Windi ng a Coil CondenserHow to wind a small copper coil condenser, by hand, without filling. By HookThis particular condenser in this tutorial is a 15mm !"#$ long continuous double coil, for a 5mm !%#$ diameter column, and uses ".& mm !1'&#$ copper tube. This si(e doub le coil condens er com) fortably handles %&w of water steam. !*ut some mesh or scrubber packing in the top section.$ + ou can increas e the condenser lengt h up to %mm without any probl em. But longer tha n that and you start running into increasing back pressure, and hence a reduced maimum coolant flow rate. + ou can also incre ase the coil diame ter !widt h$. - would not go bigger than to suit a 5)/mm column. 0arger diameter coil s are much easier to wind than smaller diamet er. This tutor ial only describes how to do a continuous double coil, but it is the same basic skills and techniues for a single co il, and a single coil is much easier. 2ouble !and single$ coils can also be made using &.5 mm !3'1"#$ 42 tube. This si(e tube is both easier to work and more efficient at heat echange, though it is less robust than larger si(e tube, and might not be as easy to locate either. ingl e coils can also be made usi ng 6.5 mm !3'/#$ tub e. -t is hard to wind 6.5 mm tub e smalle r than about 3% mm !1.5#$ 42, which euals a mandre l of about %5 mm !1#$. Wi nding conti nuous double coil s in 6.5 mm by hand is mor e diff icult, e7en lar ger ones for a 5 mm column. The changeo7er from the inner to the outer co il is particularly tricky . ".& mm tube is a 7ery good si(e for our purposes. Winding a coil, especial ly a double conti nuous coil like this, is not easy. + ou are like ly to make mistakes the first time you do it, especially forming the first turn of the coil. 8ead through the whole tutorial carefully before start ing. -t will help you understand the reason for some of the steps earlier in the process. The pics were taken during 3)& condenser builds, so the condensers will not all look eactly the same. !9y hands might look i n a slightly awkward position in some of t hese pics. That is because - had to get into a good position for the camera and lighting.$
How to wind a small copper coil condenser, by hand, without filling.
By Hook
This particular condenser in this tutorial is a 15 mm !"#$ long continuous double coil, for a 5 mm
!%#$ diameter column, and uses ".& mm !1'&#$ copper tube. This si(e double coil condenser com)fortably handles %& w of water steam. !*ut some mesh or scrubber packing in the top section.$
+ou can increase the condenser length up to % mm without any problem. But longer than that
and you start running into increasing back pressure, and hence a reduced maimum coolant flowrate.
+ou can also increase the coil diameter !width$. - would not go bigger than to suit a 5)/ mmcolumn. 0arger diameter coils are much easier to wind than smaller diameter.
This tutorial only describes how to do a continuous double coil, but it is the same basic skills and
techniues for a single coil, and a single coil is much easier.
2ouble !and single$ coils can also be made using &.5 mm !3'1"#$ 42 tube. This si(e tube is botheasier to work and more efficient at heat echange, though it is less robust than larger si(e tube, and
might not be as easy to locate either.
ingle coils can also be made using 6.5 mm !3'/#$ tube. -t is hard to wind 6.5 mm tube smaller
than about 3% mm !1.5#$ 42, which euals a mandrel of about %5 mm !1#$. Winding continuous
double coils in 6.5 mm by hand is more difficult, e7en larger ones for a 5 mm column. Thechangeo7er from the inner to the outer coil is particularly tricky.
".& mm tube is a 7ery good si(e for our purposes.
Winding a coil, especially a double continuous coil like this, is not easy. +ou are likely to make
mistakes the first time you do it, especially forming the first turn of the coil.
8ead through the whole tutorial carefully before starting. -t will help you understand the reason for
some of the steps earlier in the process.
The pics were taken during 3)& condenser builds, so the condensers will not all look eactly the
same.
!9y hands might look in a slightly awkward position in some of these pics. That is because - had
to get into a good position for the camera and lighting.$
+ou will need to anneal 7arious sections of the copper tube during the pro@ect.
