Bridgeport Series 1 CNC conversion to Acorn etc.

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martyscncgarage
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by martyscncgarage »

Did you take pictures as to how the original steppers were wired at the stepper motor and the old control?
Remember, I suggested you find the specs to the original steppers to be able to calculate and size the replacement power supply.....or search to see what others were using.

Remember to benchtest everything including on motor and drive before wiring the cabinet. Hopefully you identified and tagged wiring that stays on the machine.

Good luck with your build.

Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
jim2000
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by jim2000 »

martyscncgarage wrote: Mon Jun 14, 2021 8:33 am Did you take pictures as to how the original steppers were wired at the stepper motor and the old control?
Remember, I suggested you find the specs to the original steppers to be able to calculate and size the replacement power supply.....or search to see what others were using.

Remember to benchtest everything including on motor and drive before wiring the cabinet. Hopefully you identified and tagged wiring that stays on the machine.

Good luck with your build.

Marty
The motor wiring is still attached to the AHA box, but definitely will bench test the drives and the E-stop with jumpers along with the VFD. Your suggestion of buying a new transformer is a real good one and I did buy one from Antek. I have to wait to hook up everything till I get the gecko drives and the transformer. I am keeping the whole AHA separate cabinet hooked to the wiring till I can bench test all of the new wiring. Will upload all pics when its working. I have 3 pieces to make for a helicopter jet engine transmission the size is 6"Wx 12"L X 2"H and the machine shop bid it for $4300 each. I can understand a machine shop having to make $ but this simple machining is a $2000 job, it has to be done on a CNC machine or I could make it on my manual Bridgeport. We have no serious machine shops in my area. So $6000.- was my budget and it seems that I will be half of that, but it could change and it's kind of fun doing this. Will put all pics online once its further along.
I am thinking of buying a new water cooled spindle for this Bridgeport, please somebody give me some input because I have no idea on this subject. My old collets have to fit the new spindle motor if I upgrade to it.
polaraligned
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by polaraligned »

The BOSS 5 machines went from a 1:1 belt reduction to the ballscrew, to a 2:1 reduction sometime during that BOSS 5 run. I recommend 2:1 if you don't have it already.

As for the hardware, check your ballscrews for wear. I had mine re-balled. It needs to be done before the wear is too great. Also, the dual angular contact bearings that hold the leadscrew end are subject to wear. Best thing is to put a dial indicator on the end of table and then push hard back and forth and see how much slop there is. Do it for both axis. Don't forget, these machines are 40+ years old now and many have notable wear. The Centroid software does a great job at correcting for backlash, but you start getting above about .001" and you will be disappointed with the cuts.

I have seen some people keep the original steppers, but if one can afford new ones, they simply blow away the old technology steppers used by Bridgeport.

As for the spindle, I have not seen anyone change it, only alter the head to eliminate the varidrive, but that is not a good idea. These heads when rebuilt run pretty darn good. If you put on a chinese spindle, how are you going to have a Z axis without a lot of work to put it on linear rails...then you would need a brake on it. Those chinese spindles are all underpowered anyway, and as you slow them down power drops off dramatically.

Using a VFD is not a great way to control spindle speed over a wide range. As you decrease the speed, the torque may remain constant at the cutter, but the power at that cutter has just dropped way down. There is no replacement for gearing to lower spindle speeds and maintain power at cutter, so I would just rebuilt the head and you will have a good working machine. I find that cutting aluminum without flood coolant is best at about 3000 RPM max with a 1/2" EM and maintaining a fairly heavy chip load to get your MMR up. Higher SFM has a lot higher chance of plasticizing the aluminum and the cutter ends up clogged and ruined.

The rigid ram machines are the better choice if you have one. I had a lot of trouble holding my old Series 1 CNC machine trammed with that V-ram setup.

It is not cheap rebuilding these machines and doing a thorough job. I have about $9k into my Series 2 machine which includes a full mechanical rebuild along with upgrade to servos.
jim2000
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by jim2000 »

polaraligned wrote: Mon Jun 14, 2021 6:38 pm The BOSS 5 machines went from a 1:1 belt reduction to the ballscrew, to a 2:1 reduction sometime during that BOSS 5 run. I recommend 2:1 if you don't have it already.

As for the hardware, check your ballscrews for wear. I had mine re-balled. It needs to be done before the wear is too great. Also, the dual angular contact bearings that hold the leadscrew end are subject to wear. Best thing is to put a dial indicator on the end of table and then push hard back and forth and see how much slop there is. Do it for both axis. Don't forget, these machines are 40+ years old now and many have notable wear. The Centroid software does a great job at correcting for backlash, but you start getting above about .001" and you will be disappointed with the cuts.

I have seen some people keep the original steppers, but if one can afford new ones, they simply blow away the old technology steppers used by Bridgeport.

As for the spindle, I have not seen anyone change it, only alter the head to eliminate the varidrive, but that is not a good idea. These heads when rebuilt run pretty darn good. If you put on a chinese spindle, how are you going to have a Z axis without a lot of work to put it on linear rails...then you would need a brake on it. Those chinese spindles are all underpowered anyway, and as you slow them down power drops off dramatically.

Using a VFD is not a great way to control spindle speed over a wide range. As you decrease the speed, the torque may remain constant at the cutter, but the power at that cutter has just dropped way down. There is no replacement for gearing to lower spindle speeds and maintain power at cutter, so I would just rebuilt the head and you will have a good working machine. I find that cutting aluminum without flood coolant is best at about 3000 RPM max with a 1/2" EM and maintaining a fairly heavy chip load to get your MMR up. Higher SFM has a lot higher chance of plasticizing the aluminum and the cutter ends up clogged and ruined.

The rigid ram machines are the better choice if you have one. I had a lot of trouble holding my old Series 1 CNC machine trammed with that V-ram setup.

It is not cheap rebuilding these machines and doing a thorough job. I have about $9k into my Series 2 machine which includes a full mechanical rebuild along with upgrade to servos.
I thank you very much for your info!! I will use this machine maybe 1 to 2 days a month for small aluminum parts. From your info the spindle will stay the same.
jim2000
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by jim2000 »

Waiting for the 70 VDC transformer to test the new system.
Attachments
CNCPic1.jpg.jpg
jim2000
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by jim2000 »

Received the transformer, it's very nice like Marty said.
CNCCompBoard2.jpeg
CNCCompBoard2.jpeg
martyscncgarage
Posts: 9912
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by martyscncgarage »

Generally easier and better to wire the panel out of the cabinet and for bench testing. Easier to correct issues.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
jim2000
Posts: 29
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by jim2000 »

CNCPic6.jpeg
martyscncgarage wrote: Mon Jun 21, 2021 8:59 pm Generally easier and better to wire the panel out of the cabinet and for bench testing. Easier to correct issues.
I fully agree with you but all the wiring is still attached from the AHA system and the motors are still on the machine and it's very easy to jumper all the systems from the cabinet. To disconnect all the wires from the machine and hook it up on the bench would have been a bigger job. Will certainly let you know real soon. The 4th axis will be on the bench and it will be jumpered. The 70VDC, 21 amp transformer from Antec is really a nice unit I'm really glad that I took your advice.
jim2000
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Re: Bridgeport Series 1 CNC conversion to Acorn etc.

Post by jim2000 »

It was very hard to get a Bridgeport Series 1 CNC maintenance manual with all the right part numbers and all the adjustments, assy and dissassy., if anyone needs this manual please send me a message and I will send you a copy of it
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