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Startrite 352s bandsaw phase conversion 3 phase to single help

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RC23

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Hi All,

I am completely new to this forum, so apologies if I have posted in the wrong section!

First came across the forum searching for some advice and after reading some of the threads quickly realised that everyone on here really knows their stuff and it is packed with useful information and great ideas!

Setting up my own small workshop in my shed and recently acquired a startrite 352s bandsaw from my wife’s school. It’s in great condition, has the built in lamp and the school site team even delivered it!

The only issue is it is three phase, and I only have a 240v domestic supply. After reading some of the threads on here, I thought a converter would be best, so I contacted Transwave, who were very helpful. After sending some photos they said that I would need a rotary converter as my motor is two speed. They quoted me £795. Unfortunately this is a bit out my price range (I know they are an investment but I am not planning to get any other 3 phase machines in future.)

I got in touch with ALT Spares, who were very helpful, sent me the manual and for half the price sold me the correct sized bore single phase 1hp motor (less power then before), new overload and new contactor. They said that the two transformers (the one in the base is for the lamp apparently) I already have are dual voltage and can be rewired from 415 to 220v easily.

Now this is where I am after some help/advice if anyone can. The manual is pretty rubbish and I am by no means a confident qualified electrician. But I can rewire a lamp and wire my DC train layout no problems.

I’m trying to reuse as much wiring as I can, namely as it is quicker and simpler. Plus if I do need to rewire then I know that is beyond me and I will need to get in an electrician. Something I will need to save for, so if I can do it myself then I will, but if I can’t then I won’t.....

Rewiring the transformers looks simple - I am guessing i just move the one wire from 415v to 220 on both.

I’m guessing for the new overload and contactor It’s just a straight swap and wiring is like for like.

Unbolting the old motor and attaching the new motor looks simple enough, I know they both have the same sized bore so I do not have to worry about pulley sizes etc.

I’m hoping the original armoured power cable I can reuse as well, it’s in really good condition, I am hoping I can ignore the fourth black wire and put a normal three pin plug on the end (using the blue, brown and earth wire)

Re-wiring the New motor has me stumped. I removed the top cover of the old motor control box and the cable that enters from the Main control housing on the bandsaw has 7 wires. Six black and one earth wire. I am not sure that I can even connect so many wires to the new single phase motor let alone the order in which to do so.

Can anyone point me in the right direction? I appreciate any help.
Thanks in advance.
 

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SteveW1000

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I've not worked with two speed 3 phase motors so take my advice as you see fit. 3 phase motors usually have 3 wires going to them from the control gear so I presume as it was two speed thats where the 6 wire come into the situation. What you need to do is pick 2 of the black wire for the motor wiring use a meter to find the two ends of each wire which you want to use, you could cut the other back so they don't cause a short but better to tape the ends. Should be a simple exercise after that. My older 352 is also ex school and 3 phase run off a phase converter. Good luck with the conversion and come back if you need more help.
 

clogs

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I converted a Wadkin panel saw for somebody....3phase to single phase....ripped everything out and supplied new wiring and a No Volt stop start contactor....
all realy straight forward.....
the DC transformer should be no problem but if u are worried disconnect it and use 12v charger similar to a phone charger (straight plug in from a mains socket ) can be used...
Ikea sells a range of flexi lamps if ur worried......
 

Andy RV

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Another option is to fit a digital inverter, I’d imagine that your motor is dual voltage so you’ll be able to run it on 240v three phase. A suitable inverter will be approx. £100 - £150 and will provide variable speed.

Can you post a picture of the motor data on plate? It may say 240 Delta / 415v Star
 

Myfordman

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The original motor is almost certainly Dahlander connected pole switching motor generally thought to be unsuitable for inverters but im not 100% convinced.
The op has bought a single phase motor and control gear so the obvious approach is ti rip out the existint switchgear as it is redundant and just wire up the new motor and dol starter in the standard way. the starter will quite likely have a diagram inside. the transformers need to be wired from the 415 tap to the 220/240 tap. it is that simple.
 

RC23

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I've not worked with two speed 3 phase motors so take my advice as you see fit. 3 phase motors usually have 3 wires going to them from the control gear so I presume as it was two speed thats where the 6 wire come into the situation. What you need to do is pick 2 of the black wire for the motor wiring use a meter to find the two ends of each wire which you want to use, you could cut the other back so they don't cause a short but better to tape the ends. Should be a simple exercise after that. My older 352 is also ex school and 3 phase run off a phase converter. Good luck with the conversion and come back if you need more help.
I think your right Steve, looking at the diagram inside the motor housing it looks like there is 2 x L1s L2s and L3s. Guess the speed switch on the front switches from one set to the other.
 

