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Old Jul 04, 2013, 10:18 AM
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Thanks Pete, It makes sense to stick with it. The paper one look interesting, I think I'll buy mine though, for some reason I have bad luck soldering electronic kits although I have a new soldering iron now. I have the phidget stuff still and I think I'll still use that for the turrets but get another arduino.

Jeff the chemical plant is really neat, is it on a forum somewhere? I forgot when I started the dd project but it was many years ago, things move at snails pace sometimes. I just ordered a pump last night so probably won't see it for a few days, and I'll be out of town for parts of the next two weeks, but will put some updates in when I can.

Cap

PS: that torpedo was the first version, the second version had two electric motors with the shaft of one running through the shaft (tube) of the other for counter rotation.
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Old Jul 04, 2013, 01:16 PM
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Quicker update than expected. The "cork" is about done. It's all there the heating coils, the copper tube, the stirring paddle and motor, and the thermocouple. I'm not sure how to treat the wood cork, any suggestions? I think epoxy or polyurethane would melt or smoke, I'm not sure the wood won't burn at 400 F, doesn't paper burst into flames at 454 F or so? Also the paddle is soldered on, I assume solder won't melt at 400 F.

Just need the pump now. I ended up getting a different pump, I needed a bunch of other stuff they didn't have at that robokitsworld site. I got a bigger mosfet just in case, I feel like a total nerd buying a transistor, oh well.

Sorry for the poor picture. The thermocouple is in the center just sticking out of the end of the dowel. The paddle is hard to see to, it's just a piece of brass bent into propeller shape.
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Old Jul 04, 2013, 02:46 PM
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That looks fantastic! I am not sure on the cork, seems dodgy... =( Only one way to find out.
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Old Jul 04, 2013, 02:49 PM
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Research indicates cork will be okay, good shout! See here:

SECTION 6 - FIRE AND EXPLOSION HAZARD DATA
FLASH POINT: 300-365C (572-671F)

http://www.yemmhart.com/materials/wi...tiles/msds.htm
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Old Jul 04, 2013, 02:51 PM
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Quote:
Originally Posted by capricorn View Post
Quicker update than expected. The "cork" is about done. It's all there the heating coils, the copper tube, the stirring paddle and motor, and the thermocouple. I'm not sure how to treat the wood cork, any suggestions? I think epoxy or polyurethane would melt or smoke, I'm not sure the wood won't burn at 400 F, doesn't paper burst into flames at 454 F or so? Also the paddle is soldered on, I assume solder won't melt at 400 F........
Paper flashes at 451 F. I think the epoxy or PU would get soft at that temp, but I'm not sure. I've used a soldering iron to soften epoxy to unglue parts. The cork would be toast at that temp. Can you get hold of some silicone, it might be a good substitute for the cork. I know they make cooking utensils from it, it has a very high temperature tolerance.

EDIT: Here's the flashpoint from that link. But it may begin to breakdown before that temp. Have a fire extiguisher on hand when you test it.
CORK SECTION 6 - FIRE AND EXPLOSION HAZARD DATA
FLASH POINT: 300-365C (572-671F)
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Old Jul 04, 2013, 04:01 PM
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If the cork doesn't hold up. I might suggest a fire blanket instead of a fire extinguisher, you have electricity, water and hot oil all together. Get a ceramic baking tray to use as a bund for the experiment.

PTFE would work see here: . http://www.druflon.com/ptfeprop.html
260C = 500F, we get slabs of it at uni for bushings and stuff. It is easy to work with, soft but rigid, problem is that it is not cheap. I think some plastic cutting boards have ptfe in them and they are cheap. Just through one in the oven in a tray at 425F and see what happens.

