Swede Posted September 29, 2008 Share Posted September 29, 2008 Guys, I'm stuck. My new perchlorate cell is complete except affixing the electrodes. The electrode shanks are 1/16" thick by 1/2" or 3/4" wide titanium strips. These have to go through the lid of the cell, be secured in place, leakproof, chemically resistant, and able to handle some heat. Tough requirements. The problem is this... it is easy to cut slots for the shanks in thin material. It is very difficult to do so in thicker material, say 1/2" or 12mm thick. In the past, I've used hot glue, regular consumer epoxy, and silicone sealant. The hot glue is completely unacceptable, while the latter two fail under the assault of heat and chemicals. The question, then, how to create thin slots in thick material (CPVC) and how to secure the electrodes. This is what I've come up with. 1) broach a square hole 1/2" in the CPVC. Insert the shank, then drive in a rectangular piece of CPVC to fill the remainder of the square hole. I am leaning in this direction. 2) Drill a hole perhaps 3/4" in size, position the electrodes, and fill the hole with some sort of material that will cure. Options include chemically-resistant potting epoxies, 2-part urethane plastics, and finally, using "Sculpey" clay, which is a PVC-based material that can be hardened in an oven. The hardening takes place at 110 degrees C, so it may be possible to harden the sculpey with the CPVC lid, electrodes, and filler, all as 1 unit. Being PVC-based, the sculpey should give good service. How else can I get a thin shank through thick material, and secure it? I'm going nuts! I need some fresh perspective. Thanks! Link to comment Share on other sites More sharing options...
Miech Posted September 29, 2008 Share Posted September 29, 2008 Have you thought about melting it through? It won't look very nice, but it does work. Another option would be drilling al line of holes and filing/sawing them to the size and shape you want the hole to be. Yet another way would be to drill a large round hole, and use some kind of plug that fits snugly in it. You can easely saw from the side of the plug and put your electrode in the cavety. Then put the plugs in the holes and glue it in place with for example PVC cement. Link to comment Share on other sites More sharing options...
Swede Posted September 29, 2008 Author Share Posted September 29, 2008 Thanks Miech. I took some pictures to try and show what's going on. I think I have figured out the cathode. I welded two titanium cathodes that will be positioned on either side of the anode, and located centrally. These are going to work fine. One of the two tabs is seen in this pic. What I need to do now is figure out a way to get the anode through this 1.375" disk: http://www.5bears.com/perc/tc041.jpg The disk goes into the bored hole in the lid, and is sealed with an o-ring. The beauty of this is I can make more disk plugs and do some anode swapping as needed, without having to engineer another lid. I am leaning towards the square hole and wedging in some CPVC stock to secure the anode shank. Link to comment Share on other sites More sharing options...
tentacles Posted September 29, 2008 Share Posted September 29, 2008 (edited) The question isn't how to mount the anode in that 1.375" disc, it's how will you get your 2"+ wide anodes through that 1.375" hole? But to mount them in the retainer.. take two chunks of your CPVC, retangular in section such that they make a square when together. Mill the faces for a smooth fit. Now put one in your milling vice mating side up, and cut a relief for the anode shank. Glue in the anode with your regular CPVC glue (perhaps with a mechanical retainer of some kind in there as well, a pin or something) and then turn the anode sandwich round on your lathe. A good, tight fit, sealed in with an appropriate material, and no funny business. (Plus it's easy to do, if not super quick). If you want it to be even easier, then use a square piece and another o-ring channel, and just screw it onto the lid. Or just turn half of the anode retainer round, and screw it down onto the lid. There's a number of ways you could play this out. You could even do it without the glue, and screw the two pieces together to hold the anode in, and use some teflon tape/packing to seal the joint. Question, how will you be venting the gases from the cell? It's sure as day that you will get some collecting in both sides of the cell. If the two chambers aren't level, I could see a problem developing. By the way, that 6V 90A power supply works. Also, it's 115/230V, and apparently autosensing. All that in a mere 90lb package! You're going to hate me when I tell you I picked up some 8" CPVC pipe the other day - schedule 80. It's going to be a milling jar. Edited September 29, 2008 by tentacles Link to comment Share on other sites More sharing options...
