The first build - Part 1 components and an overview

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24 Feb 2024 11:46 #294195 by olli_
Hello everyone!

My hobby-interest in TIG-welding has opened up new paths on my fabricators journey. I mainly build exercise machines for my own use and I want to expand on my capabilities by building a CNC plasma table. Taking the long way is my go to in pretty much everything I do. I seem to be unable to just buy a plasma cutter and start cutting. I have some experience in using Fusion 360 and a few uni courses on Python coding (a long time ago). I have been relentlessly studying on my off time about plasma cutting in general, and about electrical motors for around three months.

This forum was a fantastic discovery, along with associated youtube channels. And ofcourse, I'm here to learn and ask for help before I buy the components.

MESAs mothercard and THCADs are what I want to go with and due to shortage on the EU-market I cannot pick up exactly the same parts as lets say Rod's Spaceship build.

I will be converting my laptop for Linux and use LinuxCNC. For features, I want to have voltage and ohmic sensing, as the build is going to be fairly large. (half a sheet) Having axes feedback is not a must, but would be great. The frame will be fabricated from 3 millimeters thick 70x70 steel box section. The gantry itself I might choose something like 2 millimeters thick 100x50 box section. Rack and pinion on all axes except Z-axes will have a ball screw.

The main components:
MESA 7i95T eusurplus.com/index.php?route=product/pr...=59_62&product_id=64
It has encoder feedback on all of the axes and I would like to use either hybrid-type stepper motor or servo motors for all axes.

2x MESA THCAD2 eusurplus.com/index.php?route=product/product&product_id=161 
One for controlling the Z-axes by voltage monitoring and one for ohmic sensing.

If I go with hybrid nema 23 stepper motors, do I need additional stepper drivers, or will the 7i95T be enough?

I would prefer non chinese built power supplies, but to my surprise they are not as easy to get as I would have liked them to be. Am I being too picky?

I have absolutely no idea what kind of wiring I should use in the build. We have 230 V 50 Hz mains in Finland. I was adviced not to get any wire crimpers as most of the wiring is done with screw terminals because of the added resistance from the crimps.

I have hopes of using a Hypertherm plasma cutter, but If my budget wont allow it I will choose Everlasts plasma cutter as I was highly impressed by the neat insides of one of their welders on one of Kevin Carons videos.

Any feedback on my ideas for the build would be greatly appreciated. Hopefully I can document the whole journey well enough to be shared for everyone.

Best regards,
Olli

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24 Feb 2024 12:10 #294204 by rodw
I am honoured! It was a long road selecting components, I had to order a lot from overseas.
You will need stepper drivers. Look for ones that can take 60-70 volts. 48V minimum is OK,
In Europe, consider the Lam drivers but they are not cheap.
With your rack and pinion assuming approx 30mm dia pinion, 5:1 reduction is good. We found  small Nema 34's were needed on the Gantry (Y) but Nema 23/24 is fine across the gantry (X) and on the Z.
For power supplies, consider Meanwell but for the stepper motor power, look for Toroid power supplies. The Lams can take AC power so if you use them you don't need a AC to DC rectifier with Toroids. Also Beckhoff make power supplies. I ended up getting some custom toroids made in later builds. I went with 60v AC with LAM DS1076A's but later found out LAM reccommended 55 volts.
With well designed motion, there is not really any need for closed loop drives as there are no cutting forces with plasma so you should never loose steps if properly condigured. The lam boost function lets them run hard without overheating...

Good luck.

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24 Feb 2024 19:57 #294242 by olli_
Thank you for the help and encouragement!

I will get the Lam drivers. I'm spending, and enjoying, alot of time with this build and surely I want to do it right. I'm that regular stepper motors will work, as it is one less thing to worry about at this moment.

The gantry will be quite heavy with the steel box tubing so I will up motor size like you suggested. Aluminum would be great but I have no experiences working with it and I run only a DC welding machine.

Good to hear that the meanwell power supplies work well. Toroid power supplies seem to be the next thing I have to study on.

Hopefully I can return the favour in the future If I happen to make a project that interests you aswell! Ill be sharing my progress here during the summer. Im going to spend the spring learning about the electronics side of things and insulate my garage to have a place to put the machine in and act as a year round shop.

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24 Feb 2024 20:49 #294253 by tommylight
If you are in Europe, try
www.mechapro.de/shop/
So far has the lowest prices and often DS1044 and DS1076 are on discount.
You will also need the programmer for them, it is 28 Euro, only 1 needed.
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25 Feb 2024 07:17 #294345 by olli_
Thank you for the tip!

Saved me from having to place a second order for the programmer!

Yes I'm in Europe, Finland to be exact.
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25 Feb 2024 07:42 #294346 by rodw
Also be aware the DS1076A is the one that accepts AC voltages. I think it will also accept DC voltage but check what it says.
The DS1073/DS1073A is suitable for NEMA 23/24's but is functionally equivalent to the DS1076 except for maximum current
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25 Feb 2024 14:15 #294365 by olli_
Oh, thats good to know!

I have a vendor here from whom I can custom order Noratel Toroid power supplies 230V to (2x)55V so I should be covered there too.
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26 Feb 2024 14:00 #294519 by RDA
For the ohmic sensing, I can send you a pcb that you can use to sense the height.
The pcb will just isolate the ohmic and output signal.
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26 Feb 2024 19:28 #294544 by olli_
That would be greatly appreciated RDA.

If you like, you can be in touch via email at This email address is being protected from spambots. You need JavaScript enabled to view it..

Thank you!

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