Guidance on plasma table

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Guidance on plasma table

Postby andrewbishop66 » Sat Jan 21, 2017 6:00 pm

Hi all looking for some advice on a plasma table build mainly on the electronics side in what to avoid hopping to use my uc 100 for control and buy a uc300 to run my 4 axis mill that is currently run by the uc100

I know that when i tig weld in the workshop the hf upsets the mill( or at least it used to i havent tried since swopping to a uc100)
So just wondering how to go about it any lessons learnt would be handy

Thanks Andrew
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Joined: Mon Dec 19, 2016 9:05 pm

Re: Guidance on plasma table

Postby Robertspark » Wed Jan 25, 2017 11:48 am

Any of the UC's will be great and work fine.

However, the Ethernet ones tend to be less affected by electrical noise / interference, hence I've gone UC400eth and UC300eth.

If I were you, I'd just go UC300eth for everything personally as you've got more IO's than you'll need for other stuff if you add it later on (4th axis, ohmic probe + floating head, limit switches / homing switches, THC , pneumatic engraver etc).... whatever you can think of... the cost premium is small. if you already have a UC100 then not a problem, although I thought that you wont have some features because of the size of the microcontroller such as two touch probes (but even for ohmic + floating head, you can do it via 1 input + 1output and a relay, as I do it to test which has been triggered and set the right torch offset), likewise limit switches can be done via 1 input, although to square a gantry you'll need two inputs.

My advice, get the following:
- Good motion controller - UC300eth
- Good drives - Leadshine AM882H [there are many good recommendations, this is just my selection, allows me to feed AC direct to the drives, up to 70v AC, they have their own rectifiers + filtering caps in the drives and can be had from china at a reasonable cost + are tunable via COM port RS232 to your stepper motors]
- Good power supply - I use a 2 x 50vac 800W toroidal transformer (part No: VTX-146-800-250) ~£55 inc VAT + delivery direct from manufacturer
- a 24v breakout board will help with noise immunity, he one Gerry found I'd think would be a good bet [ships from south east asia (maybe Korea?) so may take a little while), look in the hardware section of the forum under the ISOBOB thread as he posted something in the last 24 hours on it.
- UCCNC (forget mach3 for plasma)
- Sheetcam
- I use 4A 8wire steppers, I forget the inductance, ~ 3mH rings a bell, and they give me very good acceleration with uccnc + the AM882H drives once they are tuned to the motors (very quiet).

For the Z axis, you want something with a resolution of ~2 - 3 turns per inch (so it's fast for THC), I use 10mm, 10mm pitch trapezoidal rod available via aliexpress very cheap.

I use belt drives (20mm HTD 5mm pitch belts, but there are many ways to achieve the same result), I have looked at GT profile as it may give a better finish + allow faster acceleration, but cannot find it available in 5mm pitch or with a wide enough width for me. There is a lot of GT2 about for 3d printers, but at 10mm width, when you start pushing the acceleration it will slip (I can slip the 20mm pitch with my drives under really high acceleration and deceleration, hence why I keep having a look about at better profile belt). It is steel reinforced belt so it does not stretch. My table uses direct drive 20T pullies, although I know that the direct drive is not good for the stepper motor bearings because of the force of the belt wrap, but if I need to replace my motors, I will, I accept that they are my consumable bit as they are being potentially a little over voltage driven using a 50v ac supply and the calculation provided by Geckodrives on motor + drive + power supply selection.

Einstein ― “If you can't explain it to a six year old, you don't understand it yourself”
UC400eth, UC300eth, UCCNC v1.2046, Neuron Lite.
UCCNC Macro Manual
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Location: Nr Liverpool, England

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