Convert 110v power to run a 220v 12 inch table saw

333_okh · February 09, 2007, 04:48:31 PM

I was given a nice older Craftsman 220v 12 inch tablesaw. I would like to use it to resaw some of my small blocks of wood. I do not have a 220v outlet in my shop, but I am told there is converters to be had. The head on the saw looks like my wife's washer/dryer. Can you guys help?

fstedy · February 09, 2007, 05:11:58 PM

Many of the Craftsman saws are dual voltage which you can change on the motor terminal block. If you have an owners manual it should tell you how. If you don't have a manual you might be able to find one online using the model number.

333_okh · February 09, 2007, 05:12:48 PM

thanks.......why is the cord so different then?

scgargoyle · February 09, 2007, 05:15:07 PM

I don't know of any way to do that. Residential 220 is made up of two 110 volt legs. These are split into separate buss bars in your circuit breaker panel. The converter you might be thinking of is one that converts 220 single phase power to 220 three phase, which is an industrial type power source. Most houses have two 110 legs- maybe you can just run another one to your shop. Some motors can be wired differently to run on 100, but that's probably not the case on a saw that big. Look at the motor tag closely- it might be 3 phase, which would require 220 AND a converter.

oakiemac · February 09, 2007, 06:18:36 PM

Basically there is no convertor for 110 to 220volt. You could use a step up transformer but why not just run a 220 circuit out to the shop.

If it is a 220v motor then the best thing to do would be to run a 220v recept out in your shop. Every house has 220 run to the beaker box. You need to know the amperage of the motor and run wire heavy enough to support that. It should be tagged on the motor and will be labeled FLA-which stands for "full load amps". There are different type plugs for 30a, 40a, and 50a-all of these will be 220v.
If you have any questions talk to an electrician or post the FLA rating of the motor and I can look up the wire size and breaker size that you will need.

Joel Eisner · February 09, 2007, 10:03:49 PM

When I got my Grizly saw it came wired for 220 but it was easy enough to change to 110 by moving some wires in the wiring block where the cord is hooked up. No converter needed.

sawguy21 · February 09, 2007, 10:30:01 PM

There should be a wiring diagram on the inside of the cover where the power cord enters the motor. You can wire it for 120V by connecting the field windings in parallel but you will be disappointed with the results. Thje saw will be slow spooling up and will lack power. Best if you can run a 240V circuit to your shop.

brdmkr · February 09, 2007, 10:49:37 PM

On a different forum (can't remember which), there was a fellow asking this same question. There was a converter that someone posted. It has two plugs that must be plugged into different circuits. I remember thinking that it would not really make a good long-term fix. It did have a light to indicate when 220 was flowing. Sorry, I can't remember more.

pineywoods · February 09, 2007, 11:05:06 PM

U don't need a converter. Look for a step up/step down transformer. Try surpluscenter.com. their catalog lists 2 different sizes. For what a big enough transformer will cost, you can probably get 220 run to your shop, much better solution.

Furby · February 10, 2007, 01:14:22 AM

Let's stop and break this down a bit.
Where is your shop?
Is it in the basement, an out building or what?
Is there a breaker panel in that building?
If so, you should have 220 to that panel, and can run wire from it and install a 220 outlet.
It's pretty simple really.
Some folks have overloaded breaker panels or still using fuse boxes and if either is the case here, GET IT UPGRADED! Spend the $ and have it done!

JimBuis · February 10, 2007, 06:48:34 AM

What Furby said and make sure you check the nomenclature plate on the motor to find out if it is dual voltage, i.e. 110 and 220 volts. There is such a thing as a motor that is 220 only, but you need to check that first before rewiring your shop.

Jim

Minnesota_boy · February 10, 2007, 07:05:12 AM

Power is related to voltage and amperage. When you try to run a 220V motor on 110V, it must have at least double the amperage, plus usually it's performance is degraded. Many 110V circuits will not be able to handle the increased amperage.

If you opt for a transformer, it will require twice the amperage the motor specifies plus the power loss of the transformer. This kind of transformer will be very expensive and may require you to rewire the incoming circuit to handle the current.

If it's impossible to rewire the shop for a 220V outlet (hard to believe) but it has a breaker box, then yes you could plug into 2 of the 110V outlets to get the 220V if the 2 outlets are on different legs from the breaker box so there is actually 220V between the 2 hot wires. Not a good solution, but it might be necessary if you don't own the building and the owner refuses to let you have it rewired.

scsmith42 · February 10, 2007, 12:40:53 PM

333, to answer your last question - yes we can help.

First though- unless your table saw is 3 phase (which I seriously doubt) this is not a situation that would call for a "converter". Typical US 220V (also known as 240V) is made up of two hot legs of 120V each. If you look into a load center you will usually see three feed wires - two (hot legs) that go to the metal bars that all of the circuit breakers hook into, and one (neutral leg) that is a neutral / ground. Each one of the hot legs is carrying 120 volts - if you measure them from hot to neutral. If you measure in-betwen them you will read 240V (or something close to that).

(FF team - for the sake of keeping this easy I am not delving here into 3-phase load panels and the associated wiring)

As stated by Joel and Sawguy, many small hp motors are built so that they can be wired internally for either 120V or 240V, however as Sawguy stated you will probably be disappointed with it's performance.

Furby's questions have you started down the right path. In addition to answering those, let me add one more: There should be a plate on the motor for your table saw that lists it's voltage and amperage. Typically the plates would have a section that reads 'voltage" and them something stamped such as 120/240. Then, there would be a section stamped FLA or Amps, with something like 30/15 stamped in. If you can respond with this info we can assist you further.

Regards,

Scott