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snowman
12-17-2005, 01:34 AM
what are they?

I do not like the little mini-switches with the arms.

-Jacob

Evan
12-17-2005, 01:44 AM
Optical switches with covers to keep the krap out. These are for my mill project. It cost about $20.00 for 16 of them. They require 5vdc, gnd, and have a 5v/0v output when interrupted in the gap. They have built in hysteresis so then don't jitter when just barely made.

http://vts.bc.ca/pics/oswitch.jpg

snowman
12-17-2005, 02:07 AM
where'd ya get em? not Ebay I hope http://bbs.homeshopmachinist.net//smile.gif

I need to place a big mouser/digikey/newark order cause I need some other parts too.

-Jacob

[This message has been edited by snowman (edited 12-17-2005).]

Evan
12-17-2005, 02:10 AM
I got them here. Scroll down the page a bit. They were $25.00 not $20. Nice guy to deal with, no problems. The opto switches need an external 1k resistor to limit current to the LED side. The output is TTL compatible.

http://www.lasermotion.com/Servo.html

snowman
12-17-2005, 02:17 AM
Ok, it's not as much a "switch", as it is a phototransister and IR photodiode mounted in a nifty case.

Thanks!

-Jacob

Milacron of PM
12-17-2005, 05:46 AM
I need a rocker arm type limit switch for the Z axis of a Bridgeport Series II mill. They used one NC switch for both up and down limits, so it's a double pole type and therefore difficult to find a used equivalent. New it's $125 and up depending on distributor !

I would just repair the current switch but the previous owner saw fit to discard some of the internals and straight wire it http://bbs.homeshopmachinist.net//rolleyes.gif

John Stevenson
12-17-2005, 05:53 AM
Don,
Picture ??
I have scrapped a few of these and have some bits.
Are you in a rush as I go away tomorrow until new year.

Sir John

PTSideshow
12-17-2005, 07:51 AM
Here is another source for things electronic and other.They are on the web and easy to deal with and the price goes down as the quan goes up. All Electronics.
http://www.AllElectronics.com/


------------------
Glen
Been there, probally broke it doing that

Mcgyver
12-17-2005, 08:20 AM
another cool 'no moving parts' way is with a hall effect sensor and rare earth magnet. expoxy the sensor (like a transistor) in a non magnetic tube or such and cement the magnet to the moving part, when they are close the sensor conducts making a closed circuit

Dawai
12-17-2005, 10:34 AM
Are you ready?

RF or Hall effect limit switches are sensitive to all outside interference. Seen a woman lose her hand in a punch press, the "so called electrician" replaced the limit with a RF type switch. You could tap the switch with a screwdriver and it would cycle the machine, no longer being on top dead center..

Optical switches are a bad choice for any machining enviroment with coolant or other chips. Unless you want to cable drive them? or put them on the ceiling away from harm.

Bite the bullet, buy some lever-arm quality allen bradley or Square D, or Cutler Hammer off ebay. Your repeatability, desired reliability depend on them working in exactly the same place everytime, time after time, after time. You can cheap, buy one switch and put two activators on each axis like my bridgeport.

I used to think, well you don't ever need the end limits and the software would catch it.. yeah right.. Don't depend on software.

http://www.micom.net/oops/WindowsPanel.jpg
"I wonder what they were thinking?" It is cheaper to program a button in Visual basic than to buy one.. I do it all the time.. but you want some buttons to grab control back from bills mistakes..

Ohh, if it is a toy, go ahead and use toy switches, otherwise you want industrial hardened.

Leigh
12-17-2005, 11:56 AM
Just a comment:

When it comes to safety equipment, including limit switches, simple and mechanical is definitely the way to go. Sure you can program something to read a sensor. But would you trust your life to windoze?

------------------
Leigh W3NLB

Evan
12-17-2005, 12:32 PM
I worked on equipment for 23 years that used every possible type of limit and position sensing switch in one of the nastiest environments possible, the inside of a photocopy machine. There isn't anything that contaminates as well as micron sized electrostatically charged jet black powder. Also present is ozone and the worst is fumes of silicone fuser oil, much worse than cutting fluids because of the incredible tendency to migrate. Some of the machines I used to work on had as many as 200 various limit, position and motion sensors and encoders in one machine.

