Advice required!

[stee369]

Hello all,

I have been given an old bench saw, with four blades. It currently has a 5HP 3 phase motor.

I have been given contradictory advice regarding the possibility of changing to a single phase motor. I understand that you can get a converter. However, I could probably get a single phase saw for similar money.

I would apppreciate any advice regarding the details of a suitable motor size if a swap is possible.

 

[Newbie_Neil]

Hi Stee369

Welcome to the forum.

Sorry I can't help with your question, it might be helpful to know the make and model.

Cheers
Neil

 

[stee369]

Hi Neil,
Thanks for reply, Not sure if this will help?

Make - Cuilliet & Fils Auxerre France ( Brevete SGBG )

Brook motor. Ref R11. B422733
5 HP
Full load speed 1440
Full load amps 7.4

It may well be that this saw isn't practicle for general use, due to size and age. However, we have an oak barn with permission to refurbish and it could be very usefull, if viable.

Regards
Steve

 

[beech1948]

Hi,
You could leave it as a 3phase machine and use a Phase (voltage) converter from single phase to 3 phase.

A Phase (voltage) converter comes as a static and rotary converter. Static are cheaper but less flexible. Rotary often combines speed control.

If you search ebay you will find a number for sale. You would need one able to cope with 5 HP. Check costs as ebay might be cheaper but costs of auctions vary.

Many companies and individuals successfully run their machines off a phase converter.

regards
alan

 

[Scott]

Dunno anything about phase converters but welcome to the forum anyway Steve

 

[Scrit]

Hi Stee

The maker is Guillet & Fils, a company which I believe still exists today. They are a very old firm indeed.

With a 1440rpm motor I'm betting this saw has a large diameter blade (18in plus?) and that the motor drives the blade directly, i.e. there is no arbor for the saw with a belt and pulley to the motor. If that is the case then a motor swap will be all but impossible. That leaves you with the option of buying or building a three phase converter. Fundamentally a converter comprises a single phase motor at one end of a shaft which is connected to the mains and when the power is switcged on that drives a three phase motor, which generates 3-phase electric current. The only problem is that the starting load of older motors can be quite high.

The other possibility is that this might be an earlier machine converted from flat belt drive in which case conversion just takes a motor swap.

If you could post a couple of pictures maybe I could identify the period and give you a better idea of what would be involved in getting it to run from single phase

Scrit

 

[shockingmoment]

Check the motor. If its a dual voltage motor you may be able to fit a single phase to three phase variable frequency inverter.

These are intended for speed control of three phase motors but can be used for what you want. Fixed speed at 50Hz. I've fitted one to my sedgwick morticer.

If its dual voltage, the motor will have a label which will say 240 / 415 VAC if its dual voltage. If so - what you need to do is (in simple terms):

Change the links in the motor from star to delta
Swap the contactor out for a 240V AC version 16A at least.
Obtain and fit the inverter (ebay)
Make sure you have at least a 16A 240VA supply. On full load the unit will pull 20A on 240VAC but if you don't intend to work it that hard you'll be ok.
Configure the inverter - autostart on power up, single speed (50hz), flc (20A) acceleration (10s)

Even if you fit a rotary converter you'll still need a big supply - 20A plus - as there are more losses in this kind of set up.

Inverter will give a nice soft start, running the blade up to speed smoothly.

Its straightforward if! you know what you're doing!!!!!!!! There's a surprise!
You'll be looking at £200 to £300+ though for all the bits (Inverter, contactor etc etc).

If you're unsure - you'll need an electrician. Not a house basher type though - someone who's familiar with 3 phase.

If you want any more info - PM me.

SM

 

[stee369]

Thankyou for the detailed information, it,s much appreciated.
As a matter of interest, one of the blades is around 18", and is driven directly via 3 x v belts.

Regards

Steve

 

[Scrit]

Sounds like it could be a non-tilting rip saw, possibly 5 to 6in depth of cut? Either way I tjhink you'll find motor swaps are probably out.

Scrit