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mr2monster
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Joined: 05 May 2007
Posts: 22
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 Posted: Sat May 12, 2007 7:49 pm Post subject: Water heater tank preperation, and some other questions... |
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So, i picked up a water heater today. 30 gallons. I think that should fit nicely. Anyhow, as i was driving it home, i noticed that there was some sediment in the tubes and that it was loose. Obviously there is going to be a build up of gunk in the bottom of this thing and I was wondering what people did to flush them, or clean them, etc.?
Also, when cutting the pieces out of the plastic sheet, what do you use to cut it with? I was thinking a hot wire would work but some of the stuff that i have to cut is rather complex. My goal here is clean cuts, as fast as possible. I'm going to be mass producing a run of about 130 of the same object and I'd like to make it as painless as possible.
Question 3: In the vacuum chain am i correct in assuming it should go as follows?
High Vac pump>Filter>Hose>Shut off Valve>Tank>Hose to table>2nd Shut off valve>Check valve>Plenum
Or should I put the filter between the shut off valve and the tank on the outgoing air side (towards the pump)?
Obviously the shop vac will be on the other end of the check valve and I'll have to modify it to work properly.
Question 4: Has anyone located a good spot to get the ceramic bits used for the oven?
Question 5: Where do i get nichrome wire?
I think that'll cover it for now. I did do a search, but didnt find anything about the tank prep so i figured I'd just ask the other questions while i was here.
Thanks for the help in advance!
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mr2monster
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Joined: 05 May 2007
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| Posted: Sat May 12, 2007 7:58 pm Post subject: |
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Ah yes... and which Check Valve are people most frequently using?
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CJanssen
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Joined: 17 Feb 2007
Posts: 215
Location: Beaverton OR
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drcrash
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Joined: 04 Sep 2006
Posts: 705
Location: Austin, Texas
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| Posted: Sat May 12, 2007 10:41 pm Post subject: |
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It wouldn't use ceramic insulators at all, if you're using hardibacker board. (It's one big ceramicish insulator.)
I'm making a Hardibacker oven using plain cotter pins to hold the nichrome, and saving my ceramic insulators for an aluminum oven, where I'll need the electrical insulation to keep the nichrome isolated from the aluminum.
You can get about two dozen ceramic insulators for $2 at a Goodwill Blue Hanger store, if you buy a waffle iron with nichrome elements and gut it for the insulators. They're not the kind of of ceramic insulators that people use for TJ ovens (posts or donuts), but they might be useful with a sheet aluminum oven, especially an over-and-under.
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Paul (a.k.a. Dr. Crash)
Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com |
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mr2monster
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Joined: 05 May 2007
Posts: 22
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| Posted: Sun May 13, 2007 1:08 am Post subject: |
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| drcrash wrote: | It wouldn't use ceramic insulators at all, if you're using hardibacker board. (It's one big ceramicish insulator.)
I'm making a Hardibacker oven using plain cotter pins to hold the nichrome, and saving my ceramic insulators for an aluminum oven, where I'll need the electrical insulation to keep the nichrome isolated from the aluminum.
You can get about two dozen ceramic insulators for $2 at a Goodwill Blue Hanger store, if you buy a waffle iron with nichrome elements and gut it for the insulators. They're not the kind of of ceramic insulators that people use for TJ ovens (posts or donuts), but they might be useful with a sheet aluminum oven, especially an over-and-under. |
Good call. I've been spending my fair share of time in the local Goodwill stores lately and it never occurred to me. There seems to be a surplus of toaster ovens there too!
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jegner
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Joined: 30 May 2003
Posts: 2144
Location: Texas, USA
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| Posted: Sun May 13, 2007 10:56 am Post subject: |
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The ceramic posts, stand-offs, insulators, etc. are really used for keeping the oven wires neat and tidy, and are also used for the tapping posts. Me, I followed Thurston James' instruction and tracked down the proper ceramic posts. I did think about using ceramic beads, from the hobby store, or even making my own, using the local art school's kiln, but in the end I got mine from www.infraredheaters.com, and they have served me well. I got 60 of them, and although not cheap, they get it done.
Get them if you want an easy oven construction. But not the cheapest option.
Jim |
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drcrash
Guru
Joined: 04 Sep 2006
Posts: 705
Location: Austin, Texas
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| Posted: Sun May 13, 2007 11:44 am Post subject: waffle iron ceramic insulators |
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More about waffle irons & ceramic insulators:
Most waffle irons have either two calrod loops or two nichrome coils.
The waffle-making aluminum plates (often with a teflon-type coating) come off for cleaning; there are a couple of springy retaining clips that you can just push back with your fingers, and pull the plates off. That exposes the heating elements, which are just IR elements used to heat the plates, which in turn heat the waffles by conduction.
The nichrome-coil-type waffle makers (most of the older ones) typically have 24 funny-shaped ceramic insulators stuck in slots in an aluminum base plate, plus 4 pass-through-type ceramic posts for the end wires of each coil.
The 24 regular insulators are usually 2-shaped, something like this side view:
| Code: |
+---------------------
| \
| \
+----------- \
--- \
\ |
nichrome \ |
coil goes | |
through | |
here / |
/ |
--- |
+----------- |
| |
| |
| |
| +---------------+
| | <- slot for fitting over edge of
| +---------------+ hole in aluminum base plate
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| |
| |
+-------------------------+
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Notice that the insulator is open on one side where the nichrome coil goes in.