RC23

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I converted a Wadkin panel saw for somebody....3phase to single phase....ripped everything out and supplied new wiring and a No Volt stop start contactor....
all realy straight forward.....
the DC transformer should be no problem but if u are worried disconnect it and use 12v charger similar to a phone charger (straight plug in from a mains socket ) can be used...
Ikea sells a range of flexi lamps if ur worried......
Hi Frank, it is tempting but I have all the bits, plus if both my transformers are dual voltage and there is nothing wrong with them then I prefer to reuse them. Plus with a no volt switch - if I am right on this after reading other forums - there is no overload protection for the motor.
 

RC23

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Another option is to fit a digital inverter, I’d imagine that your motor is dual voltage so you’ll be able to run it on 240v three phase. A suitable inverter will be approx. £100 - £150 and will provide variable speed.

Can you post a picture of the motor data on plate? It may say 240 Delta / 415v Star
This was my initial thought, and I nearly bought one from Transwave, however I thought I would ask them first if it was suitable, they said an inverter is not an option and rotary would be my only option.
Alt spares mentioned that the motor was specifically built and designed for the 352s. Have attached some more pictures
 

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RC23

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The original motor is almost certainly Dahlander connected pole switching motor generally thought to be unsuitable for inverters but im not 100% convinced.
The op has bought a single phase motor and control gear so the obvious approach is ti rip out the existint switchgear as it is redundant and just wire up the new motor and dol starter in the standard way. the starter will quite likely have a diagram inside. the transformers need to be wired from the 415 tap to the 220/240 tap. it is that simple.
I think this is my best bet to be honest, but I am a bit stuck with this, the New motor has the attached diagram inside the box housing. The instruction sheet that came with the motor is poor and only one sheet. I am unsure if I can reuse the original wires or whether I have to rip it all out.
 

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Geoffo

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Hi All,

I am completely new to this forum, so apologies if I have posted in the wrong section!

First came across the forum searching for some advice and after reading some of the threads quickly realised that everyone on here really knows their stuff and it is packed with useful information and great ideas!

Setting up my own small workshop in my shed and recently acquired a startrite 352s bandsaw from my wife’s school. It’s in great condition, has the built in lamp and the school site team even delivered it!

The only issue is it is three phase, and I only have a 240v domestic supply. After reading some of the threads on here, I thought a converter would be best, so I contacted Transwave, who were very helpful. After sending some photos they said that I would need a rotary converter as my motor is two speed. They quoted me £795. Unfortunately this is a bit out my price range (I know they are an investment but I am not planning to get any other 3 phase machines in future.)

I got in touch with ALT Spares, who were very helpful, sent me the manual and for half the price sold me the correct sized bore single phase 1hp motor (less power then before), new overload and new contactor. They said that the two transformers (the one in the base is for the lamp apparently) I already have are dual voltage and can be rewired from 415 to 220v easily.

Now this is where I am after some help/advice if anyone can. The manual is pretty rubbish and I am by no means a confident qualified electrician. But I can rewire a lamp and wire my DC train layout no problems.

I’m trying to reuse as much wiring as I can, namely as it is quicker and simpler. Plus if I do need to rewire then I know that is beyond me and I will need to get in an electrician. Something I will need to save for, so if I can do it myself then I will, but if I can’t then I won’t.....

Rewiring the transformers looks simple - I am guessing i just move the one wire from 415v to 220 on both.

I’m guessing for the new overload and contactor It’s just a straight swap and wiring is like for like.

Unbolting the old motor and attaching the new motor looks simple enough, I know they both have the same sized bore so I do not have to worry about pulley sizes etc.

I’m hoping the original armoured power cable I can reuse as well, it’s in really good condition, I am hoping I can ignore the fourth black wire and put a normal three pin plug on the end (using the blue, brown and earth wire)

Re-wiring the New motor has me stumped. I removed the top cover of the old motor control box and the cable that enters from the Main control housing on the bandsaw has 7 wires. Six black and one earth wire. I am not sure that I can even connect so many wires to the new single phase motor let alone the order in which to do so.

Can anyone point me in the right direction? I appreciate any help.
Thanks in advance.
Hi I have a saw exactly the same 352s 3 phase same motor ID on as the one you showed in photos and only have 240 in my workshop did you get it sorted out. Could you please let me know what and how you did it it would be much appreciated. Forgot to mention the is my first time on here just joined up today thanks
 

Ttrees

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Hello and welcome to the forum Geoffo
I suggest you look at Bob's, AKA Myfordman's induction motor document which is the best resource
you will find on the matter.
If this doesn't work, I suggest you seek it out at "the other place"



Plenty of VFD/inverter documentation on this forum also, which might be a bit more digestible, and will correspond and make sense of everything should you be unsure of everything.

Maybe some keywords for you might be ...VFD, Inverter, Dual voltage motor, 240v delta.
Plenty of juicy posts, quite a few with Startrite 275/tilt arbor tablesaws.

Tom
 

Spectric

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Firstly as this is not your day job I would remove all the old wiring and fit the new motor first, will save a lot of confusion. Then logically wire as per diagrams. Did the supplier of the motor tell you it will still be two speed?

