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  • DIY Electric Foundry for Metal Casting (120V)

    Kanthal is 65-75% iron, but no carbon. Steel is an alloy of iron and carbon, so Kanthal is not steel.Using plain steel as the heater, it wire would not last long. Even stainless would corrode quickly at these temperatures.

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  • DIY Electric Foundry for Metal Casting (120V)

    A couple comments.First, without an isolation transformer, isn't that that coil live and a safety hazard? You may want to at least add a disclaimer.A more minor point, you referred to the heating coil as being steel wire. The link you have is for FeCrAl (aka Kanthal.) I don't think steel would hold up too well at these temperatures.And one question. I assume you've been working with wrought aluminum alloys (6000 series.) How well do they cast? Have you been adding anything to them to improve castability?

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  • Manual Milling Machine/Surface Planner

    You should be able to eliminate binding if you connect the two lead screws with a basic timing belt such as XL profile.

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  • skrubol commented on Brooklyntonia's instructable Snuggly Heating Pad

    I'd avoid microwaving just a small scrap of fabric on its own. On older microwaves especially, running them basically empty can damage them.

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  • Usually if you buy the resistors in a kit/assortment each value comes in a small bag with a label. The kit I've got, those bags fit fairly neatly in a baseball card pouch. Random strips of SMD components fit well in extra pockets.

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  • If you had the system open, you will need to have it done by a shop. The system needs to have all the air and moisture evacuated before it can be filled properly and the equipment to do so isn't cheap.

    If the system is low enough that the low pressure switch has disabled the system and the compressor won't engage, you really probably shouldn't DIY this. A, if it's that low, it's probably got a fast enough leak that you're going to just be leaking this expensive and hazardous stuff out too. B, if it's really low, some air may have gotten in, and that's not good for the system.Maybe if you're just trying to get one last summer out of it..

    If the AC works at all, it'll be the colder line that you want to add to.

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  • Why does it need that much torque? That's probably at least 10x what the tire could put to the ground in good conditions. Stepper motors are quite inefficient, you will likely run out of battery just getting to and from the field. Also as far as not needing much top speed, again the concern of getting to and from the field.. Also stepper motor torque drops drastically at higher RPM.BLDC would be the most suitable option. A 2Nm NEMA 34 BLDC motor will have 2Nm all the way up to 3000 RPM, whereas that stepper probably will get down to 2Nm around 1200-1400 RPM. The bldc motor can also have short term overloads up to 3x the torqe, whereas a stepper will just lose steps. They also generally have a hall encoder built in, so you can do plenty precise positioning when running through a gear…

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    Why does it need that much torque? That's probably at least 10x what the tire could put to the ground in good conditions. Stepper motors are quite inefficient, you will likely run out of battery just getting to and from the field. Also as far as not needing much top speed, again the concern of getting to and from the field.. Also stepper motor torque drops drastically at higher RPM.BLDC would be the most suitable option. A 2Nm NEMA 34 BLDC motor will have 2Nm all the way up to 3000 RPM, whereas that stepper probably will get down to 2Nm around 1200-1400 RPM. The bldc motor can also have short term overloads up to 3x the torqe, whereas a stepper will just lose steps. They also generally have a hall encoder built in, so you can do plenty precise positioning when running through a gear box.

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  • Should be fairly easy to do without a welder. Just need a bit of imagination (use a door hinge instead of the pivot he welded? Of another piece of square tube slightly larger or smaller that could be cut and drilled.)

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  • Old working ovens can be found on Craigslist for pretty cheap (or roadsides for free.) Biggest cost would probably be getting the 30A 240V electric service where you need the oven.

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  • skrubol commented on makjosher's instructable The Ski Sled

    You mentioned an angle grinder and aluminum. Grinders with abrasive wheels (other than specialty aluminum specific wheels,) should NOT be used on aluminum. Aluminum will clog up the wheel and ruin it, or worse can make the wheel shatter. This goes for angle grinders, bench grinders and abrasive chop saws.You can get away using a table saw, miter saw or other circular saw normally used for wood on aluminum with the right blade. They typically run a bit too fast for aluminum though, so the blades won't last too long if you can't reduce their speed.Milling machine and a carbide chop saw would be the best tools for doing the cuts you did. But if your options are an angle grinder and a hack saw, the hack saw is by far the better tool for the job.

