The Chinese...

Gerald, excuse for the confusion.

You're right ofcourse, I meant motors, not drivers, my English thinking is not straight yet. Glad you consider explosion proof not to be an item in a typical woodwork workshop. In my relation with the Stögra salesman there where a lot of chemicals (nasty stuff) involved, that's why he probabely made a point of it.

Never the less if the OM is a good thing on this point I'am not going to argue against it. Last weekend a ship in our harbour burnt down, due to an electrical circuit breaker that didn't do what it supposed tobe doiïng, breaking the electrical circuit. I hate fire.

cheese polder

Hey, that ship burnt on 30 July! (unless you have these electrical ship fires every week?) :D

I am sure that you are talking of the Prins Willem fire

Gerald,

You mention a price of about 250 USD for the PK296A2A-SG7.2 stepper motor.

I got a price quotation of 391 USD in Belgium for the PK296AE-SG7.2.
This price is tax included (+25%). Price without tax is 314 USD.

Is your price of 250 USD tax included?

Regards,

Bart

Gerald,

The Prins Willem burned down on august 8! A remarkeble day since I was in Den Helder that day returning from a sailing trip with my wife to the Shetland Isles.:)

The yacht I talked about was also a historical wooden ship, an one of build from 1923, based on a "gauntlet". A big loss because it was a very fast sailing yacht, 18-22 knots with 7 bgt winds, and steady as a rock. Loved it like a MM.

happy sailing polder:D

Bart,

Wait 2 more days. I will have a confirmation on a offer for the PK296AE-SG7.2, which is the European equifalent of the PK296A2A-SG7.2. Its less then 250 euro if everything works out right. Will keep you informed if you wish so.

cheese polder

Polder,

That sounds like a very good price. Please keep me informed.

Thanks,

Bart

I am currently sourcing items and came across this Stepper motor for sale in the UK.

http://www.arceurotrade.co.uk/Catalo...Stepper-Motors
Item Number: 160-010-00450

Specs are (for parallel): Current=4.2 A/Phase, Resistance=0.8 Ohm/Phase, Inductance 3.5 mH/Phase, Holding torque=3.5 Nm
Supply Voltage would be, using 20xVoltage= 20*(4.3*0.8)=69V or 32*Sqrt(3.5)=60V, so lets say 60V
Corner speed would be (0.191*60)/(0.0035*4.3)=761 rpm, geared 3:1=254 rpm, which compared to other motors mention here, seems ok.

It is pretty cheap at £35 (~60 $US) and i am thinking it should be ok with a 3:1 Belt drive.
It only has a 10mm shaft with no flats, but apart from that it seems pretty good for the price.

I would be very grateful if anyone would comment on it's suitability and/or check my calcs
Cheers, Greeny.

You used a different set of calculations than I use, but the end results were almost identical. I figured about 60V for the power supply and about 250 RPM when using a spur gear that had 1.25" pitch diameter and the speed set to 5" per second.

Most of the stepper motors that I've tested work very well up to about 1,000 RPM, so, assuming that your motor is typical, you would still be in the high torque range of the motor.

Thanks Mike,

I used formulas that i'd gleaned from this and other threads, but really know very little about it!
I'm sure yours are more up to date.
I appreciate you taking the time to run the calcs, it's a big help.

Cheers
Greeny

Hello Anybody, can you explained to me about motion king spec that i dont understand 580 N cm Min - 18 N cm Max ? is spec require min for MechMate ? that i heard min 4.51 N m ? i still dont understand that convertion unit which one i use for checking min tourqe min or max ? hope anybody reply me soon thanks.....

Octobpra,

Your question is not clear. However, if you want to convert from Newton Centimeters to Newton Meters, you simply divide by 100. So, 580 N cm would equal 5.80 N m.

For any conversion you need, simply do a Google Search and you will find links to conversion calculators. For instance, Google: "convert Newton Cm to Newton Meters"

580 N-cm = 5.8 N-m = 821 oz*in

"Holding torque" is the value that I normally use when checking a motor's torque. Holding torque is the amount of torque that the motor produces when the motor is NOT turning and the stepper driver is giving full current to the motor. Holding torque is usually much higher than running torque. Running torque is the amount of torque that the motor produces at a specific speed.

When you look at a stepper motor's torque chart, you'll normally see a graph that shows the torque produced at specific speeds. As the speed goes higher, the torque goes lower. At a certain speed, the corner speed, torque drops dramatically. The larger the motor, the lower the corner speed. Most mid-sized 34-frame size stepper motors (at least the ones that I've tested) have a corner speed greater than 1,000 RPM. Even with a 7.2:1 transmission, and a 1.25-inch pitch diameter pinion gear, 1,000 RPM will move an axis at about 540 inches per minute.

With a 3:1 or a 3.6:1 belt-drive, I would like to have a motor that produces between 450 oz*in holding torque and 600 oz*in holding torque. (450 oz*in = 3.18 N-m = 318 N-cm, 600 oz*in = 4.24 N-m = 424 N-cm). That means that an Oriental Motor PK296-F4.5A, if connected bipolar parallel would work, or a PK299-F4.5A, wired half-coil, would work. Any other motor with similar torque curves would also work (PK299-03AA wired half-coil, PK299-02AA wired half-coil, PK296-03AA wired bipolar series).

