I recieved my copy of November American Woodworker today. It has a short article about 4 new bandsaw models. One statement regarding the new Delta model 26-475X 14″ saw caught my attention (it’s on page 78); I think it is either in error or exaggerated. It states, “The 110/220 dual-volt motor delivers 1 1/2 and 2 hp respectively….”
I was under the impression that switching a 110 motor to 220 volts might increase power slightly, but this article appears to claim a 1/2 hp increase which is quite a bit (33%, right?). I have a Delta BS with 1 HP motor. If I remember the manual right, it can be rewired for 220. I would be interested in hearing from anyone who has done this and how much increase in power did you notice.
The reason I’m asking is, I have been considering selling mysaw and buying a 16″ or 18″ model for bigger motor to increase power for resawing. If I can gain even a little extra power from a voltage switch I’ll probably keep the saw, because otherwise it’s been a good saw. Thanks for any replies on this. GP
Replies
This is the month for electrical stuff. Popular Woodworking has an article entitled, of all things, "The TRUTH about 240V." Can't wait to see the letters to the editor next month.
Anyhoo, to quote: "You won't save a dime and your motors won't be more powerful if you switch to 240V. But, if you're running multiple motors at the same time, or you're using the pre-existing wiring in your house, switching to 240V will eliminate voltage drops and stalling, as well as lengthen the life of many of your motors." [Emph. added]
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
In the Delta 2003-2004 Mini Catalog, there is no mention of the 28-475X sporting a 2 hp motor. The motor is described as "1-1/2 HP, 115/230V, 60 Hz, single phase." However, if you have the set-up to rewire for 220 with a minimum of hassle, then I would recommend it for the reasons forestgirl mentioned. I have the same saw as yours, and I recently put on a riser block and a 3/4" Timberwolf blade. While the results I'm getting are good, I think I might be taxing the limits of my saw. Also the blade leaves quite a big kerf, something I don't care for since I like to get maximum yield from a board when I'm resawing. I think I might get a 5/8" or 1/2" blade at the woodworking show this weekend.
This particular question was answered on another forum. The motor is wound such that at 240 the hp is increased. It is in the construction of the motor, not the voltage that increases the hp.
Roger
Roger, could you please provide a link, or at least the name of the forum. Inquiring mind(s) wants to know!
According to the formula: "One horsepower equal 746 watts and watts = volts x amps." Watts number always stays the same, and when the volts go up the amps go down (120 goes to 240; 18 goes down to 9). How does Delta "construct the motor" so that this equation is affected?
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Edited 11/5/2003 11:21:46 AM ET by forestgirl
FG -
Normally that's right about 120V vs 240V motors. But, if you have a long line (or small line) to the motor, then there will be additional line loss when using 120 volts. Another furmula for power (watts) is: Watts = Current(squared) X Resistance in Ohms. P = I**2 x R. (not quite right for AC and inductive loads, but close enough)
So, as the current is doubled, the power lost in the lines will be squared. That will take a little edge off of the starting and running torque of the motor. But, not generally enough to be of concern to an average woodworker.
When you convert a 240V motor to 120V, the line current will essentially double.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood
Thanks for the info, makes sense. However, it doesn't really explain Delta claiming an additional 1/2HP for a particular motor, right? forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
No, that sounds a little bogus to me. The tech manual probably was written by the sales people.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood
Planewood & FG I agree with you both on the logic of the motor power but...
Current Watts Voltage
All are important but the big issue in the motors running better is the unspoken
Resistance.
The 110 volt line (wire) can only pass so much current (think of a pipe) The bigger the pipe the more current. 2 Pipes (220 volts single phase) 2 times as much current. Of course the motor will only take as much as it can use. It is a self limiting design.
The resistance is in the building wires and in the motor windings (wires)
Motors run better on 220 because they have all the current they can use. 110 volts, unless the building is wired excessively, just doesn't have the ampacity.
Most of these discussions start with a perfect world theory. Unlimited current in the shop doesn't exist. You need to think like an electron, right from the electrical drop at the building service entrance all the way to your device.
I wire everything I can at 220 v. You should see my toaster!
PS the motor HP spec difference must be a typo unless they have separate (additional) windings in the motor. I guess it is possible but unlikely given 2 speed windings are limited to HVAC applications normally.Jack of all trades and master of none - you got a problem with that?
Well, as I understand it (as someone pointed out to me here a long time ago) most AC motors that can be rewired to run on 240V have two windings. When wired for 120V, those two windings are hooked in parallel. When wired to run on 240V those two windings are hooked in series. So, the same voltage drop is across each winding and the same current flows through each winding regardless of how it is wired. Aslo, the total winding resistance is the same and the hysterisis losses are the same.
This does bring back vague recollections from my EE classes 40 years ago. If I had worked as a power engineer I probably would remember all this stuff. But, then I probably wouldn't have developed a love for woodworking!
You ever wonder why they recommend a bigger wire for 240V operation? That's probably cause somebody will someday come along and rewire a 240V motor to 120V!
Good night all!
PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood
Booch, I don't have any doubt that 220V is the way to go, and had my sales figures been normal this summer, I'd be swimming in 220 myself. But this thread's question was very specific and straightforward -- was Delta's claim valid? Every time the general topic of 220 vs. 110 (or 230 vs. 115) comes up, volumes and volumes are written about it, strangely IMO, since it really is a fairly simple technical issue in practice. It's unfortunate that Delta would issue such a bogus specification to further muddy things up. [Correction: evidently not bogus. Didn't see Edward's post. See quote below.]
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Edited 11/6/2003 12:04:05 PM ET by forestgirl
See post 10177.7 right here on Knots. Seems it is supposed to be a special motor with different wiring for 110 vs 240.Edward
Thanks EF, here's a copy of the post which was from Howie:
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Darn! I meant to post that to "ALL" Here it is again.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
For jobsites and shakey 110, I have a couple setups:
If I can get a good 110 outlet, then a regular 12 guage plug and short cord goes into a box where it is converted to 10-3 and I have 100 feet of that which terminates in another box with a quad outlet. That 10-3 cord is about 3/4 inch thick.
If I can't find a good outlet, I wire directly to the service panel with 12 guage wire which terminates in another box with a single outlet. Plug first set up into second.
My shop was converted to 240 about 5 years ago when before I bought a spate of antique machines that had to run on 240. Before I converted, table saw and radial arm saw would blow breakers and I had motor problems. Now it is seamless. I just love 240 volt.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Interesting motor!
I've never wound one but I supply lots of devices to run them ...contactors, VFD's, and auto-transformers (generally power and control devices) in my day job.
The HVAC and rock crushing industries use what they call part winding motors to decrease inrush in getting monster motors to get up to speed. They actually goose the moter to run at slower speed with the partial winding so that the inrush is lessened. Then after it is spinning they switch to a different setup and the motor continues up to full speed. Inrush is the 6x running current that a motor pulls in the first milliseconds. Inrush causes a power lag and the resultant lag creates a power factor problem. The power factor is big to an industrial user as it can jack up their bill by 6 times what you & I pay for electricity. Multiple windings can cut that power factor problem.
I guess Delta has gotten a bit of publicity out of this. and turned out a better product. Now will it translate into more sales?
There are many ways to get metal to spin in a motor but this is the first I've heard of that type of winding in a power tool motor.Jack of all trades and master of none - you got a problem with that?
Delta has the same rating on other tools as well. The motor on the old contractors saw (prior to the X5) was rated 1.5/2.0 HP too. Haven't seen a new one yet. The detuning for 110V seems reasonable considering most home wiring is 110V, 15 amp circuits. Most 2HP motors would pull at least a steady 15 amps when you considered the power factor and require even more on startup.
JW
I re-wired my Rockwell contractors saw. The instructions were right on the motor. It made a significant difference. My saw used to blow the breaker under a heavy load, ripping 2" oak eg. Since re-wiring it is a different saw, much more powerfull, no breakers tripping. I recently overheated the motor when running 13/16" dados to ease the back of some casings. I was using a power feeder and running stock back to back for over six hours straight. The built in thermal overload kicked off the motor and I had to wait for it to cool. I slowed down my feed and it has not overloaded again. The 1 1/2hp motor would not have handled more than a few pieces without the 220 re-wire. It really snaps to attention when the switch is flipped. I feel like I have a new saw.
I re-wired my Rockwell contractors saw. The instructions were right on the motor. It made a significant difference. My saw used to blow the breaker under a heavy load, ripping 2" oak eg. Since re-wiring it is a different saw, much more powerfull, no breakers tripping. I recently overheated the motor when running 13/16" dados to ease the back of some casings. I was using a power feeder and running stock back to back for over six hours straight. The built in thermal overload kicked off the motor and I had to wait for it to cool. I slowed down my feed and it has not overloaded again. The 1 1/2hp motor would not have handled more than a few pieces without the 220 re-wire. It really snaps to attention when the switch is flipped. I feel like I have a new saw.
All of this is indicative of the fact that you were probably trying to use the saw on a 110V outlet that was woefully inadaquate for the task. 1 1/2 hp motors running on 110 draw alot of current. They need a dedicated circuit, or at least one designed to handle the load. It sounds like you were just using a pre-existing branch. The current overload blew the breaker, and the voltage drop on the inadequate wiring made it run so inefficiently that the termal overload kicked in.
Dual-voltage motors can run just as well at 110V, if they are wired to a branch circuit that can handle it. In most cases, they are not. So the owner sees a dramatic difference when they hook it up to a 220V branch, which due to the fact that the current draw is cut in half and the circuit is usually a new, dedicated one, is better able to supply the motor the power it needs.
Well said. I do have a dedicated circuit in the shop but on the job site juice can be hard to get. I up graded my cord to a 12ga but the breakers blew more quickly. Once I changed to 220 and added a plug that fits dryer and range outlets no more problems. Judging from the difference in performance I would recommend switching the couple of wires and going 220.
My 1948 Unisaw has a Delta branded replacement motor manufactured by Marathon Electric that is 1.5hp@115 volts and 2hp@230 volts.
Dave Koury
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