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Upgrading Benchman VMC-5000
« on: April 13, 2011, 07:33:59 AM »
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

Offline Hood

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Re: Upgrading Benchman VMC-5000
« Reply #1 on: April 13, 2011, 07:49:17 AM »
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
Re: Upgrading Benchman VMC-5000
« Reply #2 on: April 14, 2011, 04:29:12 AM »
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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Re: Upgrading Benchman VMC-5000
« Reply #3 on: April 14, 2011, 08:37:28 AM »
Looks like a nice wee mill :)
Hood
Re: Upgrading Benchman VMC-5000
« Reply #4 on: April 14, 2011, 08:39:39 AM »
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


Offline Hood

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Re: Upgrading Benchman VMC-5000
« Reply #5 on: April 14, 2011, 08:42:53 AM »
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
Re: Upgrading Benchman VMC-5000
« Reply #6 on: April 21, 2011, 06:55:07 AM »
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.
Re: Upgrading Benchman VMC-5000
« Reply #7 on: April 21, 2011, 07:32:12 AM »
Won't the whale3 limit you to 2500rpm with those motors?
Re: Upgrading Benchman VMC-5000
« Reply #8 on: April 21, 2011, 08:04:07 AM »
The old drivers have the same output voltage as the whale, so it shouldn't be a problem. Or are we missing something?
Re: Upgrading Benchman VMC-5000
« Reply #9 on: April 21, 2011, 08:47:00 AM »
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.
« Last Edit: April 21, 2011, 08:49:28 AM by jrobson »