Also, motors that have an Inductance rating between 1.5mH and 6mH are best suited for use with Gecko stepper drivers.

Don'r mean to be buttin in, but I am presently using nema 23, which are too small. If I go with the geared motors will my existing 24V power supply and breakout board work, or will I needd to replace it all? I am presently coming directly off of the breakout board with 4- 280 OZ NEMA 23 motors.

Toad,

There are normally four components in the stepper chain:

1. A power supply

2. A break out board (i.e. PMDX-122)

3. A stepper driver (i.e. Gecko G203v)

4. A stepper motor (i.e. Oriental Motor PK296A2A-SG7.2)

The inductance of the stepper motor determines the voltage of the power supply, i.e. 32 X SQRT( Inductance ) = MAXIMUM voltage. When wired half-coil, the PK296A2A-SGxx motor is rated at 1.5mH, so it can be used with a power supply up to about 39VDC. When wired bipolar series, that motor is rated at 6mH inductance, so it can be used with a power supply up to about 78VDC.

The stepper driver has a minimum voltage and a maximum voltage. You must stay within the voltage limits of the power supply, even when the formula computes a voltage out of the range of the stepper driver.

Toad, you also need to consider the currents (Amps) and load capacity (VoltAmps) of your drives and power supply. There is a strong possibility that your existing drives and power supply are also too "lightweight".

Toad, what is your PSU type & rating?
From what I learn here, in theory, if its a 300VA unregulated 24Vdc, then you will need to find a motor with 0.5625mH (from V=32*Sqrt(mH)). I wouldn't guarantee much but at least you will be near.
If its a switching mode power supply, & its regulated, then you need a lot more meaty one.

sounds like I need to start all over in the drive department. just hoping what I had would work, but apparently not. Thanks for the info.
Does Gecko sell a kit with 4 motors and all necessary components, or will I need to find each one individually.
Where is the most inexpensive place to find the rack and pinion?

Toad

Toad,
Best place for rack is Standard Steel. Gecko only sells drives. You can order the motors directly from orientalmotor.com.

I am having a really hard time selecting a motor. REALLY
I want the most precise cutting mechmate possible to cut High Density Polyurethane, now the question I have is: What is needed for precise cutting? Does it have anything to do with the motor, and if it is geared or not? I have been looking at http://www.orientalmotor.com/product....html#shgeared PK/PV Series 2-Phase stepping motor with SH Gear. Looking at the motors on my own is pointless, I have been looking at the criteria. But for me to know which motor is going to provide me with the most PRECISE cutting / working is really pointless. I have been going to-and-thro the forum, but really the only result is getting me more confused. Price also plays a role, but I want the pieces I am going to cut to be as clean as possible. Please I am a fish out of water here to be honest :)

Iclazion,

Wanting the "best cut possible" from a Mechmate is a lofty goal. Your cut quality is only partly dependent on your motors, the workmanship quality in construction and alignment plays a factor also. Maybe if you would define what permissible error is then guys with existing machines can tell you if their setup would work for you.

What you might want to look at, though, is constructing belt drive reduction units in lieu of using the standard gear reduction unit. That will eliminate some backlash. High density poly though is among the least demanding materials to cut accurately, consistent density, soft and tools well, no knots etc. I suspect a standard Mech built with the geared drives will more than fill the bill.

Other things you can do to increase resolution (and sacrifice cut speed) are deep reductions on your motors and sizing pinions appropriately. Your tooling quality and feed speeds are another factor as is the quality of your programming.

Chuck

Also good to note, that as you push the gear reduction higher and reduce the pinion size, to get the same top speed, your computer now has to put out a lot more in terms of speed. Mach 3 also has a high limit on the rate at which it can ouput step and direction signals, so this could limit your top speed.

Thank you Skypoke and domino11 for your quick response. I have been looking at the Nema 34 for a while now (that is the only descent motor available in South Africa) but that would mean I will have to add/build the belt reduction unit for each motor. But I would rather invest in a motor from orientalmotor. What is the verdict on the http://www.orientalmotor.com/product....html#plgeared PL Geared Type? Max Holding Torque of 13.2 ~ 26 (lb-in). Will that sort our my reduction problems? Is this the investment I am looking for, for the Mechmate? :)

Iclazion

To re-iterate Chucks request, you need to give us mor info regarding what "accuracy" you need to achieve.

OM motors are rediculously expensive here so unless you have a willing partner in the states to send them to you, I suggest you get in touch with Greg at www.cncdirect.co.za He will also be able to help you out with belt reduction drive components, spindles, Geckos etc. He is just down the road from you in the big smoke (Jhb) and is very knowledgeable on these items.

