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Thread: r4z0r7o3's Crucible-furnace lifting mechanism / transport-stand.

  1. #261
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    I did explain why... ...at least about chasis ground anyways.

    You don't switch neutrals because for one they are a reference to ground (safety), and two because if you do and test for power against it makes it appear as though the hot you're checking is dead, which it may not be, (safety).

    FWIW, I'm furthest thing removed from a safety Nazi. You just appeared to be proud of your bad control design because you manage to conceive a method to work around it flaws. However all you did was make it more dangerous...lol For all the effort you've put into this project, now is not the time to half ass something.
    FLAME ON...!!!!

  2. #262
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    We switch neutrals all the time so long as it's a ganged or double pole switch that takes out the phase with it. Often a neutral will 'float' slightly above earth depending on the earth system. Double insulated normally refers to a case within a case where a fault can't make its way to an external metal body (Usually shown by the two squares as reference)

    I've worked on farms where the neutral was fused, used to be common but was banned for obvious reasons! Then again so was paper wrapped lead sheathed cable lol.

  3. #263
    Senior Member caster's Avatar
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    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  4. #264
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by J. Vibert View Post
    FWIW, I'm furthest thing removed from a safety Nazi. You just appeared to be proud of your bad control design
    Ahh hmmm, dang, didn't mean it that way..was more of, finding it humorous (after the fact) that it's got TWO off switches. Though you are right, and I agree that both bad-design and half-assism don't belong here (also being a member of F.A.S.N. myself - Fathers Against Safety Natziesm).

    There's another problem you missed WRT switching neut...It makes it possible for a HUGE inductive sparkie-sparkie (voltage spike) to come from the mains side of the transformer if: You unplug the unit from the wall (leaving it switched on), then accidentally touch the conductors (on the plug).

    There's also another similar problem I found with adding a pair of snubber-diodes between the limit switches and motor: They cause a short-circuit :S

    SSSSSooooo...okay, I'll get fritzing (awesome "free" program BTW) out and make some mods to the drawing. Thanks for pointing out the flaws.

    • Find a three-conductor cable for the plug, ground goes to chassis.
    • On the low-side of the PSU, tie both 12v and 60v - to ground.
    • Figure a better place/way to connect the motor snubbers w/o causing a short.
    • Optionally, drop the snubbers on the motor side and proclaim F.A.S.N. membership (again)


    - - - Updated - - -

    Quote Originally Posted by Peedee View Post
    Double insulated normally refers to a case within a case where a fault can't make its way to an external metal body (Usually shown by the two squares as reference)
    Yes, totally forgot about the "no metal case" part (durrrr).

    - - - Updated - - -

    Quote Originally Posted by caster View Post
    "Things that are complex are not useful, things that are useful are simple."
    Dang, I thought the electrical design was fairly simple. Now I've got to complex it all up with a stoopid ground-connection! Good thing Mikhail wasn't into electrical engineering, that shit's always complicated, even when it's "simple", hahahaha. Perhaps a better word/translation for that quote would be 'novel'. I dunno, don't speak that much Russian.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  5. #265
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    Quote Originally Posted by Peedee View Post
    We switch neutrals all the time so long as it's a ganged or double pole switch that takes out the phase with it.
    Now there's a great idea for an entertaining thread. We can build what I'm sure will massive thread wherein we list the stuff people do all the time even though it's still a bad idea...lol
    FLAME ON...!!!!

  6. #266
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    It's code over here (main feed and some appliances) not a random thing, earth never gets switched and is a completely separate line. I'll not sully this thread with it anymore.

  7. #267
    A lot of people get confused between Neutral and Earth, this is mainly because, on cars it is one & the same thing, In reality though it should be referred to as Neutral on a car.
    I don't know about the US, but here in the UK we have Live ('s (if 3 phase)) Neutral & Earth. the Earth can sometimes be deleted if the equipment is double insulated.
    Generally for industrial equipment it is always there. The Earth is just that, a wire that is ultimately grounded in the soil "Earth" in olden days that's all it did, now with modern RCD's it can be incorporated into the system so any voltage detected on the Earth line throws the trip.
    The only time You're not following your nose is when your going backward!.......Andy (ME) .
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  8. #268
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    A handful of years ago after a few to many "debates" on the subject matter, I made myself a promise not to engage in any online discussion regarding anything that was electrically based. I inadvertently broke that promise in this thread. I have since apologized to myself and renewed my vow.

    My online disdain for the subject matter has nothing to do with this great forum, and simply would rather keep it that way...lol.

    Sorry for the derail
    FLAME ON...!!!!

