Mitutoyo Millstar III knee mill conversion.
- karmicthreat
- Offline
- New Member
-
Less
More
- Posts: 2
- Thank you received: 0
02 Oct 2013 16:05 - 02 Oct 2013 16:20 #39477
by karmicthreat
Mitutoyo Millstar III knee mill conversion. was created by karmicthreat
I'm converting an old knee mill with a 3 axis Mitutoyo Millstar III control. The mill has Mitutoyo on all axis and only tach on the servos. The servo amps are Glentek SM 7115-150-1 amps with +/- 12v and tach inputs. Don't know the model of the servos, nameplate is worn off all of them. Opened them up though and they only had tachs, no encoder on the ends.
Manual for the Glentek amp: www.glentek.com/glentek/admin/documents/SMA7115%20Manual.PDF
I know linuxcnc really needs encoder feedback so I'm thinking of making an adapter for some AMS AS5078B encoders and reading them with a USB to I2C adapter. Datasheet here: www.ams.com/eng/content/download/438523/1341157/143016
Will I be able to read those magnetic encoders in linuxcnc? I'm assuming the mesa cards only act as counters for encoders and don't do anything else with the value.
What Mesa cards do you think are appropriate for taking care of the servo end and will my cheap mag encoder plan work?
Manual for the Glentek amp: www.glentek.com/glentek/admin/documents/SMA7115%20Manual.PDF
I know linuxcnc really needs encoder feedback so I'm thinking of making an adapter for some AMS AS5078B encoders and reading them with a USB to I2C adapter. Datasheet here: www.ams.com/eng/content/download/438523/1341157/143016
Will I be able to read those magnetic encoders in linuxcnc? I'm assuming the mesa cards only act as counters for encoders and don't do anything else with the value.
What Mesa cards do you think are appropriate for taking care of the servo end and will my cheap mag encoder plan work?
Last edit: 02 Oct 2013 16:20 by karmicthreat.
Please Log in or Create an account to join the conversation.
02 Oct 2013 17:29 #39478
by BigJohnT
Replied by BigJohnT on topic Mitutoyo Millstar III knee mill conversion.
USB is not fast enough to read an encoder in real time. I would fix standard encoders to the ball screws if possible and use Mesa 5i25/7i77 combo to control the mill. There may be other ways to read the scales ( I assume you mean glass scales by Mitutoyo).
The +/- 12v is not normal... usually it is +/-10v for velocity input. At least you have a good manual for your drives. My Anilam converted BP knee mill drives I had nothing to go by except tracing wires out...
JT
The +/- 12v is not normal... usually it is +/-10v for velocity input. At least you have a good manual for your drives. My Anilam converted BP knee mill drives I had nothing to go by except tracing wires out...
JT
Please Log in or Create an account to join the conversation.
02 Oct 2013 18:10 #39479
by andypugh
I think that LinuxCNC can be persuaded to work adequately with tachs + scales.
You need to find a way to get the velocity data into LinuxCNC, and that will require some A to D hardware. You can then connect the velocity value into the PID controller feedback-deriv pin
www.linuxcnc.org/docs/html/man/man9/pid.9.html
This pin is used for calculation of the D term so ought to stabilise the loop somewhat. I _think_ that if you then use the FF1 gain parameter you get a semi-separate velocity loop running in the PID controller. (P, I and scale position control position, D, FF1 and tach voltage control velocity).
If you do want to use the AMS encoders then you ought to be able to interface to them via SPI. The Mesa cards have an SPI firmware module (in fact the Mesa 7i65 uses it).
Replied by andypugh on topic Mitutoyo Millstar III knee mill conversion.
I know linuxcnc really needs encoder feedback so I'm thinking of making an adapter for some AMS AS5078B encoders
I think that LinuxCNC can be persuaded to work adequately with tachs + scales.
You need to find a way to get the velocity data into LinuxCNC, and that will require some A to D hardware. You can then connect the velocity value into the PID controller feedback-deriv pin
www.linuxcnc.org/docs/html/man/man9/pid.9.html
This pin is used for calculation of the D term so ought to stabilise the loop somewhat. I _think_ that if you then use the FF1 gain parameter you get a semi-separate velocity loop running in the PID controller. (P, I and scale position control position, D, FF1 and tach voltage control velocity).
If you do want to use the AMS encoders then you ought to be able to interface to them via SPI. The Mesa cards have an SPI firmware module (in fact the Mesa 7i65 uses it).
Please Log in or Create an account to join the conversation.
