Limit / reverse switch

[Turbo]

You could do it with the trigger switch from a cordless drill.
When the table reaches the end of the stroke a lever would operate the fwd/rev switch first selecting off and then reverse, table goes backwards.
Hopefully momentum will be enough to keep the lever moving from the off to the reverse position.

Arcing could be a problem as these don't normally switch over under power.

 

[Bsmith]

This is the motor control that I have, it's fed by 12v dc which is fine, I can reduce the speed with the pot and change motor direction with the 2 way switch. (The motor actually runs fine in reverse just by swapping the polarity, I tried it to begin with, with a 12v battery).

The coupling that I made, which is fastened to the motor output shaft, has a grub screw in the other end and a grease nipple on the opposite side. I nip in the grub screw when I want the table to motor feed or unscrew it when I manually feed.

Now, I definitely need a stop switch incase the table was ever to reach the end of it's travel when motor feeding, if that was to happen for any reason it would probably burn the motor or some of the electrics. It would also be good to stop the feed at the desired length of travel on every cut, so a limit switch would need to be moveable along the length of the table.

If I was to fit a limit switch which opened when the desired travel was reached, I would have to switch off the motor, undo the grub screw, wind the table manually until the limit switch closed, then tighten the grub screw and start the motor in reverse. This is what I am trying to avoid by having a reverse switch.

The table resistace stops the motor abruptly, I think it would be ok to change into reverse immediately although a time delay as someone suggested would be better.

Hope I'm making sense.

Thank you for your replies fellas.

 

[Pete.]

If I was to fit a limit switch which opened when the desired travel was reached, I would have to switch off the motor, undo the grub screw, wind the table manually until the limit switch closed, then tighten the grub screw and start the motor in reverse. This is what I am trying to avoid by having a reverse switch.

All you need to avoid all that rigmarole is a momentary override button.

I have some limit switches that will probably suit your purpose, and some lovely new momentary buttons too. The switches have one NC and one NO contact in each and are high quality industrial kit. Send me a PM and I'll let you know what I have got. if they suit you then you can have them FOC.

 

[Turbo]

Another way would be to use a small 3 phase motor and a vfd drive to control it.
Program the vfd to slow the motor down when the table hits a limit switch before reversing the motor.

 

[Bsmith]

All you need to avoid all that rigmarole is a momentary override button.

Yeah, I never once thought about a momentery switch to override the limit switch, (showing my ignorance where electrics are concerned).

I'll write you soon but unsure of exactly what I will need.

Thanks Pete.

 

[Robotstar5]

Now, I definitely need a stop switch incase the table was ever to reach the end of it's travel when motor feeding, if that was to happen for any reason it would probably burn the motor or some of the electrics. It would also be good to stop the feed at the desired length of travel on every cut, so a limit switch would need to be moveable along the length of the table.

If I was to fit a limit switch which opened when the desired travel was reached, I would have to switch off the motor, undo the grub screw, wind the table manually until the limit switch closed, then tighten the grub screw and start the motor in reverse. This is what I am trying to avoid by having a reverse switch.

Instead of moving the limit switches why not have a slotted rail with adjustable strikers?, it would save having loops of wire long enough to move the switches.

As for overriding the limit a "jog" button is normally used to short out the limit allowing the table to driven until it's clear of the switch.

 

[Bsmith]

Instead of moving the limit switches why not have a slotted rail with adjustable strikers?, it would save having loops of wire long enough to move the switches.

Yes, good one. I could do that with a longish piece of tube through a short piece that has a pinch screw.