Limit switch ???

[turmite]

I have a limit switch that persistently trips during a program and requires me to stop the program, re-reference etc. I need some help in trouble shooting this thing. Following info might help:

Mach for the controller

Micro switches for the limits and home combined. A total of three dual purpose switches.

Mach does not indicate which switch is tripping.

Switch wires are shielded and grounded with the only bare area just before the screw terminals.

X and Y switchs are mounted upside down with the plunger hanging down.

Z switch is mounted with the plunger horziontal.

Wired for nc.

Due to Mach allowing it, Z and Y are using the same pins but when referencing the axis reference at different times.

Limit are set so any switch will Estop the machine.


Any help would be appreciated. I am at a loss and this is costing me precious time.

Mike



General Purpose Snap Action Switch, Actuator Roller Plunger, Panel Mount, Maximum Operating Force 8.8 to 12.3 Ounces, Maximum Pre Travel 0.016 Inch

[UKRobotics]

Not wanting to hijack your thread or anything but I have a mach/limit question which you might be able to advise me on....

Is it possible to use a single input for both x+ x- and x home ?

[pminmo]

A couple of points. How much current do you have flowing throught the limit switches? S/B 5ma or more. Do you have a value in mach for debounce?

[turmite]

Originally Posted by UKRobotics Not wanting to hijack your thread or anything but I have a mach/limit question which you might be able to advise me on.... Is it possible to use a single input for both x+ x- and x home ?

Uk I am not concerned with thread content if someone needs help!

How well do I know the feeling of needing help.

With Mach software you can use both the +- on one switch and in fact I have my y +- and my z+ all on the same input.

Mike

[turmite]

Originally Posted by pminmo A couple of points. How much current do you have flowing throught the limit switches? S/B 5ma or more. Do you have a value in mach for debounce?

Hi Phil,

I had 5vdc running through the switches with a 2000 debounce set it Mach.

I posted this over on both the Mach forums and Mariss had mentioned using a .1uf cap across the switch in an earlier thread and someone brought that to my attention. So......I installed the caps and haven't had an interrupt since, including when I should have!

I have the money coming tomorrow to buy top notch switches and will be replacing them as quickly as possible.

Mike

[pminmo]

I was going to suggest a cap, but if you didn't have any debounce set, that would be the first option. Regarding 5V on the switches, there is a resistor some where in the circuit to limit current. It needs to be 1K or less.

[something2do]

Originally Posted by turmite I have a limit switch that persistently trips during a program and requires me to stop the program, re-reference etc. I need some help in trouble shooting this thing. Following info might help: Mach for the controller Micro switches for the limits and home combined. A total of three dual purpose switches. Mach does not indicate which switch is tripping. Switch wires are shielded and grounded with the only bare area just before the screw terminals. X and Y switchs are mounted upside down with the plunger hanging down. Z switch is mounted with the plunger horziontal. Wired for nc. Due to Mach allowing it, Z and Y are using the same pins but when referencing the axis reference at different times. Limit are set so any switch will Estop the machine. Any help would be appreciated. I am at a loss and this is costing me precious time. Mike General Purpose Snap Action Switch, Actuator Roller Plunger, Panel Mount, Maximum Operating Force 8.8 to 12.3 Ounces, Maximum Pre Travel 0.016 Inch

I just changed my drivers to full step and moved my speed up 50%. Now miine is doing the same almost like when it should loose a step it trips the limits .Running steppers? I change the speed back it runs a full program.

[turmite]

Originally Posted by pminmo I was going to suggest a cap, but if you didn't have any debounce set, that would be the first option. Regarding 5V on the switches, there is a resistor some where in the circuit to limit current. It needs to be 1K or less.

Yep Phil I got the 1k resistor in too. I plan on installing either optical, inductive or capacitive. I have to get some advice first. The optical worries me a little due to this being a wood and foam machine that does create a lot of dust and very floaty shavings with the foam.

Any advice?

Mike

[turmite]

Hi something2do,

yep I'm running steppers. Running at X10 micro steps. After installing the capicators I can't get the thing to trip other than touching a switch! Right now my switches are not repeatable enought for me. Back when I used full step I could literally touch off the home switches and go anywhere on my 5ft by 9ft table and many times and I wanted to repeat the process and it would always be the same. Since I have gone with Mach and Gecko using the micro steps I can't do that. Then on the other hand I had to change my switches too and I'm sure that is what the problem is.

Mike

[pminmo]

What size cap did you use? Do you have a drawing of how your switches are wired, resistor, LPT ?

[turmite]

Phil no drawings. The caps were .1uf 50 or .50 something or other. I have the extras at the shop and don't have access to them at the moment.

Mike
ps the caps were the only .1uf that Radio Shack had in stock.

[pminmo]

With the caps installed you may want to really reduce the debounce time in mach. With a 1K resistor and a .1uf you should be less than a couple of hundred us respose to an open switch. I wouldn't think that would give you such bad results with a switch opening.