Marquip Servo

[ironmonger]

I have a Marquip servo motor and I have not been able to find the power requirements as yet.

It has a PN of 9601606 and a SN of 5011/6353170
case is 3.25" in dia. X 8" long
Has a 1/2" dia output shaft with a 1/4" encoder shaft
mounting bolt circle is about 2.5"

If anyone could supply me with operating voltage, current draw and max RPM I would be glad to hear from you.

Thanks

paul

[MaxHeadRoom]

Is this a brushed or BLDC/AC type?
There are certain ways to find servo characteristics.
Max.

[ironmonger]

This is a brushed PM motor. It has one pair of brushes. The motor leads are approximately 16 gauge.

I was thinking of checking with Helwig Carbon to see what they thought about the current capacity of the brushes...

Can I derive any useful information if I were to measure the current draw at 24 volts and then raise the voltage to 36 and check current there? Does motor current go up linearly with voltage increase though out the operating range?

The motor barely turns at 12 volts... leading me to believe that the actual motor voltage might be quite a bit higher... possibly 90 volts. The original motor had a tach on the small shaft, but it was damaged when I got it.

I have mounted a CUI encoder on the small end. Might be jumping the gun considering I don't even know what the operating voltage is.

Hope to use this for the leadscrew drive on a cnc lathe conversion

Thanks

paul

[macona]

A lot of those motors run in the 80v area, some even higher. Put a tach on it and start turning up the voltage. These kind of motors are usually happy around 2000 rpm. I would suspect the motor is in the 200 to 300 watt range.

[MaxHeadRoom]

One way, assuming the maximum rpm for this motor is around 2000rpm which has been stated is typical for this type of motor, back feed it at 2000rpm and check the generated voltage, this will equal the maximum applied voltage.

This is some notes I made when I was looking for similar information and found them in various sources:
Personally I think that a simplified model of a DC motor can be derived
assuming the armature inductance to be zero and ignoring the resonance
effect. With these stipulations the equations are:
1. V=Ia R + Ke omega (Ia=armature current, R=armature resistence,
Ke=electr. constant, omega=speed)
2. Tg=Kt Ia (Tg=costant, Kt=torque constant)
3. Tg=J d(omega)/dt (J=inertia, d(omega)/dt=accel.)
The DC motor transfer function is:
Gm(s)=(1/Ke)/(1+s(Rj/KtKe)), which can be written Gm(s)=(1/Ke)/(1+sTm)
where Tm=mechanical time constant.
To measure the parameters you are asking for, I suggests the following:
A. To Measure the armature resistance see note 2 below, then apply voltage to the motor without load and measure the current and speed. From equation 1. you can easily derive Ke.
B. Apply nominal current to the motor (with the shaft locked) and by means
of a variable voltage source. Measure the torque on the shaft. From this you can derive the torque constant Kt=Torque/Amp. See note: 3.
C. You will find that Kt is approx. equal to Ke
D. For the inertia you can obtain it by calculation from the size and
material of the rotor.

Note1: inductance can be ignored- the electrical time constant is
very short compared to the mech time constant so that it can usually be
ignored.
You can measure the mech time constant by running the motor up to
speed at no load, disconnecting the supply and letting it coast down- plot speed vs time and fit to exponential N=No(e^-t/Tm) time to drop to 36.8% of original speed is the time constant.

Note2: If it is a permanent magnet motor, you can determine the internal emf by spinning it at rated speed and measuring the open circuit voltage. The voltage at any other speed will be directly proportional to speed. To measure the winding resistance, lock the rotor so it doesn't turn and measure the current with a small voltage applied (so as not to exceed rated current) Don't bother using a multimeter's ohm range- not worth the effort.
For inductance, you should use a scope- apply a voltage, rotor locked and look at the current trace vs time.
This will be of the form i=K[1-e^Rt/L] where i is the current at time t.
In most cases the inductance can be ignored as its effects are generally swamped by the mechanical inertia in transient cases and is of little importance for steady state.

