[blasttiod]

Hi all from a newbie,
Could anyone tell me any suppliers in New Zealand please for the parts to make my own CNC router.


Regards

[blasttiod]

Hi all,
Has anyone got any info on where I can purchase CNC parts in New Zealand Please. Regards

[dearlovr]

what sort of parts are you after , stuff is available , price is another matter

[blasttiod]

Hi dearlovr,
Thanks for answering.
I'm looking for 3 stepper motors(for x,y,z), stepper motor controllers and LPT interface. Because I don't really understand things I'm looking for either a kit or speak to someone who can help me put the items together.

Regards
Kevin (New Plymouth)

[dearlovr]

I got some quotes from these guys , have attached , I built my own parallel port interface , I will advise if i see a commercial one , havn't purchased any from these guys as am also looking at servo drives as i need fairly high powered units .

Hi Russel,

Attached is a pdf of our latest prices for the Lamtech range of products
and some brochures.

Best regards,

Nico Diedricks

Flexible Automation Ltd.
Tel: 09 273 5170
Fax: 09 273 5190
Web: http://www.flexibleautomation.co.nz

[dearlovr]

Oately electronics in australia have the stepper driver kits , parallel port interfaces and constant current source units that you will need
http://www.oatleyelectronics.com/ have got some stuff from them years ago without a problem .

[blasttiod]

Hi,
Thats great, just what i'm looking for and not to pricey.....

Just got to find some steppers at a reasonable price.

Thanks for that

Regards
Kevin

[blasttiod]

Hi dearlovr,
Been looking at the oatley site. Am I right in thinking I need the following:
K142A x 1
K142B x 3 (if I get the 4 wire motors)
K142C x 3

I'll then need to source some kind of power supply for the motors ?

Also could you tell me the diffence between 4 - 5 and 6 wire motors ?

Regards
Kevin

[dearlovr]

stepper motors commonly are 4 wire , 5 wire and 6 wire , basically there are 2 coils , 1 wire for each of the ends of the coil and in the case of the 6 wire a wire that is connected mid way thru the coil , 5 wires are just that 2 of the connections are paired to minimise duplication , check the web or stepper documentation for detailed view on how they are wired .
see http://www.educypedia.be/electronics/motorstep.htm

parts list looks good , the constant current units will ensure torque available thruout rpm range , real trick is to determine what size of stepper that your rig will require , cnczone is the place , just see what others have done , also utube has some great video's of homemade cnc units , but do look around , I've read some good articleson the web about turning dc motors into servodrives as well . http://www.truetex.com/machinery.htm

[Big S]

You can get some cheap steppers at New Age Materials in Wellington,
http://www.trademe.co.nz/Business-fa...-158677149.htm

They had some different ones to the auction above that were better but still only around 130oz/in.

Shannon.

[FieldingBlue]

blasttiod,
I'm currently building the same kits that you refer to. I'm pretty happy with the boards and components. I'm not so impressed with the instructions but there is enough info there to muddle through.
:idea:
There is one point to watch with those kits. The driver boards are supplied with MOSFETs which are rated at a lower voltage than the supply shown in the diagrams. If you want to use the max supply voltage you will also need to purchase replacement MOSFETs for your driver kits.

Working out the size of steppers to get was/is a problem for me too. I tried to derive some equations from first principles but I'm not that good a physicist. So I ended up using a rule of thumb I found on this site: http://buildyourcnc.com/torquemotion.aspx
There is some fiddle factor in there because you have to take your best guess at the friction in your system. However it gave me a warm fuzzy feeling that I was in the ball park. I assumed that I would have 50% efficiency, which is reasonably conservative.

[blasttiod]

Hi fieldingblue,
Thanks for you input. Out of interest what spec motors are you going to use and are you building your cnc from a plan ?.

Although I've been looking at the Oatley Electronics stepper drivers I have been told that they won't microstep.

I'm still finding out things and reading as much as possible before making a purchase, so any further info you might have will be greatly received. Have you any pictures of your build ?

