[seanreit]

I want to add spindle control to my lathe which is a monster motor on 120vac.

I suspect startup amps are around 25 amps. What relay or contactor would I need to use to hook up to the cnc4pc board?

[Al_The_Man]

Depending what you switching voltage is, a P&B, Potter & Brumfield PRD Relay series is a good alternative to going with an actual motor contactor.
They come in 12v or 24vdc versions for low voltage control.
A PRD-7DY0-12 is 12vdc coil with DPDT 25A contacts @ 270VAC.
Al.

[seanreit]

I've got 5vdc readily available, I think if I go with a higher voltage on the relay contactor, I will need an additional transformer, I was trying to avoid that if at all possible. 12 and 24dc and ac relays in this amp range are readily available at mcmaster, I was hopingsomoen here had been down this road before with the cnc4pc breakout boards. Thanks for your suggestion and any follow up information you might be able to add.

[Al_The_Man]

If this is a Tower and not a Laptop, What is wrong with using the PC 12vdc from the P.S. 4pin sockets?
Al.

[jalessi]

Al,

What about one of these?

http://www.crydom.com//userResources...crydom_ha6.pdf


http://tinyurl.com/5wks2g

$8.00 Each + $6.00 shipping!

Jeff...

[seanreit]

Jeff, I ordered one of those, pretty good price! I will see if it works. If anyone else has any other suggestions, please add for those that come in behind me.

Al, you are right, I did not consider all the 12 volt in the tower. Good suggestion.

[jalessi]

Seanreit,

A more elegant, however much more expensive solution would be a VFD.

Hope the SSR works out for you.

Jeff...

[Al_The_Man]

A SSR should work also, but it is important to incorporate this in the E-Stop string, especially when using a S.S. device, also the E-stop should be hardwire activated.
i.e. not by screen button etc.
I know you can get away without following safety measures on a hobby machine, but the same dangers exist as found on a commercial M/C.
Al.

[Zumba]

The 12v from the PC will work fine.

Or get yourself a Meanwell 12v/5v combo power supply. At $25 a pop, it seems pointless to make your own. The external supply will keep everything tidy in your computer tower.