looking for help with Bridgeport servo

I notice alot of retro-fits have been done using the original Bridgeport stepper motors that come on the machine.Has anyone ever done a retro using the original servo motors?The ones I have are SEM servos.Thanks Chris

These are decent servos.

They have tach fedback and position feed back. They were commonly used with Motion Science analog (+/-10vdc) servo amps.

These servos out put tack signal to the amp BUT the servo encoder signals go right back to the PC's via BMDC card in the DX-32 PC based controller.

Al the Man has provided input on how to interface tach F/b servos numerous times. Rutex is an amp that should interface readily to them.

All the interact machines used these SEM motors but with BOSCH drives and with Heidenhain controls. As NC Cams said, they are good and popular. Also used on the EZTRAKS, and V2XT machines with the DX controls. In other words, very adaptable.

George

I have talked with Tom at Rutex about the drive cards I would need,but I get confused when it comes down to putting all the componets together.Also I see Gecko come up alot, but from what I gather they still dont make a card to drive servos.I didnt want to take to much of Tom's time and was joting notes as we went.That was three months ago and Im not a very good note taker.So Im hoping sombody has gone thru this process and willing to coach a little.Thanks Chris

Hi Chris, I'm mid way through a full retrofit of a Bridgeport Series 2 Interact 4 using the original SEM servomotors with Rutex servodrives. I hope to have everything up and running within the next month so I'd be quite happy to talk you through everything I have learnt so far.

Feel free to contact me on here, or if you prefer to communicate over the telephone, send me an email or pm - I spend far too much time on the computer each day as it is!

Gecko do make nice servodrives but they are far too small to run the SEM motors in question.

Gecko make drives for DC brush servos (G320, G340).
I dont have any experience with servos but from what I gather you will need to find out their voltage and current to see whether the drives will work for you, I think Geckos have a max of 80V and 20A and Rutex 200v and 40A
Hood

Hood: I"m pretty sure the motors in question are rated for use with 100vdc systems. Unless you are willing to NOT obtain the max power/speed potential of the motors, the 80vdc Gecko's won't cut it.

It is therefore Rutex or one of the more expensive high dollar commercial drives (Motion Science, CMC, AMC, Siemens, etc) that you are limited to using.

I"m pretty sure however that these commercal drives are often analog +/-10vdc for speed and direction. If you plan to use Mach, again, looks like Rutex has the S/D to analog conversion board you need to convert the S/D signals to the analog voltage needed to operate these drives.

You can also use of these http://www.skyko.com/products/ S/D converter boards and run the machine with Mach.

dennis,
Thank you for the information on the sourse of boards
Paul/tenmetalman
:banana:

Not to grab anyone's thread, But, can anyone answer me the following questions, 1.) Are the servo's used on the SX controlled system the same as the one's used on the DX controlled system ? 2.) Are the analog motor command output resolution (8-bit, 12-bit)?
Thanks Paul/tenmetalman
:withstupi

Paul:

1. In a word, Yes, I think. The SEM's were the brand of motors used on MANY different variation of the DX system. These motors ran on mills (2, 2.5 & 3D), lathes (Expath 1 and 2), and grinders (Ezsurf) and some VMC's (3D and 4D). They were sized in accordance with the power requirments of the particular machine.

2. The ones I'm familiar with were all interfaced thru an ISA slot in a PC via the BMDC card. This controller card had a 12bit D-A chip on it that generated the +/-10vdc analog drive signal that went to Motion Science, Siemens and other servo drive cards.

NC cams,
Thanks for your reply, Part of what I'm trying to clarify before buying anymore parts for my conversion is: 1.) Being's I have a "SX control system" with a "FMDC BOARD" rather than a "BMDC/Bridgeport control system" DO the driver's still use the 12 bit standard. I don't mean to belabor this point, but I hadn't asked enough questions before now and have a small box of parts that I most likely wont use. My drivers are MSI and chances are than they use the 12 bit standard but I'd like to be sure before spending another $300 for conversion cards. I hope your answer fits the SX system, that would mean I'm getting a lot closer...................
Thanks Again
Paul/tenmetalman
:wee:

8 bit Vs 12 bit resolution:

An 8 bit board divides the 20 volt range (+/-10) into 256 parts or 78 millivolt speed steps. If you have a motor that puts out 3100 rpm at full scale voltage, a 256 part resolution yields a 12 rpm step potential

A 12 bit board divides the same 20 volt range into 4096 steps or 4.8 millivolt steps. Same motor with 3100 full scale RPM would see a step potential of 0.75 rpm step potential.

Probably not anything that may be really noticeable but the difference is there to be wary of. Thus, either will work as they put out +/-10 volts (or thereabouts full scale) but only the resolution potential differs.

I'd think that your servo tuning procedure should be able to get either an 8 or 12 bit system (FMDC or BMDC) to adequately drive the amps and therefore the motors reasonably close to what you want/need. However, when the utmost in speed diffrential needs to be maintained, 12 bit should outperform 8 bet for the reasons cited above.

I dunno if you'll REALLY see the difference however.

Thanks for staying with me on this one, Some of this stuff, very hard for me to "get it"
Paul/tenmetalman
:idea: