I've just received an e-mail from Grant Beebe at Oriental Motor who verified that the two motors are the same - electrically.

Hi i like to build CNC machine with dimensions 2400x2000mm and i found some motors and i like to know are this is good for my machine the motors are : VEXTA- A4496 – 9215K 0.72DEG/STEP DC 2.9A 0,23 OHM 8mm 5 -PHASE ORIENTAL COMPANY MOTOR LTD and if this motors are small for my machine please let me know which size is preffered for this motors ?

If the shafts are 8mm then they are too small - we need 12mm to 14mm. The body of the motor must be about 90mm square and 90mm long if you do not have gearboxes.

the problem is only with dimensions of the motors or the motors will dont have power ?

Dimensions and power are the same thing. A motor with small dimensions has a lower power than a a bigger motor - it is as simple as that. I have looked at many motor specifications and have learned to look only at the size of motor that I have suggested.

Also, those are 5 phase steppers, which require special drivers. 5 phase steppers are arguably an obsolete technology branch these days; if you inherit a set with matched drivers that fits your application, fine. If not, you likely don't want to engineer a new design with them.

hi

will this motors MT34FN26 be good for machine with dimensions of 2400x1400x150 mm ?

MT34FN26
Phase voltage Vdc = 2.45
Phase current A = 4.3
Phase resistance Ohm ±10% = 0.57
Phase induttance mH±10% = 1.7
Bipolar holding torque Nm±10% = 3.4
Rotor inertia g.cm² = 1000
Detent torque Nm = 0.08
Max. radial force N = 220
Max. axial force N = 60
Step angle = 1.8° ±5%
Front shaft diameter mm = 12.7
Terminal or lead wires = 8 lead wires of 400 mm
Protection = IP30 (IP54 for motor with terminal box option)
Ambient temperature ° C = - 40 ~ + 55
Insulation class ° C = B, 130
Dimensions mm = 86 x 86 x 65
Weight Kg = 1.70

The MT34FN26 motor has specifications somewhat similar to the Oriental Motor Pk296-F4.5 motor, so it would probably work well IF you added a belt-drive gearbox to it. With about 480 oz*in torque, it does not have as much torque as the Oriental Motor PK299 series of motors that have been used without a belt-drive or gearbox.

If you use Gecko stepper drivers and if you connected the motor using parallel or half-coil connections, you could use a power supply up to about 41VDC. A standard 35VDC power supply should work fine. If you connected the motor using series connections, you could use a power supply up to the Gecko's 80V maximum. 70VDC would be my preference with a series connection.

Gorantec, they will work if you have 3:1 ratio belt drives or gearboxes. Their torque will be too low for direct drive.

(The 86x86 millimeter is good, but the 65mm is too short. You need about 90mm length if you want direct drive. See the MT34FN31)

What about MT34FN47 its 6A and have 8.5 Nm torque and the body is 86x86x118 ?

Please advice

The MT34FN47 motor might be too large. At 8.5Nm (1,200 oz*in) it produces a lot of torque. Look at the thread "Why a stepper motor should not be too large".

The motors that seem to work best are in the 2.5 Nm (with gears or belt-drive) to 4.5 Nm range (may be used without a gearbox or belt-drive). My personal experience is that even a 4 Nm motor works much better with a belt-drive transmission (3:1). The quality of the cut was much better with the belt-drive transmission. Right now, the two x-motors and the one y-motor have 7.2:1 gear boxes and the quality is very good compared to an un-geared motor.

Gorantec, our friend in India, Vishnu, is going to try some 114mm long motors soon - see his post here today:
http://www.mechmate.com/forums/showthread.php?t=973

I am a bit concerned that the range of motors you have found (MT34FN26, MT34FN31, MT34FN47 . . . . . ) have lower inductances, which gives lower voltages and higher currents than the more common motors in this size range. This could change the decisions a bit - maybe those motors are good, maybe they are too rough.

You might notice from these numbers MT34FN26, MT34FN31, MT34FN47 that the motors are 3.4 inches square and that the lengths are either 2.6 inches, 3.1 in, or 4.7 inches. The motor length is an important factor in motor choice.

Please advice i have scheme for 5A driver but my motor is 6A will work in 5A driver and what will louse only torque or ?

Some of the older motors that I first tried with Gecko G202 stepper drivers were poorly matched to the Geckos, but they still ran just fine. The old round PH299 motors and the round Superior Electric motors ran rough when compared to the square PK299, PK296 and PK268 motors that I now use.

All of the motors were accurate and dependable. They never missed a step when properly loaded, but they sounded rough and felt rough when I held a hand to them while they ran.

The difference would be like comparing a new well-tuned car to an old car that needs its timing adjusted. Unless you drove both cars, you might not realize how nice the new car was.

Even now with Oriental Motor AS series Alpha 7.2:1 geared motors (with Oriental Motor's Alpha stepper drivers) on my Shopbot, when I run a true 3-D pattern, the motors sound very rough when compared to the long cuts that I normally make when cutting parts for cabinets.

what about this motors http://www.marelmakina.com/files/msm34H280-3IP.pdf

gear ratio on oriental motors
 

Hi,
I have been reading and researching for a while and am now getting ready to start ordering parts. By the way, thank you everybody for providing long nights of interesting reading.

