Hello from Suffolk

[Tony Goodwin]

Hi Geoff, used to live in sunny sudders, If you are considering microswitches, most machines I have worked on have used a quality made switch say Honeywell, with at least a 1mill cycle life expectancy. Also belive it or not apart from bad setting the single cause of premature failure in these switches is the tendancy to fully compress them when they are unpacked. I have admonished many an apprentice for clicking a new switch in the hand. also limit and ot switches should be a roller type working from a cam with an actuation ramp length of at least 4 times the dia of the switch roller.
Guide protectors are available but expensive, the integral wipers on bearings cannot be relied upon permanently especially when passing the screw caps of the rails. One system I have used is to assert a low air pressure to each bearing therefore blowing out contamination, but these were relatively low traverse speeds and the particulate was brass, all the best Tony

[lockyg]

Hi Geoff, used to live in sunny sudders, If you are considering microswitches, most machines I have worked on have used a quality made switch say Honeywell, with at least a 1mill cycle life expectancy. Also belive it or not apart from bad setting the single cause of premature failure in these switches is the tendancy to fully compress them when they are unpacked. I have admonished many an apprentice for clicking a new switch in the hand. also limit and ot switches should be a roller type working from a cam with an actuation ramp length of at least 4 times the dia of the switch roller.
Guide protectors are available but expensive, the integral wipers on bearings cannot be relied upon permanently especially when passing the screw caps of the rails. One system I have used is to assert a low air pressure to each bearing therefore blowing out contamination, but these were relatively low traverse speeds and the particulate was brass, all the best Tony

Hi Tony,

Thanks for that. Liking the idea of the air blast through the bearings. In you opinion which approach is less likely to have problems due to dust - the linear rails and bearings I have linked, or stub bearings running on cold rolled box section? (I`m not too concerned about the accuracy- it`s a plasma cutter afterall!).
I like the idea of buying in the linear rails and just bolting them in as opposed to building up carriages to run on box section. I don`t have a mill or lathe for accurate work, so any bearings on carriages would have to be adjustable (I can cut slots with my steelworker). Must admit the design hasn`t moved recently as I`ve been too busy with paying work - still thinking about it though

Cheers

Geoff