Advice on Bridgeport converted to CNC for sale

Jealous.
Can you walk me through the basic components I would be looking to replace to achieve similar?
Is it largely just the black control box on the BP that would need to be upgraded - or significantly more components?
 
Mainly the controller and the operating software. Motors and drives can be reused. I would add linear scales and tie those back into the controller, my preference is magnetic scales. The only real requirement is that the controller be compatible with an analog command signal, +/- 0 to 10V. This is an industry standard command signal for axis control.

My machine uses the original motors and drives. The 4th axis does use a stepper. I installed a modern industrial motion controller and I wrote my own software to run the system. There are off-the-shelf controllers and software available.
 
I forgot about brushed DC motors being back-driveable. Good point.

But I'm not sure it's got those. The thread I referenced earlier had three or four people all discussing their Centroid CNC4 system as using steppers, including pics of the stepper drives and motors:

1621338210148.png

No brushes on that thing.

But I suppose it wouldn't be hard to replace the steppers with brushed DC motors and get some drives while upgrading the controls.

-R
 
slodat said:
DMM AC Servos bolted in place of the existing brushed DC servos on my Tree J425. I use Centroid Acorn for the control. Very nice machine with the new motors and control.
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Slodat - very impressive build. Gave me a good sense of what it would take.
Perhaps my prior analogy of fire hydrant was the wrong one.
Is there a term for when your work gets caught and flung across the garage and sticks in to the wall?
Between your build and Jims' comments, the scope is now more clear, and it's a pretty steep mountain.

May have a chance at a second look today or tomorrow on BP - where I can understand what the tooling that comes with it is.
At that point - I can properly weigh the trade offs of getting a working CNC machine with an aged system that I might modify to allow disengagement - but also provide a learning machine for CNC vs passing.

Much better sense of things from the yesterday's flurry of input.
Thanks guys.

-CM
 
This is just my opinion, coming from a guy that is not a machinist. There's a lot you can do with CNC mill that you just can't do easily, or practically with a manual machine. With the right control (Centroid in my case), you can use the built in conversational programming to do things you would normally do turning handles, but with a consistent feedrate, etc. You don't have to use CAD/CAM software to run a conversational control. It's crazy how nice it is to have a CNC mill in the shop.
 
slodat said:
This is just my opinion, coming from a guy that is not a machinist. There's a lot you can do with CNC mill that you just can't do easily, or practically with a manual machine. With the right control (Centroid in my case), you can use the built in conversational programming to do things you would normally do turning handles, but with a consistent feedrate, etc. You don't have to use CAD/CAM software to run a conversational control. It's crazy how nice it is to have a CNC mill in the shop.
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^This is a major draw.
An old Bridgeport, nicely cleaned and polished, that gave me the ability to do this - as well as simple drilling and milling operations - would be a stunning tool to have.

However - if honest - seeing your build was insightful/impressive, but also pretty damn intimidating.
Swapping stepper motors for servo ones - fairly straight forward.
When it came to the controls - I was naively expecting a smaller, sleeker, off the shelf box with some bright lights and a few arrow buttons, that would replace the big black box on the current machine. Throw in an LCD and Bob was my uncle.

The $8K price tag for taking it there, also was an eye opener.
Have I got my numbers approximately right?
 
The control piece is easy, point-to-point wiring. While it may look intimidating, it's not hard one circuit at a time. I spent around that amount, if I recall correctly. I never bothered to get an exact total. Things that contributed to the price: replaced the servos and drives, upsized VFD for single phase supply, I used nice industrial wiring supplies, relays, sockets, terminal boards, etc, touch probe, tool touchoff device and more. It *can* be done for less, but I wanted to build an industrial machine that had all of the features it originally had with some new stuff like probing and auto tool measurement.
 
The way I see it, if you buy this and disconnect the motors, you have a manual BP with some tooling in good condition for $3500. Not bad.

As far as the CNC side goes, consider it non-functional but well set up for future work. Sounds like a good investment in my mind.

If the budget allows, I'd say go for it.
 
macardoso said:
The way I see it, if you buy this and disconnect the motors, you have a manual BP with some tooling in good condition for $3500. Not bad.

As far as the CNC side goes, consider it non-functional but well set up for future work. Sounds like a good investment in my mind.

If the budget allows, I'd say go for it.
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What @macardoso said ^^^^^^^ The hard work is done, the mechanical modifications are already in place, and it can be operated as a manual machine, and the controls can be upgraded at your convenience. I bought my mill in 2012 and ran it as manual only until I really had a need for a CNC in 2013. I couldn't even spell CNC in 2012, but the machine was too good of a deal to pass up.

Just to put the controller complexity into perspective, here is a complete CNC system on the bench for testing. (This is actually the CNC back gauge controls for our press brake) https://www.hobby-machinist.com/threads/cnc-music-machine.87085/

Consists of a power supply, mini computer, motion controller w/built in stepper drives, and my software. Not a heck of a lot to it, probably took me about an hour to set it up and get it working. I paid $112.65 for the 4 axis controller (used), delivered, from eBay. I think the mini computer (new) was around $175, from Amazon. This system would run that BP no matter what motors are on it.
 
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