Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: jab_814 on April 03, 2011, 02:38:04 PM
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Hey guys,
Its been about a year since I worked on my Bridgeport boss 6 retrofit.
My problem is when I start the spindle using MDI, my z++ limit trips .
-My z++ limit and z home is shared by a optical sensor via pin 12 and normally closed.
-My z--, x++,x--,y++, and y-- is in series via pin 11 and is normally closed using mechanical switches.
- I do not have and x or y home switch yet.
When I home the z it homes correctly.
When I exceed the z++ limit it trips correctly
however, like I said when I start the spinlde via mdi through mach3 (T1S1000m3;) the z++ limit trips
I know its the z++ limit because when I deactivate the z++ in the inputs page, the spindle runs and does not trip a limit.
I do use a vfd in my machine.
Has anybody have had this issue, thanks Joe
I plan to finally post pictures of my design shortley thanks to all those who have helped me (hood).
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Do you use shielded cable for your limit switches.
If not, this could be the problem.
VFD generate a lot of electrical noise.
Jeff
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You could also try a value of 2000 in the debounce setting in general config, on the top right of the page.
Jeff
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Thanks Jeff,
Yes I use shielded cable.
I have tried the debounce also.
If i eliminate the z++ as a limit in the inputs page I do not have a problem, wondering if it is a software problem in my control.
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Do you see the led in the diagnostic page.
How close are the Z home switch and the Z++ switch from each other.
Does it trigger at the moment you start the spindle.
I've seen it when the spindle start, there was a very very little movement of the head, enough to trigger the limit switch.
The point where the switch is open or close when homing is maybe 1/1000 of an inch so already had this problem before.
Jeff
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Could you have duplicate pins set, ie you have the same pin configured for your spindle as you have for the limit
Hood
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Hood I will check to rule that out !
Jeff I have tried to activate the spindle away from the home switch and limit, the quill is halfway down
Let me rephrase that, my z++ limit and z home is a optical sensor ( they are the same switch) on pin 12.
So I have only a mechanical limit for z-- at bottom and a optical sensor at top for both limit and home.
Joe
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Hood I have checked my pins in mach 3 under motor settings. the spindle outputs are 16 and 14 for step and direction.
I am also using the usb from the computer to power the bob and spindle board.
I have also used straight connections from the power supply by cutting a molex connection.
I went to usb from the molex to see if that would make a difference, it didn't.
Should I have a dedicated power supply for 5 volts, could this be causing a problem?
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Dont think power should be the issue.
What kind of switch is it? If a mechanical switch is there a chance that vinration is the issue?
Hood
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It is a optical switch, I am using it to control the Z++ limit and z home via pin 12
I have a mechanical switch on z-- limit, and vibration does get into the switch at times, which i will have to investigate a little further after I am past this task.
Hood I have noticed in other threads you have built a beautiful bridgeport retrofit. May I ask, did you just use the mechanical switches as both homes and limits.
Or did you use the mechanical switch as a limit and put a more accurate homing sensor such as a slotted optical sensor. If so how did you mount the optical switches under the machine for the x and y axis. I bought and use pmdx slotted switches for my machine.
Thanks
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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
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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.
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Here is a pic of the X limit switch.
Hood
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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
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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
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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!?!