it after you've gotten it packed. Not sure how you would anneal the copper after you've packed it without melting whatever was inside it you used to pack it with.

[rad14701]

I agree with everything Usge has stated, and have stated so in previous posts...

It is entirely possible to wind any size copper around a mandrel 3x the diameter of the tubing being wound... Winding 1/4" around 3/4" is not a problem...

One thing I have noticed, based on several posted experiences is that people are attempting to wind too fast, as mentioned by Usge... Someone posted recently about winding a double helix coil in just a couple of minutes... That is way too fast... When I wind coils I go extremely slowly... It may take a minute to wind a single complete coil... Why...??? Because going faster generates heat which softens one side of the copper while work hardening the other... Winding slowly enough to eliminate heat buildup is the key to successfully making a coiled condenser... If the copper feels like it is bending easily then you are winding too fast... The copper should bend hard, giving the same resistance, from beginning to end...

I don't need any filling when winding coils because I have learned to become one with the copper...

OM
ASATOMA SADGAMAYA
TAMASOMA JYOTHIRGAMAYA
MRITHYORMA AMRUTANGAMAYA
OM SHANTI, SHANTI, SHANTI

Lead us from darkness to light
From ignorance to truth
And from death to eternity
Let peace prevail everywhere

[Barney Fife]

I don't need any filling when winding coils because I have learned to become one with the copper....

Well, for the rest of us mere mortals who aren't One with copper, or who simply don't wish to risk a kink and ruining 10 feet of copper and half an hour's work on the final turn, spending 2-3 minutes filling the tubing with salt is a fine way to go.

As for sugar, well, have you never seen what happens when you heat or wet sugar? It turns hard, very, very hard. Salt, on the other hand, melts nicely, and kept dry, it'll just pour right back out of the completed coil. Just pinch one end of your tubing, pour the salt in using a small funnel, tapping the tubing with a screwdriver or something, often, until it won't take any more, then pinch-off the open end and "roll" it to eliminate all air from the tubing. Proceed to bend your coil around your mandrel of choice...

[Usge]

Thanks for that Barney. One question though..... Are you straightening out your annealed copper first before filling with salt? Or are you saying you just fill one end of the coil and tap/roll it around till it's full? I wasn't quite clear on that.

I honestly didn't find winding the unfilled copper that hard on 1" or over mandrel. I did find the inner coil to be tricky, particularly the turn back over the top where it really flattened a lot. I absolutely could not turn it without it flattening regardless of speed/time. I even took breaks to let it rest/cool to make sure I wasn't heating the back side. It still flattened quite a bit....BUT...when I checked it...it still had plenty of flow when hooked to my sink. So, I guess it was ok none-the-less..despite it being scary flat. I cut it apart anyway and used just the outer coil to make a coldfinger version using a .75" stubout. I found trying to solder that up was rather tricky as well. But that one flowed just over 2L a min hooked to my sink...and started vibrating in my hand when I really pushed it. I think it should do just fine!

[The Baker]

Ice(and water) contains dissolved air, so it, too, can compress and allow a kink when you least want one.

...

Maybe that is why some people (IIRC) use some liquid detergent in the water...

[Dnderhead]

something to check on,,if I remember right, unlike most other metals copper is more ductile when cold.

[goose eye]

sand

so im tole

[MexicanCustard]

Sand is what we use in the plumbing industry if we don't have access to a tubing bender.

[seaguy]

I wonder if glass bead blast media would be any easier to get out afterwards. Probably make the bending easier because the beads are round but they don't dissolve easily

[Caveguy]

Glass beads sand blast media is what i use and it works perfectly.
You can blow it out of the tube with compressed air.

[lampshade]

If salt is used, can you re-anneal the copper? In other words, does heating the salt, which is inside the coil, cause any problems?

For example, to fill the coil with salt, I would think that the coil must be unwound somewhat. This work hardens the copper. I would think then that the coil must be re-annealled. If so, must you heat the coil before filling it with salt, or can you heat the coil after it is filled with salt?

[myles]

Heat before adding the salt.

Bending large diameter coils is easy, its the small ones that cause trouble. For normal coils with a coldfinger down the centre, I use 6 mm tube with no packing. If I want to wind a coil on a small mandrel - say 15 mm or 1/2" - I increase the tube to 8 mm and fill with salt.

When you wind at less than the minimum bend radius you need to have packing. The alternative off course is to go for a shotgun, but generally these are bigger than a coil. A coil packs a lot of surface area into a small volume.

[lampshade]

Heat before adding the salt.

Bending large diameter coils is easy, its the small ones that cause trouble...

Thanks, myles.

Just to be sure I understand, you are saying:

• never heat (anneal) a coil that is packed with salt
• winding a 3/8" (8 mm) OD tube on a 3x mandrel produces less flattening than winding a 1/4" (6 mm) OD tube on a 3x mandrel

[Ben Stillin]

This coil was made with sugar packing and I used my grill to melt it out afterwords

3/8" wound around a 1.5" pvc pipe