My son has a Bridgeport Ez-trak CNC series 1 mill dating from 2002 which is fitted with an Accurite cnc controller and MTS074-44 servo motors. It looks like the servo motors have an encoder fitted, there are also glass scales which feed into each servo assembly.
We would like to use this machine with Mach3 which we also use on a Seig KX3 with great success.
As it looks like the servos are self contained is it possible to use a breakout board or something like that to connect to a pc and Mach?
Or has anyone has some experience of the machine and is able to point us in the right direction or have we got to change the servo motors for steppers?
Can you give more info on the servo amps. I think the Motors will be SEM with that code and high possibilty the amps will be either Anilim or Bosch.
If not can you post pictures of the wires and connections going into the amps.
There's high chance they are Analog amps in which case you'll need external controller that outputs +/-10v analog signals.
The fact it has Glass scales suggests what you think are encoders are actually tacho's. The glass scales are providing the position feedback. This also backs up the +/-10v possibilty. Tacho Also suggests they are Brushed DC servos which are often fitted to older machines
Last edited by JAZZCNC; 02-07-2016 at 07:44 PM.
Thanks for the reply. Yes they are brushed servo motors and made by SEM. Inside the display unit it looks like there is a breakout board and then further boards, seems to spread everywhere!
Since posting I've read more and it seems a better way would be to replace the originals with NM 34 stepper/servo motors asnd use an appropriate breakout board so thats what we're considering doing?
Yes there will be board but it's not forced to be Breakout board in the same sense as what your thinking. It will I/O board that's designed to work with the Accurite controller. Similiar to this below. This can't be used as BOB like what your thinking.
Regards Replacement I would think very carefully about what you use and all that goes with each. ie:
Steppers are simple and easy to impliment and can be if required (but wouldn't) run direct from parallel port. However they do not compare to DC Servo's so you'll take a big hit on performance/smoothness/power.
AC Brushless servo's which you'll most likely repace the DC Brushed ones with will be direct replacement and will perform equal or better. However then they cannot be run direct from PP because doesn't provide high enough pulse rate. This then means you need External motion controller to get full performance from servos.
That said even with Steppers you'd be best advised to fit external motion controller to get the best from steppers.
Another option If the drives and motors are working fine is to just replace the controller with Analog external motion controller designed for mach3. Like the excellent Cslabs IP-A which I personaly use or Kflop from Dynomotion.
Third option is to just replace the DC drives with Step/Dir drives and then you can use Standard setup.
The honest truth is that there's no cheap way to do this correctly. Yes you could just replace the motors with steppers and use the PP. But do this correctly still isn't cheap because large steppers are not exactly cheap also require drives that can accept high voltage which are not cheap. Then take into account the massive performance hit you'll take and potential hassle the PP can give. This to me would rule them out.
This approach is the old school way it was done because Servos where stupidly expensive and external motion controllers for mach few and far between. This is no longer the case.
Chinese AC Servos while still not exactly cheap are much lower in price than years ago and within reach of DIY. Put it this way you'll pay as much for large Stepper/Drive setup. You'll still need an external motion controller for mach because of pulse rate required but to be honest you'd need one for steppers to get the best from them.
If it was me and the DC Drives/motors are working fine then I'd just buy the IP-A controller and away you go. There's no Break out board required and it offers loads of I/O along with built in spindle speed control.
If at later date have any issues with drives/motors then replace with Chinese Servo/drives which accept both step/dir and Analog input.
See this Video I made showing the chinese servos/drives. It also shows the Cslabs IP-A and explains couple of things why I used it rather than Step/Dir version. (which I also own)
Last edited by JAZZCNC; 03-07-2016 at 10:42 AM.
Thanks for the comprehensive reply, Lots to consider there! Think the stepper/servo motor route looks most attractive as it would enable a 4th axis to be easily added--but we will see after we have thought about it a bit more.
I have been looking at some controllers recently that are reasonably priced and have up to 5 axis capability with rigid tapping too and they have not been too bad in terms of price. I am still trying to verify if they are legal in the EU though.www.emvioeng.com
Machine tools and 3D printing supplies. Expanding constantly.
Thanks for the reply. Yes it does seem a big step to make so many changes to the machine espacially as it works. We looked at an upgrade for the existing controller but it was very expensive and as we also have a Seig KX3 which runs Mach3 we are familiar with it. Havent decided yet but the Mach route was also give us options on adding more axis.
If was me and DC Servos/drives are working fine then I'd just go with the Cslab's IP-A. Doesn't get any easier just little rewiring and away you go and with top notch controller from Top company.
This type of upgrade is a no brainer, like Dean suggested. Everything could be ripped out and rewired in a day.. ~700 euro but you keep the good motors you have. Final result- a modern machine that will do 3d, 4rth axis and so on. Which otherwise could cost arm and leg. Then you could fit a stepper if you like for the additional axis.
He needs the Cslab's IP-A for those Dc motors but can that do step and direction for the 4th axis ?John S -
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