Anyone had any experience of dropping a new single phase motor into
something like the old 10" Wadkin I've been offered for notalot?
It seems like too good an offer to pass up, but I'm concerned that
there'll be more to the three-phase to single phase conversion than
simply exchanging the motor. I guess there's all the switches etc to
consider as well.
I've done a little research on the Net into phase converters but it
seems a bit like overkill buying an inverter for just the one piece of
kit. And they're not cheap either...
No experience of the Wadkin, but I did a similar job on an old Metalclad 10"
some time ago.
You'll need the new motor and a new starter box (the "switches"). The
outfit that supplies the motor will usually supply the correctly rated
starter for it.
Things you need to take into account:
Motor output power. You'd need at least 1HP for a 10" machine. 2HP would
be better, assuming your shop electrics would handle the load, as it would
allow you to take heavier cuts on the full width.
Output shaft dia and length. Some old machines like the Metalclad had the
motor installed inside the body of the machine, with the output shaft
running through the side of the machine. The pulleys for the motor shaft
and cutterhead and, obviously, the drive belt, were on the outside of the
machine, covered by an easily-removed guard cover. This arrangement meant
that it was fairly quick and easy to get at the belt, but - and this was the
sticking point - it also meant that the motor needed a 6" long shaft. Most
of the cheapish Chiwanese motors from places like Clarkes/Machine Mart were
less than 4". I ended up getting the base machinist to make me up an output
shaft extension with a keyed sleeve to join it to the new motor shaft.
You also need to consider the dia of the shaft and the keying arrangements
for the pulley. If you're in the UK, the chances are that your old pulley
will be an imperial size and the new motor metric, in which case you might
need to consider a new pulley as well. Places like Machine Mart will also
supply a range of pulleys. Choose the one with the closest external
You also might need a forklift to handle the machine!
It's a worthwhile investment, I'd say - the old Wadkin machines were built
like tanks, spares bearings etc are still available, so it'll probably
outlast the both of us.
Best of luck, enjoy your machine.
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Not familiar with the 10" Watkins. If you can change to a single phase
motor without much hassle, that would be the way to go. If the motor is
a specialty motor, built to fit the machine, it doesn't cost much to
wire in an old three phase motor to use as an idler. You can spend a
little more for caps to equalize the phases and a start circuit. Some
folks use a lawn mower type rope start. Gets the job done. Costs
p.s. I've done this stuff a little so I'm not just repeating something
I've been told, read somewhere. I've started a three phase idler by
standing on the idler motor and spinning a pulley on its shaft with a
rubber soled shoe.
You can build a static phase converter for about $10 worth of parts.
Will provide about 70% of the HP of the motor. Do a Google search
on "static phase converter" and you will find a coule of sites that tell you
the capacitor values needed.
On 11 Oct 2004 11:28:29 -0700, firstname.lastname@example.org (oddjobboy)
A 10 AGS ?
I've got one of these.
Long before I got it, someone had converted it to single phase. The
(retired) guy I bought it from had a fairly large home workshop,
filled with tools from his past commercial workshop. This was the only
machien that was vaguely usable, as he was using a static phase
converter for the others and had a lot of trouble with them.
Unfortunately the conversion was a "materials to hand" job. The motor
he'd used was _way_ underpowered and the saw was bordering on the
dangerous. So, that motor had to go.
I thought the task would be easy. It wasn't !
Getting the motor was easy - a 3HP single phase Clarke from Machine
Mart, £80 + VAT You have to buy them new because motors of this power
rating just don't show up S/H - industrial motors are 3 phase,
domestic motors aren't that powerful. If you're on Machine Mart's
mailing list, they send you invites to weekend open days (most bank
holidays) where Clarke own-brand kit is reduced by 17.5% - worth
knowing for the big stuff.
Switchgear was no problem, as I can sparkie with the best of them. A
NVR starter from Axminster and a rotary isolator switch. Machine Mart
also sell starters, but theirs have tiny buttons. As the starter has
a proper contactor inside, it's easy to extend this with extra stop
buttons. Your existing starter may well be usable, but check the
setting on the overload relay.
IMHO, a separate isolator switch is essential. It's not safe to work
on the whirling bits unless you can either shut off _two_ switches, or
Now the awkward bit - the pulley. The new motor is a 24mm keyed
shaft, the old pulley was a 1" shaft fitted to a 3/4" motor shaft with
a home-made adaptor sleeve. I couldn't re-use the existing pulley
without machining it out to take a bigger sleeve. I have a lathe to do
this, but it would be getting marginal on thickness for either the
sleeve or the bottom of the pulley grooves. It would also make the
change irreversible, should I screw things up.
So I bought a new pulley. That would be easy I thought....
Seems that triple pulleys are now a rarity, owing to modern belt
materials and the preference for polygroove belts in high power
applications. I considered swapping both pulleys, but couldn't easily
fit one to the old arbor.
The nearest triple pulley I could find (made by GKN) was expensive
(some tens of quid !) and wrong for both pitch between pulley grooves
and the groove profile. Seems that 40 year old pulleys were sized on
the cubit scale, and modern ones aren't exactly the same - still, it
seems to work now. A modern taper-lock bush in the pulley at least
means that I can fit any motor shaft to it in the future, without
swapping pulleys again.