02 Oct 2013 22:24 #39484
by Jerre122
Replied by Jerre122 on topic Mitutoyo Millstar III knee mill conversion.
If the tacho output goes straight to the servo amps (and I think they do from reading the manual) it wouldn't even be necessary to change anything on the motor. The glass scales might give some trouble if they have a weird signal. I think mitutoyo scales sometimes have sinus signal as output.
I am not an expert on cnc conversions, but my knee mill has tacho's on the motors and glass scales on all axis and it works fine with linuxcnc.
The +/- 12V might not be a problem, on my milling machine the amps take a +-10V signal, but even at rapids the voltage is about 6V max. (This ofcourse means a higher rapid speed is possible, but I chose to keep the original rapid speed).
I am not an expert on cnc conversions, but my knee mill has tacho's on the motors and glass scales on all axis and it works fine with linuxcnc.
The +/- 12V might not be a problem, on my milling machine the amps take a +-10V signal, but even at rapids the voltage is about 6V max. (This ofcourse means a higher rapid speed is possible, but I chose to keep the original rapid speed).
Please Log in or Create an account to join the conversation.
02 Oct 2013 23:03 #39486
by andypugh
Good point. LinuxCNC should have no difficulty at all controlling velocity-mode servo amps on the basis of linear scales.
If the scales have sin/cos output then there are devices out there that can convert to quadrature with very high resolution.
www.ichaus.de/ic-nqc
Development boards are £65 each for a pre-mounted IC and supporting components.
As a bonus we are extremely close to having a BiSS interface for the Mesa cards integrated into LinuxCNC, so in theory the encoder channels on the 7i77 (for example) could be connected to BiSS interfaces in the FPGA rather than encoder counters.
Replied by andypugh on topic Mitutoyo Millstar III knee mill conversion.
If the tacho output goes straight to the servo amps (and I think they do from reading the manual) it wouldn't even be necessary to change anything on the motor.
Good point. LinuxCNC should have no difficulty at all controlling velocity-mode servo amps on the basis of linear scales.
If the scales have sin/cos output then there are devices out there that can convert to quadrature with very high resolution.
www.ichaus.de/ic-nqc
Development boards are £65 each for a pre-mounted IC and supporting components.
As a bonus we are extremely close to having a BiSS interface for the Mesa cards integrated into LinuxCNC, so in theory the encoder channels on the 7i77 (for example) could be connected to BiSS interfaces in the FPGA rather than encoder counters.
Please Log in or Create an account to join the conversation.
06 Oct 2013 00:47 #39589
by JR1050
Replied by JR1050 on topic Mitutoyo Millstar III knee mill conversion.
The 12v tach signal only goes back to the amps. You could very easly mount encoders on the motors,as thats what Fadal did with very similar motors. If the glass scales are sin/cosine you might be able to use a mesa resolver board as they read sine/cosine resolvers. Just a thought. I have a set of those mtors off a millstar,Ill get you the model number.
Please Log in or Create an account to join the conversation.
- karmicthreat
- Offline
- New Member
-
Less
More
- Posts: 2
- Thank you received: 0
12 Oct 2013 14:48 #39796
by karmicthreat
Replied by karmicthreat on topic Mitutoyo Millstar III knee mill conversion.
Thanks for all the suggestions. I think just to get it going I will use only the scales feeding linuxcnc. I will order the cards needed from mesa next week. The scales are incremental so that helps. And JR if you know the model of those motors that would be fantastic.
Please Log in or Create an account to join the conversation.
15 Oct 2013 05:00 #39843
by JR1050
Replied by JR1050 on topic Mitutoyo Millstar III knee mill conversion.
Glentek model# gm4020-39
23 inch lbs
3500 max rpm
6.6 max current
180 vdc max
Sorry it took soong to.get back.to you,life gets in the way....
23 inch lbs
3500 max rpm
6.6 max current
180 vdc max
Sorry it took soong to.get back.to you,life gets in the way....
Please Log in or Create an account to join the conversation.
- 5axisormore
- Offline
- Junior Member
-
Less
More
- Posts: 28
- Thank you received: 2
23 Jan 2015 04:40 #55275
by 5axisormore
Replied by 5axisormore on topic Mitutoyo Millstar III knee mill conversion.
Were those the motors buit by SEM, as I hjave an Anilam Crusader II that I am looking to update to the Linuc CNC system.
Please Log in or Create an account to join the conversation.
Moderators: cncbasher
Time to create page: 0.123 seconds