Note 3: A pulley or lever attached to the shaft can be used with a string around the pulley and a spring scale used to measure the torque.
Hope it helps a little.
Max.

[ironmonger]

Thanks Max

I am constantly surprised by the obvious... should have thought of the generator angle... oh well.

I spun the motor at 1700 rpm and got 65 volts. That would be about 76 volts at 2000 rpm, which is near enough to the 90 volts that I suspected.

More tests to follow...

The next step for me might be hooking it up to a servo driver and power supply and see what happens for torque. Don't think that will be a problem, as my application will require about 200 rpm max, so I will be using a reduction belt drive.

thanks for the help

paul

[macona]

What drive are you going to use?

[ironmonger]

I am considering the Gecko G320X but I am open to suggestions.

I do want to use encoders. I thought the ability to use the encoder for the DRO function when the drive was not engaged would be a plus.

That was the main reason I steered away from steppers. I could add encoders to a stepper, but I didn't find any drives that accepted the encoder input.

paul

[MaxHeadRoom]

You do know the encoder does not go back to Mach, if this is what you are using?
You would either need a controller that closes the loop or take the encoder back to Mach or other control of the same type.
Max.

[ironmonger]

In one of my bookmarks I have seen a board that passes the encoder data back to the pc... I should look for that again...

I don't know about these:
http://www.cnc4pc.com/Store/osc/product_info.php?cPath=64&products_id=338
But this appears to have the dro built into the drive...

paul

[Hood]

At the moment encoders can be fed back to Mach but Mach will not act on them and they are for user reference only.
There is a board from Ron Rogers that puts encoder data to Mach and the plugin it uses will fault Mach if the following error is greater than a user settable value and the user can update the machine coords from the encoder position.

You can also do this without that board and just use a macropump or possibly a brain.

The problems with these however is the max frequency of the inputs, with the parallel port you will likely get a max of around 25KHz, if using an external controller then it will be dependant on that device as to the max frequency.

Currently I am testing encoder inputs for Brian (Artsoft programmer) with his new plugin interface and a PoKeys and things are looking good. I have a servo drive hooked up to a 4000rpm motor with 2000 line (8000 ppr) encoder and I can keep track of the drives encoder outputs at full revs, thats 533KHz. I have not lost a pulse over many millions of pulses put into Mach in my tests.
It is planned to be able to use this info to update the machine coords on reset or after an E-Stop and also it would be possible to fault on a following error if wanted.
Other plans are for index homing feature, when this will be done I have no idea but hopefully it will be in the near future.
Hood

[macona]

Ugh, don't use the Gecko. I have and I really don't like them. I would look at something like the Whale3 or a Granite drive. Both get high reviews. The one you linked to is the Whale3.

http://www.thecubestudio.com/ServoDriveReview.htm

You can split off the encoder , run it thorough a buffer, and to the PC. I had a setup similar when I first did my first re-retofit. None of the drives will actually send back position info to Mach.

The thing is, I never used the mill manually. EVER. So that got yanked in the latest re-retrofit. Once you get the hang of g-code you can enter commands manually through the MDI and get better results than running the mill manually.

I do like the sound of index mark homing.

[ironmonger]

I see the smooth stepper boards
http://www.cnc4pc.com/Store/osc/product_info.php?products_id=366

and the offering from Ron Rogers
http://www.rogersmachine.net/encoderinterface.html

Remembering that I am new to this and most likely know enough to be dangerous, am I correct in assuming that I can start with the whale3 board driven by my parallel port and graduate top the high speed boards later?

I haven't decided if I will include DRO at this point, only that it might be a good idea to at least have it be possible.

I taught Autocad for 16 years, so the cad to cam route will be my most likely path. I would be just as comfortable with a pendant as I would manually spinning a knob. This conversion is planned for a lathe, and as such is as much a learning experience as it is practical. When I quit teaching a few years ago i purchased ProgeCad, and have been happy with it so far.

