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MatB
18-02-2019, 01:23 PM
Hi everyone
I’m an engineering student in Switzerland with an interest in CNC machines. So far I’ve built one small machine (Chinese XY Table and custom Z) but the results were not pretty😊 Already down the rabbit hole so now I'm trying to build a bigger, better machine for Hobby work that can handle everything up to light steel cuts. As the MYCNCUK site is already on my daily internet browsing stops I’ve decided to formally join fun.
I’ve already got a specific question for which google had no answer:
An excellent deal on eBay recently brought some very heavy duty second hand linear rails into my possession. In trying to get the most bang for my buck (maximum travel length). The carriages on these are massive but also have 5cm wide wipers on each side (10cm lost travel for wipers). Now my question: Does anybody know of a commercial machine (or built one yourself) where the wipers (but not the balls) travel over the edge of the rail end? If the ends were deburred or even had a small angle facet the wipers shouldn’t get wrecked. Right? Any dirt should collect at the end of the rail.
I’m interested to hear anyone’s thoughts on the matter.

Cheers
Mat

Doddy
18-02-2019, 05:49 PM
Not by design, and not to any advantage for me, but I replaced the Z axis on a small Starmill with a plate driven on linear rails, and the wipers overshoot the top of the rail by a few millimetres before the legacy end-stop activates. It always worries me when homing the machine (the risk of exposing the balls) but it never has yet. Being at the top end of the Z it does give me a problem that random crap and dust could settle within the bounds of the wiper, but I never leave it there for very long.