Swede Posted September 30, 2008 Author Share Posted September 30, 2008 The question isn't how to mount the anode in that 1.375" disc, it's how will you get your 2"+ wide anodes through that 1.375" hole? But to mount them in the retainer.. take two chunks of your CPVC, retangular in section such that they make a square when together. Mill the faces for a smooth fit. Now put one in your milling vice mating side up, and cut a relief for the anode shank. Glue in the anode with your regular CPVC glue (perhaps with a mechanical retainer of some kind in there as well, a pin or something) and then turn the anode sandwich round on your lathe. A good, tight fit, sealed in with an appropriate material, and no funny business. (Plus it's easy to do, if not super quick). If you want it to be even easier, then use a square piece and another o-ring channel, and just screw it onto the lid. Or just turn half of the anode retainer round, and screw it down onto the lid. There's a number of ways you could play this out. You could even do it without the glue, and screw the two pieces together to hold the anode in, and use some teflon tape/packing to seal the joint. Question, how will you be venting the gases from the cell? It's sure as day that you will get some collecting in both sides of the cell. If the two chambers aren't level, I could see a problem developing. By the way, that 6V 90A power supply works. Also, it's 115/230V, and apparently autosensing. All that in a mere 90lb package! You're going to hate me when I tell you I picked up some 8" CPVC pipe the other day - schedule 80. It's going to be a milling jar. Tentcles, NOOOOOOooooooo! Hahaha! Don't do it! That pipe costs $60/foot. Save it for a chlorate tank! Argh! Excellent suggestions guys. With the cathode solved, that's 80% of the issue, because I knew the stupid cathode shanks were going to be huge. Tentacles, I recognized what you were getting at with regards to the rim on that plug. With the anode glued in, it is uninstallable. If I turn the rim off, and install from below, it might fall off/down. How anout this? Turn the plug sideways, and mill (with a 1/16" thick little slotting saw) a slot from the rim, towards the middle. The shank will install into the plug from the side. The slot will be just deep enough so that one edge of the electrode shank will be just inside the o-ring. That might work. With the rim on there, I need to come up with a NOT permanent fixture; otherwise, I need to re-engineer the plug without a rim. The good part, if I screw up the plug, it's no big deal, whereas if I mess up the lid with all it's major components, I'm screwed... that's why I did it this way. Venting - I need to buy some 1/2" or 3/8" CPVC pipe + fittings to make a vent for the lid, and the big CC (Tank) will be vented as well, "teed" to the EC. I'm REALLY jealous about your power supply. That is an awesome bargain, and frankly when I called them, I was ready to buy every single one they had at that price. Incredible. Did you get one or two? If you got two, you could put them in series. If just the one, it'll still kick ass for chlorate, but the voltage *might* be an issue for perchlorate. Either way, great find. Where'd you find the PVC? I'm half joking, but that really would be a waste as a jar for a ball mill. CPVC is scary-expensive stuff. Link to comment Share on other sites More sharing options...
tentacles Posted September 30, 2008 Share Posted September 30, 2008 (edited) They just had the one, which is probably why they sold it so cheap - not enough of them on hand to warrant buying the service manual and recalibrating it. Keep an eye on that site, this wasn't the only thing they had really cheap. This unit over there ought to serve all your needs, and it could replace your welder! Agilent HP 6690A 15 V, 440 AMP, Switching Power Supply $1,490.00 Current and voltage programmable, even. The CPVC was left over from some water main work, guys said we could have it if we hauled it off. It was just scraps to them. It's printed on there (none to clearly, you know how that is) C PVC. It's kind of an assumption to call it CPVC, but it machined better (less gummy) than the regular PVC we turned that night. Our buddy put the stuff on his SB lathe and trued up the ends real nice for us. Got some 6" stuff to make some little jars with. They'll be so cute! Edited September 30, 2008 by tentacles Link to comment Share on other sites More sharing options...
GraniteStateRecovery Posted December 26, 2008 Share Posted December 26, 2008 (edited) on your problem of attaching electrodes use a two part electrode so they will screw into each other and seal at the same time. one tapped and one died Edited December 26, 2008 by GraniteStateRecovery Link to comment Share on other sites More sharing options...
Arthur Posted February 17, 2009 Share Posted February 17, 2009 Cut the plug in half to two D shapes file or mill a slot for the electrode hanger then taper the hole on the lid so that it all fits snugly and clamps as the taper grips. Link to comment Share on other sites More sharing options...
Swede Posted February 17, 2009 Author Share Posted February 17, 2009 (edited) Thank you all for the suggestions. What I ended up doing, and it seems to work, is measure the width of the hanger or "strap", and with a bandsaw, simply slot one of those plastic, o-ring equipped plugs far enough so that when the strap is inserted in the slot and the o-ring installed, it all seems to snug-up decently. One thing I did notice was that there was still a bit of salt creep, but worse, chlorine gas seemed to work its way through a tiny channel, and when it contacted the aluminum block, it corroded it badly. I think what I am going to try is a piece of sheet teflon, thin stuff, maybe 0.016", and slot that for the strap. It will then be installed over the strap, between the PVC lid and the aluminum clamp. It is really hard to make one of these truly gas tight and totally sealed, but I think I've come close. Arthur and GSR, both of your suggestions have merit and would work. Edited February 17, 2009 by Swede Link to comment Share on other sites More sharing options...
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