Like many other projects, this one started from a desire to find a quick change gearbox for my lathe.... and grew into something more. I have been scrounging as many parts as possible, and still think that the cnc conversion will be no more costly than adding a gear box plus I can sell parts off the lathe to those that wish to live in the 1920's :-) Some of the parts and gears might be cast in my backyard foundry... looks like my shaper might finally be of more use. Retirement is fun... got some time and lots of projects.

Thanks again for allowing me to tap your knowledge base. I have a strong background in electronics, but no cnc experience.

BTW macona, the XMT 304 that I fixed a few years ago is still happily consuming weld rod...

paul
WB9HCO

[Hood]

I do like the sound of index mark homing.

Can your drives not do that? Most of mine can and that is how I do the homing, external to Mach but a few dont so i am looking forward to it.

Hood

[macona]

I helped you with an XMT? You have a better memory than I! Sounds familiar...

Parallel port will be fine and will probably be more than enough for the lathe. Though I have having problems getting consistent threading results with the parallel port, the smooth stepper should alleviate that issue. For now just mess around with a parallel port and get a breakout board from CNC4PC. This one is specifically designed for the Whale4/Dugong.

http://www.cnc4pc.com/Store/osc/product_info.php?cPath=33&products_id=324

[macona]

No, they are older drives. Probably 10 years old now.

They do have open collector outputs on index for homing, though. I supposed I could just AND them together.

I am getting ready to replace the 3 HP spindle motor on my mill with a 3.5kw servo and HTD belt drive. It will be nice to get rid of the varispeed.

[Hood]

I see the smooth stepper boards
http://www.cnc4pc.com/Store/osc/product_info.php?products_id=366

and the offering from Ron Rogers
http://www.rogersmachine.net/encoderinterface.html

Remembering that I am new to this and most likely know enough to be dangerous, am I correct in assuming that I can start with the whale3 board driven by my parallel port and graduate top the high speed boards later?

Yes you can but it all depends on encoder count as to whether it will be fast enough for you. Eveyone says oh X IPM will be plenty fast enough for me as I am not doing production but believe me 50IPM soon becomes very slow ;)


Ok so lets say you go the old route (pre external controller days) and choose a 500 line encoder, that will mean you have 1000 pulses per rev of the motor. If the motor is geared 2:1 then thats 2000 pulses per rev and say you have 0.2 pitch screws, well that means 10,000 per inch so you max theoretical at different kernels would be
25KHz = 150 ipm
45KHz = 270 ipm
65KHz = 390 ipm
100KHz= 600 ipm

Now how high a kernel you can get will depend on the computer and its port, count on 45KHz being the max and any more is a bonus.

Now a higher encoder count will give you better resolution and likely better motion (assuming the drives can handle it) so say you go the norm of around 2000 line (8000ppr) then with the parallel port your max theoretical speeds would be

25KHz = 18.75 ipm
45KHz = 33.75 ipm
65KHz = 48.75 ipm
100KHz= 75 ipm


So as can be seen if wanting to use the parallel port then you have a trade off to make, low resolution or low rapids.

You can however switch to a motion controller in the future and with the ESS then its not too much to alter, in fact it can be as simple as setting up the Ethernet and supplying 5v to the ESS.



I see the smooth stepper boards
http://www.cnc4pc.com/Store/osc/product_info.php?products_id=366I haven't decided if I will include DRO at this point, only that it might be a good idea to at least have it be possible.

I taught Autocad for 16 years, so the cad to cam route will be my most likely path. I would be just as comfortable with a pendant as I would manually spinning a knob. This conversion is planned for a lathe, and as such is as much a learning experience as it is practical. When I quit teaching a few years ago i purchased ProgeCad, and have been happy with it so far.
WB9HCO

Using MDI will be a lot better than using any hand wheel whether it is real or electronic. Using MDI for simple moves is simple enough as it will just likely be G1's and G0's you would use. I often just type into MDI when needing to dress material off.

