Thread: Thor, or should that be Zeus?
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08-06-2017 #271
You should be aware that mechanical switches often have a minimum switching current needed for those kind of expected lifespans. If switch contacts don't switch enough current, they oxidise and fail to conduct, as they rely on a certain amount of arcing to keep the contacts conducting.
The same also applies to relay contacts.Avoiding the rubbish customer service from AluminiumWarehouse since July '13.
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08-06-2017 #272
So many options.
http://uk.rs-online.com/web/c/automa...sort-order=asc
Id probably consider the ones like this (http://uk.rs-online.com/web/p/limit-switches/0199046/) or similar.
Panasonic, so not cheap crap. NC, Easy to mount, should work for me but I dont really want to buy 6 if I can avoid it.
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08-06-2017 #273
You should be fine to wire them in series no problems but only if you use them as Normally Closed, if you use them Normally open they won't trigger! Normally closed the circuits is flowing and your detecting a break it doesn't matter which one triggers. Normally open the circuit is closed and unless you trigger both microswitches at the same time (Which can never happen in real world use) the circuit can't complete.
There's no real power going through them so wire from one to the other so should be no need for anything else.
If I were you I would wire a 2nd set of limits to the Estop regardless as it seems more reliable than relying on the software and you really can't afford a crash.http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm
If you didn't buy it from China the company you bought it from did ;)
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08-06-2017 #274
You're paying for the IP rating mostly if you're not running liquid coolant I would be happy with Cherry or Happ microswitches simply because arcades have used them since the 80's pretty much unchanged design and they have proven themselves to be ultra reliable over a long time and arcade machines were abused! They are certainly not suitable if your cutting under running liquid but they are so cheap 6 would cost the same as 1 panasonic and although the panasonic might be better the happ's or cherry's have certainly had a lot lot more real world testing as almost every arcade machine, including gamblers in the 80's, 90's, 00's and even today had/have either happ or cherry switches
Last edited by Desertboy; 08-06-2017 at 10:41 AM.
http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm
If you didn't buy it from China the company you bought it from did ;)
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08-06-2017 #275
True. At the moment I'm not sure if Ill be using coolants. Ive been thinking to get some form of metal / material bellows system in place, id be more comfortable to have them IP Rated, just in case. Suppose in the overall costs of the machine, paying £50 for switches is not really an issue.
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The Following User Says Thank You to Chaz For This Useful Post:
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08-06-2017 #276
Ok, fundamental question.
Is it normal or acceptable to use the same switch (mechanical or proxy) for both home and limit? I dont understand how the machine would know if it was simply sent home or it actually needs to stop as its a limit. Is there logic that says 'ref all' and it goes home but if its hits the home limit during any other movement (manual or programmed) that the machine will then stop?
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08-06-2017 #277
That I didn't know I built an arcade cabinet to Jamma specifications including the correct jamma wiring loom, sanwa joysticks & cherry microswitchs and a pirate 200 in 1 cart but I cannot remember how I wired it up now lol it was over 10 years ago, the cabinet still works fine after a hell of a lot of abuse, sits on a campsite my mate owns in Luxembourg on free play.
Arcades could take a hell of a lot of abuse but there was 1 type of game that killed the microswitchs in an insanely short time, Daley Thompson's Decathalon type games lol.
I would think that if you got even 1% of the performance out the microswitches (100,000 presses) unpowered it would last any cnc machine well over 10 years as you don't really trigger the limits much a day even if you're using the machine 24/7.http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm
If you didn't buy it from China the company you bought it from did ;)
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08-06-2017 #278
I know how it works on grbl (Arduino cnc solution) when it's doing a home it ignores the limit so doesn't go into shutdown mode. If it's not homing then it treats it as a limit switch and shuts everything down until reset G code is sent.
I'm sure Mach 3 treats it the same way (I think LinuxCNC does)
If I were you though I would fit another set of limit switch further back that trigger an E stop as well as extra protection! I can maybe help you source high quality IP64 rated microswitches I have a friend who services and repairs 4 poster lifting ramps for steam cleaning bays I'll give him a bell see how much he would charge for new ones if they're cheap enough I'll use them lol.Last edited by Desertboy; 08-06-2017 at 11:12 AM.
http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm
If you didn't buy it from China the company you bought it from did ;)
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08-06-2017 #280
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