;nnealing is done by heating the copper to red hot and letting it cool, either slowly in air, oruickly with water. -f you use water then dry it off before working further on the coil.
;nnealing copper makes it much softer and easier to bend !work$. <reshly annealed copper tubecan kink easily, so take it fairly gentle until you get the hang of working it.
;nnealing also wears off uickly once the copper starts being worked. Because it work hardens
uickly, try to get a bend right the first time. -f you need to ad@ust an imperfect bend, some select )i7e re)annealing can be 7ery useful or e7en necessary.
4nly anneal the area you need to work. +ou want as much as possible of the tubing in the finishedcondenser to be work hardened.
Aonetheless, don=t be afraid to anneal, more than once if necessary. The right use of annealing is thekey to sol7ing most problems with winding a coil by hand.
: Try not to bend the tube feeding from the original big coil as you wind, it makes it stiffer andharder to wind when it gets to your hands. -t is a bit tricky and you can=t a7oid some bending as it
straightens out when it comes off the coil. ust keep it to a minimum, and do some re)annealing of
the feed section if necessary.
: ;lways keep as much tension on the tube as possible as you wind it. -t is this tension that stops it
from kinking. This is not necessary when bending it with a bending spring.
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%. tarting the Wind
Hang coil on a hook or angled peg about chest height.
;rrange and hold the tube and mandrel like this. !The tail is coming out the bottom of the picture. -
am right handed, lefties might prefer to do e7erything mirror image.$
0ea7e a 3 mm tail, and start with a &)&5 degree angle between the tube and mandrel
Holding it all as tight you can, and keeping as much tension on the tube as you can, pull the hand
holding the tail down and around the mandrel, keeping the angle between the tube and the mandrel.>se your thumb as the pi7ot point.
+ou will get some degree of flattening of the tube as you wind the coils, mainly on the inner coil.This is not a problem, as long as it is only minor.
+ou might find it easier to use the bending spring to put the first 1" degree of bend in the tube!anymore than about 1" deg can make it 7ery difficult to remo7e the bending spring$. -f you do it
this way, then use a slightly smaller mandrel @ust for this first bend, to allow for the thickness of the
bending spring. 8emo7e bending spring and continue...
8eposition your hands, and continue...
Deep the original angle between the tube and the mandrel until you get most of the way through the
first turn, then start changing the angle towards 6 degrees.
wap sides and hands, and continue the wind until you ha7e a full turn.
This is the hardest part of the whole pro@ect. -f you can get this far, you are halfway home.
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3. -nner Coil
Continue winding 1'3 a turn or so at a time, then repositioning your hands, another 1'3 turn, etc,until you ha7e 15 mm of full coil. !When measuring this distance, allow for the fact that the
widely spaced turn or two at the start will be compressed down in a later step.$
The first 3)& turns can be a bit tricky, but @ust persist a little bit at a time. +ou will find that the tail
will tend to wind around the mandrel in the opposite direction, because as you wind the main coilyou tend to le7erage against the tail. This is difficult to a7oid, @ust keep it to a minimum. +ou will
usually end up with an etra 1'%)1 turn, at the tail end. This counter winding reaction is why you
8emo7e the inner mandrel. +ou may ha7e to loosen the coil a little by gently twisting it against thedirection of the wind. !Hand on left of pic is twisting up, hand on right is twisting down.$
Check to make sure you can easily re)insert the mandrel.
;nneal the transition between the starting tail and the first closely spaced turn of the coil. !;lso an)neal the first 5 mm or so of the tail coming off the last turn at the other end of the coil. This is for
a later step, but might as well also do it now.$
+ou can clearly see the annealed sections in this pic, the dull, discoloured, burnt looking areas at
either end of the coil
8e)insert the mandrel. ;lternati7ely compress, tighten, and align the widely spaced turn or two atthe top of the coil, in steps, and generally work it until it is matched up with the rest of the coil.
