Inserting an extension to the OEM extensions cables

Hey Moggy,

sorry I don’t have much time at the moment but hope this quick answer helps:

the references to the connectors used with the Onefinity and the information to make your own stepper cables can be found here, and the Application Info here.

Retrofitting better connectors

and adding shielding and PE wire to the stepper cables

Yes that’s right, I said that here, I was planning to do that. But I haven’t done it yet, and I’m not sure I will. For one thing, I haven’t put the machine into operation yet because I’m still waiting to move to have a bigger workshop where I can start up the CNC and some other machines.

Secondly, although I ordered a Onefinity Controller with the Onefinity CNC machine because I’m fascinated by the Buildbotics project (and the Onefinity controller is a fork of it), I had planned to use a different controller in the first place, so I’m not sure it’s worth the effort to upgrade the Onefinity controller to other connectors. The question is especially whether you just replace the connectors on the rails of the machine, which would become more reliable, especially when you have to sometimes unplug them, or whether you also replace the sockets on the controller housing. That would be a certain amount of work, because the stock Molex/Amphenol jacks are soldered into the pcb, and you can’t replace them directly with anything else, because neither the anchor points in the pcb nor the holes in the controller housing will fit other jacks in place. However, serious sockets that are led to the outside and are operated by the user should not be anchored to the pcb anyway, but are fastened with a nut in the housing (like the Phoenix Circular Connectors, M12 in this case)(see links below). It would be easy to solder the short wires of the new Phoenix M12 connectors into the solder points on the pcb after having removed the stock jacks, but it would mean you would have to punch corresponding holes into the controller housing, or use another housing with appropriate holes.

Also, after finding suitable Phoenix industry-grade connectors with gold-plated connectors in their M5–M12 Circular Connectors Catalogue (PDF), I added up the costs, and I come to more than 200 EUR, depending on whether I want to add an additional possibility to separate the cables also between X and Y, to be able to remove the X-axis as a whole (e.g. for transport). That’s an idea, but this will not work with the 3d-printed drag chains parts I’ve seen so far. I would have to design those, but as mentioned above, I haven’t even gotten to the place where I can set up the machine and get it running.

But anyway, I can tell you what plugs and sockets I have picked out for stepper motors though. However, I would not take 4-wire unshielded cable like found on the Onefinity stock cables, but always 4+PE+Shield (I buy cables from LAPP).

For the stepper motors, I picked the following connectors:

-S408x408-FJPG

Flush-type connector - SACC-E-M12FSK4PE-M16XL/0,2-1,5 Nr. 1425636
Power connector - SACC-M12MSK-4PECT-CL SH Nr. 1027474
Flush-type connector - SACC-E-M12MSK4PE-M16XL/0,2-1,5 Nr. 1425635
Power connector - SACC-M12FSK-4PECT-CL SH Nr. 1027476

Anyway currently, if you own a Buildbotics or a Onefinity Controller, I would tend to leave the stock jacks in the controller housing, but retrofit strain reliefs everywhere on the machine. This should first drastically reduce the susceptibility to errors, and secondly, I would make the cables for the Onefinity in any case with the length to measure and with the best craftsmanship (correct crimping insert) and avoid any superfluous connection.

If I were sure I was going to stay with the Onefinity controller and stock steppers, I would consider retrofitting gold-plated circular connectors at any point I might disassemble the machine in the future, whether for transport or for service and diagnostics.

Also if you think of replacing the stock steppers by closed-loop steppers or by servos one day, often these come with their own connectors.

2 Likes