  9. #269
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by J. Vibert View Post
    A handful of years ago after a few to many "debates" on the subject matter, I made myself a promise not to engage in any online discussion regarding anything that was electrically based. I inadvertently broke that promise in this thread. I have since apologized to myself and renewed my vow.

    My online disdain for the subject matter has nothing to do with this great forum, and simply would rather keep it that way...lol.

    Sorry for the derail
    Lolz, no worries man. In Electronics (and most/all engineering) there's always more than one way to do things. People seem to use that as an excuse to argue their way is better. Clearly, even the experts and code/legislation committees don't even agree, how can us humble forumn-trolls have any hope at all hahahahaha.

    Let's just lay down the rule here for this thread: No ideas are bad, unless they're terrible, or someone's about to get badly hurt from a "murphy's law" type accident. The only exception is, if you can't explain why your idea is not bad, keep your damn mouth shut

    Anyone here watch Dave Jone's EEVBlog?

    I think I remember learning from him, we have separate (mains) Live, Neutral, and Earth (where Neutral and Earth bonded at service entrance?) for redundancy. i.e. To, on, or in your device, you can have a fault in either neutral or earth and everything is still "safe" (there's still one return path that doesn't go through your body).

    Also (IIUC) this is how those safety GFCI outlets work, they detect when (to, on, or in) your device shorts hot to neutral or ground (or both). So when cute little Jane drops her hair-dryer (or it's cord bumps the toaster-ovan) into her bath, she doesn't get shocked. Hot cuts off, anything leftover heads to ground through the drain pipe and/or through the plug.

    In any case, I've re-done my schematic and even included a drawing of the power-supply (to illustrate how trivial/simple it is). Note to the uninitiated: These schematics almost always make things look more complicated than they really are. I promise if you stare at it long enough, it will make sense (or just ask) or I've made some terrible blunder (to which all card-carrying members are required to shout "Horseshit!" and then bludgeon me with a trout):

    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  10. #270
    Senior Member r4z0r7o3's Avatar
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    Thank god for unreliable neighbors

    I was suppose to weld on a pair of step/rails onto this guys jeep, but he never materialized. So, tackled a few hours of TODOs here instead.

    I re-positioned and tacked up the right lifting-arm and braces (that I removed earlier due to bad fit). Much better fit this time, it even matches the positioning of other side now (who'd a thunk it possible!).


    Got the lower-frame support-braces lined up and tacked to the lower-frame only, not down to the base yet.


    Clamped the braces in place because I couldn't get very good tacks on them. Unbolted the lower-frame from the rails, and took it over to my table where I could more comfortably weld and my foot-pedal.


    This also let me position the part in much more convenient orientations. Got good solid welds on as many sides as I could access. Not perfect welds, but they're getting better IMHO. Certainly more than strong enough for this application.


    Had a little bit of under-cut welding the support running horizontally in the pic. It's always tricky to get the amps dialed-in correct when you've got two dissimilar thickness materials. In this case the tubes are 3/16th in. thick (more at the corners) and the angle-iron is more like 1/8th in. thick. I tried to focus the heat mostly on the tube, but, well, you can see what happened. Oh well. Call it "practice" and move on. (Note: Ignore that little round speck that looks like I welded out in la-la-land. That's just a loose piece of scale from the weld on the opposite, downward-facing side).


    Finished welding up the lower-frame joints as they were only tacked before.. Had to grind down the corner one a bit because these sides are a really close fit up against the insides of the rails. I also beveled the unneeded corners (not shown here) so keep me from snagging things on them.


    Bolted the lower frame back onto the rails only to discover a perfect fit on one support, and giant 1/4-in gaps on the others *cry*.


    I ended up sticking some little 1x1x3/16th in. thick pieces under the tubes. Welded those shims down to the bottom plate, then did about six or seven passes ontop to make sure everything was thoroughly melted together. Very little under-cut this time, but very blobby-welds. Mind you I had to do this all with scratch-start because there's absolutely no way to use a foot-pedal while sitting on the floor.


    Maybe somebody knows some on-the-ground pedal technique, but I couldn't figure any out. I'm aware they sell torch-mount controls for these situations, but they're pricey, $150 - $200. I opted to spend my money on an argon tank upgrade instead. Swapped in two 80cf bottles for one monster 150cf. Only costs $40 to fill it, whereas it was $30 (each) to fill the smaller ones.

    Oh, I also converted my O/A gas-welding rig over to run on propane. Not to be used for welding, but for heating and cutting instead. Propane is about 1/3 the price of acetylene, and I can use the same regulator. I did have to buy a "T" rated hose though, apparently propane can eat up regular rubber welding hosts. No matter, the host I had was from the '70s anyway, and beginning to show some (very) minor cracking.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

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