On Thursday 06 August 2015 12:02:06 andy pugh wrote: > On 6 August 2015 at 16:48, Gene Heskett <[email protected]> wrote: > > That's good too, as is the swarf ejector disk on top of the motor. > > And I see you used reflective opto's for limit switches too. Are > > they accurate enough for homing? > > That disc is just how the motors are built. > As for the optos, they worked, but I don't use them any more. > Homing accuracy was excellent, but they tended to get contaminated.
I wondered about that, both from the point of the sensors faces being contaminated by coolant mist, and long term oxidation of the metal tab changing its reflectivity. > I > prefer inductive sensors now. Hall effect? Well shielded from swarf, but what about any lubricants? I once wrecked about a dozen hall driven keyswitches in a very expensive Cherry keyboard by giving them a shot of wd-40 to ease thier dragging from old age & dirt. 3 days later, and about 7 dead keys by then, I was advised by Cherry to run, don't walk, to the nearest dishwashing machine and run the stripped keyboard thru at least 2 cycles, one with std dishwasher soap and one for an insurance rinse. That stopped 99% of the failures, but the keyswitch assemblies were $17 each. 3 more failed, one at a time, over the next month, and I rewashed it each time I had to replace another. Then it was ok for another 10 years or so, until the CG it was used on was replaced by a pc running CG software. And it could use any old $10 keyboard. But it didn't help the CG operators speeling a bot, you should see some of the musteakes that actually get on the air. Just yesterday someone was dieing :) The ones I see being used by you and several others are in an expoxy package, which may be more lubricant proof than the Cherry version, which was on a small ceramic subtrait the magnet rubbed on and just covered with a blob of Epoxy-b on the other side. The ceramic was maybe 20 thou thick. The ceramic was porus enough to let the wd-40 soak thru from what Cherry said. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
