Speed Control for Variable Speed Motor/Winder

[jrdamien]

Can any of you wizards help me reason this out? I just picked up a new mini lathe to replace my old winder. It has a 110v 0-3800 rpm variable speed motor with an on-board speed control. I want to add a foot pedal to control the speed. Before I crack it open, start inventing solutions and building them, can anyone see any trouble in just using something like this:

http://www.amazon.com/dp/B000VV4SDS/...I1622XZL81NC32

Just an off the shelf rheostat. I'd just turn the controller on the lathe to the highest setting and use this pedal to control it from there. Any obvious potential troubles?

[big_teee]

This should be moved to the "Tools and Coil Winding Gear" Forum Area.

[jrdamien]

This should be moved to the "Tools and Coil Winding Gear" Forum Area.

Damn, I thought that's where I started it. An admin needs to move it, yes?

[big_teee]

I don't think we have much intervention Here. lol
One mod is never here anymore, and one mod that is retired checks in, only now and then.
I would just carry on! I was just pointing out for next time, that we have an area for that.
I see you already knew that!
T

[salvarsan]

I just picked up a new mini lathe to replace my old winder. It has a 110v 0-3800 rpm variable speed motor with an on-board speed control. I want to add a foot pedal to control the speed. Before I crack it open, start inventing solutions and building them, can anyone see any trouble in just using something like this:

Amazon.com: Nippon Labs STK-975PS Switch Pedal for Flexible Shaft Grinder: Electronics

Just an off the shelf rheostat. I'd just turn the controller on the lathe to the highest setting and use this pedal to control it from there. Any obvious potential troubles?

It's a little more complicated.
Those mini-lathes have DC motors with PWM controllers, don't work by directly throttling the AC.
You'll need to open up the controller box and measure the pot.
The pot on mine was ~10k.

You could install a normally-closed 1/4" audio jack (stereo) and switch out enough of the pot leads for a 10k foot pedal of your own.

-drh

[jrdamien]

It's a little more complicated.
Those mini-lathes have DC motors with PWM controllers, don't work by directly throttling the AC.
You'll need to open up the controller box and measure the pot.
The pot on mine was ~10k.

You could install a normally-closed 1/4" audio jack (stereo) and switch out enough of the pot leads for a 10k foot pedal of your own.

-drh

Good idea. But what do you mean by "switch out enough of the pot leads?"

[mr fab]

the foot pedal is a switch and not a rheostat.

I would leave the speed controller intact and add the footswitch to turn on and off. you set the speed via the speed control and stop and start with the foot pedal.

the foot pedal would combine with the start/stop switch to activate the machine

the stereo jack mentioned above enables the unit to function normally without the pedal connected. you may consider a switching jack in the event you are not switching connections which are earthed

I had a start/stop pedal with my first winder and eventually took it off as I found it easier to just use the speed control pot and start stop switch which were easily accessible at the front of the machine.

[jrdamien]

the foot pedal is a switch and not a rheostat.

I would leave the speed controller intact and add the footswitch to turn on and off. you set the speed via the speed control and stop and start with the foot pedal.

the foot pedal would combine with the start/stop switch to activate the machine

the stereo jack mentioned above enables the unit to function normally without the pedal connected. you may consider a switching jack in the event you are not switching connections which are earthed

I had a start/stop pedal with my first winder and eventually took it off as I found it easier to just use the speed control pot and start stop switch which were easily accessible at the front of the machine.

I want a foot pedal to control speed, not on/off. It's a huge thing to have both my hands free when winding.

So likely I'll try and wire in a jack off the existing pot. But how might this get wired? If the original pot is left in place plugging in a cable to go to a footswitch won't bypass this pot. So wouldn't the pot have to be removed altogether, the jack hard wired in place, and connected to a pedal with a similar valued pot?

And then what are we talking about for a foot pedal? An old wah, maybe, with a correct value pot?

[big_teee]

I wind without a foot switch.
I have the Mojo winder and it has a speed control on the front that I control with my left hand.
I use my right hand to feed the wire.
To stop the winder, you just roll off the speed control.
My winder has a foot pedal jack, but never saw a need for one.
I wind from 0-1200 rpm, without incident.
I would wait and only consider the foot switch, after trying it without one first.
You may decide that you don't need the foot pedal.
YMMV,
T

[jrdamien]

I wind without a foot switch.
I have the Mojo winder and it has a speed control on the front that I control with my left hand.
I use my right hand to feed the wire.
To stop the winder, you just roll off the speed control.
My winder has a foot pedal jack, but never saw a need for one.
I wind from 0-1200 rpm, without incident.
I would wait and only consider the foot switch, after trying it without one first.
You may decide that you don't need the foot pedal.
YMMV,
T

I wind without a foot switch, too. My winder works the exact same way. I wind 0-3000+ rpm without incident.

I don't NEED a foot pedal.

But if I can make a foot pedal work, I'd really like one.

[jrdamien]

Well this dried up on the subforum so...here's what we've got.



This is the right side of the pcb. In the far back and on the right you can see the speed pot. I don't know the value - I'll have to take it out to find out. It has two leads coming from it (red & white, looks like middle and left lug) to a connector on the board (the connector on the far right). I think I could disconnect the wires from the pot and connect them to a jack to be mounted in a different hole. That jack would connect to a foot pedal. Thoughts?

Here's an overhead view of the speed control and motor temp. connection.

Anyone know if this motor temp connection is or can be used as an inhibit switch? There is no other motor reset or or safety control here and the inhibit switch is what's used to shut off the motor when the counter reaches a preset number of turns.



Here's 4 connections. The one's the furthest left are marked ACL (ac line) and ACN (ac neutral). ACL is the white coming from the power cord. ACN is a blue wire coming from the on/off switch. To the right of these are a black and a red wire both going to the motor (M- & M+). This is the DC going to the motor? I must be able to put a dpdt switch in here and reverse the motor, correct?

[tedmich]

That appears to be a Fego (TW) fan speed micro-controller.
see: Fego Precision Industrial Co., Ltd.

Its missing many components which are probably associated with remote operation of the controller, but maybe reversal or a Hall effect sensor on the motor is lacking too. It might be easiest to switch to a timer based PWM circuit using a 74AC14 or 555 timer. Or you can just duplicate the speed pot in a crybaby type gear driven potentiometer pedal with a switch to give knob or foot control.

[jrdamien]

That appears to be a Fego (TW) fan speed micro-controller.
see: Fego Precision Industrial Co., Ltd.

Its missing many components which are probably associated with remote operation of the controller, but maybe reversal or a Hall effect sensor on the motor is lacking too. It might be easiest to switch to a timer based PWM circuit using a 74AC14 or 555 timer. Or you can just duplicate the speed pot in a crybaby type gear driven potentiometer pedal with a switch to give knob or foot control.

So how would YOU implement the foot control?

[Jazz P Bass]

I would put another pot directly across the existing pot.

[jrdamien]

I would put another pot directly across the existing pot.

By which you mean wire the foot control straight to the existing pot?