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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.
 

frank horton

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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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