Re: I need a latching relay...or do I?

Smoke,

Yes, your setup will work, but for this project I need to latch the
relay so I don't have to keep my foot on the pedal.

I'm implementing the first step in automation of a cut off saw. It's
a Dake cold saw where the operator manually downfeeds it with a long
handle. With the automatic downfeed and return there'll be time to
debur or other operations on the last part cutoff. Plus, on this
type of saw you get better blade life with a consistent feed rate.

I got the inspiration for this modification at a tool show I attended
yesterday, Dake showed a saw nearly identical to mine with the
hydraulic feed. Next step will be some sort of bar feeder mechanism
for total automatic operation.

thanks,

Doug

-- In CAD_CAM_EDM_DRO@y..., gordonr@r... wrote:

> Yes, there is a much simpler way. All you need is a relay with two

sets of

> contacts..one N.O. & one N.C., the foot switch and two N.C. limit

switches.

>
> Wire the foot switch and one limit switch in series with the relay.
>
> Wire the N.O. set of relay contacts in series with the Fwd

solenoid.

> Wire the N.C. set of contacts and the other limit switch in series

with the Rev.

> solenoid.
>
> The system will operate as follows:
> Depress the foot switch and the relay will energize. The N.O.

contacts will

> close energizing the Fwd solenoid while the N.C. contacts will open

ensuring the

> Rev. soleniod remains de-energized. When the ram stroke reaches

its forward

> limit, the limit switch will open and de-energize the relay. The

Fwd solenoid

> will de-energize while the Rev solenoid energizes causing the

required reverse

> motion.
>
> When the ram reaches the reverse home postion , the extra limit

switch will open

> and cause the system to stop.
>
> During any forward motion, the foot switch must be held down...a

good safety

> precaution in case you need an "instant reverse"
>
> You can also put in an emergency stop button to cause all

motion...forward and

> reverse to cease.
>
> Smoke
>
> Smoke
>