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Post by blueuk on May 25, 2017 10:57:40 GMT -5
I'm just thinking out loud here as I've never seen it on any manufacturers tools so here goes; Why don't the manufacturers or a manufacturer produce the tool in cordless format but can also have a corded mount on the battery connection point instead of the battery for those times when continuous cutting or workshop conditions mean that powered is the better option or when on site or suchlike, the tool can become cordless by inserting a battery. Would the large 18/36v transformer be the deal breaker on such a tool? It could be something incredibly obvious that I'm just not seeing.
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Post by kraftt on May 25, 2017 11:18:19 GMT -5
I believe they feel the simple solution is to purchase a second battery & swap them while the other charges thereby avoiding the cord and cost of power supply.
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Post by mafelluser on May 25, 2017 12:26:12 GMT -5
I reckon it's a good idea and would be worth ironing out the design challenges.
Equally, when I look at the low-voltage Mirka sanders, I wonder why they don't do more to offer a rechargeable battery option (perhaps in a backpack, worn by the user, during sanding). This could be a boon to second-fix contractors working on new builds, where mains electricty supply may not always be up-and-running.
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Post by mafelluser on May 25, 2017 18:30:23 GMT -5
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Post by mafelluser on May 26, 2017 7:26:23 GMT -5
Why don't the manufacturers or a manufacturer produce the tool in cordless format but can also have a corded mount on the battery connection point instead of the battery for those times when continuous cutting or workshop conditions mean that powered is the better option or when on site or suchlike, the tool can become cordless by inserting a battery. I stumbled upon a remark about exactly what you're describing, in the following table-saw review (at about 40% down the article, under the sub-heading 'Room For Improvement'), in relation to a DeWalt mitre saw: www.protoolreviews.com/tools/power/cordless/saws-cordless/dewalt-flexvolt-table-saw/30777/
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Post by blueuk on May 26, 2017 8:12:01 GMT -5
Why don't the manufacturers or a manufacturer produce the tool in cordless format but can also have a corded mount on the battery connection point instead of the battery for those times when continuous cutting or workshop conditions mean that powered is the better option or when on site or suchlike, the tool can become cordless by inserting a battery. I stumbled upon a remark about exactly what you're describing, in the following table-saw review (at about 40% down the article, under the sub-heading 'Room For Improvement'), in relation to a DeWalt mitre saw: www.protoolreviews.com/tools/power/cordless/saws-cordless/dewalt-flexvolt-table-saw/30777/[ Cheers, at least I know I'm not the only one who thinks it'd be a good idea for when there's quite a bit of work to be carried out in one area and there's power rather than trying to get max capacity from a battery with 25-40% charge.
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Post by ohan on May 26, 2017 11:16:20 GMT -5
I think the DeWalt has to have that tech because the flex volt system trades off voltage for amp hours.. It's nice to have mains backup so you don't have a boat anchor on your hands while the batteries charge.
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Post by huntsgemein on May 26, 2017 20:23:10 GMT -5
Yes, not only does the DeWalt SCMS have a mains adapter available as an accessory, but I seem to recall that they also tried it once before, several tool generations ago with their 28v?? Ni-cad powered tools too. In that instance, I can only assume that it was less than successful - either operationally or commercially - as there's been an intervening decade or two since.
Nevertheless, it superficially seems like a good idea. Most universal motors are equally accommodating to both AC & DC current. How EC motors fare is an unknown. Given that EC is the current gold standard for contemporary power tools, and that both battery powered and mains examples now exist, I'm sure its possible. That very high torque outputs are also now available from at least constant speed EC motors, such as those fitted to the 2400w input/1800w output Metabo 36v grinder, makes it viable for at least some larger tools. SCMS & Site saws, SDS Max combis & breakers could all benefit from corded/cordless functionality, although of course the latter would tend to shake the living shaisse out of the poor long-suffering battery/s which might actually result in a limited lifespan.
I'm not all that particularly clever at Physics, but I assume that to electrically commutate any motor, a DC input current would have to be inverted/rectified into an AC signal to allow the rotational motive force in Electrically Commutated field wiring. That rate of Current Alternation would have to be RPM dependent, and not at a fixed AC frequency. In other words, there must be some extremely sophisticated and clever electronic control circuitry involved: expensive too, no doubt.
If that's an accurate assessment, and I'm not saying that it is, then it's a pretty simple matter of supplying a constant 18-20v+/- DC (or 36-40v Dc for bigger tools) to the battery terminals of any cordless tool at a current commensurate with the particular tool's anticipated draw, plus a headroom allowance for safety & longevity. In fact, prior to the changeover to Metabo powered motors & batteries that's exactly what the Rothenberger company had done with their own cordless/corded swaging tools: you could opt for either a battery (AEG I seem to recall) only powered swager/crimper, or purchase an accessory 220v "battery eliminator" power pack that simply slotted into the battery's place on the tool. I also seem to recall that the accessory power pack was pretty damned expensive too, as was/is DeWalt's.
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