Drum Switch Vs Cam Switch

[Harry Knutz]

Hello,

Can anyone tell me if there is a difference between a drum switch and a cam switch?

 

[benmychree]

I'd wonder if the cam switch might last longer than the drum switch due to the contacts would not be wiping and wearing each other away, this has taken place on a 2 speed fwd and rev drum switch on my lathe, only took it about 30 years to take place, no parts available, obsolete ---

 

[Harry Knutz]

I guess they do the same job, Its just easier to see the drum switch internals, These cam switches are confusing to me.

 

[Ulma Doctor]

The difference is in how the contact is made and broken between the switch poles.
They both provide the very same function.
So long as their ratings are equal, there is no difference, electrically, between the two in a circuit

 

[cathead]

My preference would be a drum switch. The innards are easily accessible if one needs
to refurb the contacts or braze on some silver to the contacts. The cam switch has too
many parts and not easily repaired for my way of thinking.

 

[Harry Knutz]

My preference would be a drum switch. The innards are easily accessible if one needs
to refurb the contacts or braze on some silver to the contacts. The cam switch has too
many parts and not easily repaired for my way of thinking.

You are probably right, The advantage to the cam switch is it mounts flush on the machine, I guess that's the only upside I can think of. Why would these lathe companies go to the trouble and expense of using transformers and magnetic contactors when they could have mounted a drum switch of sorts mounted sideways connected to the apron switch. Can someone answer that? I have been wondering.

 

[markba633csi]

Contactor systems have several advantages over simple switches:
1) ability to incorporate a latching E-stop function- safer
2) greater current capability possible
3) ability to switch high power motors remotely with small switches

 

[projectnut]

I have an older (1942) horizontal mill and an older lathe converted from a line shaft that both use drum switches. Since they are single phase low hp (1 1/2) machines the drum switches are more than adequate. I also have a Bridgeport mill, Racine power hacksaw, Baileigh cold saw, and a Sheldon lathe that are 3 phase machines. They use contactor systems allowing the control circuits to be 120 volts.

 

[Harry Knutz]

Contactor systems have several advantages over simple switches:
1) ability to incorporate a latching E-stop function- safer
2) greater current capability possible
3) ability to switch high power motors remotely with small switches

Thanks for the clarification, I knew there had to be a good reason, That's a lot of extra stuff.

 

[markba633csi]

Yeah, if you have a lathe so big you need a stepladder to get to the chuck you ain't going to be using a drum switch LOL