Bridgeport series 1 centroid CNC4 to acorn conversion

[Jason Birch]

Hello all, I've been lurking about trying to figure my best option for my machine, I did a little messing about trying to get the original 1991 CNC4 operational with no luck so I'm going to go ahead with the original plan of converting it to acorn control. It's a Bridgeport series 1 with varidrive head converted by Centroid in 1991. The machine was only able to have the spindle motor verified and checked for runout when I bought it. The table has very little wear or slop,I brought my professional machinist friend along with me to inspect it. The original old tech CNC4 powers up but will only say diskette boot failure. It also makes terrible digital unhappy noises out of any axis motor that one of the micro1 drives is hooked(I switched things around to determine what the source was) to so fairly certain that it's bad.
It's already equipped with ballscrews and has mae1350 stepper motors with encoders. I am aware that upgrading the dc steppers to servo is probably a good idea but I would really like to try to get by with the motors I have for the time being, spreading out the chunks of money to throw at people. So at the very least I need a motor driver to replace a micro1 and I need a VFD for the 1.5 hp 4.4amp at 230v spindle motor. There are lots of choices out there from $95 Amazon units to hundreds of dollars from automation places. I've been in touch with centroid and they said the micro1 will run fine with acorn. I've been told by some people that the motor and driver need to be replaced together but others said I can switch out to a newer driver with the old motor.
I'm ordering the acorn tonight and want to get the thing hooked up and operating to be able to test what I have on the machine already. I've got a nice touchscreen computer that my brother built to the acorn requirements so that's ready to go. Any input in VFD and motor drives is welcome. Thanks in advance.

[Jason Birch]

Acorn on its way. Can't wait to make some noises and chips !!

[martyscncgarage]

You have seen the schematic for the Centroid CNC4 Microdrive?

[Jason Birch]

You have seen the schematic for the Centroid CNC4 Microdrive?

I have. Was that you that emailed it to me? I actually looked at some replacement nema 34 steppers and was shocked to see a motor /driver pair for 100$. That's great too.

[martyscncgarage]

If you were to upgrade motors, I would go hybrid closed loop at the very least. I think your motors are NEMA 42. Measure the flange and mounting bolt pattern.

Marty

[BDubs]

Leadshine makes a really nice NEMA 42 Easy Servo motor and drive that's hard to beat. It's a closed loop stepper. Bolts right up aside from maybe needing a different size taper lock. Save yourself a lot of agg by not putting N34s on it. It's not a place to scrimp. Otherwise you wind up buying motors twice... been there done that.

[polaraligned]

I need a VFD for the 1.5 hp 4.4amp at 230v spindle motor. There are lots of choices out there from $95 Amazon units to hundreds of dollars from automation places.

Don't waste your money on a $95 VFD. Get a high quality Hitachi WJ200-015SF and it will provide you with many years of service. I have 2 of them running flawlessly on my machines for 10+ years. They are easy enough to program and control by the Centroid, plus they are sensorless vector for better low end torque, though that is no replacement for gearing of the spindle. Power at the cutter will drop off as the speed drops off even if the motor provides constant torque.

[Jason Birch]

If you were to upgrade motors, I would go hybrid closed loop at the very least. I think your motors are NEMA 42. Measure the flange and mounting bolt pattern.

Marty

I was honestly guessing nema 34 by measurements I read without measuring the motors. The bolt pattern is 87-88mm.
Edit. Just checked and yes 88.9 mm nema 42 would be correct.

[Jason Birch]

Hello again everyone. It's been a year and a half since I've touched this project until a week ago. I finally got my main 240 3phase power to my machine area sorted.
I have completed my initial bench test with my new CNC computer and the acorn only. Everything is communicating solid and looks to be operating correctly. That is the most in-depth I ever went into settings in a computer I'm pretty sure. I'm definitely more of a mechanical brain, I can fix pretty much anything if I can see the gears turning. Computers are not exactly my thing with none of that to guide me.
I'm now preparing to disconnect the drive belts on my Bridgeport stepper motors and connect the micro1 drives to the acorn and "bench" test them without worry of crashing things. The thing I want to be clear on is on the schematic from centroid on the micro one drive hookup. There are three jumpers that are soldered in and apparently are corresponding with the channels 1 through 8. On my 3 drives(and a 4th #3) the jumpers are in 1/2/3 spot respectively, which would make perfect sense for the ribbon cable to work. I just want to be certain that I would use the corresponding pins associated with the channel the jumpers are in. Meaning; jumpers in channel 3 use pin 7/8/9 for pulse/dir/power regardless of which channel it goes to on the acorn.
Writing this it seems that should be obvious but I'd rather be safe than sorry. I am fairly certain that one of the drives is bad so I may have to move things around to get my x and y axis moving for the time being while I sort the other, and possibly just change them all to new hybrids or servos.

[Jason Birch]

I got to looking carefully at this pic on my phone and I'm a little ashamed of myself for not seeing the fairly obvious way this works. I now see the jumpers just change which pins the driver's being input by and there is really only 5 pins of this plug active on any 1 driver board.