Mechanical switches like cherry or micro are ok but they always eventually fail and the repeatability is poor plus they aren't perfectly sealed. Oil and other fluids will creep in and kill them. For power switching the contacts eventually burn and for signal switching there is no self cleaning action even if they are self wiping. They are extremely poor for signal switching.

Hall effect sensors are excellent but tend to be pricy. They can have repeatability issues caused by external magnetic field changes and usually have large hysteresis. Opto switches are the best compromise in most situations. They need to be mounted in a way that prevents contamination. This isn't usually difficult as they can be actuated by many means and don't need to be in the actual dirty area. Various simple levers and rods can be used to transfer the motion to the switch and keep the switch out of the crap.

On my mill the switches will be away from the chip and coolant area and will be in sealed housings with a simple spring loaded rod operating through a metal wall to interrupt the sensor. Optical sensors are cheap and very reliable plus very precisely repeatable.


"But would you trust your life to windoze?"

Absolutely not. I'm going to use Turbo CNC in DOS.



[This message has been edited by Evan (edited 12-17-2005).]

Milacron of PM
12-17-2005, 01:13 PM
John, it's a MicroSwitch model LSM2D

http://www.alliedelec.com/Images/Products/Small/642-2024.jpg

JRouche
12-17-2005, 01:36 PM
<font face="Verdana, Arial" size="2">Originally posted by D. Thomas:
it's a MicroSwitch model LSM2D
</font>


D, as much as you like Ebay http://bbs.homeshopmachinist.net//wink.gif I'm suprised you didnt just do a search. JRouche

http://cgi.ebay.com/HONEYWELL-MICRO-SWITCH-LSM2D-H-D-LIMIT-SWITCH_W0QQitemZ7559665046QQcategoryZ55833QQssPage NameZWD1VQQrdZ1QQcmdZViewItem

http://cgi.ebay.com/HONEYWELL-MICROSWITCH-LSM2D-NIB_W0QQitemZ7568324257QQcategoryZ55833QQssPageNam eZWD1VQQrdZ1QQcmdZViewItem

Milacron of PM
12-17-2005, 01:44 PM
Wow, JR, guess I'll be doing some "Buy it Now", huh ?

I did a search on eBay a few days ago but didn't bring up anything...maybe I typed in Microswitch as one word...dunno...

Anyway, thanks for the heads up !

Dawai
12-17-2005, 01:54 PM
DOn't type in microswitch, thou most of them have cherry type switches inside a dust-proof oil-proof housing, type in LIMIT switch.. Roller switch.. and any variation you can think, * and hope someone mis-listed them under.

There is always competetion for them, they are of course industrial and new they are overpriced to $120+ per switch.

I got sixteen for $35 about a year back but I need what I got left.

Milacron of PM
12-17-2005, 03:17 PM
<font face="Verdana, Arial" size="2">I got sixteen for $35 about a year back but I need what I got left. </font>

Note I said double pole type...these seem much rarer to find used in the larger size rocker type than the standard single pole type. I suspect the only reason the two LSM2D's are still on eBay and priced so high (not relative to new, but relative to the plethoria of good used single pole ones out there) is so few folks need one like that.

JCHannum
12-18-2005, 02:11 PM
<font face="Verdana, Arial" size="2">Originally posted by D. Thomas:
John, it's a MicroSwitch model LSM2D

http://www.alliedelec.com/Images/Products/Small/642-2024.jpg </font>

It has been several years since I ordered Micro Switches, but that series is modular and individual components were available for it. The actual switch is replaceable, and should still be available from Micro Switch dealers.

You can probably find it here; http://content.honeywell.com/sensing/prodinfo/basicswitches/

Dawai
12-18-2005, 06:38 PM
2900 ebay hits on limit switch... make sure you get the brad harrison cable or roller arm cause buying them locally is not cheap.. when they priced the cables for my 5 quadrature encoders were priced at $75 each, I cut the plug sockets out and installed $1 terminal strips.