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  • FYI MeshCAM can produce toolpaths from grayscale images directly (without converting to STL) the last I knew.

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  • So these are left as open links? (IE C's, not O's?)

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  • In my (limited) experience with a Drill Doctor, they can be very effective, but they aren't as easy to use as you would think. If you don't follow the instructions to the letter, (and iirc there are some counterintuitive things in the instructions,) you will not have good results. I think the DD should be good for sharpening a bunch of bits at once, because if you've got a bunch, you can afford to sit down and re-read the instructions and do it right. DD regrinds split points as well. I think if I only had 1/4" and larger drills to sharpen I'd do it by hand. A jig of some sort is more critical on the smaller bits.

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  • Close enough to pass electrical current through the magnets to the copper.

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  • For preventing rust I've heard CLP (Cleaner Lubricant Preservative) by break-free is one of the best out there. I can't remember which formula is best for tools, but it's a much heavier oil that leaves a thin, slippery coating.Probably worse than the WD if you're going to be using it with wood right away, but I would expect it to do much better at holding the rust off if you're storing it. You'd probably need to clean the CLP off with something like WD-40 before use.

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  • Aren't ballast transformers often current limiting (usually with some magnetic gap or something similar to how simple AC stick welders work.)?

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  • The code looks like it'll only count a transition from 00 states to 01 or 10 states. Other transitions will be ignored. Effectively it'll only count 1/4 of the transitions. Is this the intent?

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  • Can't buy MAPP in the US anymore. I guess a few too many cylinders blew up or it's bad for the environment or something. The stuff sold now that resembles it (MAP-Pro) is somewhere in between propane and MAPP.

    I've read this elsewhere as well. Though that's the only quantified study I've seen.Heat still works better, assuming that's an option. Nothing beats an oxy-acetylene torch, propane works as well.

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  • XPS = eXtruded Polystyrene (pink or blue wall board insullation) and EPS = Expanded Polystyrene? (usually white, like disposable coolers and rigid packing material.)

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  • Evolution makes blades as well and they're decent blades. Looks like the only table saw they make is a 10" 2500 RPM saw, gear drive, brushed motor (looks like.) Looks to be the same motor assembly as out of their 10" miter saw (which I have.) One negative of their 10" saws, they have a 1"(25mm) arbor, which won't fit most blades. Their general purpose blade is good for wood, but pretty lousy for aluminum, chips get stuck between the teeth too often. Their aluminum only blade is $100+ and I've yet to find a 3rd party aluminum blade with a 1" mounting hole.Most belt drive table saws can be under-driven if you replace the pullies. I've done this on my Craftsman and now have a 2-speed saw, 3450 RPM for normal cutting, 1725 RPM for cutting aluminum (with the appr…

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    Evolution makes blades as well and they're decent blades. Looks like the only table saw they make is a 10" 2500 RPM saw, gear drive, brushed motor (looks like.) Looks to be the same motor assembly as out of their 10" miter saw (which I have.) One negative of their 10" saws, they have a 1"(25mm) arbor, which won't fit most blades. Their general purpose blade is good for wood, but pretty lousy for aluminum, chips get stuck between the teeth too often. Their aluminum only blade is $100+ and I've yet to find a 3rd party aluminum blade with a 1" mounting hole.Most belt drive table saws can be under-driven if you replace the pullies. I've done this on my Craftsman and now have a 2-speed saw, 3450 RPM for normal cutting, 1725 RPM for cutting aluminum (with the appropriate blade.) Would work fine for this as well.

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  • A 2-3 ohm .5+W resistor will protect the LED, but not help with the brightness variation.I thought I'd be able to find an inexpensive LED driver for running from a single Li-ion cell easily, but I can't.I did find a basic driver chip that may work:http://www.sunrom.com/p/amc7135-dc-led-driver-ccThere are some example circuits on the page.

    No current limiting for the LED? An LED like this direct driven by a lithium ion battery won't last long, especially with the minimal heat dissipation of a little LED star stuck in a plastic box.I'd also think the brightness varies significantly with the charge of the battery?

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