Newbie- Completely Lost

[hydronuclear]

I have been surfing CNC zone for about a week now, doing research and what not.

I have even emailed keling and found out they do ship to South Africa

My biggest and probably my only problem is the electronics side, Steppers, Drivers and Controllers.

I cannot make heads or tails of it.

my main concern is that if the electronics are too expensive i am not going to be able to do this build.

I would like advice on what hardware to get.
I was thinking of getting:
KL23H2100-30-4BM 495 OZ-In
and this driver KL- 5042

I would also like to know how to pair a Power Supply with the rest of my setup and what controller to get..

Any Advice is greatly appreciated

Thanx in advance

[JD_Mortal]

I can't tell you what drivers to get, as I am biased to the "all-in-one" drivers, and completely hate primitive and touchy/buggy printer-ports...

However, online, you might want to look at e-bay for decent all-in-one drivers.

If you want to do this all with separate components, you will need these things...

(Computer -> LPT port) goes to...
1x (Controller card) Isolates and protects LPT and sends data to drivers... Look for optically isolated versions.
3x (Driver boards) Translates controller data into motor-control... Depends on motor setup and requirements.
3x (Motor) The end... Motors depend on workload required... Fast/slow, adequate/accurate, small/large.

The controller usually uses about 5.0 VDC for the sensitive computer chips. The driver usually has two power inputs, one at 5 VDC for the chips, and one at 0.1 to 60.0 VDC for the motor control. (Not all cards accept that last range of voltage, you need to know what it can handle.)

The driver card is an advanced pulse-width speed and force regulator. It controls VOLTAGE (speed), and AMPS (force). You must be sure that the card can deliver what your motors wishes to consume, plus some to spare. If your motors are "rated" at 12v and 1.5a, they will require voltage near 12v, to operate correctly, and will handle a constant amperage of 1.5a. (12v x 1.5a = 18watts) Your motor will consume, at-least 18w under normal load. Your controller will possibly need 2x that wattage, to drive the motor at that average speed. EG, you need a controller that can handle 12v @ 3.0a, at minimum, or 24v @ 1.5a, which is also 18w x2.

In reality, the motor will get, and handle, short pulses of up to 10x what the rated voltages are, and up to 10x the amperage. What makes a good controller good, is the ability to control and limit those powers, so it does not damage itself or the motor, or the power-supply. (DIY circuits rarely have protection. While all-in-one circuits have limited protection. While separate components offer the greatest protection.)

Using separate components allows you to match drivers to motors, and power-supplies, as needed. It also costs less, in the long-run, when things go boom. (Things will go boom, if you are new to this.) You don't want a $300 all-in-one needing to be replaced every BOOM... However, replacing one controller that went BOOM, which only costs $100, is a lot easier to digest. Especially since that telly you, you might need a more powerful driver. (You may be at your limit with an all-in-one setup, and not be able to upgrade, due to the driver being too powerful for your other smaller motors.)

So, you have to weigh your options, and make a decision. If you are just tinkering, get an all-in-one, run it into the ground, and replace it with a better matched modular setup as desired.

When it comes to power-supplies... That is a lengthy topic...

The short version...

Your power-supply must be able to deliver all power, to all running devices, and have some to spare.

Your driver sucks-up 18w x2, for each motor. Assume you have 3 motors which will all be running at the same time. 10x that is your "peak" load.

18w x2 = 36w
36w x10 = 360w

You should have at-least a 370w power-supply. The extra 10 is for +/- error of the power-supplies and drivers, and motors rated power. Multiply that times 3, for the "ultimate" power supply. (1110 watts, or 1.11 kW, will never be underpowered.)

Now you just need to know the boards limits... in amps...

A 3.0a board will tell you that you need about 6.0a ability from the power-supply. 360w/6.0a = 60VDC, peak. You can run your board at 60V peak. So if you have a 370w power-supply, running at 36v, you will have a maximum amp-draw limit of 10a. The controller will swap volts for amps, using 36v as the base, as the motors demand it. That is why they get hot, as they limit and step-up and step-down voltage and amps quickly, that regulation is done with resistance, heating up the motor driver. Where as the motor heats-up only when high wattage runs through it. (High [volts x amps] wattage.)

