Centroid Community CNC Support Forum

Hi, I have inherited CNC conversion project - adapting a Bridgeport Series 1 Model 2J2 to use an M400S "S-Function" Stock System from Centroid. The Bridgeport mill does not currently have any CNC modifications and I have not purchased any other components for this project. I am looking for input on what else needs to be/could be purchased to complete this.

Notes:
- If possible I would like to retain use of the existing manual handles of the machine.
- I would consider adding a VFD for spindle control but I don't think that is essential.
- I would like to keep the drive motors for the axes as compact as possible, ideally they could be positioned vertically to minimize the horizontal space that they take up. Are there any premade solutions that can achieve this?

Milling Machine Information:

Bridgeport Series 1 Model 2J2
Bridgeport SN: BR267102
Bed size: 48" x 9"
The spindle drive motor is 3 phase, 2 HP
The mill currently has a Sony LH31A-2 magnescale read out for the X and Y axes.
Current Power Feed: Type 150 Servo Feed from Servo Products Company

Centroid kit serial number or system ID number:

Model: M400
Serial #: 104882
CNC Control Board: ALLIN1DC
Motor for XYZ axis drive, Model No: GM4030-41
Software version: CNC12 Mill Pro

What should I look at purchasing to complete this CNC conversion?
- Ball Screws: Looking at Rockford Ball Screw Bridgeport kits, part numbers BRP-2248PF and BRP-2209PF would seem to be what I want. Is that correct? Other vendor suggestions?
- I see that the motors that come with the Centroid kit have encoder wires so that should provide closed loop feedback without using the existing magnescale readouts. As long as the magnescales don't get in the way am I able to leave them in place and use them for manual machining?
- Other components, any suggestions?

Link to the photo album -

Thank you

remoteMachinist wrote: ↑Wed May 14, 2025 6:35 am Hi, I have inherited CNC conversion project - adapting a Bridgeport Series 1 Model 2J2 to use an M400S "S-Function" Stock System from Centroid. The Bridgeport mill does not currently have any CNC modifications and I have not purchased any other components for this project. I am looking for input on what else needs to be/could be purchased to complete this.

Hello and welcome to the forums!

I don't know all the specifics of retrofitting a Bridgeport but there are other users who will be able to help with that. I can answer some of your more general questions.

Notes:
- If possible I would like to retain use of the existing manual handles of the machine.
- I would consider adding a VFD for spindle control but I don't think that is essential.

You will be able to keep using the machine manually with the ALLIN1DC system you have. Encoders on the motors will keep track of the position so it is easy to switch from manual to CNC machining. I remembered reading something on how to set this up or use it but have not found it yet.

It is not difficult to add a VFD later if you find that you need spindle speeds controlled from the gcode.

- I see that the motors that come with the Centroid kit have encoder wires so that should provide closed loop feedback without using the existing magnescale readouts. As long as the magnescales don't get in the way am I able to leave them in place and use them for manual machining?
- Other components, any suggestions?

As long as the magnescales do not get in the way, you can leave them in place. I've seen several installations that keep the existing DRO system and also use the DRO in CNC12.

Hiwin also makes good ball screw retrofit kits for Bridgeports and clones. As previously mentioned, no problems going manual as the drive encoders provide position feedback. As simple as hitting the Axis Free button on the operator's control panel.

Your bigger problems will be attaching the drives to your axis. Elrod Machine used to make some great castings for X and Y as well as an excellent quill drive for Z. They have gone out of business, but Servo Products purchased their IP and supposedly sells those parts now.

Getting in touch with Servo Products is problematic. Email doesn't work; repeated calling is your best bet.

alternative path is to find a CNC knee mill and install the Centroid Controller on that machine. keep the manual machine manual or sell it.
such as https://www.centroidcnc.com/bridgeport_ ... dx-32.html
or
https://www.centroidcnc.com/bridgeport_boss.htm