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bred posted:We also just moved and I have 2 ladders I've inherited over the years: an 8ft fiberglass A frame and a 12ft+ aluminum extension. We impulse-bought one of these ~3 years ago because we couldn’t believe how light it was and it’s now my go-to ladder for anything indoors: https://gorillaladders.com/product/gla-3/
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May 1, 2021 02:44
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BIG-DICK-BUTT-gently caress posted:why does a power tool draw more current under load? I’m talking about how you can trip a breaker if you push a big saw or grinder too hard. I would assume the current draw to be constant, how does the tool “know” to draw more current? Just to expand slightly on the previous answers - a motor is in equilibrium when the motor torque is equal to the load. DC motor torque is proportional to current, and current is driven by net voltage (i.e. the input voltage minus back-EMF, which depends on speed). So when you load the motor, it will slow down because the torque is too low to match the new load level, so the net voltage goes up, which causes the current (and therefore the torque) to increase, eventually reaching a new equilibrium at a lower speed and higher torque. A stopped or stalled motor has no back-EMF and therefore the maximum current for a given input voltage, but it's reasonable to assume you're always just getting Ohm's law current (I = V/R) based on the resistance of the windings and the net voltage at that time.
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Aug 31, 2022 04:33
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SEKCobra posted:Or to put it in simpler terms: When the motor is spinning freely with no load it only needs a little bit of energy to maintain the rotation. When you "brake" the motor (which is essentially all you are doing when cutting/drilling/etc.) there is more energy needed to overcome this mechanical resistance. This is true but most power tools do not use closed loop speed control (with exceptions like the good track saws) so it doesn’t explain how the motor “knows” to increase current. more falafel please posted:The other part of this that I've maybe never fully understood: that means the motor has a speed it's always trying to run at, which is determined by some relationship between the windings and the voltage/frequency of the AC supply? At equilibrium, the motor will run at a speed which depends on its input voltage and the external load. Supply frequency isn’t really important here - for tools with brushed motors, the brushes are what keep the magnetic field rotating at the right speed; brushless DC motors in battery tools instead measure the motor shaft angle and control the rotation of the magnetic field by varying the winding voltages.
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Aug 31, 2022 16:59
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Trabant posted:Seems wasteful, I guess. Plus I'm then probably forced into using stock of the same thickness as the donor box vs. what I'd like to use (~1/4" wood). I have no direct knowledge but got curious and it looks like you’re meant to jam those hinges into a saw kerf: https://go.rockler.com/tech/RTD10000246AA.pdf
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Sep 28, 2022 03:25
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Trabant posted:I'm missing something See those marks near the thumb?
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Oct 28, 2022 23:12
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