You may want to check out http://shop.vitcas.com/vermiculite-f...FTIQtAodFXkArg
VITCAS Vermiculite Fireproof Board Refractory to 1100C (2010F) Perhaps building a box from this stuff could protect the rest of your lovely work.
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Last edited by bermylizard; Jul 04, 2013 at 04:02 PM. Reason: wrong temp listed
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Old Jul 04, 2013, 08:31 PM
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Great, thanks for all the info, I'm sorry I should have clarified, the cork is actually wood, a flanged cylinder, it fits loosely i planned on using tape to hold it on. It's two pieces epoxied together, which at the time i didn't think of but as Pete says the epoxy may not hold up well, a couple screws probably would do to keep it together.

I'll look at some other materials too as suggested, i've probably got one more pass after this. The copper tube maybe too narrow too, alll the old pieces I had that size are plugged, will require cleaning the tube after every use, which with me will never happen...

Cap
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Old Jul 05, 2013, 08:59 PM
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Looks like 15 amps is too much I'm finding my garden tractor batteries are going dead, I've charged them a bit here, I'm charging overnight tonight hopefully that will get them back.
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Old Jul 05, 2013, 09:16 PM
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Lizard, that refractory cement is interesting, I think I'll get some. I've done some casting of plaster but it doesn't hold up in the heat very well, the castable refractory would be useful. Hopefully it can contain uranium fission because that seems to be where I'm headed. Cap
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Old Jul 06, 2013, 09:58 PM
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Originally Posted by capricorn View Post
Looks like 15 amps is too much I'm finding my garden tractor batteries are going dead, I've charged them a bit here, I'm charging overnight tonight hopefully that will get them back.

You might like to look into converting a computer power supply for your bench as a cheap 12V rail. I have never done it but have looked into it see here:
https://www.google.co.uk/webhp?sourc...w=1344&bih=759


JUST BE UBER CAREFUL, Those caps will even shock a cap!
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Last edited by bermylizard; Jul 06, 2013 at 10:06 PM.
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Old Jul 06, 2013, 09:59 PM
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Originally Posted by capricorn View Post
Lizard, that refractory cement is interesting, I think I'll get some. I've done some casting of plaster but it doesn't hold up in the heat very well, the castable refractory would be useful. Hopefully it can contain uranium fission because that seems to be where I'm headed. Cap
Yeah, actually I was only looking at the wood stuff, thanks for pointing out the refractory stuff, it is cool. I was thinking you may like to set up a dedicated air vent into a fireproof housing for your fogger. The dedicated air vent could be actuated to block all air inlets and outlets so you can starve any disaster that occurs. A fireproof box would limit the extent of the damage. Not saying that will happen, but should be thought about.

Have fun!
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Last edited by bermylizard; Jul 06, 2013 at 10:12 PM.
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Old Jul 07, 2013, 11:17 AM
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LIzard, good ideas as always. I'll need to shift to the garage if the fogger works and puts out a lot of fog, don't want to fill the house with it, so the power supply would need to be portable. The batteries are back, overnight charging did it. I guess they don't have unlimited energy stored in them after all..... I'm going to look at the computer power source though, it sounds interesting and I have an old computer whose head is on the chopping block.

I've been thinking about fires too, as great a video as it would make I guess I'm not eager to have any catastrophes. It doesn't need air except for the duct that carries the fog away. encapsulating in an insulated, fire resistant box would probably be the way to go.

Off to go out of town for a few days. cheers, Cap
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Old Jul 13, 2013, 08:30 PM
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Attached quick clip of the gear motor with the pump. It's a 3 to 24v dc pump, 176 rpm at 12v. It's running at 12v and in the bottom left you can see the flow rate a drop every second or two. It has a good range so I think it will be workable. Cap

http://s326.photobucket.com/user/cai..._0143.mp4.html
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Old Jul 13, 2013, 10:02 PM
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Looking good 3V -24V is a great range to have for finding the sweet spot. Hope you had a good break.
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Old Jul 16, 2013, 04:57 PM
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Just was thinking about the stirring action. If you implement it, turn it really slowly. All you need is some movement for forced convection. How fast is it spinning now? 30-60rpm would be my guess at a decent slow, yet effective speed.

How is it coming otherwise?
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