As to whether your choice of OM moter is the investment you need to make on the MechMate, that is a question only you can answer! You need to read a lot more to fully understand what the MechMate is capable of and who has used what combination of motor or reduction or integral gearbox. The path to enlightenment is not a short one...:)

:) Lol. Thanks alot Alan

I am starting on the initial design of my table at the moment and I will be documenting the progress as best I can to help those who might one day like to rather copy me. It's so much easier to follow a recipe, whoever I feel like I will be the guinea pig for the rest to come.

Quick question:
Do you think a Nema 34 would be able surpass even the most expensive Oriental Motor if the right belt reduction is fitted to the motors? My goal is to eventually cut/router 2” thick HDPE and to engrave aluminium or (praying) to have the ability to cut it.

I will be uploading my table specs, with 3D (lightwave) drawings and diagrams for people to follow. Because I am a masochist I might even upload the cost involved in the construction as I go along.

Hi iclazion,
The NEMA34 is the generic stepper motor size frame size used for MM, if I remember correctly, the OM are NEMA34, so are the motionking motors & keling motors.
NEMA stands for National Electric Manufacturers Association, more details read here

What you should be more concern are the steps/rev, No. of phase, Torque, Inductance, Resistance & current rating.

You should read all the "sticky" threads in this section especially this particular thread if you wish to learn more about stepper motors.

Hope this helps.

Merry x'mas

I have a question I would like to ask.

I am in the process of buying 4 X nema 34 motors with 10 micro step drivers. I have been looking at the “Gear Speed Step Freq Calculator” and would like to know the following. I am going to for the 24 teeth pinion on the motors, and I am a bit concerned about the “Belt/Gear reduction”. What is the advantage of a belt gear reduction ?

His is the specifications of the motor and driver:
Motor Specifications:
Frame Size: NEMA34
Step Angle: 1.8 degree
Voltage: 5.7V
Current: 3.0A/phase
Resistance: 1.9 Ohm/phase
Inductance: 22 mH/phase
Holding torque: 9.3N.m 1317oz-in
Rotor inertia: 3600g-cm2
Number of wire leads: 4
Weight: 5 kg
Length: 151mm

Driver Specifications:
Geckodrive Step Motor: G201
7A, 80VDC 10-microstep drive, Optoisolated step and direction inputs, Mid-band resonance damping, Silent 20kHz PWM switching, No low-speed vibration

The major advantage of a belt drive (belt gear reduction) is that you will have no backlash.
I use the OM with 7:1 gear reduction. I even had different backlashes in the drives so I had to take care to find two "matched" for the x. On my next MM I`ll go definetly with belt reductions.

Hi Claudiu

I had a change of heart with the motors. I came on a topic that suggested I rather use a smaller motor, so I chose 873oz-in Nema 34 stepper motor instead of the 1317oz-in. In the end I want a CNC router that doesn’t tear or rip through my medium I will be cutting. I have payed for my motors and their driver, controllers, voltage regulators and breakout boards just a few hours ago. Very excited at the moment, and can’t wait for their arrival.

I am also going shopping tomorrow for my pinions and belt reduction gears/belts. There is a couple of questions I want to ask later on about setting up the belt reduction, and how you would mount yours.

PS: Do you think it is a good idea to use 2 motors on the X-axis? I ordered 4 motors. 2 for the x-axis, 1 for the y-axis and 1 for the z-axis.

Iclazion, if you are using underpowered motors there is a risk of loosing steps.
Ripping through medium is another discussion about feedrate, spindle speed and chipload.
Using two motors on the x is mandatory, as seen in Gerald`s plans.
Good luck with your build and post some pics.

Iclazion did you get your stuff from Greg in Edenvale?

Hennie I ordered my motors from Hong Kong. The companies name is www.wantmotor.com they also supply me with the needed drivers, breakout boards and voltage regulators.

Claudiu I am a bit confused. I have been following this forum for a while now, and came upon http://www.mechmate.com/forums/showthread.php?t=255 where Gerald_D explains that a motor with High torque would be troublesome. Should I stop my order and rather get the 1317oz-in Nema 34 motor?

Iclazion, do you have gearboxes on the motors?

Hennie it looks like I will have a look at a belt drive. At the moment there are no gearbox/gearhead on the nema 34 830 oz-in stepper motor. The company will custom any motor to your requirement ,the same with the voltage/drivers and breakout boards.

PS they say their drivers are better and more advanced than that of gecko drives, but that remains to be seen. Will let you know if that is indeed the truth when my MM is finished and cutting.

VARISPEED is an Oriental Motor Distributor in SOUTH AFRICA!

Got a quote for 4x PK296A2ASG7.2 motors, as described on the first page.
R7600 per motor. = R30400

Just bought 6 MotionKing stepper today... Total price delivered to my doorstep R 4120.63....will be here in less than 20 day's

That's a good deal. :)

Sorry my mistake...worked on 5 steppers for my friend and that was R 4120.63. Six motors were R4944.75.......each stepper R 824.13.

Still a good deal

checking MotionKing part number
 

Kobus,

Is 34HS9801 still the most appropriate motor from Motionking,

want to use 203V drivers,

going to build 3:1 belt drive for all 4 motors

thanks

Graeme