New Build Thoughts

[Dingo745]

Hi All,
This is my first post and my first foray into Plasma cutters but not my first CNC build.
I have previously built three small CNC Routers and now I'm going to have a go at a Plasma
I intend to build a small 5' x 5' budget machine with rack and pinion on the X&Y axis and Ballscrew on the Z axis.
I will be using a Gecko 540 with Nema 24 540oz. steppers 48V power supply from http://www.homanndesigns.com/index.php? ... 42ete2k817
I will be using Mach3 and maybe ? through a Smoothstepper
I will be only using a cheapie Lotos 50A Pilot Arc Cutter and one of the low end THCcontrollers.

So what I want is your advice on my proposed build, the good bad and the ugly so that I don't go and make some basic mistakes with any of my combo's parts and the do's and dont's for a newbie like me.
This will be an all home built steel framed table and I have a lathe and mill to make most of my own bits and pieces needed for the build.
Oh, and if it makes any difference I am located down in rural South Australia so I don't have ready access to most parts and it all has to be ordered from wherever.

Thanks in advance.

[slauk84]

The only thing I would be able to say is was looking at the lotos 50a and I found some not so favorable reviews. I ended up going with a Everlast power plasma 60s and love it.

[acourtjester]

I would not use a Smooth stepper on a plasma table I have talked with other and they had the same belief.
I have had great success with wit this cheap BOB
http://www.ebay.com/itm/361527280383?_t ... EBIDX%3AIT
there are many sellers on eBay that you can choose from to ship to Australia.
One bit to look out for is don't do "Ref All Home" on a plasma table as the Z will drive the torch down and the Y may crash it.
Do Ref Y and X separately if you want to go to machine 0.0.
Router home Z up no problem with crashing up therre.

[msimpson99]

I second the not using the smoothstepper. It has enough latency to cause some issues when working with a router, with plasma its horrible for doing the precise timing needed. A lot of what you will be using is in the experimental machine I am working with. It is a converted KRMx02 CNC. IT uses a G540 and 48v power supply with R&P drives.

You may want to go with some sort of reducer as direct drive with R&P will give you very little torque on a 5' plus steel or even aluminum gantry.

An Everlast 50s or 60s is a great start. I can tell you both the power requirements and air requirements are very modest.

You can follow some of my experiments here:
http://www.kronosrobotics.com/krmx02-plasma/

Also, just know you will have issues getting decent consumables for any of the Chinese machines. Good luck finding a shielded cap for doing an Ohmic sensor.

[msimpson99]

One other thing to concider is the G540. You only have 4 extra inputs for homing/limits n such. I am running into this now.

I'm currently maxed out using the following:

1-Homing
2-Probe (Ohmic)
3-Z limit (Floating head)
4-Arc transfer

Now with the smoothsteper (if you go that rout) you have the option to add a second interface (breakout board) Personally I will probably just add a second parallel port to my mother board to gain access for THC control.

[Dingo745]

Thanks for the input guys.
The Smoothstepper was just an idea as finding decent motherboards with a parallel port is getting harder by the day and the thought of a laptop appealed to me for a change. Has anyone tried Mach4 as I wonder if they have crawled out of the dark ages with the new version and will it run on an ethernet or USB interface ? My old laser engraver ran on USB no problem at all so why should Mach be so difficult I wonder.
Is there any alternative for a plasma as I have only ever used Mach3 for cnc routers myself.
As for the rack and pinion drives, they are going to be belt driven gear reduction, I forget the ratio for the moment.
The Plasma I was going for , a Lotos, is meant to be a popular brand according to Ebay, so what is ok to use but in a budget price range $1K or less that consumables are available as suggested.
I have had cheap chinese that worked fine and others that crapped themselves in a matter of days so that is why I have used the Gecko 540 ever since, but are they worth double the price or should I roll the dice on Ebay again ? as the money I could save buying chinese driver kits is money I could spend on a better Plasma maybe ?
Sorry for all the questions, but I'm the newbie this time round

[gamble]

Don't use a lotos

[msimpson99]

The Everlast s series are suited for CNC use. And while they dont have the consumable types the Hyertherms do, they have many more options than the Lotos. You can get a 50s for under $900. Everlast is not a cheap Chinese. I classify them as middle of the road plasma cutters. The S series even come with the plug for wiring your own CNC cable. Also many models of the Lotos came with CNC ports. This is not the case anymore. Also, if they are not using a blowback pilot arc, you need to stay far far away from them.

The problem is that USB has inherent latency, No matter what software and no matter what OS. It is not suitable for precise timing. Its job was to through tons of data in a long stream.

As for Mach4, I feel they have some real licencing issues. I often switch from machine to machine (computers) for doing specific jobs. With Mach 4 it is tied to a specific machine as are any of its purchased plugins. If you ever go pro then the price of Mach 4 goes through the ceiling. I think if they ever stop selling Mach3, you will see a lot of people looking at alternatives.

[Dingo745]

Thanks again for the input.
I had a look at the Everlast and I like what I see but here in Oz a 50s is close to $1200 AUD.
If I can get by by using an Ebay 3 AXIS Kit without too many dramas then I can put the money saved over the Gecko540 can help me pay for the Everlast
Now seeing that there are so many different Ebay (Chinese)cnc kits anyone recommend a particular model,company or seller on Ebay as freight on anything that heavy from the USA is cost prohibitive as we get raped on shipping costs by the usual carriers which makes the free shipping from China, slow as it is, a good way to go.
BTW I am on a very tight budget being on a pension, hence I am the penny pinching tight ass

[R0bKin]

My Lotos Ltp5500D works great on my LinuxCNC table I built

[acourtjester]

Thanks for posting your experiences other DIY types may be looking at options for their builds. The plasma unit and software are 2 main selections to make. Feel free to share more info.