The Oriental Motor series PK296A1A goes all the way up to 36:1. Do I understand correctly, that there is a sacrifice of speed for accuracy in going up the gear ratio? Why is the choice a 7.2:1?

Another question I have is, Gerald in the first post in this thread recommends the PK296A2A-SG7.2, the post is from 2006. Since then is there nothing new and worthwhile on the market?

Thank you,
Tim

Going up the ratio means:
1. the PC must run faster to generate the higher pulse rate
2. risk of increased backlash in the gearbox
3. the only possible benefit is a smoother cut, but we already have a good smooth cut at the 7.2 ratio.

Nothing else has even come close to the OM PK296A2A-SG7.2 when we look for an already packaged motor/reduction combination with proven low enough backlash. At $260 each, they are very expensive but convenient. Belt-driven are better (lower backlash), but are restricted to about 4:1 ratio at most, and are not ready packaged.

Tim,

There is a huge difference in performance between the PK296A2A-SGxx motor and the PK296A1A-SGxx motor. The A2A motors have lower inductance which means that they perform better at the voltages that the Gecko stepper drivers can handle.

The PK296A2A-SGxx motor requires a 70VDC (to 80V) power supply if wired bipolar series and a 35V (to 40V) power supply if wired half-coil. I ALWAYS wire the PK296A2A-SGxx motor half-coil. The extra torque produced by wiring it bipolar-series cannot be used by its gearbox and the extra speed produced by the half-coil wiring can be used by the gearbox.

The PK296A1A-SGxx motor would require a power supply of 150V to 177V if wired bipolar series and a 80V to 90V power supply if wired half-coil. You could wire the PK296A1A-SGxx motor half-coil and use a 70V to 80V power supply and get excellent results, but I would still choose the PK296A2A-SGxx motor for my own use.

Thank you all.
I will try to stick as closely as possibly to drawings. It is going to be little difficult to get some of the things here in Mexico. I am a lot further south than the other two Mexican builders.
I will go with the PK296a2a-sg7.2, the 203V Geckos and the PMDX122.

Hello all. I have found a local person with some motors that may be a good deal. I want to post for review what they are to see if they would work or not. I compared some of the suggested specs and they seem to be similar to what is suggested with the exception of them being round cases and not square. They are new/unused and about 4 yrs old (for a CNC project that never happened). Thanks for any assistance.

Ametek Brush-type DC Servo motors with encoders that you can run with Step and Direction signals, just like a stepper motor. If you’re used to working with steppers, you will not believe the performance from this motor. It is compatible with the low-cost ($114) and high-performance Geckodrive G320 servo drives, G340 servo drives(www.geckodrive.com), as well as other brush-type servo drives including the Rutex R990H (www.rutex.com) which has some really nice features including step multiplying.
This is a great solution to upgrade a stepper machine to servos, or retro-fit a medium to large size mill or lathe with CNC controls. If you’re building your own CNC Router, this is by far the most economical way to go for high performance.

The motor body measures 4” diameter X 4-7/8” long with a 3.25” diameter, 4-bolt hole circle on the face. The shaft mounting surface is .625” diameter X 1” long, with a shoulder of 7/8” X 3/8” long. Overall length with the 1000 CPR (4000 pulse per revolution) Renco encoder is 7”.
Advantages over comparably sized stepper motors are:
• Closed loop control- The encoder feedback ensures that the motor is in position, but doesn’t require an expensive control system that uses analog signals. When used with the Geckodrive, you only need step & direction signals.
• High Speed and torque- High peak torque allows for faster acceleration and deceleration, and better continuous torque at cutting and rapid speeds than steppers. Torque doesn’t suddenly drop off at medium speed as with steppers.
• Smoother operation- Because these motors don’t rely on the “steps” that you feel when turning a stepper motor shaft, they run much smoother and quieter than stepper motors.
SPECIFICATIONS:
• Torque Constant 44oz-in/amp
• Voltage Constant 32.5 V/1000RPM
• Nominal Voltage 40 VDC
• Maximum Voltage 60 VDC
• No-Load Current <.51A
• Demagnetization current >20A
• Terminal Resistance 2.60 ohm
• Mech Time Const(max) 18.3 msec

That motor will not have enough holding torque unless you add a very significant belt/gear reduction.

See Servo versus Stepper motors

Hi

i have 3 step motors now with torque of 8.5 Nm and i planing to build machine with dimenzion X=2100 Y=1200 mm cutting area im planing to put only one step motor on X axis will be enough ? Since the motors are with big torque ?

You need 2 motors on the x-axis to hold it square with the table. The 2 motors are exctly synchronised by Mach3.

what will happen if i put only one motor ? will not work or ? please let me know more ? Becuse i can not find another motor it will be hard since i was waithing 3 months to get these :(

It will only work for very light cutting if you use one motor on the x-axis, and it will have a low accuracy.

i need these machine only for making some simple desing for mdf doors i think will work for theat or im laing my self :o

Sorry, but it won't really work for MDF doors. :(

It starts with a little design and ends up with something big.Use two on the x-axis one on the y-axis and get another smaller one for he z-axis.

ok it's me again :o will this motor MT34FN26 http://www.tinel.com/products/pdf/MT34FN_GB.pdf be good for z axis or ?