Is a starter necessary?

[Bi11Hudson]

graham-xrf provides a very detailed and very good description on how a "small" motor does what it does. I would disagree with a few points but those would be technical and largely a difference in US vs UK electrical systems. Where I would comment here is more a matter of personal preference than an "approved" setup. A "Soft Start" is indeed a nice device, and if you wish to spend the money for one I hope you see the result in your power bill. I'm just not a fanatic of solid state devices when they aren't useful.

The answer you were looking for though can be expressed a little less technically for the (electrical) novice. Like many other small shop machines, the basic ON/OFF function is handled by a simple switch. Usually a "toggle" switch. Folks often use a light switch, though this is not the best idea. Light switches do not have the contacts to handle motor Start/Stop surges. What I describe below is the way my machines are set up. The arrangement is not universal, a "work in progress", as and when I feel like it.

First off, my compressor. 5 HP, single phase, huge inrush. Nominally, 5X run current. I installed a starter with the control circuit consisting of a simple toggle switch and the pressure switch. The concept being that the starter handles the motor current and the pressure switch has only control power. And the ON/OFF switch so I don't have to use the mechanical latch to turn off the compressor.

Next, the table saw, admittedly the most dangerous machine in my shop. I don't do "large" work, like a sheet of plywood. Mostly repetitive work where the fence is set up and I run a number of pieces. I do plywood with a "Skil saw" and "cut-offs" with either a Radial Saw or a Mitre Saw. The table saw NOW has a paddle switch, ON being a push button and off being the "paddle". I would like it to be on a starter, but not willing to spend the money. One day. . .

Answer to your question​

What you have looks to be a magnetic(electrical) arrangement for Stop/Start. Definitely worth keeping, although it isn't absolutely necessary. Ya got it, USE it. The push buttons will be a "3 wire control" station. Simply stretching the wires to a practical location is all you need. A paddle arrangement can be finagled from a couple pieces of plywood and a hinge. The only advice I can offer is to use a piece of 3 wire cable and a box. Don't use "loose" wires. The push button looks like plastic (insulated), a "ground" wire isn't vital but a good practice. I often buy a heavy 3 wire extensiom some 25 feet long to make line cords. The short cut-offs are a handy source for this sort of work.

The point being is that it isn't necessary to remount the starter. Just punch out a KO(Knock Out) and use a Tommy connector to mount the cable. The push button station can mount wherever you want. I would suggest mounting it where you can "swat" the off paddle when you're running. Don't "look and resolve" in an emergency. Just swat it off as you go by.

Bill Hudson​

 

[graham-xrf]

@Bi11Hudson : Agreed. A separate soft-start can run to three digit $$$, and what you get is the non-violent "safe" start without surges, with no savings on power nor anything else to soften the blow to the wallet.

They are now becoming more standard in mass produced kit. I purchased a 10" sliding compound mitre saw "Evolution" brand from a UK store for £150. I was in a hurry at the time, with a lot else on my mind. It looked like it would cut 2 x 4s and did not make the eyes water when paying up like would be for the DeWalt, which looked much the same.

When I tried it WoW!
Soft start, and built in electronic braking to come to a stop. I had bought the whole saw for less than a unmounted soft-start gadget from RS Components.

I noticed it cuts the wood just fine, though seems to run "slower" than expected, and it has a weird trick blade tooth getup. Then I start paying attention. "Multi-material" ! This one cuts straight through 1/4 inch steel, somehow without making it incredibly hot.
--> Soft-start saw
My point is - if soft-starts can be built into kit at that price, it should be more affordable to get the electronics for external use.

Other motor start switching.
Centrifugal switches built into the back of some 3-phase motors to change the wiring from STAR during run-up to DELTA when at speed. Some motors have the smaller built centrifugal switches intended to be taken out to the external contactors where the wiring change-over happens.

For motors with wiring to reverse direction, both 3-phase and single phase sorts, they have arrangements to sense when it has come to a stop before getting going in reverse. Some have ON-Delay relays with time-outs. With simple direct wired switching, say to a lathe, I don't know in detail what happens if you take the lever knob straight across from FWD to REV while running, but I am pretty sure it cannot be anything good!

Sure - you can make most stuff start and stop with ghetto switching, but expect that the (many) starter switching gadgets available were not invented for nothing! The yellow/red/green goodie in post#6 cost me £14.95.

[Edit: @DavidR8 - I should mention that if you do have a E-Stop switch in series with OFF, while being NC (normally closed) with momentary open operation, proper E-stops have a mechanical click-latch to keep them open after being pushed, usually released by giving the knob a little twist]

 

[projectnut]

As mentioned I would leave the starter in place and wire in a remote start/stop switch in a convenient location. Here are a pictures of a couple of my machines that have starters and remote start stop switches.



Note the start stop switch just behind the table on the right side of the picture. It's attached to the box with the starter and overloads.



