[PhilCNC2020]

I bought a Bridgeport Series 1 CNC Machine planning on retrofitting it. Now I have the time and money to make it all happen, but I still need some advice. I am pretty well along at this point, and I have learned so much, but I want to hear what your advice is because maybe I'm doing something that is obviously wrong to you, but makes sense for me. So, this isn't the first CNC project I've done. I built a desktop CNC 3 axis wood router Dremel tool CNC with Mach3, NEMA 23s and a Gecko G540. Basically a educational starter project. I purchased a used Bridgeport Series 1 CNC for a price I couldn't pass up. The machine is in superb condition. It look like it wasn't used. It was purchased from a local university. I got it going pretty quickly with Linux CNC, a 48V 10A power supply and the same Gecko drive. It's nice and fast, but the z axis stepper motor was losing steps, had low torque, and the G540 drive isn't meant to drive a machine of this size. My end goal is to have this machine be fast and accurate, basically something that I could make some money with while I go to college. I don't want to use the original steppers just because one of them already seems to be having problems. Are there any good guides I should read through before I lay down my money and buy a power supply, break out board, motor drivers and motors? The person I bought it from included 3 servo motors that I think would be suitable for the upgrade. Are there any threads I should read of someone who went through a similar situation? I already had the machine making chips. I'm open to all advice but right now here is my plan. I

[Jim Dawson]

It depends on what servo motors you have. Some can be run with an aftermarket drive, but most times it's better to have a servo motor and drive that are a matched set.

[PhilCNC2020]

Thanks Jim for the reply. I have 3 brushed DC motors and with some tuning and setup I think they will work fine with the Gecko servo drive. Anyway, I have some more questions. Anyone should feel free to answer.


Is there any reason to switch from LinuxCNC to Mach4? I'm going to use Fusion360 anyway for my CAM design. I have used Mach3 and kind of see it as the wrong way of doing things. It totally feels outdated and hard to use, I've only used Linux for the past month and it seems like it's pretty easy to get things configured right. Maybe there is something I'm missing.

How do I know what size stepper motor or servo motor to use with my machine? I have an idea of how fast my machine should be and how much torque I need, but I'm not sure if the servo motors I have already are adequate. Also, how do I know what size power supply to use? If I have 3 50V and 3 amp stepper motors, do I need a 50V and 9 amp power supply? I called gecko and they said it isn't necessary, but I'm not sure why exactly. What about servos? Basically servo motors require different amount of power depending on how much speed and torque is to be delivered. I hoping somebody has a link to some good reading materiel on this subject, or maybe someone has a Bridgeport Series 1 retrofit they completed successfully and I can base my purchases of that, if they are satisfied with their machines performance.

Right now I am using an older computer with a parallel port, others have used more modern computers with a Ethernet smooth stepper card or a Mesa card to drive their machines and have the right number of inputs and outputs. Is it necessary for me to buy a Mesa card or ESS? Right now I think I will only need a simple breakout board to deliver pulses to the 3 gecko drives I plan on purchasing, as well as setting up an E stop and limit switches. Eventually I need to also be able to control my spindle speed with the VFD, and eventually using the motor on the speed change on the Bridgeport head, will it then be necessary to have more I/Os then the parallel port is capable? What about hooking up a pendant? I will eventually like to have homing switches, but I'm not yet sure about how I will integrate them into the system. There is just so much to learn. I think I will also need to put an encoder or something on the Bridgeport spindle to eventually support rigid tapping, thread milling and accurate speed control. Thanks to everyone who has taken the time to read this post.

[Jim Dawson]

Nothing wrong with LinuxCNC if you are happy with it. And I think the Gecko DC drives would work fine for your DC motors. I have a similar sized machine and am running the original 140V DC servo motors on a 75V power supply and have had no problems with torque or speed, but I do limit my rapids to 100 IPM, but I know it will do 200 + IPM rapids. I'm just not in that much of a hurry.

I would not put steppers on that machine. If I were to repower mine, I would use 0.75KW servos from DMM Technologies, inexpensive and they work very well.

[dbsharp]

Jim, On this machine (I am also doing a retrofit), I would be concerned about coolant splashing on the servos. The OEM servos seem to be better protected against water ingress than the 400w DMM servos I bought for my lathe. Any suggestions for a good 750w servo that is water resistant or IP rated?.

[Jim Dawson]

The DMM 0.75KW motors are IP65 rated. Install with the cable entrance down, and leave a drip loop. Putting a shield over the top of the motor wouldn't hurt either.

[dbsharp]

The DMM 0.75KW motors are IP65 rated. Install with the cable entrance down, and leave a drip loop. Putting a shield over the top of the motor wouldn't hurt either.

No kidding? Why in the world did they pick such a cheesey looking connector... ever hear of someone changing them out? I got a bunch of deutch connectors in the garage.

[Jim Dawson]

No kidding? Why in the world did they pick such a cheesey looking connector... ever hear of someone changing them out? I got a bunch of deutch connectors in the garage.

I would think that changing the connector would not be a big problem, but not sure it's really worth the effort. The 1.0, 1.3, and 1.8 KW motors have mil-spec looking connectors, but the cable entrance to the connector does not look very watertight.