Newbie. Plasma Table Refit. General/Basic Questions.

09 Nov 2017 09:33 - 10 Nov 2017 07:34 #101540 by RedNZ
Hi there,

My name is Jeremy, from New Zealand. I have recently acquired a plasma table. Its an older FastCut CNC plasma cutter, 1.5mx2.8m. It is currently running the original Testra SS4454 controller. Only X and Y axis and is powered by a Hypertherm PowerMax 1650 G3 plasma unit. It uses Millwrite to create the Plotter code for it.

My main goal is to implement a THC and Z axis system.

I am currently happy with the performance of the machine in terms of speed and accuracy. My problem lies in trying to add the THC to the existing Testra controller. There is minimal information available online. I have been in contact with Testra and when they reply, they are helpful. Yet the replies are far and few between.

Compared to the amount of information regarding programs like Mach3/LinuxCNC, I think this maybe the way to go. I have been researching as much as I can.

I only have a limited knowledge on CNC stuff, being a Diesel mechanic by trade. The mechanical side and even the basic electrical side is fine. I understand the process/fundamentals, just not so much the implementation.

From my research into LinuxCNC, my concern is the amount of code that people have to do. Im curious to see if you guys recommend it as a way to go? I have been reading the Wiki pages. Also read Rodw build from start to finish and see the complications he had. Im guessing its not a plug, tune and play system? My main problem is, I don't have a computer setup for Linux. Otherwise I would install it and start playing around with it.

The current stepper motors for X and Y are Vexta PK296-F4.5A units. (DC 4.5A, 2 Phase, 1.8/Step, 0.48ohms). There is roughly a 3:1 ratio on both axis. Both axis belt driven.

I understand at a minimum need a, power supply, BOB, the THC card and drivers. When I look at the Messa website it gets a bit overwhelming.

Im curious if any of you guys do this for a living, sell the parts or your expertise? I'm not here because its open source, im happy to make a payment/donation if it works.

Thanks for your time! Jeremy.

We all like photos, don't we?

Digger Ear, 25mm plate!

Early FastCut table.
Last edit: 10 Nov 2017 07:34 by RedNZ. Reason: Fix Pics

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10 Nov 2017 02:35 #101585 by tommylight
Daymn, those are nice pictures......of colors !!! :)

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10 Nov 2017 07:35 #101589 by RedNZ
Yea, not my finest hour! Should work now...

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11 Nov 2017 08:09 #101644 by bjames28
Hi Jeremy,

Unfortunately the e-mail sending doesn't work through the forum , so write me a short mail to jb19676 at gmail dot com.
Let's see how far we can go ..


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11 Nov 2017 08:47 #101646 by rodw
One option you have is to just install an external THC such as Proma, Neuron, Robot3t and the like. Just buy a z axis stage and maybe a snapcut magnetic breakaway. In fact I have a THC surplus to requirements which I think I could ship to you for about AUD $35 soon with contract rates with Australia Post once I sign off on their offer.. If you went this way, you'd keep your your existing table which would be none the wiser of the new smarts. Send me an email if interested.

If you did go down the path of a retrofit you should be able to keep your existing stepper motors, drives and limit switches. I would check the number of inputs required before you chose a hardware platform as plasma needs quite a few. Once you go past a simple parallel port setup, a Mesa 5i25/7i76 or a 7i76e ethernet card are hard to beat.

I am determined to crack the PID based torch height control after a few speed bumps which you've noted. I seemed to have finally solved my noisy plasma cutter issue today so I will be able to make a bit of progress from here on after doing nothing for months.

I think on balance LinuxCNC is by far the better motion controller over Mach3 but plasma is not yet well supported. However, Mach's support is pretty poor anyway as evidenced by CandCNC moving to LInuxCNC. Once the external offsets branch is merged into master branch (which some were proposing on the developers mailing list last week), LinuxCNC will be positioned to provide a very high performance torch height control integrated right into the trajectory planner. This is disruptive technology and potentially will render the external THC's obsolete. But it won't be an easy journey..... it will be more likely be an equipment manufacturer who cracks it.

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