A row of these things generally has them mounted in alternating directions, and staggered a little bit, so that the coil zig-zags through them, with the open part of the insulator facing the outside of a bend in the routing of the nichrome. The coil has to be a little bit taut and maybe a little bit springy, so that it will stay in the hole. If it is overstretched, it will flop right out.
The tension from the coil can also keep the insulator where it's supposed to be in a hole in the aluminum reflector/base plate.
In this kind of setup, the insulators are fairly close together, and the nichrome coil is taut enough that it will not sag down and touch the aluminum base plate, creating a short.
Sometimes the insulator is just mounted in a rectangular hole as big as the footprint of the insulator. You just put the bottom part of the insulator through the hole, then slide it sideways so that the slot near the bottom goes around the edge of the aluminum sheet. Sliding it sideways leaves a gap where the insulator could slide back over and fall out, but the tension of the nichrome coil routing snugs it up---the nichrome holds itself into the top hole in the insulator, and snugs the insulator against one side of the hole in the aluminum.
A more secure way of mounting one of these into the aluminum is to cut a sort of C-shaped hole in the aluminum, bend the middle tab up to make a rectangular hole, put in the insulator, and then bend the tab back down to close up some of the hole and keep the insulator from moving back that direction.
The hole looks something like this top view:
| Code: |
+---------------------------+
+-------------+ |
| |
| |
| |
+-------------+ |
+---------------------------+
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and when you bend the tab up you get a rectangle big enough
to slide the bottom of the insulator in, like this:
| Code: |
+---------------------------+
++ |
|| |
|| |
|| |
++ |
+---------------------------+
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When you slide it to the right and bend the tab back down you get this top view:
| Code: |
+---------------------------+
+-------------+ +-----------+-------------+
| | |
| | insulator |
| | |
+-------------+ +-----------+-------------+
+---------------------------+
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This raises a few questions:
1. How hard is it to string the nichrome with a little bit of tension; do you need to worry about whether the nichrome will fall out of the insulator?
2. How hard is it to string the coil taut enough that it doesn't sag much at all, and doesn't touch the aluminum? If you do this by hand, should you only do it for an over-and-under setup, where the nichrome would sag AWAY from the aluminum?
3. What's the easiest way to cut a C-shaped hole in a thin sheet of aluminum, preferably using only commonly available tools? I'm thinking that if you used aluminum flashing, you could drill a starter hole with a fairly large drill bit, and then use the tip of some tin snips to square it up and cut the long slots that make it C-shaped. If the tab part was too long, you could just fold it over to make the remaining hole the right size. Aluminum that thin would need some support structure, but would be locally rigid enough to hold the insulator. You could just pop-rivet the flashing to some extruded aluminum struts.
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Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com |
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crashmann
Guru
Joined: 27 Sep 2005
Posts: 501
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| Posted: Mon May 14, 2007 11:55 am Post subject: Re: Water heater tank preperation, and some other questions. |
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| mr2monster wrote: | | So, i picked up a water heater today. I noticed that there was some sediment in the tubes and that it was loose ...wondering what people did to flush them, or clean them, etc.? |
My ole rusty water tank had lots of stuff crunching around inside (it was manufactured in the 60's!) I didn't do any sort of cleaning out with the tank, since the connector hoses are at the top, and the junk is at the bottom. Also, since there is a filter between the tank and vac pump, then there's no worry about crusty bits ruining the pump. I did replace the pipe fittings since the old ones were incredibly corroded.
| Quote: | | when cutting the pieces out of the plastic sheet, what do you use to cut it with? |
I use a utility knife with sharp blade, making several light passes, then flex nd snap. Also, wear leather gardening gloves to prevent burns, and to prevent cuts to your hands from the knife slipping, or on the edge of the plastic (those corners can be very sharp!) Nichrome wire would work with VERY thin plastic (.020 gauge), but probably not much thicker. I have also used a bandsaw, and a jigsaw (cutting from the back side of the plastic) However, if you're cutting too fast, the plastic will melt itself back together!
| Quote: | Question 3: In the vacuum chain am i correct in assuming it should go as follows?
High Vac pump>Filter>Hose>Shut off Valve>Tank>Hose to table>2nd Shut off valve>Check valve>Plenum
Or should I put the filter between the shut off valve and the tank on the outgoing air side (towards the pump)? |
Either way will work fine, as long as the filter is somewhere between the tank and pump. Having it closer to the pump will filter out any bad stuff that may build up in the hose.
Go with the good Doctor's recommendations for ceramic bits and Infra-Red Heaters for nichrome wire.
Charlie
TI-386 |
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mr2monster
Newbie
Joined: 05 May 2007
Posts: 22
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| Posted: Mon May 14, 2007 5:15 pm Post subject: |
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Thanks for the replies! Keep em coming.
In other news, I found a solution to my trimming problems i do believe. I'd imagine that this would cut the plastic very well. And it seems as though someone found a cheap way to make replacement blades, haha. I love DIY stuff..
http://www.youtube.com/watch?v=GoXWztxKBJI
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