Motor choice for Wadkin AGS10 restoration

[Megaweasel]

Hi all,

I have a Record/ Minimax C26 universal but find I rarely use the sliding table these days, favouring my track saw for panels and Kapex for cross-cutting duties and i rarely use the Spindle moulder. I’d like a planer with a (quiet) helical cutter rather than the straight Tersa blades so started thinking about a change to a small table saw and a stand-alone planner/thickneser.

At least that was my logical reasoning - really, i think I just wanted an excuse to buy an ancient table saw as a restoration project - hence after watching a few on eBay and a good bit of negotiation and van hire, I have a nice Wadkin Bursgreen AGS 10 (or possibly AGS250) table saw of I think 1977 vintage.

looks terrible at the moment but its actually in pretty good nick - its complete, no cracks in the cast iron, no missing teeth, rise-and-fall works nicely, tilt works nicely, tops looks great, so all good. Had a large custom dust chute fitted (see pic) which I hope to remove and replace with something a bit more ‘modern’ around the blade.

Anyway, initially what I need to do is get a motor and fire it up. It came with a 2 hp, 2800 rpm 3 phase motor which seems to be of the same vintage as the saw (Newman). It’s 400V and not capable of being configured to Delta - at least not without stripping and doing scary wiring mods that I really don’t want to try myself.

So I need a motor and I’ve spent a good many hours researching and reading up on VFD’s etc. I get it for adapting a drill press or lathe to add variable speed and perhaps DC braking for rapid deceleration but given I’ve got to buy something, are there any real reasons why investing in a Delta 3-phase 240 v motor and VFD would be a better idea than buying a new single-phase motor?

I can get a ‘period’ 3-phase that will work for around 100 quid, or a new one for perhaps 150 quid. VFDs (Chinese) seem to be around 80 quid or so - so £180 to £230 or so for the VFD - then it needs mounting and wiring to use stop/start and emergency stop.

Lots of options for single phase motors - period one that looks nice or a new one. Simple to use and wire with a new NVR.

So - bit long and windy, but any reasons to go VFD for a table saw resto when buying from scratch?

 

[SkinnyB]

It's been a while since I was in the market for a VFD but would something like this work with your current motor?
220 single phase in 380v three phase out.

 

[deema]

For resale value I’d swap the motor for single phase with new starter. A 2.2KW motor is a good fit. Needs new mounting holes drilling. You will need a new pulley, but they are a jelly bean part and easy to get from almost everywhere. You want cap start cap run, two separate capacitors. TEC do good motors.

 

[Megaweasel]

@SkinnyB - thanks for that, didn't realise you could get a VFD with a 380V output. Means I could try with the current motor - although just the VFD is still more than a single phase motor.

@deema - also thanks - really looking to see if there is any point, other than financial, in the VFD rather than single phase. I'm thinking (much as I like a gadget and a bit of tinkering) that I don't need variable speed or reverse, and it probably isn't that slow to stop so single phase is the way to go. I can see a few cheeper TEC motors that fit the bill on eBay right now.

On pulleys, The Wadkin has a triple belt pulley and three separate belts - given I've got to replace one one the pulleys anyway, would there be any value in replacing the triple belt setup with a single wide ribbed ploy V belt? I saw someone had done that to a unisaw somewhere and wondered if it might run better that way?

 

[Fitzroy]

I'm currently contemplating a motor upgrade on my bandsaw, currently its a 3P 750kw motor with a VFD. The only reason I can think of to switch to a higher powered three phase and VFD rather than a single phase is that it will mean less wiring changes as the current on/off and door interlocks are set up for feeding signals to the VFD. So to answer your question, no I can't see a reason to go for a 3P motor and VFD rather than a 1P motor.

You will also have to change the switch gear out in either case.

The VFD 240-380 linked is another option, but one thing to consider is where you mount the VFD, it will need some form of protection from all the dust, so ideally in an enclosure/box of some sort, bought ones are also not cheap £50+

F.

 

[Megaweasel]

@Fitzroy - yup, mounting the VFD is another whole thing. Mounting it on wall gets it out of the way, but it means I need to run multiple cables to the saw - one for the power and another for the control. Mounting it on saw means its in the way or in the dust. Given I want to add 'proper' dust collection, I might be able to mount it in t he cabinet bottom in a shielded and vented box, but seems a lot of work. I'm edging towards the single phase motor now...

 

[Spectric]

If a single phase motor can deliver the power you need then there is no need for a three phase motor. The only way to use a more powerful three phase motor is if you use a digital phase convertor , with invertors you may get the variable speed but no more power than a single phase motor.

 

[Ttrees]

Anyway, initially what I need to do is get a motor and fire it up. It came with a 2 hp, 2800 rpm 3 phase motor which seems to be of the same vintage as the saw (Newman). It’s 400V and not capable of being configured to Delta - at least not without stripping and doing scary wiring mods that I really don’t want to try myself.

Have you taken the cover off to see if it were "fixed star wound" for sure...
There might even be a diagram on the underside of the lid.

If so, beware of what VFD/inverter you might actually get, even if dimensions are given.
Some are little bigger than the panel, and being passed off as the regular ones you may have seen.

Make sure you either match the 2hp rating, or if choosing to go bigger for future possibilities
then get one which can "de-rate" motors...
i.e which have the parameters for amperage and kW rating.


I won't get into what to look for if needing "emergency stop" but suggest you skip through a video regarding the "huanyang, dynamic braking"

That should be enough to mention should it turn out to be a dual voltage motor.

All the best
Tom

 

[Myfordman]

About the only advantage of vfd & 3 phase motor is to get controlled braking of the saw and bear in mind not all inverters support the necessary braking resistor needed to absorb the energy stored in a high inertia machines such older table saws and planers when braking.

