1. Join Date
Jul 2012
Location
Bertie County,NC
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## Re: For those who build your own, which table saw?

Originally Posted by Acebird
Mechanical power is torque times speed. Electrical power is current times voltage. So to simplify you can think of current being the torque factor and voltage being the speed factor.
For a DC (direct current) motor amps relates directly to torque almost exactly. It is practically a straight line curve. An AC motor doesn't follow exactly because there is frequency involved but it does follow in the portion of the curve around the stated RPM of the motor. It is only when you pull the motor down (out of phase) that bad things happen. Variable speed AC drives (inverters) work by changing the phase and voltage. In so doing the HP varies with the speed. For the most part any AC motor can be variable speed by using an inverter (AC drive).
ok?

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## Re: For those who build your own, which table saw?

> Variable speed AC drives (inverters) work by changing the phase and voltage.

Variable speed in an induction motor is accomplished by varying frequency, not phase.

And in a variable frequency drive (VFD) induction motor, an inverter is indeed part of the process, but an inverter simply converts DC to AC. If the supply power is AC to start with, then there is also a rectifier to convert the AC to DC, and a controller to set the appropriate frequency for the AC output of the inverter at the frequency needed for the speed desired.

In VFD drives the inverter needs to be designed to output AC power at a variable frequency called for by the control circuitry, which will vary as the desired speed of the motor varies.

In ordinary inverters such as those that you might use with 12 volt car batteries the AC output frequency is fixed at 60 hz to match residential line power.

It does seem unlikely that any Beesource members will encounter a tablesaw with a variable speed induction motor!
Last edited by Rader Sidetrack; 01-25-2014 at 10:19 AM.

3. Join Date
Sep 2011
Location
Reno, NV
Posts
3,798

## Re: For those who build your own, which table saw?

My make it myself factor may have altered drastically. I met a guy yesterday that has over 20 years either running or owning his own sugar pine mills. I started talking to him about getting in contact with some of them in regard to purchasing end mills. he asked me how long. when I told him the longest piece in a hive is 20 inches. he sort of rolled his eyes and smiled. then he said he can get truck loads of that stuff. random widths though. Btu if it drops the cost of the lumber as much as I think it can. Commercially made boxes may never be on my list again.

4. Join Date
Sep 2007
Location
Hudson, WI USA
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## Re: For those who build your own, which table saw?

Daniel, as I recall, that is exactly how Michael Palmer gets his lumber.

5. Join Date
Mar 2011
Location
Utica, NY
Posts
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## Re: For those who build your own, which table saw?

> [COLOR=#333333]
Variable speed in an induction motor is accomplished by varying frequency, not phase.
You are correct, I used the wrong term.

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