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

34HS9801 is what I am using and the new one is the same. I use 202 drivers, but am sure the 203 will work as well.

If you look hard enough, you can see the similarity of the model codes, I can't work out the exact system, some use 34 to indicate Nema 34, other use the motor frange size, some has the length of the motor, but you always see the familiar 4-digit number which are very closely spec.

Chinese Steppers to match 203V
 

Thought others maybe interested in this, thanks to Matt for pointing to the MS Motor.


Graeme,



I would recommend the motor that requires 4.5A as you will most likely get better high speed torque from it. You can run that all the way up to 80VDC with no problem (83VDC is the motor’s maximum) and the G203V will perform just fine with it. We do not sell fuses but would be happy to send you some for free. If you email your mailing address to [email protected] and say you need some fuses for the G203V we will send them out. Please let me know if you have any more questions. Thank you!



Marcus Freimanis

Geckodrive, Inc.

14662 Franklin Ave.

Suite E

Tustin, CA 92780

(714) 832-8874

[/I]From: Graeme McClure .
Sent: Wednesday, January 27, 2010 9:10 PM
To: [email protected]
Subject: Chice of two motors to go with 203V



Hello,



My intention is to use 203V drivers on a CNC router I am making at the moment (Mechmate)



I was looking at 2 motors and wonding if you would care to comment of suitablity of both and best choise (from and engineering view point)



MS Motor Motionking

34H280-45-4A 34HS9801



Torque 4.5 N.m 4.9 N.m

Rated I 4.5 amps 4 amps

ohm/phase 0.9 0.98

mH/phase 6.8 4.1

Rotor Inertia 1.6 1.55

kg 2.4 3

length 78mm 98mm

Wires 4 8



angel 1.8 1.8[/COLOR]

Graeme, I look at the weight and length for a start, and see you are comparing a single stack (light/short) to a double stack (heavy/long) motor. Single stack is okay with reduction (belt/gear) but it won't drive a MM if used direct drive like Kobus does.

(I am rather surprised that Geckodrive would venture an opinion when they were not informed of the application)

Gerald,

using 4:1 belt drive. Sorry cut that out of email paste

Graeme

Gerald.
I made a cnc router 3 years ago, 1200 oz-in on X axis, 640oz, on Y, both belt drive 3.75:1, and size 23, 230oz on Z, leadscrew drive, the machine has been working ok, but not fast enough, now i want to uprgade it to make it more ridgid and faster using the mechmate gantry plans, i have known that the most recommended motors are the PK296A2A-SG7.2, or PK296A2A-SG3.6, also i know that wired unipolar is the best choice for driving fast and slow speeds, my question is what kind of power supply is the most suitable for this motors, i would like to use the PK296A2A-SG3.6 and i need at least 350 ipm. of cutting, do you think can i achive that speed with that geared motor without getting too hot? Im using Deskcnc software and contoller, and gecko drives 203, my actual power supply is 36v, im not sure the amp. thank you in advance.

Noel.

Looking for bits and pieces
 

Would these steppers be enough with belt reduction 3:1 ?

They are 3.5Nm , 4.2A per phase and 3.5mH , nema34 lenght 75mm

here is the data sheet :

http://www.arceurotrade.co.uk/projec...-010-00450.pdf

As I am still in process of understanding plans and calculations, with modul 1 rack 30tooth pinion and belt 3:1 what would be the possible speed for cutting 19mm MDF? and would be these steppers be enough?

If someone is using similar motors any feedback would be nice.

Thank you

Those motors should work well with 3:1 reduction (even 2:1 should work). My rule of thumb is that you need at least 600 oz*in (4.25 Nm) to reliably drive an axis. The 34-size motors that I have are usually rated at about 300 oz*in or 600 oz*in (PK296 or PK299). The smaller motors would require a belt-drive but the larger motors can be used without a belt-drive (although resolution is about 0.0016 inch when driving direct).

You could probably use up to 60VDC for a power supply and still run the motor at 4.2A. At full voltage computed by Mariss' formula, the motor can heat up to about 80C when it's working hard. The motors that I've tested, when run at full voltage, all run faster than needed on a CNC machine, so by either limiting voltage or by limiting torque, you can keep the heat down to a point that you can touch the motor without getting burned. (Steppers are not resistors, so just plugging in different voltages in a formula won't give you the exact watts created, but it will be representative.)

ms motor
 

hello,

Found these motors at a good price in Australia are they good for belt drive? torque looks low?:(


model #

34H280-45-8a

http://www.ms-motor.com/HB3418.htm

they look OK, are you planning on using a belt reduction?