Cnc wiring!

[Desertboy]

Regulated or Unregulated Power Supply
Both regulated and unregulated power supplies can be used to supply the drive. However,
unregulated power supplies are preferred due to their ability to withstand current surge. If regulated
power supplies (such as most switching supplies.) are indeed used, it is important to have large
current output rating to avoid problems like current clamp, for example using 4A supply for 3A
motor-drive operation. On the other hand, if unregulated supply is used, one may use a power supply
of lower current rating than that of motor (typically 50%～70% of motor current). The reason is that
the drive draws current from the power supply capacitor of the unregulated supply only during the
ON duration of the PWM cycle, but not during the OFF duration. Therefore, the average current
withdrawn from power supply is considerably less than motor current. For example, two 3A motors
can be well supplied by one power supply of 4A rating.
Multiple Drives
It is recommended to have multiple drives to share one power supply to reduce cost, if the supply has
enough capacity. To avoid cross interference, DO NOT daisy-chain the power supply input pins of
the drives. Instead, please connect them to power supply separately.

Selecting Supply Voltage
The power MOSFETS inside the AM882 can actually operate within +20 ~ +80VDC, including
power input fluctuation and back EMF voltage generated by motor coils during motor shaft
deceleration. Higher supply voltage can increase motor torque at higher speeds, thus helpful for
avoiding losing steps. However, higher voltage may cause bigger motor vibration at lower speed, and
it may also cause over-voltage protection or even drive damage. Therefore, it is suggested to choose
only sufficiently high supply voltage for intended applications, and it is suggested to use power
supplies with theoretical output voltage of +20 ~ +72VDC, leaving room for power fluctuation and
back-EMF.

http://www.leadshine.com/UploadFile/Down/AM882m.pdf

[Cobey3289]

Thanks guys, the wealth of knowledge on here is great.
My cnc is going to be 100cm x 75cm c beam construction. I intend to cut wood, acrylic and some aluminium with it. At this stage, the aluminium cutting will be to cut bulking blocks for the stickmaking world. Anything else will be ideas that come into my head at a later date.
As stated it will be run by nema 23's 425 oz 3amp motors x4 with8mm threaded rod. I can't say it's going to have a hard life, but that's just my thoughts at the moment. Once built and working, my thoughts and practices may change.
I plan to use a MacBook as my computer for the cnc. This I think will necessitate using a USB breakout board. Are there any particular boards suited to the USB side of things and as I'm heading for USB, was looking at chilli pepper as opposed to Mach 3/4.

Thanks
Mick

[Clive S]

As stated it will be run by nema 23's 425 oz 3amp motors x4 with8mm threaded rod.

Threaded rod and cutting ally don't go together very well

[Cobey3289]

What would you suggest, as that's what come with the mechanical build. I thought at least that's a step up from the belt system!
Mick

[Cobey3289]

Hi Clive,
That's tr8 lead screws not threaded rod, my mistake.
Mick

[Desertboy]

Hi Clive,
That's tr8 lead screws not threaded rod, my mistake.
Mick

still lead screws are only 50% efficient ballscrews 95%

That means 50% of energy is lost to friction! It just doesn't make sense anymore to use them for our application.

Where they work well is using really big ones for lathes, etc. Where ballscrew prices are prohibitive.

[JAZZCNC]

Hi Clive,
That's tr8 lead screws not threaded rod, my mistake.
Mick

Mick starting to appear you are a classic case of the internet searching leading you up the wrong path.
In the early days of DIY CNC components like ball screws and good off the shelf drives etc cost lot of money. Things have changed massively and now the cost is down to sensible figures we can afford.

Now it's very easy and we see it all the time that new builders find old build's which used components like Tr8 and even threaded rod and all sorts of DIY methods and follow this route. Unfortunatly often they are sadly dissapointed and waste lot of money.

So my advice is to take a step back do little more research and ask any questions you may have no matter how stupid you think it may be.
UNDER NO CIRCUMSTANCES BUY ANYTHING Until your sure it's correct for your build.

For instance, all the previous info regards Voltages drives etc to achieve best speeds is mostly irrelevant because the limiting factor to speed will most likely be the Tr8 and everything that comes with it not the voltage. So you would have wasted money building PSU etc that's much more than needed.
Said this many times that machine is only as good as it's the weakest link and for a great machine you need components which are well matched to give balanced machine.
Trying to save money only costs you money when comes to CNC, so don't try cutting corners because will only regret it.

Suggest you start build thread if you haven't already which shows your design. Then ask any questions there. If we can see what you have in mind it's easier to advise the correct components or approach.

[Cobey3289]

Hi jazz,
Seems like a total re-think is in order.
Just off the bat then, having already purchased the nemas and drivers (already en route)! What would you recommend for the rest of the kit to complete my 750x1000mm . I have c beams already, may need to add to this to adapt to ball screws etc.
Thanks
Mick

[Cobey3289]

Where do you guys get your kit from, as it seems like ooznest is the most popular place for purchases?
Mick

[Desertboy]

Thanks guys, the wealth of knowledge on here is great.
My cnc is going to be 100cm x 75cm c beam construction. I intend to cut wood, acrylic and some aluminium with it. At this stage, the aluminium cutting will be to cut bulking blocks for the stickmaking world. Anything else will be ideas that come into my head at a later date.
As stated it will be run by nema 23's 425 oz 3amp motors x4 with8mm threaded rod. I can't say it's going to have a hard life, but that's just my thoughts at the moment. Once built and working, my thoughts and practices may change.
I plan to use a MacBook as my computer for the cnc. This I think will necessitate using a USB breakout board. Are there any particular boards suited to the USB side of things and as I'm heading for USB, was looking at chilli pepper as opposed to Mach 3/4.

Thanks
Mick

8mm threaded rod, NO, NO, NO, NO!!!!! My reprap used that for a drive lol this is not reprap territory.

get ballscrews, get a free PC with a parallel port ask on forums and then you can use a £5 breakout board and linuxcnc with the money saved you pay for the ballscrews.

it'll cost ~£250 for 4 ballscrews and fittings for this size.

I think you're better off belt driving than threaded rod, you can do a belt and pinion setup which will be a lot better I'm sure. Just google it there's a few setups out there.