Prototrak CNC conversion help !

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Refuse1

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I recently bought a Bridgeport at an auction. It came with a Prototrak system minus the monitor/control panel.

The ballscrews/drive motors ( X & Y) and main control box are there. I do not know if these motors are functional or not.

I am wondering if I can adapt another control system to use the Prototrak motors?

I know exactly nothing about CNC or Prototrak so please type slowly so I will be able to understand !

Any help you folks can provide would be greatly appreciated.

Jeff
 
Last edited:
astjp2 said:
Contact is guy, he probably has the right parts you need. That is a nice machine, don't cobble some crap together and think you are going to make it work as good. Tim

Its a small local business.

https://www.facebook.com/APGProductsInc
Click to expand...



astjp,

Thanks for your insight but I have seen quite a few CNC machines built by the members of this forum that I don't consider cobbled or crap.

I guess what I was really looking for was if anyone here might have knowledge of whether the Prototrak motors could be run by another type of control system. I don't plan to make a living with this machine so I am thinking I might be able to learn about CNC and utilize some of the existing hardware.

Does anyone have any experience with these motors ?

View attachment 66493

View attachment 66492

Anyone know how I could test them to see if they are functional ?

Thanks !

Jeff
 
Yes, a Mach 3 or similar controller can be configured to run your ProtoTrak motors just fine.
 
Refuse1 said:
astjp,

Thanks for your insight but I have seen quite a few CNC machines built by the members of this forum that I don't consider cobbled or crap.

I guess what I was really looking for was if anyone here might have knowledge of whether the Prototrak motors could be run by another type of control system. I don't plan to make a living with this machine so I am thinking I might be able to learn about CNC and utilize some of the existing hardware.

Does anyone have any experience with these motors ?

View attachment 66493

View attachment 66492

Anyone know how I could test them to see if they are functional ?

Thanks !

Jeff
Click to expand...

your attachments don't work please upload the photos
steve
(" cobbled together cra* " owner :roflmao:)
 
These look like conventional Brushed DC motors with shaft encoders. You can determine if this is the case by analyzing the cable structure. Now there are two cables, so which one is which? The one by the back of the motor is most likely the shaft encoder cable, so feel free to ignore this for the moment.

The motor cable will have either two or three wires. If there are two wires, it is definitely a brushed DC motor and all you need to do is apply a voltage to the terminals to see it moving in one direction (reverse the connection polarity and the motor will move in the opposing direction). I would do 12V just to be sure, but 24V could work as well (really, any voltage should give you some motion, but the speed will be directly proportional to the voltage you apply). If you have H bridge drivers (which I am thinking you most likely don't) then you can run all sorts of tests.

If you see three wires, then it is either a 3 phase BLDC or a brushed DC with a GND connection. I doubt it is a BLDC, though, because I can see the brush terminals on the pictures. Chances are the three wires will be RED, BLACK and GREEN. In this case, the GREEN is the GND/NEUTRAL terminal and you can ignore it for your testing. The ones you will want to try on are the BLACK and the RED.

To use these motors with MACH3 you will need a SERVO controller which can take STEP inputs and generate the servo positioning PWM control. I bet there is a ton of them out there, although the reality is the great majority of users out there have done steppers. Steppers are way easier to interface to because you do not need the shaft encoders. But since you already have encoders, why not use them?

Once you find the STEP to SERVO controller/drivers, all you need is a breakout board, a MACH3 license and BAM! you have a CNC machine. It is that simple!

Good luck on your project!
 
Avayan,

Thanks for the input. They are 2 wire DC brushed motors and I tested them at 12 volts and they operate !!

Any chance you can give me any advise on where to look for the servo controllers ?

Is there a source that can provide the controller & breakout board ? I would assume that I will need a power supply too.....

Thanks again for the help.

Jeff
 
Hi Jeff,

Yes, you will need a power supply; good catch!

The breakout board you can find on a trillion places. They are usually around $25 or less. I even designed my own a couple of years ago and opened up an eStore but the volumes were so low I closed it down. Hence I won't be able to sell you one, but you can check some of the ones that come out from this search (on Google: CNC breakout board):

https://www.google.com/#q=cnc+breakout+board

Or on eBay, the same search:

http://www.ebay.com/sch/i.html?_fro...t=1&LH_SALE_CURRENCY=0&_sop=12&_dmd=1&_ipg=50

Do note the eBay search is only for continental US. You can change this on the Search settings or just start your own search.

I did a search on Google for CNC DC Servo, and found these guys: http://www.easycut.com/Servo.htm

I have never done the DC motor servo CNC implementation but a few months ago, a friend told me he was going to go this way. Not certain which controller he ended up getting, but I will definitely ask next time I see him.

Here is another place but I think the "low cost" is relative... http://www.lowcostcncretrofits.com/20ampservosystem.html

Like I said before, the great majority of people will be doing steppers, so DC motor Servo controllers are not as frequently found as the stepper ones.

Good luck on your search!
 
There is a couple more things to keep in mind when using servos:

1) BE VERY CARELFUL!!! A misconfigured or miswired servo motor can run awyay or cause some serious vibrations. Make sure your E-stop works.

2) Find someone familiar with servo controls to help you set up your gains for your controller. Getting this right is the key to good performance of a servo.

3) When selecting a controller, try to find one that offeres some kind of "Feed Forward". The Standard servo loop only responds to error, so more error=more tourque. But in order to keep you following errors small, you can also calculate the approximate required torque for the acceleration you're running and the loop now only needs to correct that estimate.


If you have friends in the area that are familiar with servos, please get them to help you out. I have been working with Servo Control systems at work for ~18 Years now, and even I still get some nasty suprises sometimes. And having a machine axis come flying your way and then (hopeullly) hitting the hardstop is NOT fun. It's also very hard on your poor machine. But it is not impossible either. I just think for your first foray into the world of CNC, steppers might be a better option.

Good Luck :)
 
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