The diagram within the new motor shows how to wire the motor for either clockwise or anti-clockwise rotation, so you wire to one OR the other. It is currently wired for anti-clockwise rotation according to your picture. In either case you will have two wires that need to be supplied 230 volts from the starter switch, but this is only single speed. The previous diagram shows the three phase wiring with star configuration for high speed and the low speed diagram which is delta does not show the links but this is irrelevant as you are wiring the new single phase motor.
 

Ttrees

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Oh my bad I thought this machine stated it had a dual voltage 240 delta motor .
I see it is stamped 400v delta, but nothing stated for the star.
Could one assume this might be a dual voltage motor, and is fixed in star...
Leading one to dig out the windings to convert to dual voltage?

Tom
 

Spectric

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The guy has purchased the motor and starter, it is just a wiring issue but with questions hanging over the dual speed aspect. If only going to be used for wood then single fast speed will be ok.
 

Fitzroy

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This thread is from a year ago, it was bumped by another post asking if they got it resolved. Wire crossed folks!
 

Geoffo

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Firstly as this is not your day job I would remove all the old wiring and fit the new motor first, will save a lot of confusion. Then logically wire as per diagrams. Did the supplier of the motor tell you it will still be two speed?

The diagram within the new motor shows how to wire the motor for either clockwise or anti-clockwise rotation, so you wire to one OR the other. It is currently wired for anti-clockwise rotation according to your picture. In either case you will have two wires that need to be supplied 230 volts from the starter switch, but this is only single speed. The previous diagram shows the three phase wiring with star configuration for high speed and the low speed diagram which is delta does not show the links but this is irrelevant as you are wiring the new single phase motor.
Hi thanks for your reply I have not bought a new motor yet I don’t know anything about delta or star. I have tried a static converter I have had several electrical friends here with testing equipment the converter was up to 2 and a half hp no good. It worked perfect where I bought it two speeds great I phoned a company up for a price on a vfd the guy said it would not work that I need to spend several hundred pounds. I do a bit of all kinds of cutting just want to know what motor to buy and speed controller or what vfd I have had the saw since January this year. Thanks for your time. Geoff
 

RC23

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Hi Geoffo,
Yes I did manage to get it sorted. Works a treat now. Single speed 1hp but more than adequate for woodwork.
It did require a motor swap, new contactor and overload to be fitted. Luckily the 24v transformer for the lamp was dual voltage so just needed the wires moved from 415 to 240.
I got the parts from Alt saws and spares plus the wiring diagram.
It was not cheap for the parts, and unfortunately the original motor cannot be converted - something about it being a custom made motor for that specific model.
I was fortunate that the bandsaw only cost £100 (my wife’s best friend is a resistant materials teacher) so to spend £350-£400 to convert it was still more than worth it. It is a very good bandsaw.
Most of the wiring had to come out, I posted an job on checkertrade asking for an electrician to help. Most said no but I had one chap who called me and said his retired electrician father would love to help. In all lovely elderly chap took him a couple of hours and he charged me £30 not forgetting a cup of tea, tried to give him more but said he loves tinkering with old machinery.
Hope this helps 👍
 

Spectric

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Either way you will need another motor, the two speed three phase motor you have is great if you have a three phase supply or can run a digital phase convertor but otherwise forget it, I believe in the day they were called pole changing motors because that is how they delivered the two speeds. The easiest solution is to fit a single phase motor but you will not get the two speeds, if you fit a 230 volt / 400 volt three phase motor then you could run it from an invertor and get variable speed but a decent invertor is going to be several hundred pounds unless you gamble on a cheap asian job which I would never recomend and have never used as the end results can be dramatic. Something like this is what I would advise if you go this route, ABB ACS150 2.2kW 230V 1ph to 3ph AC Inverter Drive, DBr, C3 EMC - AC Inverter Drives (230V)

The invertor has to be able to supply the full load amps of the load and therefore needs to be larger than just matching the motor, for those electrically minded think of 1.73 and the supply for the invertor must meet that of the invertor and not the motor.

So do you really need the two speeds, and would you want to cut both metal and wood on the same saw? I worked for a company that in their metal fab area had two sections each with a bandsaw that they cut pipe and tube on, as well as other equipment and one was ferrous and the other for stainless just to prevent contamination, amazing lengths you can have to go to to meet a standard.
 

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So for a single phase replacement, a 2 pole 2840-3000RPM, TEFC
motor with suitable shaft which fits the pulley, seems like it might be one choice?

Can we see the mounting, as it could be foot, face or flange mounted, should one want an quicker or less bothersome installation.

On the other hand if Geoffo wants to retain the function for cutting differing materials...
and sees some dual voltage motors going cheap...
Which pole motor should be used, from what I've seen on different machines, a 4 pole slower motor seems the choice for most things not a fixed speed.

Whats the issue if one chose to run a 4 pole motor (around half the speed of 2 pole)
with an inverter at 100hz?

Is there some torque issues at double the rated speed of the motor?
Is this an application for having a fancier vector drive?

Thanks
Tom
 
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