Most motors can handle spikes up to 600v, for short bursts, at low amps. They can also run at low voltages, but not for long, as lower voltage equals higher amps. That is where micro-stepping has flaws. It reduces the voltage, resulting in higher amperage to the motor, which is good for slow speed with high force.

[hemsworthlad]

JD Mortal,
Didn't you read this post before replying.? This kind of overly complicated information hisn't helpfull to somebody who's heading starts "completely lost"

Also IMO the scarmongering is not needed, Most modern drivers are very good at protecting them selfs against "newbie mistakes" providing miss wiring and overvolt/current etc protection so the comment "(Things will go boom, if you are new to this.)" is not neccesary or helpful.

Hydronuclear:

Really before we can advise properly on motor/driver etc we need to know some information on the machine.
Things like size and style IE:moving gantry or fixed, how it's driven IE:ballscrew's, leadscrew, threaded rod etc. Kind of linear motion IE: Profiled rails, round rail, ballbearing on steel setup etc.
The weight of the gantry or moving table and what you intend to cut with the machine and desired speeds n feeds all need to be known to get a true idea of the best size motors.
After this info is known and motor size determined then it's easier to choose the power supply and driver to suit the motor.

The sizing of the PSU is not rocket science but it is very important that it's matched to the motors for best performance this then leads you to the right drivers to run the motors for best performance.

Stepper motors need volts for speed and amp's for torque, volts are the key to best performance speed wise and where the right size PSU comes into play. The amps is just a percentage of max amps all your motors will pull if running flatout underload.

Stepper motors are spec'd with amongst other things volts,amps and a rating called inductance, these are needed to size the PSU and driver selection.

To determine the volts needed their are a couple of ways, the rule of thumb way or calculated way. Rule of thumb is to say a max voltage of 20x the rated voltage of the motor.
The calculated way is to use the inductance rating in a formula which is 32x Sqrt of the motor inductance rating which will be given in Mh in the motor specs. IE Motor inductance = 7Mh = 32x2.65= 84V PSU needed for best speed performance.

The PSU amps needed is some what easier to determine, all you have to do is take the rated amps of all the motors used and add them together then 68% of this figure is the amps the PSU will need to supply.
The reason you dont need the same amount of amp's as the total for all motors is because it's very unlikely that all motors will pull max amps at the same time.
That said I always allow a bit more for extra's like if you power the BOB from the PSU etc and it doesn't matter if you have a PSU that is over rated on the amps because PSU will only supply whats demanded by the motors/drivers etc and as long as the PSU as enough capacity for the demand you dont have a problem.
Apart from making sure you have enough capacity for the motors etc one of the reasons for sizing the amp's is to keep the cost's down.! . . No point paying for an expensive 20A supply if your only using 11A max.

The voltage is the magic number for steppers, a stepper in the example above would run fine at 40v but would run half as fast.

When you have this info then you just choose a driver that can handle the voltage and provide the amp's the motors need.

This is why it's very important you choose the right motors to match the machine.
Dont think bigger is better it doesn't work that way and if not matched properly can make for an under performing machine with expensive motor/drivers that you didnt need.

Best tip is dont rush into buying motors/drivers etc without knowing the weight's forces to move first then and only then think about motors/drivers.
That said you dont have to go crazy on the calculating force's etc which some people do go a bit OTT.
A good way(cheat) to find motors size is to determine the materials it will be made from and the size then go searching the zone for a similiar sized machine made from similiar materials then work from the size motors they use and maybe ask how it performs with these motors etc. This will give you a starting point to work from and just scale up or down a bit as required.

Hope this helps and provide a bit more info and it will be easier to advise on a good motor/driver/psu setup.

[TSJ]

I could be wrong, but the setup for the AC servo looks to be a lot simpler that that for a DC servo or stepper. If I am incorrect I am sure someone will let us know. I do not know how you put a monitary value on ease of installation vs. figuring it all out for yourself.

