Re: [CAD_CAM_EDM_DRO] Ultrasonic cleaners for delicate parts?

motoproto wrote:

> Group,
>
> The homing switches on my mill are failing sporadically, and a single
> switch is $327.00. I can't disassemble the switch without digging
> the glue out of the back (where the wire exits), so, I'm wondering if
> cleaning them in an ultrasonic tank will harm them?
>
> The switch is quite small, and appears simple, but the price suggests
> otherwise. The switch is cylindrical, two wire, and looks to have a
> glass plunger about 1/16" dia. Must be some kinda super precision
> unit. The machine uses the switch to home/set limit, and to
> calculate backlash upon initialization.
>
> The machine was quite dusty/greasy when I took delivery, and I think
> this dust/grease has gotten inside the switches.
>
> Is ultrasonic cleaning ok for such delicate electrical devices?

probably not, in general. I have disassembled Micro switch brand
micro switches and cleaned them. but, usually, when sensing switches
like this stop working well, it is because the over-center leaf inside has
become fatigued. Although, the big limit-switch type units have a fair
bit of mechanism between the actuator and the switch inside. in that
case, the mechanical linkage may be binding in some way. just dunking
the whole thing in an ultrasonic cleaner will be a waste of time or a big
mistake. If the unit is still sealed, the cleaner will make the outside
nice and shiny. If the seal is cracked or leaking, it will serve to drive
gunk into the innards, and you'll have a switch that likely will not work
at all, or ever again.

There's an outfit that sells limit switches and industrial controls on eBay
a lot. they also have a web store. The outfit is CPI surplus. I couldn't
find the URL for them right now. They are honest! I won a bid on eBay
for what were listed as limit switches, but they were only the actuator hed
from the switch units. So, they sent out another box of a different brand
of switch that I picked out of their online store, at no cost to me!

They had a whole BUNCH of Micro Switch, Telemechanique, AB, CH, etc.
limit switches, all under $10 each. I got a bunch of Micro Switch compact
units, and will use them for all functions (limit and home) on my mill.

Jon