Electric clutch

[Greenpully]

I have a band saw with electric clutch.Clutch and water valve tied together pulls 4.5 amps with 12 volts.Heavy duty onoff switch does not last very long.Question would a condenser connected across switch As used in tractor distributor help?IF so, can you recommend what size?I am in over my head.Thank you GP

 

[PJH]

You could add a relay. Your switch would only control the voltage to the relay coil.
an example

 

[Janicholson]

What does water have to do with a band saw? Any way try the condenser, it can't hurt anything to try one. Use a regular auto condenser. 99% of those removed are not bad at all!! Jim.
switch

 

[Russ from MN]

4.5 amps is not that much, you should be able to fine a switch that will handle it.

 

[Russ from MN]

They run water on the blade so the pitch doesn't stick, at least that's what the guy from Sauk Rapids did when he sawed my oak.

 

[Janicholson]

I run bandsaws, 8 of them, but they live inside and cut dry wood, plastic, wax, aluminum, and steel. So I asked. Jim

 

[Jaden]

I assume this is 120 volt AC powered. If so, the condenser will make minimal difference. Is there an amp rating on the HD switches you are using?

 

[teddy52food]

Sawing green logs will coat the blade with sap and pitch so water is used to keep it clean.

 

[Steve@Advance]

Is this 12v DC?

If so, the switch needs to be rated for DC.

Must be something different in the contact alloy, but it will make a difference. Can't hurt to try the condenser.

 

[David G]

An automotive condenser should help arcing on the contacts, there is a lot of back EMF from a clutch.

Make sure it IS 12 VDC.

 

[Mutt and Jeff]

Maybe a diode to block reverse current when de-energizing.

maybe a HD wall light switch type switch

 

[MarkB_MI]

OK, if a read correctly, you have a water-cooled bandsaw that has its own 12VDC power supply that's used to control a clutch and water valve. And the switch that controls the clutch/water valve circuit keeps burning out. If that's not the case, ignore the rest of my post.

The first thing to do is to make sure your switches are DC rated for the current you're switching. A 10 amp AC switch may be good for only 1 or 2 amps DC. That's because AC power shuts itself off 120 times per second, so a switch has an easier time switching inductive AC loads than inductive DC loads.

The second thing you can do is to add a diode to the circuit to prevent inductive "kickback" from arcing the switch. The diode is installed in parallel with the switched load such that it is reverse biased when the switch is turned on. When the switch is turned off, the diode becomes forward biased, allowing current to flow through it instead of arcing across the switch points. The diode needs to be rated for the switched current and at least 50 volts. Note that the clutch and valve will deactivate slightly slower after adding the diode, but the difference is probably in milliseconds.

 

[jeffcat]

Even better would be to have the pump with it's own switch. The one on this little pump is 47uf. Just tripple your voltage rating so 35 volts would be plenty. Just make sure the polarity is the right way around.

 

[Greenpully]

Thanks for ALL replies.Our saw uses water mixed with soap for blade lube and cooling.My problem is the induced current when opening switch,very hefty spark at that time. I like idea using diode will seek local help TOOOO deep for this old grey head.Again thanks to all. GP

 

[MarkB_MI]

> Even better would be to have the pump with it's own switch [I think you meant capacitor]. The one on this little pump is 47uf. Just tripple your voltage rating so 35 volts would be plenty. Just make sure the polarity is the right way around.

JC, using an electrolytic capacitor for kickback suppression is a bad idea. When the switch is opened, the capacitor becomes reverse biased, which is exactly what you don't want to do to an electrolytic cap. An unpolarized capacitor is better, but a diode is the best solution by far.

 

[MarkB_MI]

GP, I suggest using the readily available 1N5401 diode. Although it's only rated for 3 amps continuous, it can handle up to 200 amps for a few milliseconds. This is about the largest diode available without going to a stud mount package.
1N5401