Look at: Servo products

[hydronuclear]

Thanx for the replies

I would use either aluminium or MDF, round Linear rails and a moving gantry

Probably end up making up my own ACME screws or atleast thats my plan (keep costs down a bit)

I was thinking 2m by .75m (approx 80" by 30") with a z travel of 15cm 6"

And those servos are way out of my price range, converting it to rands.

I was also wondering if any controllers come in usb instead of parallel as it seems my gaming mobo only caters for a com port
If not can i use a converter?

[hemsworthlad]

Servo's and steppers work in differant ways and have differant reqirements, but the compant you mention also take all the work out of selecting by providing a prity much plug n play kit.
I will be getting one of there packages very soon and if starting again and could afford the little extra would buy one of there servo kits over a stepper setup.

[hemsworthlad]

Originally Posted by hydronuclear I was also wondering if any controllers come in usb instead of parallel as it seems my gaming mobo only caters for a com port If not can i use a converter?

No you need a parallel port or an external motion controller card like a smooth stepper. . . Cheaper to get a second hand PC.

[hydronuclear]

Well in that case im gonna have to put summin together or steal a pc from home

Are you sure i cant use a USB to parallel converter, sure would make my life easier then opening up my graveyard of P4 mobos and processors to unearth something that works...

Ok well i just read on mach3's website that parallel adaptors are not supported... i guess ill go with the pci parallel port then.

I was wondering, do i need a linear encoder?

[hemsworthlad]

Originally Posted by hydronuclear I was wondering, do i need a linear encoder?

No you dont need an encoder with stepper motors. You can use a encoder with step motors but then special drive's etc are needed to make use of them.

Linear encoders are used on servo's motors and servo drives have all the neccesary trickery built into them to talk with the encoders.

[hydronuclear]

it helps if i read :P

is there any specific ration between holding torque / torque and the load that needs to be moved (so that i can calculate motor size and what not)?

[hemsworthlad]

Originally Posted by hydronuclear Thanx for the replies I would use either aluminium or MDF, round Linear rails and a moving gantry

Go with aluminium much better than mdf and worth the extra expense.

Originally Posted by hydronuclear Probably end up making up my own ACME screws or atleast thats my plan (keep costs down a bit) I was thinking 2m by .75m (approx 80" by 30") with a z travel of 15cm 6"

Depending on how you do this then chances are your home made screws wont be very effiecient which will mean larger motors to overcome the sticky screw, which inturn means larger drive's, larger psu's etc all equal more Rand.! Then you'll still have an underperforming screw with all the headache's it can and probably will introduce into the overall performance of the machine.

From experience and helping others it doesn't save money trying to make important components like screw's etc it just cost's money and the only bennifit is that you know sooner that your machine just ain't up to the job and you wasted hours/days/weeks of time and a bunch of Rand.

With the length you propose then I wouldn't use screws, at 2m theres a good chance you will encounter whip unless you use large expensive screws or go to the trouble of rotating the nut, both of which cause extra work and money.
Better would be rack & pinion or belt drive for the long axis.
Belt drive is quit a good and relatively cheap way and hisn't overly complicated to do, it's also quit effiecient if done right and wouldn't require large motors.

R&P is usually cheaper than Screws and takes all the whip issue's away and far better suited to long axis's over 2m but it does have some negative sides.
It's still quit a bit more expensie than belt drive, not as effieceint needing larger motors/ drives etc, Both belt and R&P often need gear reduction to get the neccesary resolution. R&P needs carefull alignment and setup requiring prepwork and maintenance, it's also noisey compared to belts.

IMO upto the length you propose then belt is the better cheaper option for some one on a budget. My way would be belts on X axis screws on Y&Z axis.

[hemsworthlad]

Originally Posted by hydronuclear it helps if i read :P is there any specific ration between holding torque / torque and the load that needs to be moved (so that i can calculate motor size and what not)?

Yes there's a very accurate calculated scientific way to know exactly what's needed but i'm not going into it because life's to short.

Do a search for "sizing stepper motors" and you'll find all the brain aching info you need.