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Author Topic: Spindle and Limit switch  (Read 8420 times)

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Offline Hood

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Re: Spindle and Limit switch
« Reply #10 on: April 05, 2011, 07:28:39 AM »
I used optical switches on X Y and Z for Home and limits. One switch does both pos, neg and home for each axis.
I bought them from some place in the USA but they no longer make them, the Z I made myself along the same lines. Basically its an alu box with a rod going right through from side to side and there is a flag on the rod inside the box. Either side of the flag is a spring to hold the rod central. The rod as I said protrudes either side of the box and this is what gets pushed by the posive and negative stops on the axis thus moving the flag out of the way of the opto.

I am presently re-doing the Bridgeport and will be using Honeywell roller switches like this http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170602753301&ssPageName=STRK:MEWNX:IT
These switches are very accurate but I will also just be using them as triggers for my servo drives to then seek the index pulse on the encoder, thats the way I do it on my Bever NC5 mill and also my Computurn lathe.

Hood
Re: Spindle and Limit switch
« Reply #11 on: April 11, 2011, 09:44:25 AM »
Hood,
Thanks for the info on the rollers.  How did you enclose and mount your optical switches to protect them from coolant or chips?
Did you mount the optical switch under the table?

I have solved the problem for the z++ and z home shared optical switch. We put a scope on the switch and measured around 3 volts with noise. When we turned on the machine and vfd on but not activating the spindle the voltage dropped around 2.5 volts with noise. When we activated the spindle the voltage dropped more and had noise still.  So we replaced the shielded wire with a larger wire with a better shield. It stayed around 5.14 volts when machine and vfd was powered. When the spindle was running we found that the voltage dropped to around 4.85 volts.  The switch seems to work great now. However the only concern we have now is mechanical vibration getting into the mechanical switch on the z-- limit. It is somewhat touchy at the moment, we will try to adjust the debounce to see if that helps that switch.

I will post pictures this week of our cabinent that holds the power supply, drives, wiring,...etc. Right now it is a wiring mess and quite embarassed of how it looks at the moment. I will clean it up a bit. I am in no means any good at electricity and thats why I refer myself as we. As I have a partner in helping me with the electricty part of the machine. I just knew what components that was required to retrofit the machine and the communication side of things. I thank all of you for your help.

Right now we are trying to mount an encoder on the spindle to inform mach3 of the true rpm so the vfd can tell the spindle to adjust to what I have programmed. We are researching the encoders to find out what pins do what . The are are 23 pins on this encoder from litton. I am also going to mount home switches on the x and y axis. We are using the optical switches from pmdx. Very confused on where to hide the switches so no coolant or chips will interfere with the optical sensors.


It truly amazes me how cost effective it is from doing a retrofit yourself.  Let alone that if the machine breaks down that you should be able to diagnosis what is wrong. So you don't have to pay the machine technician $200 /hr to fix the machine.  

A littl about myself and what our shop composes of:

I am 29 years old and work for my old man. we have a great Father and Son relationship. Hard at times, we have our battles as you could imagine if any of you worked for your old man. Any how our shop is a small shop consisting of 10 people.  They all work full time and are great employees, none of which are machinist, they are basically button pushers who know how to measure dimensions on our parts.  We do work for the powdered metal industry.  Basically powdered metal is a process in which consists of pressing a part with powder and pressing it to a shape that is required by the buyer. The pressed part is then sent through an oven which sinsters the part ( melting the particles so they fuse together). Once that is done the part is near shape and sent to us and other companies that do machining like us.

Our shop consists of about 7 bridgeport mills, 6 mori seiki lathes, and 1 Kira pallet machine.  We have various forms of geared and manual equipment.
What made me interested in retrofitting was the day we bought our Kira Production center and I opened the door to the drives . It amazed me in what little was in the cabinent that contained the drives. I then did research to see what was out there as far as retrofit kits. I came acrossed ajax and other vendors that made an older machines capable of cnc. The packages were quite exspensive, so I did more research and came acrossed mach3. I read the forum for months interested in what you have all accomplished in your builds. Then I finally talked to my old man into buying a bridgeport that did function but not great with the current original hardware, in which I mean the boss control. The boss control is nice but what is not like by me and others that use it, is the fact that the transistors blow from some god awful reason on a weekly basis.  It took time for me to convince my old man that I could do this, that there was a forum of guys like me interested in what they could possibly do with there imagination with the support of others that have succesfully done it. After months of researching I came acrossed Hoods retrofit on his bridgeport. I used his retofit as a foundation for mine. So once I was comfortable with what was shown on the forum I went and bought drives and various other equipment to start my build. I will post with pictures and info of what I used shortley this week. I thank you Hood and all of you on this forum for your help. In no means could I have ever accomplised this myself.

Offline Hood

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Re: Spindle and Limit switch
« Reply #12 on: April 11, 2011, 02:04:10 PM »
Here is a pic of the X limit switch.
Hood
Re: Spindle and Limit switch
« Reply #13 on: May 17, 2011, 09:43:03 PM »
Hello, I had a similar problem, when I turn on the spindle some limit switch is triggered. I solved the problem separating the 220 Volt spindle cable of the limit switch cables inside the cabinet. I have a PMDX126 controller and all my limits and home switchs are proximity switch.
Lorenzo
« Last Edit: May 17, 2011, 09:46:45 PM by lorenchio »

Offline Jackal

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Re: Spindle and Limit switch
« Reply #14 on: May 31, 2011, 10:04:55 PM »
lorenchio,

Could you tell me more about your set-up? I have the 126 board, and am in the process of wiring for   limit switches. It would be nice to have a similar machine with the pmdx 126 board  ( proven working ) to copy this from. My switches will be mechanical, like the one Hood is using . Either Omron, or Honeywell brand.

Thanks a lot,

JAckal
« Last Edit: May 31, 2011, 10:07:42 PM by Jackal »
Everything is bio-degradable if you run over it enough with a lawnmower.
Re: Spindle and Limit switch
« Reply #15 on: April 11, 2013, 07:09:28 AM »
wow, i have the opposite problem. When i trip the upper Z limit switch by jogging it upwards. Z will stop jogging when it trips limit, but then the spindle starts to jog!?!