The near Bullet proof reflux condenser
Posted: Sun Nov 06, 2016 5:09 pmSo I finally finished my new reflux condenser after several attempts and building methods.
It's 26 x 3/8 tubes at 100mm long, 100% hard solder construction.
After the first several attempts of trying to flare the tubes, using thick end plates and trying to resolve the dreaded tinking (which is the different cooling rates of each individual parts causing fractures),
I have found a method that has worked with great success. It's requires a bit of patience in forming the end plates but is well worth it in my view.
The only reason I have made it from 3/8 tube rather than 1/2, is I had used up all my 1/2 tube in previous attempts, It actually worked out better, the distance between tubes was increased which allowed the room for more of a flange.
I wanted to flange the join to the 4" tube. By using the thick copper end plates as a die, (from a previous attempt) worked perfectly. It took a few times to get the flange shape right, also a couple of times of annealing, but I was happy with it in the end.
For flanging the tubes I worked out that a tapered pin punch I owned had the perfect start and finish sizes for the 3/8 tubes. There was no drilling needed at all in the end plates and just by using the tapered punch and a hammer to drive the punch through the plate is all that was required.
Now with all the tubes slotted neatly into the end plates, everything cleaned and fluxed, time to hard solder it all together. Once it was all soldered I pressure tested it and found two leaks which were easily sorted.The extra surface area made it easier to get the hard solder to bond the two pieces together and having the two materials the same thickness allowed for them to heat up in the same rate.
Once it was acid bathed and rinsed I did a small cleaning run to test its knockdown power and the control I could achieve with a new needle valve I bought for it. Needless to say the knockdown is HUGE It can knockdown full 4800w of power and with my needle valve the working range is within one turn of the dial.
It's 26 x 3/8 tubes at 100mm long, 100% hard solder construction.
After the first several attempts of trying to flare the tubes, using thick end plates and trying to resolve the dreaded tinking (which is the different cooling rates of each individual parts causing fractures),
I have found a method that has worked with great success. It's requires a bit of patience in forming the end plates but is well worth it in my view.
The only reason I have made it from 3/8 tube rather than 1/2, is I had used up all my 1/2 tube in previous attempts, It actually worked out better, the distance between tubes was increased which allowed the room for more of a flange.
I wanted to flange the join to the 4" tube. By using the thick copper end plates as a die, (from a previous attempt) worked perfectly. It took a few times to get the flange shape right, also a couple of times of annealing, but I was happy with it in the end.
For flanging the tubes I worked out that a tapered pin punch I owned had the perfect start and finish sizes for the 3/8 tubes. There was no drilling needed at all in the end plates and just by using the tapered punch and a hammer to drive the punch through the plate is all that was required.
Now with all the tubes slotted neatly into the end plates, everything cleaned and fluxed, time to hard solder it all together. Once it was all soldered I pressure tested it and found two leaks which were easily sorted.The extra surface area made it easier to get the hard solder to bond the two pieces together and having the two materials the same thickness allowed for them to heat up in the same rate.
Once it was acid bathed and rinsed I did a small cleaning run to test its knockdown power and the control I could achieve with a new needle valve I bought for it. Needless to say the knockdown is HUGE It can knockdown full 4800w of power and with my needle valve the working range is within one turn of the dial.