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changing over a 3ph saw

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Forum topic by Duffman posted 08-02-2015 02:13 AM 1370 views 0 times favorited 34 replies Add to Favorites Watch
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Duffman

61 posts in 793 days


08-02-2015 02:13 AM

hey guys,
If i were to buy a 3ph table saw, how easy is it to change over to a single phase saw, if I already have a single phase motor? Is it as easy as unbolting one motor and bolting in the new one, or is it more complicated than that?

-- I'm not addicted to buying tools or wood... I can stop any time I want!


34 replies so far

View Nubsnstubs's profile

Nubsnstubs

826 posts in 1194 days


#1 posted 08-02-2015 03:14 AM

If the motor mounts are the same, yes, it’s just about that simple. You would need to change the switch also. If the wiring is good, just use two hots and the ground for 220 volts, or one hot, a neutral and ground for 110. . Make sure you use the same colors at each end…...... Jerry (in Tucson)

-- Jerry (in Tucson)

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TheFridge

5765 posts in 950 days


#2 posted 08-02-2015 03:27 AM

Has to be same frame size. If it is, it’s pretty easy. Mechanically. Electrically, it’s a little bit more involved.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Fred Hargis's profile

Fred Hargis

3942 posts in 1958 days


#3 posted 08-02-2015 01:13 PM

Make sure the new motor is turning in the proper direction. Some of them are reversible, and it might be going the wrong way.

-- Our village hasn't lost it's idiot, he was elected to congress.

View MrUnix's profile

MrUnix

4226 posts in 1663 days


#4 posted 08-02-2015 04:15 PM

Is it as easy as unbolting one motor and bolting in the new one

99% of the time, no. The frame (in particular, the size of the motor and the mounting plate) needs to be the same or you will have to do some modifications as to how you mount it. The shaft size needs to be the same if you want to use the old motor pulley, otherwise you will need to find a new pulley with the same outside diameter and the proper bore size for the new motor (or get a new arbor pulley to compensate). The speed (RPM) of the motor needs to be the same, or you might have to do some creative pulley swaps to get it back to spec (which may or may not even be possible). The rotation direction needs to be the same or the new motor will need to have the ability to reverse direction. The new motors HP needs to be roughly the same, or at least not exceeding the manufacturers max HP recommendation. The existing 3-phase starter most likely will also need to be replaced/modified to use for single phase, and the heaters usually will need to be replaced to match the new motor. Some starters can be used for both, some can’t.

For most situations, it’s usually easier (and cheaper) to just run it with the existing 3-phase motor… either with a VFD or a static phase converter. For larger (3hp+) motors, it becomes a crap shoot as you will need an RPC which may or may not be more expensive than a new motor. Also, a 3-phase motor is much more efficient and reliable, and if coupled with a VFD, can give you extra features not possible with a single phase one.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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Duffman

61 posts in 793 days


#5 posted 08-02-2015 06:00 PM

wow brad, thats a lot of info, thanks. the table saw that I am looking at is a PM66 the person selling it has the 3ph motor currently installed with a 1ph baldor motor that he is including with the table saw. I guess I will have a few questions to ask him, thanks
-Ryan

-- I'm not addicted to buying tools or wood... I can stop any time I want!

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MrUnix

4226 posts in 1663 days


#6 posted 08-02-2015 06:07 PM

Unless the Baldor is a significant upgrade in HP and as long as the existing motor is 3HP or less, tell them to keep the Baldor and knock $100 off the price. You can pick up a VFD for that motor for under $200, and can sell the 3 phase starter (not needed with a VFD) to make up the difference.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View bonesbr549's profile

bonesbr549

1176 posts in 2531 days


#7 posted 08-03-2015 12:07 AM



Unless the Baldor is a significant upgrade in HP and as long as the existing motor is 3HP or less, tell them to keep the Baldor and knock $100 off the price. You can pick up a VFD for that motor for under $200, and can sell the 3 phase starter (not needed with a VFD) to make up the difference.

Cheers,
Brad

- MrUnix

+1 on what he said!

-- Sooner or later Liberals run out of other people's money.

View Duffman's profile

Duffman

61 posts in 793 days


#8 posted 08-03-2015 12:08 AM

ok a little more info…
both motors are 5HP and have the same size shaft, and both spin the same way, is it worth the buy

-- I'm not addicted to buying tools or wood... I can stop any time I want!

View 01ntrain's profile

01ntrain

146 posts in 535 days


#9 posted 08-03-2015 02:51 AM



ok a little more info…
both motors are 5HP and have the same size shaft, and both spin the same way, is it worth the buy

- Duffman

Like MrUnix mentioned, anything over 3hp can’t be used with a VFD, so I would say go with it. Tell him to knock some money off and keep the 3ph stuff. Or buy it all, change it over to 1ph and sell the surplus motor/starter. Can’t say that I’ve ever seen a 5hp motor in 1ph for a saw…. that’s gotta be a pretty big motor.

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Duffman

61 posts in 793 days


#10 posted 08-03-2015 03:51 AM

...Can t say that I ve ever seen a 5hp motor in 1ph for a saw…. that s gotta be a pretty big motor.

- 01ntrain

Powermatic has made 5hp 1ph saws for a while, you can currently get them in the PM2000 model, I believe they are about $3700 or so with 30in rails. SawStop makes one as well for around $4300.

-- I'm not addicted to buying tools or wood... I can stop any time I want!

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Duffman

61 posts in 793 days


#11 posted 08-03-2015 04:01 AM

@01ntrain, if I end up getting it, I’ll post some pics

-Ryan

-- I'm not addicted to buying tools or wood... I can stop any time I want!

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01ntrain

146 posts in 535 days


#12 posted 08-03-2015 04:20 AM

What is the guy asking for the saw?

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MrUnix

4226 posts in 1663 days


#13 posted 08-03-2015 04:21 AM

Sounds like you might get lucky and the motor was obtained specifically to replace the 3-phase one, but never installed. If the mount is the same, then all you would need to worry about is the electrics, which would be much cheaper than trying to find an RPC for it.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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Duffman

61 posts in 793 days


#14 posted 08-03-2015 02:44 PM

@01ntrain – the guy wants $525 for the saw

@MrUnix – He did buy the baldor 1ph motor to replace the 3ph motor. He bought the saw from a defunct cabinet shop.

-- I'm not addicted to buying tools or wood... I can stop any time I want!

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01ntrain

146 posts in 535 days


#15 posted 08-03-2015 03:35 PM



@01ntrain – the guy wants $525 for the saw

@MrUnix – He did buy the baldor 1ph motor to replace the 3ph motor. He bought the saw from a defunct cabinet shop.

- Duffman

For that price, I think you’re getting a great deal no matter which direction you decide to go.

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