Kevin

[FieldingBlue]

Blasttoid,
I'll answer your questions out of order because then it will make more sense.

and are you building your cnc from a plan?

In a word: No.
I like to do things the hard way. <drops and shakes head> I've spent about 4 months looking around at various designs and images that other people have used. I've tried to pick the bits I like and discard the bits I don't. The end design is somewhat different from anything I've seen but I am fairly confident it will do the things I need. I've tried to make it modular so that if one aspect fails, wears out or is just plain wrong I will be able to recover from the issue.

what spec motors are you going to use

In short: I'm not sure yet.
I am confident that I will be able to find the right thing when I need it.
Because the design is new I've not settled on the motors yet. I'm waiting to see how much friction the linear bearings and lead screws introduce before I settle on the specs needed. I've got a couple of surplus steppers that I am intending to use to test the electronics with.
The rule of thumb I've used to determine a likely size is along these lines. I know that it feels like less than 10kg of force I need to push against the router when I am using in my work bench. So setting that as an upper limit I then ran the numbers through the Torque = ((weight)(inches/revolution))/2(pi)(efficiency) formula. I set efficiency as 0.5 (50%) and came up with 0.6239Nm. Uh oh!
Now that you have asked the question and my notes are not with me, I've just gone over it all again and discovered that it's wrong. Bugger. The formula given on the buildyourcnc.com site is based on a conversion between horsepower and torque. Here: http://www.merkle-korff.com/technical_advice.asp?id=48. Unfortunately for me, horsepower is a measurement of work, not force. So I'll spend some time over the next couple of days and see if I can get a better formula for conversion between torque and linear force on a lead screw. Sorry! The lessons here are "don't believe everything you read on the net" and "submit your design for peer review". Thanks for the prod, really.

Although I've been looking at the Oatley Electronics stepper drivers I have been told that they won't microstep.

As you say, these devices do not micro step or half step. There are two Flip-FLops used to sequence the stepper. That means there is only 4 possible combinations of output, which means that the half steps are not accessible. Use of half steps would require a total of 8 output combinations. For me this is not really a problem. I'm doing routing in wood, not machining engine components. At 2mm per revolution on a lead-screw and 200 steps per revolution that gives me 0.01mm resolution. More than adequate.

Last note. I spent some time over the weekend assembling the constant current supply, as it was supplied in the kit. That's a pretty fiddly piece of work. I'm going to have to take my time to put it together. Again I think better instructions would really help but I'll muddle through.

[FieldingBlue]

Blasttoid,
I've had another hack at it and I'm much more confident now.

what spec motors are you going to use

I'm solving the issue with selecting stepper motor specifications in the following manner.
To begin with, I know how much linear force I need. Motor specifications only come with a torque rating. So I want a way of converting between these two values. I need a transform. I looked for a common property that both Force and Torque relate to in, this application. The best property I could find was Work.

For linear motion:
  Work = Force by distance ( W = F.s )

For rotary motion:
  Work = Torque by angle ( W = Τ. φ )

The distance and angle values relate to the lead-screw being used. For my implementation one rotation ( 2 Pi in Radians ) gives 2mm for the distance traveled.

Putting it all together I got the following formula.
   W = F.s
& W = Τ. φ

so

→  F.s = Τ. φ
→  Τ = F.s / φ

There is a problem with this in that it assumes the lead-screw has no friction. Friction is a dynamic quality that varies with velocity, temperature, lubrication and whether velocity is increasing or decreasing. Most of the friction in this case I expect to come from the anti-back lash fittings, which I haven't worked out a design for just yet. To be conservative I am postulating that my system will be 50% efficient. That is, only half the torque provided will be used for applying a linear force. The rest will go in friction.

So to finish off.
I want a maximum of about 10kg of force. This is based on my highly precise and calibrated arms and the effort involved in wielding my router.
10kg equates to 98N. (Newtons)

 Τ = 98N * 0.002m / 2π
 Τ = 0.03119 Nm

If I assume 50% efficiency I double the raw value so I am looking for about 0.06239 Nm torque at operational velocities.
In general I have found in the manufacturer's specifications that the torque available at top speed for a stepper is about 1/5 of the holding torque.
So now I am looking for stepper motors with a 0.03119 * 2 * 5 or a 0.3119Nm holding torque rating.
That is 3.18 kg.cm or 44.17 Ounce.Inch holding torque.