+ou may need to re)anneal this section of coil about half way through this process.
+ou do not ha7e to do this step. +ou can skip it and go straight to bending the tail. -f you do lea7e itlike this then it would be better to ha7e a slightly longer condenser, 15)% mm !/#$.
Check the inner coil is straight o7erall, and carefully ad@ust if necessary. -t should be fine, but
check because you can=t ad@ust it once the outer coil has been wound.
ometimes the first turn or two on the inner coil will not come out uite perfect, but as long as
there is no kinking and nothing is too out of alignment, then don=t worry about it.
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&. Changeo7er !from inner to outer coil$
8emember that you pre7iously annealed the changeo7er section of the tube. -t was for this step.
-nsert the short outer mandrel o7er the inner coil. 0ine it up so the centre of the rounded edge ofthe mandrel is located where the tube will re7erse wind direction and cross back onto the outer
Ha7ing a roughened surface on this short outer mandrel helps to get a good grip. -t may help to
clamp the left hand end of the inner mandrel in a 7ice for this step.
Wind the tube back across the outer mandrel in the opposite direction of the inner wind, back up the
mandrel.
The first turn after getting onto the outer mandrel is difficult, and this is one of the danger points for
kinking. But @ust persist with it a little bit at a time. Try doing this turn in 3)& steps, rather than allat once.
8e)anneal 1'&)1'3 the way through the first turn, and continue till you ha7e most of the first turn.
The first turn on the outer coil usually ends up slightly larger and looser on the mandrel than the
rest of the outer coil turns. 2on=t worry about it.
The outer mandrel will be kind of loose and slightly off centre from the inner coil, and so the outer
coil will usually be slightly off centre too. But this is a minor problem that is difficult to a7oid, andthat can be corrected !ad@usted$ easily at a later step.
The net %)3 turns on the outer mandrel can also be difficult, but again @ust persist with it a little bit
at a time. ;gain clamping the non)winding end of inner mandrel in a 7ice may help. ;nneal the15 mm or so section of tube coming into the bend if necessary.
4nce the first turn has been done this way...
then - swap sides and hands like this, for the net %)3 turns.
4nce you ha7e enough turns for you to be able to get a firm hold on the wound end !about 3)&turns$, then echange the short outer mandrel for the long outer mandrel.
wap sides and hands back, and continue winding the outer coil. This last section of winding is the
;s you get towards the end of the outer coil, keep an eye on the alignment between the inner tailand where the outer tail will end up. +ou need to a7oid the inner and outer coils or tails crossing
and touching in the finished condenser.
top the wind about 1'% turn past the inner tail.
-f you ha7e some ecess tube as you get near the end of the wind, then bunch up the coils a bit anduse up that etra tube, !but make sure you lea7e enough unwound tube for the tail$. +ou can ad@ust
the spacing afterwards.
There are two ways to ad@ust the coil spacing for the outer coil.
<irst, spread and e7enly space the coils with the screwdri7er, same as for the inner coil.
- space the coils 3)" mm apart.
Then, if the outer coil is e7enly spaced but is also still slightly shorter or longer than the inner coil,you can ad@ust the outer coil length by firmly !but carefully$ grabbing both ends and pulling or
pushing it. Be careful, it is easy to o7erdo it. +ou might want to put the outer mandrel back in to
8emo7e the mandrel and re)anneal the last 1'/ of the last turn of the outer coil, and the & mm sec)tion of the outer tail immediately coming off the last turn of the coil.
8e)insert the outer mandrel.
>se the bending spring the same way as with the tail of the inner coil. 9ake sureyou use your non)bending hand to support the coil immediately net to and beneath
8emo7e the bending spring and mandrel, re)anneal the bottom half of the new bend.
8e)insert the outer mandrel, and work the tail up against it, in the same way as with the inner coil.
The outer tail has to be flush with or slightly inside the outside line of the outer coil, so that thewhole condenser can slide easily and e7enly inside the column.
