[cismontguy]

Hello Forum,

I have had my 1100 PCNC for 5 years now and had several issues with the X axis limit switch. Today it stopped working and I wanted to share what was the immediate solution for my machine. I had been making a part in the morning (2 hours op with coolant) and then came back after lunch to make another, different part. I had shut the machine completely down as we are prone to thunderstorms in the afternoon, where I live and the power can go out for a brief period. Long story short, when I went to run the X Ref on start up, my machine ran to the end of the X travel and then there was a terrible grind/hum from the Mill. I stopped the travel with the keyboard and tried to figure out what was wrong.

Long story short there was coolant in the box that houses the X axis limit switch. I shut down the machine, no power, removed the limit switch and blew compressed air through it from all sides. I put some machine grease on the plunger and wired it back up but did not reinstall it. I rebooted the system and then asked Pathpilot to Ref X axis and I then pressed the plunger of the limit switch down and it stopped. Put everything back together and it all seems OK now.

No idea what is the best way to keep coolant out of the switch. First time in 5 years this has happened. The switches cost like $7.00 USD on eBay plus shipping. No idea what they cost from Tormach cause they are closed for the 4th of July weekend. (Good on them!). Hope this helps?

Cismontguy

[jwatte]

Careful about eBay switches, though -- the repeatability of this switch matters, and even though different brands may look the same, they may be different on the inside!

Anyway, grease sounds better than nothing. The only thing I know for sure about fluid management, is that after you coat stuff in epoxy, stick it in a gasketed case, and smear silicone grease across everything, you have to drill a hole at the bottom for the fluid to come out of once it finds its way in. Because it will :-/

[cismontguy]

Hello Jwatte,

Yes, I totally agree about buying a authentic OEM part as mush as is possible. I looked at the images shown and there were some less than stellar examples that I am guessing were knock offs. You could probably order on from Digikey in MN or Tormach. I think I will get one to have on hand so I do not have to shut down work for a $7.00 part.

Cheers,

Cismontguy

[kstrauss]

You can disable homing so you would not have to shutdown due to switch failure.

[GLCarlson]

There was a reco many years ago to caulk the chromed guard at the front of the table. Did that myself, have never had a problem with coolant on that switch. I keep a spare switch on hand, too. Strongly advise against anything but OEM switches; if you must get something els, buy from Mouser or similar reputable supplier and stick to known brands; avoid e-bay.

One further option is to consider an optical switch retrofit. Since it's a solid state switch, no contacts to oxidize or plungers to stick. Readily available from the 3D printing world. There have been some discussions about the retrofit a while back on this forum. If I were using flood coolant a lot, I'd consider that. Flood seems to be a source of switch problems.