Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: technicrdd on November 20, 2006, 02:05:28 PM
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We are having trouble with homing switch failures due to overtravel before the axis backs off. Have reset the homing speed to 10% . Would like to know if there is a way to set the backoff distance from the limit switch when the switch is actvated. The manual section 5.7.1.1 itells how but have not been able to stop the axis hitting the limit switches and causing failure due to overtravel. the switches are small microswitches with a lever arm as the actuator...TNX
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Do you have the "Softlimit" option selected ?
That will slow the axis down to a crawl just before contact.
After starting the machine be sure and do a reference all first.
I started out with those small switches too.
Amazing what a 460 Ounce servo can do to em ;D
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Another thing, non contact switches would solve this also. I prefer proximity switches. You should also be able to use some cheap magnetic switches like the ones for burglar alarms.
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Do you know if they have those proximity gizmo's that are water proof ?
Must investigate,
Next project is Flood coolant system .
Splashy Splashy !!! :P
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From what I understand you seem to have seperate homing and limit switches and they must be close together. If this is correct can you move the homing switches along a bit so they are not so close to the limits, this may help.
Hood
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Yoda
I use optical limits, I have the ones from Industrial Hobbies on the X and Y and I made my own version up for the Z. They are all enclosed and are deadly accurate, I had a DRO on my mill and I homed time after time and 99% of the time my DRO read 0.000mm the other 1% it would be 0.005mm.
Worth a look and if you decide to make your own up its a nice wee project machining the box ;)
Below is a pic of my Z Axis limit
Hood
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Nice
I ordered my X/Y kit from Industrial hobbies (Over 2 years ago) and the optical limits werent included.
Ive sent him several emails asking what a pair would cost but never got a reply.
Oh well.
I can make some up in time.
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Yes, coolant proof is no problem. They make all shapes, sizes, NPN, PNP, etc.
http://web2.automationdirect.com/adc/Shopping/Catalog/Sensors_-z-_Encoders/Inductive_Proximity_Sensors/12mm_Round_(AM-z-VM1-z-PMW_Series)/Standard_Sensing_Distance_(AM1_Series)/AM1-AN-1A
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Yoda
I have just had a look on his site and I dont see any limits listed, I bought mine about 2 or 3 yrs ago and they were $50 each if I remember correctly. They are nicely made and well worth the money IMO, but if you dont count your time making them you could get the components for probaly under $20.
Hood
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We are still having a problem with the limit switches being broken when the axis go to home, they just stop and appear to not back off the switches and require us to manually move the axis from the switches to let us run a program. We are using the limits as the home position and limits. when the switches are tripped they initiate an EStop. I think we are not set up correctly up and do not know what the best solution is. I read the section on the soft limits but cannot realy understand how this setup is implemented. Can order and install optical or prox switches but will take time to order and install. We need to be able to continue running until the switches can be replaced.
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can you take a screenshot of your homing and limits page, also one of your Inputs page, that way we can see if you have them set up correctly. s n example heres mine.
Hood
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I need help--I am not familiar with the use or how to do a screen shot can you give me the directions? We are trying to recoed the setup screens for a setup to Mach3, I assume that a screenshot would allow us to get hard copies of the setups...TNX
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A screen shoot is just a picture of your screen just like the ones below your last post. Here is a link. Download the free version. It will take pictues of your whole screen, designated area, or active screen. Set up a folder for your pics to be stored in and save them as jpegs.
http://www.wisdom-soft.com/products/screenhunter.htm