A 2hp single phase ( 2 pole especially) can be on the border line of popping 13amp fuses on start up and you might need a 16amp radial supply installing. This can be a diy job in a one man private shop but your post suggests you are not confident with electrics(?).

either sort of motor unless and older type will possibly need either the shaft or the pulley machining to fit. Easy enough if you have the tooling and skills or you might find a suitable combination of taper lock pulleys to match shaft to required pulley size. Mounting feet holes might well be in a different place to your current motor and different frame sizes might need different belt sizes.

 

[Inspector]

The one upside, not mentioned so far to using a VFD, is that you can program them for a slow start over a few seconds. That eliminates the starting surge that the single phase motor has. Good for a shop without a lot of excess power.

Pete

 

[deema]

For that saw you definitely do not need variable speed. On any circular saw reverse would be really dangerous, so best avoided.
The triple belt arrangement is more than adequate for the power transfer. People like machines as original as possible when it comes to moving it on.
A 90L frame size motor works well, same pulley size and belt length, ie no faffing around. Take a gander at the Wadkin BGS restoration Sideways and I did, it’s the same saw with a few extras.

 

[Megaweasel]

@deema - I’ll definitely check that out. Read through a few of the AGS threads but didn’t realise the BGS is similar so that’s great. I’ll keep it simple and go single phase and sort out my he pulley as a start.

@Myfordman - pretty good with electrics and did fit a 16amp spur for my extractor. Really not 100% on the whole vfd thing yet though. I’m not going to bother for the AGS but I think I will have a dabble for my pilar drill later as changing belts is a real faff.

Thanks all - I’ll post some progress when I’ve got it going.

 

[Spectric]

Don't forget that VFD's can induce extra stress into a motor and if you run them too slow you also risk overheating them, when we fitted VFD's to motors we knew would be run at slow speeds we replaced the std motor fan and cowl with an electric fan to keep the air moving.

Make sure you either match the 2hp rating,

To size a VFD for running a three phase from single take the motor FLA and double it, that is the current you need the VFD to supply.

 

[Megaweasel]

I’ve bitten the bullet and ordered a 2hp single phase motor - I think it will be the quickest way to get this at least tested before the full restoration starts.

Great to have so many knowledgable Wadkin people on the Forum! - Only thing I’m missing at the moment is a nice Wadkin Bursgreen badge for the saw - Anyone got one or know where to get one for a 70’s AGS?

 

[Ttrees]

Don't forget that VFD's can induce extra stress into a motor and if you run them too slow you also risk overheating them, when we fitted VFD's to motors we knew would be run at slow speeds we replaced the std motor fan and cowl with an electric fan to keep the air moving.


To size a VFD for running a three phase from single take the motor FLA and double it, that is the current you need the VFD to supply.

I nearly got a scolding for suggesting so...
Care to confuse me a little on things?
(not trying to be confrontational or a smart alec)

I presume there's just some wires crossed here, likely related to the cheapies,
and not say (at a guess) Hitachi units, or at least on their premium line.

My comment refereed to de-rating a 5hp motor to 3hp for a 640mm wheeled bandsaw, to temporary run from the household 13a supply, with some consideration of resistance, so
for short amounts of time, and with no extraction.

It was kinda of question of sorts in itself.
Cheers
Tom

 

[Spectric]

Hi there

The basics of an invertor in very simple terms is to rectify the Ac to Dc and then using electronics to switch a bridge driver to deliver the Ac outputs at 120° phase shifts.

With a three phase supply and VFD each of the three lines delivers an equal portion of the power to the load.

With just a single phase supply it has to deliver power for all the three lines, so the input rectifier and capacitors will see 1.7 times more current and so if the three phase motor states a FLA of say 10 amps then a three phase VFD rated at 10 amps will be ok. But if you are using a single phase to three phase invertor the single phase needs to deliver 1.7 times the required output current of 10 amps so you just use one rated at 20 amps and you know the components can handle the total required current. As for the supply to the VFD that needs to be 20 amps and not the motors FLA. There are other parameters that also have an effect such as harmonics and is why you cannot use invertors for motors bigger than 4Kw. If you really want three phase then look at digital convertors, these are only limited by how much power your distribution system can provide.

 

[Spectric]

This may also help

1 = 400 volts

 

[Ttrees]

I reckon you and me are on differing wave lengths though.
Both my 24" bandsaw and 12" tablesaw will run just fine off the 13a plug, both 3hp motors with generous ramp up times (without extraction nor anything else plugged in)
My bandsaw running with a decent blade uses about the same juice as me old laptop,
perhaps I should get herself to film the smart meter on her phone...
whilst I actually use the tablesaw instead?
i.e no momentum like cast iron wheels to help matters, (a similar saw to mine, the SNAC 540 only has a 1.5kW motor on some.)

For how long things could run at max capacity for, I wouldn't wish to find out,
I keep an eye, or should I say feel of the cable for prolonged use, which admiddly wouldn't be much more than a half hour session with the tablesaw.

I suspect you are referring to normal industrial usage of any machine, or perhaps something like a pillar drill or lathe which might bog down at slow speeds.
I think I've heard folks talking about vector drives before, and pot shot guessing these are for motors which might have greater chance of stalling?

Tom

 

[Matt@Nearfield]

For my saw, I'm going fir a new 3phase inverter rated motor with an inverter. No problems with variable speeds and can be wound up yo 70/80hz... that's giving you a tip speed on a 12in blade that you wouldn't normally achieve till you were running a honking 450mm blade..

 

[Inspector]

No offence intended and I hate to take the thread off track but what the hello are you cutting that you need the saw wound up that much?

Pete