This lathe has a complete remote control station The box with the starters is on the left side of the base The forward, and reverse buttons start the motor in the proper direction. There is also a speed increase and decrease button as well as a shutoff easily within the operators reach. Since a saw only runs in 1 direction at 1 speed you would only need a start and stop switch.

 

[machPete99]

I have a similar Unisaw, but with 3HP motor, and a low voltage controlled starter system, and "remote" low voltage switch located under the fence rail (operator side). On mine there is only a remote control, it does not have any switch located at the starter.

Looking at your wiring diagram it appears that you should be able to install a separate "remote" switch. If the switch buttons on your starter are momentary contact you should be able to setup a remote. Usually the start switch is normally open with momentary close, and the stop switch is normally closed with momentarty open. You could get the appropriate separate pushbutton switches or get one combination switch of the appropriate type.

 

[graham-xrf]

@Bi11Hudson . Bill - If the motor current is going through the pressure switch, and it sticks on start-up, would the kit keep going until the pressure safety valve lets go, and even then, keep going? Of course,it may be that the pressure switch kit has thru-line contacts rated for the motor, or operates some other internal stuff - I don't know.

I only mention it because a pressure switch I have here does not have the kind of contacts common for a motor relay, small little contacts, and is wired in a 24V circuit in series with the starter coil.

This also brings about the point that in big machinery, it is common to have a little 24V power supply transformer, and 24V relay coils, so that all the push-buttons, starts, stops, E-stops, whatever anyone might touch, and mounted externally, are operated with only fused a low voltage 24V on them.

Maybe this is more of an issue in UK, where the ring main is 240V 32A, so maybe not what one wants on and around over a machine. I always specified low voltage external kit for starting and stopping the big stuff. We exclude here the exotic stuff, like "intrinsically safe", for hazard area mining kit, which gets rather special.

 

[7milesup]

Dave... I have a similar saw. Jet cabinet saw. 3hp 220v.
I made up this hokey paddle switch thingy that I have been using since 2007. A simple tap of the knee as I finish the cut shuts the saw off.

 

[DavidR8]

Dave... I have a similar saw. Jet cabinet saw. 3hp 220v.
I made up this hokey paddle switch thingy that I have been using since 2007. A simple tap of the knee as I finish the cut shuts the saw off. You could glue some velvet around the "On" button hole if the edge is too sharp.

Thanks, I might do a bit of engineering to see if I can do something similar.

 

[Larry$]

This is what I’m dealing with.
The starter.

The wiring diagrams. My apologies for the poor pics. Really hard to take shots of shiny paper glued into the corner of a box.

You've got all you need in the wiring diagram. On the page: Control wiring, combined remote & cover, the two dashed lines indicate new wires leading to you new paddle switch location. Circles at the end of wire indicate a connection of the same # on the next diagram. As you can tell by looking at the diagram. any # of start stop locations can be added. Supply power comes in @ connection 2 . and flows thru all the normally closed stop switches that are series connected. The start switches get their power from the same point. They are parallel connected & normally open so any one of them can start the motor via the pickup coil. Once the pickup coil has pulled in it is maintained by the auxiliary contact block on the side of the main block. The aux contact is also wired in series with the normally closed stop switches & the overload contacts.

When you have a dust collector in you shop and want to have start/stop stations at each tool, you can take advantage of this same wiring scheme. I've always just added a 24V transformer, with a built in fuse holder, as the power supply so I could use exposed light gage wiring, & cheap switches. The voltage of the pickup coil or solid state device needs to match the power supply. There is a catch in using really cheap switches, they are easily kept from making contact by dust between the points. Makes it hard to find the fault.

 

[WCraig]

I have a Rockwell Unisaw with a 1.5 hp motor currently wired for 220v. It came with a Square D starter in a big metal box (10"T x 6"W x 4"D) with switches that are difficult to use when handling large sheets of plywood etc.
Is a starter strictly necessary or can I replace it with a paddle style on-off switch?
I know the saw had something much simpler when it came from the factory as there's a cutout in the cabinet for a simple switch about the size of light switch.

I know you've had a lot of information thrown at you but this diagram from the Vintage Machinery site shows pretty clearly how to wire in a secondary control station for a magnetic starter:

Either Green button momentarily energizes the contactor and starts the motor. Either Red button breaks the circuit that keeps the contactor closed and therefore stops the motor.

There is a couple of good pages of info under Section 4.2 at:

Main Page - VintageMachinery.org Knowledge Base (Wiki)

wiki.vintagemachinery.org

BTW, it is also possible to buy other control station buttons that would fit in place of the ones currently in your SquareD starter. IE one with a Red mushroom top for Stop. May take quite a bit of searching on eBay to find exactly what you want.

Craig
(I have a mag starter on my 1.5 HP Unisaw. I really don't want it to restart after a brief power outage.)

 

[Janderso]

I like your Sheldon lathe Projectnut!!
How come the chip pan is so clean?