The proviso is that any motor I find, which seems to meet this specification ,will be investigated a bit deeper to see if the 1/5th assumption holds. Then everything gets re-assessed when I have a chance to test the friction in the system.

Based on the above work I expect that the MOT-120 FL42STH38-1684B (Frame 17) Bipolar Stepper Motor from http://www.oceancontrols.com.au/moto...per_motors.htm will do the job. At the least I know I am close.

I hope this helps.

[elwoodbeauchamp]

Hi, All,

I would like to offer an alternative to paying high prices locally by refering you to a couple of good places here in the States that several of my Au and NZ Clients have been purchasing their Steppers, Servos, Linear Rail/carriages
and other similar items from for over a year now...

Here is how I have saved them $$$$ for over 40+ shipments now.

• When you locate the parts you need
• Purchase the items
• Have the item(s) shipped to my address
• I repackage the item(s) into the most economical Packaging Possible
• You pay me $15.00 US + USPS Postage, $38.95 or 49.95 (depending on the size of the item(s) + International Currency Exchnge Rate (4%, average)
• I purchase Postage and Mail your Items to you.

The Details are found on our website. Just click on the Int'l Shipping menu item.

I will give you references if you wish.

Let me give you an example:

The components you need cost $73.73, weigh 19 pounds and shipping cost is $88.84...Total of Over $160...Sux, right? (estimate)

---OR---

Send the 19 pound items to me and pay $8-$12 for US Domestic Delivery.

I repackage the items and the Total Shipping and Handling costs are $56.50.

Instead of $160 to get your parts, you only pay $142.00

Let's not forget the savings on the parts here in the States.

Just offering to help....Mail me at: [email protected]

Cheers,

Elwood





http://www.kelinginc.net/StepperMotor.html

[appicnc]

I have used Woody to send me stuff in Oz for the past year, he is reliable, cheap and fast. He will not only re-pack from several sources into one, but he will cut to length if required, for example, I wanted some 20mm linear rails from VBX, there is a length limit of 1167mm from the States, the rails are 1397 long so Woody cut them into lengths to suit me, so, I was able to buy cheap LR's and have them cut, does he charge for that, of course he does! is he fair with his fee, yes to that to, He takes Paypal and it is JUST EASY to do business with him.

He used to be a fitter so he also knows about the stuff we do and has helped me with alternate suppliers, finally, I think the computer is wired into his brain, it never takes long for him to get back to you.


Ed

[appicnc]

One last thought, he will also arrange shipment by other means, last year he arranged to have some 20mm linear rails sent from the States, about 10 of them and other stuff, he not only consolidated the parts into two tubes but he put them onto a pallet and delivered them to the shipper, filled out the forms, did it all.

I wouldn't go that route again, not because of Woody but the Australian Gov' saw it as a way of balancing the Au <> US trade deficit, even tried to charge me duty ( non payable due to the free trade agreement ) and GST ON THE DUTY!!!!!! barstards!!

[FieldingBlue]

Appicnc,
I'm curious now. Did you convince customs that they were wrong? How did they explaine the tax on the duty? Is this a problem that I can expect if I order bits from off shore?

FieldingBlue

[Big S]

From what I have heard, the Aussie customs tend to weasel more than their fair share of duty and taxes out of stuff coming into the country. I guess its buyer beware. NZ customs seem to be much more honest and fair, thankfully.

Shannon.

[FieldingBlue]

Big S,
that is disappointing. I'll make some enquirers with customs and find out what they are supposed to do.
I've never had a problem with them when I've gone through the airport. They always drop big hints that you should say your new widgets are well used and that you should take a sip out of your extra bottles of booze. To bypass the duty fees.
I guess they put the people-person people (!) on the airport queues and the box heads in the box queues. 8-P

FieldingBlue