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Offline mark4

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cabinet design
« on: November 19, 2013, 12:00:47 AM »
hi i upgrade mills usually bridgeport bosses with good results. now the question i have is cabinet design i am currently looking at a bridgeport with a heidenhain control usually an upgrade canidate has two cabinets i use one for computer and break out board control the other cabinet power supply and servo controlers i usually have/make a third cabinet for vfd drive. most if not all wires are shielded and grounded on one side also i use .1 uf caps on all inputs. now onto the question the machine i am looking at has one very big box on the right hand side and a smaller box in the back, the big box houses the original drives and the power supply, the little box houses the oiler and mister. the heidenhain computer is housed in the arm. i have my own box i will be adding to the arm however the computer will not be housed there. i am planning to put the computer in the big box. i have the option of making a power/drive box however i am looking at a very big box on the right and i could house all but the vfd in there i would house the vfd with the oiler and mister in the small box which would leave the power computer drives and bob. what i am woried about is em interference as drives can be noisy. on the other hand what do you do to shield for instance if i built metal dividers into the cabinet would this shield the computer from the drives. so do i build a third cabinet or dividers i would like to know if anybody has done this with good or bad results any thoughts or advise would be appreciated thank you mark cook
ps the driver will be dugong or vipers

Offline Hood

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Re: cabinet design
« Reply #1 on: November 19, 2013, 05:57:32 AM »
If you have things shielded properly there should not be a problem.
On most of my machines I have opted to use 24v for I/O as it is industry standard practice and for a good reason, it is much more immune to noise. I also used differential Ste/Dir signalling as again much more immune to noise. Doing this meant shielding was not really required on I/O although the low voltage signals such analogue inputs I still shielded. Previously I had to make up boards to convert to and from 24v or use a PLC to do it and also had to make up line drivers to convert the single ended Step/Dir signals to differential.
 Now however I am using the controllers from CS-Lab, they are much more industrial orientated and have 24v I/O already and for the Step/Dir models they use Differential signalling. On my latest retro I have used the analogue version of the CSMIO and I feel its got extra features that make it better even than their step/dir models but of course it requires your servo drives are capable of the normal industry control method, namely +/- 10v command.
Here is a short video showing the inside of the cabinet.
http://youtu.be/ppK0D6n5XPw

My computer itself I have housed inside of the control panel where I also have extra modules for the CSMIO so that I can connect my MPG and switches and thus having these modules local means I only have to run a CANBus cable back to the main electrical cabinet to hook to the CSMIO main unit.
Pic of that is below, this was before completion as the MPG module was not in place, also attached a pic of the finished control panel.
Hood

Offline rdean

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Re: cabinet design
« Reply #2 on: November 19, 2013, 07:37:28 PM »
Mark4 I too am building a new control cabinet for my next mill project.  It will contain all electronics, computer and three Allen Bradley servo drives.
Thanks
Ray

Offline mark4

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Re: cabinet design
« Reply #3 on: November 20, 2013, 10:29:26 PM »
hi
first looked at the cabinet Hood thanks looked clean and well thought out. however you are on a bigger scale than me i want to do a machine that big one day when i said big box i didnt mean that big. i am posting pics for size and comparison. i usually use 5 volts for my signals but am not going that far to the limit switches and drives and i shield every input and encoders. on the heidenhain contol pictured the encoders are sinusiodal and report to the heidenhain computer directly the drives get there signal from the same i dont think i can reasonably replicate this so i am going to retrofit digital encoders onto the servos and replace the drives with vipers or dugongs. i am planning to reuse the orriginal power supply with some mods. the more i look at the cabinet i think i will have to put the computer into a box i am building on the arm as i will run out of space this will also settle any interference issue. and as a side note have you had any interference problems with a vfd this machine i probably going to get a vfd now do you think i should put it in the big cabinet or the little cabinet with the oiler and the mister to compleetly seperate it or am i worrying to much about interference. the fourth pic is of a hurco mill i am compleeting right now the cabinet shown is how i usually lay out a power cabinet thoughts suggestions welcome. rdean nice box technomatic corp if i am not mistaken is your computer planed to be in a computer case inside the cabinet like mine or with computer components mounted seperatly inside also how do you plan to cool the cabinet. one more question for hood the machine you showed what kind of drives are they and what kind of signal do they take. most of the time i have to scrap drives because i cant talk to them now because of what you showed me maybe i can talk to some of them thank you
mark cook

Offline mark4

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Re: cabinet design
« Reply #4 on: November 20, 2013, 10:35:03 PM »
working on my pic posting skills

Offline mark4

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Re: cabinet design
« Reply #5 on: November 20, 2013, 10:35:37 PM »
working on my pic posting skills

Offline rdean

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Re: cabinet design
« Reply #6 on: November 21, 2013, 01:01:46 AM »
The computer components will be mounted on the removable back plate not shown.  The box, purchased locally, comes from Spain I believe as the label was cutup when I installed the monitor.  I will be installing cooling fan with filtered inlet air.
 
Ray

Offline Hood

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Re: cabinet design
« Reply #7 on: November 21, 2013, 03:26:31 AM »
I have not used VFD's for a long time, usually use servos for spindles now. However on my first retrofit (Bridgeport) I used a VFD and didnt have an issue when it was in the same cabinet, all wires however were shielded and also the VFD was a reasonable quality one, I have heard some of the cheaper Chinese ones can produce quite a lot of noise.
 Regarding my Drives, they are Telemechanique Lexiums for the axes and an Allen Bradley DSD for the spindle. They can accept Step and Direction but I have chosen to use them in Velocity mode with +/- 10v analogue control signal, the controller is a CSMIO/IP-A and it is, to put simply, the best controller I have used with Mach. I also have the Step/Dir version (CSMIO/IP-S) on a small lathe and it too is a quality controller but the IP-A has some advantages, even over it.
 Personally that is the route I would take with your machine, assuming the original drives are still ok. You would have to replace the encoders as the IP-A needs ttl encoders. I see CS Lab now sell encoders as well.

Regarding tight cabinets and noise, here is a pic of the Bridgeport cabinet when I converted it over to servos, everything is in that cabinet including the computer and controller.
Hood