Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: J Borst on April 13, 2011, 07:33:59 AM
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Hello everybody,
We are students from the University of applied science of Amsterdam. We have been assigned a project to upgrade the Benchman VMC-5000 CNC milling machine from light machines corporation with Mach3.
The last couple of weeks we have been trying to figure out what kind of hardware changes we have to make to get the machine to work with the Mach3 software.
The ting is we sort of hit a wall in that we arent sure what our best course of action would be, at the moment we are thinking of ordering a breakoutboard from some place and put a interface print behind it that can supply a Industry standard -10V - +10V signal to the drivers. If this is the correct course of actions do you have any suggestions for a good breakoutboard and interface print.
What we have found out so far is that the machine has three servo motors from Litton Clifton precision, the specs of these motors are according to National Instruments the following:
Tc = Continuous stall torque
Ic = Continuous stall current
Vr = Rated Voltage
Tpk = Peak Torque
Kt = Torque Constant
Kv = Voltage Constant
Vmax = Maximum Rated Voltage
Series: C23
Model: C23-L50-W50
Size: N23
Max Tc (N-cm): 29,7
Max Ic (A): 1
Max Vr (V):
Tpk (N-cm) : 254,2
Kt (N-cm/A): 30,6
Kv (V/krpm): 32
Vmax (V):
Max rpm (rpm)*: 7396
They are controlled by a copley control 412 driver.
Here is a link to the datasheet:
http://www.copleycontrols.com/motion/pdf/412ce.pdf
The system is equipped with two limit switches per axis, the limit switches are normally closed.
There are also a couple of PCB's that we think provide the communication with the PC but we aren't sure about this since we don't have any schematics for these PCB's.
We got pictures from the machine if it would help I am willing to upload them.
Kind Regards
J Borst
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Pictures are always good as it gves and idea of what is being talked about.
You have a few options if you want to continue to use the +-10V one is the KFlop/Kanalog, another is the DSPMC and the last I know of is a Galil.
If you want to replace the drives then there are quite a few that accept step/dir and fit within your motors range. Gecko does some, the Whale or Dugong for www.cncdrives.com are a couple.
Hood
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Thanks for the quick reply, the Kflop/Kanalog seems interesting.
Here are the pictures of the machine I put them in a image shack album.
http://img846.imageshack.us/g/img0632h.jpg/
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Looks like a nice wee mill :)
Hood
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Thanks have to say it was a pain to get all the protective covers of to get to the electronics cause of the screws being "screwed".
Today we found out what kind of encoder is on the motor's, its a CP-550-1000-LD 2296.
According to the datasheet it sends out a square-wave.
Specs according to the datasheet:
power supply: + 5Vdc ± 10% @ 50 mA max (no load)
output format: incremental
cycles/revolution: 1000 std.
freqency response: 150 kHz min. @ 85 °C
linedriver output: 26LS31,EIA std. RS 422 and DIN 66259 compatible
overall length: L max = 39 mm
Datasheet Encoder.
http://www.opticalencoder.com/pdf/CP-500_size_15_hollow_shaft.pdf
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They should be fine whichever route you take. Easiest and quickest would probably get new drives and breakout, the KFlop/KAnalog route would let you keep your old drives but likely be harder to configure.
Price wise I dont think there would be much difference in either route.
Hood
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Its been a while since we updated this so here is a little update how our project is going. Maybe it will be of use for other people that are doing something similar.
How it stands we are leaning towards implementing new drivers and interface carts. We did a calculation and it is easier and cheaper to install than using the Kflop and Kanalog. The drivers we are thinking about are the whale3 drivers from cncdrives with the simple breakout board.
Beside this we have drawn a block diagram(post it later when i have access to a scanner) and out of the 10 blocks we only have 3 left to figure out what to do.
These are the power supply the spindle and the optocoupler.
We have been in contact with the manufacturer from most components and have been able to get datasheets for the motor and are waiting for a reaction about the transformers.
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Won't the whale3 limit you to 2500rpm with those motors?
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The old drivers have the same output voltage as the whale, so it shouldn't be a problem. Or are we missing something?
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The motor is Kv (V/krpm): 32, so 80 / 32 = 2500rpm, but I'm new at this and just wondering :)
Btw, kflop has some very good features like rigid tapping (true spindle to axis gearing) and instant feedhold that is not supported otherwise.
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Nice mill - looks like it has a granite column ???
I upgraded a Colchester lathe that had analogue drives, I changed it using Viper drives and new encoders.
Dugong look good and I'd give them a try on my next project.
ATB
Derek
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Hi, I have a benchman vmc4000 that I am considering converting to mach3 too. Please keep me updated on your progress. Thanks, David.
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I have many spare parts for these machines, so if there are any parts you need, let me know.
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Is a mach3 control going to be an improvement on the original benchman setup ?
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Can you run gcode or do you run a proprietary software with your Benchman?
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Sorry for the quietness we had a holiday for a week and have been busy setting up a list of needed components.
The status we are now at is finalizing the design and making a ordering list so we can order all the components in one go. We ran into a bit of luck to day since we finally found the manual for the original spindle driver and managed to figure out the in/output values of the transformers with the help of one of our teachers. Once we get the components in ill see if I can get some pictures up again.
And to answers some of your questions:
Nice mill - looks like it has a granite column ???
Its a look a like, not even sure its stone at all.
Is a mach3 control going to be an improvement on the original benchman setup ?
To be fair we don't even know what the original benchman setup was from what we understood when we started the whole software system wasn't even functioning.
Can you run gcode or do you run a proprietary software with your Benchman?
Mach3 will be running the machine via Gcode, the Gcode is created using a converter on invertor files.