Starting switch above motor in mill

[Firstgear]

My knee mill which has been in use about 10 months and only sporadically as this is a hobby not a business. I was using it making some small parts and after I changed the tooling on the end it just wouldn’t kick into full speed when I turned it back on.

The manufacturer responded quickly with parts and I am back up and running after a few days.

My question is, given my little use, how often do these contacts get burned enough to inhibit full speed from engaging when turned on?

 

[Latinrascalrg1]

My knee mill which has been in use about 10 months and only sporadically as this is a hobby not a business.

Ok, and you felt the need to share this because?

 

[Firstgear]

Anyone else have a better reply? Maybe my first question wasn't clear enough...I will ask it again, how often do these contacts get burned enough to inhibit full speed from engaging when turned on?

 

[Latinrascalrg1]

Anyone else have a better reply? Maybe my first question wasn't clear enough...I will ask it again, how often do these contacts get burned enough to inhibit full speed from engaging when turned on?

Wow! Excuse me for not being able to give you a better answer when what I Quoted in my initial post was ALL that was in your first post which had NO questions!

 

[Firstgear]

Ok, and you felt the need to share this because?

to give anyone that replies a sense of the amount of use. It isnt daily use which might solicit a different answer.

My iphone posted before I had gotten my post complete. I didn't see your reply until I went to my desktop.

 

[Latinrascalrg1]

In the spirit of this site with helping one another the switch you are referring to I believe is the centrifugal switch that turns the circuit to the start capacitor Off once the motor reaches its operating speed. So the connection this switch makes is to turn power off and Does Not turn anything ON including high speed circuit if that makes sense!

 

[Firstgear]

In the spirit of this site with helping one another the switch you are referring to I believe is the centrifugal switch that turns the circuit to the start capacitor Off once the motor reaches its operating speed. So the connection this switch makes is to turn power off and Does Not turn anything ON including high speed circuit if that makes sense!

so, my question is how often do these burnout? If a fluke then no big deal, but if they are a known weak spot should I buy a couple of extras to have on hand?

 

[RJSakowski]

On a motor with a capacitor start winding, the motor will not reach full speed if the winding doesn't disengage. This can be due to the contacts welding. The purpose of the capacitor start winding is tho get the motor spinning in the right direction. This can actually be accomplished by spinning the motor by hand. If the start winding remains engag3ed, the motor will also overheat as the current draw is usually quite high.

 

[hman]

Firstgear - In answer to the original question ... I can't count the number of capacitor start motors I've had over the years. And like you, I've generaly use them intermittently. So far, I've only had trouble with one of them, an older Jet grinder. The problem with that one turned out to be that the throw-out mechanism had loosened on the motor shaft and moved out of place. So the switch was not activated when the mechanism kicked. Once I figured out the problem, I was easily able to fix the grinder and put it back in service.

As for the contacts getting welded under the conditions you describe (intermittent use, etc.), I can only speculate that something might not have been properly sized.

 

[CluelessNewB]

I have some US made motors that are probably 60+ years old that still have original starting contacts and work fine. I also had a 2 year old motor from China that had contacts fail. I'm not sure if there is any real answer to the "how often" question. I suspect there are difference in the quality of the contacts themselves as well as the mechanism that actuates them.