Hood

[Hood]

No, they are older drives. Probably 10 years old now.

They do have open collector outputs on index for homing, though. I supposed I could just AND them together.

I am getting ready to replace the 3 HP spindle motor on my mill with a 3.5kw servo and HTD belt drive. It will be nice to get rid of the varispeed.


Have servo spindles on all my machines, well except the wee coil winder as it is a stepper. The Computurn lathe is 12.5Kw servo, Beaver Mill is 8Kw, Bridgeport is 3Kw and the wee Conect lathe is 0.75Kw.

Would hate to go back to a machine that I could not control the spindle speed infinitely without losing torque.



Hood

[macona]

I know what you mean. I have a 5kw motor on my Monarch 10EE and running slow and taking decent cuts you don't even notice. The drive is a Mitsubishi MR-H with full time auto tune so it instantly compensates when I change chucks.

I also have a 750w servo on the spindle of my little hercus cnc.

I am also thinking of replacing the motor on my small drill press with a servo for tapping. I have some basic analog servos that would be just fine for that application.

[ironmonger]

I talked to Arturo over at cnc4pc, and picked a route with a breakout board and 180 volt servo drivers. I have a PC set up to dual boot either mach III or emc3, and have a line on some older linear supplies for the servo motors.
Time to fab up the servo mounts and get going. I am using a 1 HP 1750 rpm 3 phase motor for the spindle drive with a vfd to control RPM eventually via the software when I upgrade the boards later, at which time I will add the smooth stepper as well.
I talked to the mailman when he delivered the drives that I ordered and it seems that an old friend of his used to work for KT and has been in the NC repair biz for a while. While the six degrees of separation does not apply to the Internet, I have been ahead of the curve locally as far as helpful folks in the CNC world.
We have a Makerspace [see: http://milwaukeemakerspace.org/] group here in Milwaukee, and they have a CNC sub group. Great guys and more help when needed .
Thanks to all for your help.

[macona]

You might look at the Kflop. A friend just bought one and it looks a lot better than the smooth stepper. Does cost a bit more though, but I think it will be worth it.

[ironmonger]

Thanks for the lead. Thats quite a nice looking board. Not that much more than a smooth stepper.

I will start with the parallel port driving the breakout board and DG2S-16035's for a while, and decide later once the machine is operating under power. Kind of looks like a knowledge of C++ may be required. Perhaps this will change in the future...

I do have a problem that applies to many folks with older lathes, I believe.
The cross slide channel that contains the original acme screw is not large enough to allow a ball screw nut to pass. The alternative is to use a high precision acme screw and nut.

My idea was to lock the ball screw to the cross slide where the hand wheel used to be, mounted so that it cannot rotate and rotate a ball nut that is restrained with thrust washers and fastened to the saddle. This would force the cross slide back and forth as the nut is rotated.

While the ball screw would then protrude past the nut and travel as the cross slide was moved, this would allow a decent diameter ball screw. I do wonder if there is a problem with running the ball screw nut this way. I read somewhere that the nuts cannot be used upside down, which they would be part of the time.

[macona]

For the basic stuff you don't need to know C. If you want to start adding stuff like tool changers then you will need to learn C. C isn't that hard.

There are some pretty low profile ball screws around. You should be able to for a 1" diameter nut in there, right?

[ironmonger]

This is a 1929 South Bend 11" lathe... The cross slide nut is in a channel about 15/16" wide and the C/L of the leadscrew is about .375" above the bottom of the channel. I was afraid that anything that fit in there might not like the load.
I am going to take a trip over to my local Motion Industries distributor this afternoon and see what solutions they may have.

[macona]

There is surprisingly little load on the cross slide screw of a lathe. I wouldn't worry about it.

[MaxHeadRoom]

I recently converted a LatheMaster 9x30 and was fortunate to find a miniature ball screw the was virtually the size of the original Acme.
The fine pitch of 2.5mm takes care of the loading.
Max.