Now the motor bracket. This is another job that's simple in principle,
just big and awkward. I had to re-drill four holes in the plate, to
accomodate the new motor and its new bolt location relative to the
pulley. This was done on the measure once, drill twice, curse
frequently plan. I don't quite know how I got it wrong, but I
mis-measured something. I was also drilling it on a friend's mill, 40
miles away from home....
If I knew how to strip the arbor, I'd have done that and replaced the
ancient bearings whilst I had it in bits. But it wasn't obvious
(anyone know ?), the hydraulic press is 200 miles away, and I just
couldn't be bothered. I did forge myself a nice new C spanner though,
so that I could grip the arbor nut without abusing the pin holes with
a badly-fitting rod.
Finally I had the parts. I just needed to re-assemble it (which is a
pain to do without taking the table off, but it is possible).
Amazingly it all then worked, and it even tensioned the old belts
correctly. The adjustment slots aren't generously sized.
Once finished though, the saw was transformed. No more bogging down,
even when doing full-depth rips in oak or warped blade-grabbing larch.
Well worth all the time and trouble it took.
Hope this is helpful. Post again if there's anything I can clarify.
New as I am to newsgroups (woah - talk about revelation!), I'm not sure
whether there's a usenet code by which one should abide when offering
one's thanks. If you'll indulge me - all responses have been most
welcome and beyond anything I had expected.
Tinkering with electricity is something I've always been a little wary
of, so forgive me if I don't experiment straight away with the notion
of idler motors. Although it's one of those ideas that will nag away at
me now until I'm sure one day I'll give in and cobble something
Andy, your guide to stripping the AGS reads like a Haynes manual!
Actually no, it's markedly more informative than my experience of
Haynes ever was. Brilliant.
Now you've all convinced me I'm going to have to get up very early
tomorrow to see whether I can get my hands on that saw before the other
chap who was interested makes off with it. Fingers crossed...
The starters Machine Mart sell are not the magnetic type, so they'll
stay latched on if the power trips. They are also only IP41 rated,
which if I recall correctly means they won't keep out dust, so
they could be troublesome.
I bought one recently, and it wasn't able to cope with the ~ 15 amp
starting current of my induction motor on load, even though its running
current was within the rated overload protection.
I've replaced it with a Crompton DOL, and it worked perfectly
set at the motor's specified current. And your right about the tiny
buttons too, not something I'd want on a saw.
I would have used a modern 3 phase MEM one I've got in the
spare parts box, but a 240 volt coil is only 5 quid less than a
whole new switch
I've also converted a small 10" Wadkin saw.
I went for a MEM DOL starter because it had a decent sized stop
button and it's metal cased (also in part because Axminster said the
DOL starter they were selling at the time wasn't suitable for my new
5hp input, 3hp output motor). Mind you with the overload, it cost
nearly 60 quid.
The original starter would have required (had parts been available)
both a replacement coil for 240 volt and a much higher current
The original (2hp output) motor had a narrower shaft, so getting the
pulley turned out was no bother. I had to replace the belts because
they were fractionally too short due to the new motor being a wee
Mounting the motor was just a matter of clamping it to the mounting
plate while lining up the pulleys with a steel rule, so I could centre
punch and drill the holes for the motor's foot mounting.
I think I removed the mounting plate so I could accurately mark a
line at right angles to the face that bolts onto the trunnion, so that with
the motor's foot aligned along it the motor and arbor shafts would be
With the mounting bracket bolted in place I securely clamped the
motor to it. Tilted and adjusted the height of the mechanism so I could
stick my head through the side of the cabinet to check the alignment
of the pulleys using a straight edge, then slackened the clamps so I
could adjust the motor's position once I'd got my head out of the way.
It is the same model Wadkin as yours, but unfortunately I don't
have any table extensions, there's also a few damaged teeth on the
fence's fine adjustment pinion (The fence's clamping lever was missing,
so it must have been used without the clamp). Apart from that it was
complete and in extremely good nick - it was from a college, in a nice
dry room adjoining a pottery kiln that was kept on 24 hours a day,
so it is free from rust and had minimal usage.
I have done a bunch of similar conversions. You need to see what the
motor frame number is. If it is a standard frame and mount, it's an
easy conversion. No, the switches do not usually need replacing. If it
has heaters (overload protection), you MAY need to replace the heater
elements as single phase will likely draw more current. Otherwise, just
use one or two of the three switch legs to break the hot wires. Leave
the ground straight through.
If its anything like mine it has a proprietary face mounted motor. You
could change the motor by having a 3/8 or 1/2" thick steel mounting plate
made up to adapt the new face mounted motor to the saw... Or you could make
or buy a phase converter. I made one myself from an old 10hp 3 phase motor
and capacitors, I found it fairly easy to make but your mileage may vary.
You can buy a static converter from Grizzly for reasonably cheap.
A Wadkin ?
Every one I've seen (and pretty much every UK motor of that period)
uses a foot mount. The Wadkin AGS saw uses a big folded steel
mounting tray that's pretty easy to re-drill, should you need it.
However measuring for the hole placement is less than obvious, because
you have to dismantle it from the arbor and trunnion to get access.
You can't just move the motor around until it's aligned, then mark the
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