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- Help needed: Retrofitting a CNC plasma table with new drivers and controller
Help needed: Retrofitting a CNC plasma table with new drivers and controller
29 Nov 2016 17:56 #83439
by frecel
I need some help from people who have more experience with CNC than I do.
At work we obtained a 4'x8' CNC Plasma table but it's missing the drivers and the controller. The stepper motors, the wire harness and all of the parts of the actual table are all there.
There are four 6A 3V stepper motors in it, two of them move the gantry, one of them moves the torch on the gantry, and one moves the torch up and down. It also has a couple of kill switches, one clicks when the torch hits something, another one clicks when the torch tops out on the z-axis.
The price on the original controls for this table is pretty steep and as far as I know we would still be missing the features to adjust the amperage with the controller.
Now I'm a software guy so I'm not super familiar with the hardware side of things and I have very little experience with CNC machines so any advice on how to avoid common mistakes would be greatly appreciated but I do have a few questions to start with.
Since the table has four stepper motors but two of them work on the same axis do I need three or four drivers?
It's a big table and I can see it cutting 1/2" steel on semi regular basis should I be buying drivers that are rated for more than 6A?
How do I make sure I'm buying the right drivers for the stepper motors, the right controller for the drivers and the right PSU for all of it?
At work we obtained a 4'x8' CNC Plasma table but it's missing the drivers and the controller. The stepper motors, the wire harness and all of the parts of the actual table are all there.
There are four 6A 3V stepper motors in it, two of them move the gantry, one of them moves the torch on the gantry, and one moves the torch up and down. It also has a couple of kill switches, one clicks when the torch hits something, another one clicks when the torch tops out on the z-axis.
The price on the original controls for this table is pretty steep and as far as I know we would still be missing the features to adjust the amperage with the controller.
Now I'm a software guy so I'm not super familiar with the hardware side of things and I have very little experience with CNC machines so any advice on how to avoid common mistakes would be greatly appreciated but I do have a few questions to start with.
Since the table has four stepper motors but two of them work on the same axis do I need three or four drivers?
It's a big table and I can see it cutting 1/2" steel on semi regular basis should I be buying drivers that are rated for more than 6A?
How do I make sure I'm buying the right drivers for the stepper motors, the right controller for the drivers and the right PSU for all of it?
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29 Nov 2016 18:34 - 29 Nov 2016 18:34 #83441
by andypugh
You need 4 drivers.
If this is a big machine I would suggest high-voltage drivers. Rather than bother with a PSU, get some of the drivers that take mains AC input. Don't forget breakers or fuses on the driver inputs, and _never_ disconnect a motor when the driver is powered up.
Consider buying a cheap breakout board and running with the parallel port just to get the machine moving. But don't reckon on running production with that setup.
Replied by andypugh on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
Since the table has four stepper motors but two of them work on the same axis do I need three or four drivers?
You need 4 drivers.
Buy drivers rated for the stepper motor current, or (better) large drives that can be adjusted down to the rated current. Ignore the motor rated voltage, that has very little relevance once the motor is moving.It's a big table and I can see it cutting 1/2" steel on semi regular basis should I be buying drivers that are rated for more than 6A?
How do I make sure I'm buying the right drivers for the stepper motors, the right controller for the drivers and the right PSU for all of it?
If this is a big machine I would suggest high-voltage drivers. Rather than bother with a PSU, get some of the drivers that take mains AC input. Don't forget breakers or fuses on the driver inputs, and _never_ disconnect a motor when the driver is powered up.
Consider buying a cheap breakout board and running with the parallel port just to get the machine moving. But don't reckon on running production with that setup.
Last edit: 29 Nov 2016 18:34 by andypugh.
The following user(s) said Thank You: frecel
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29 Nov 2016 19:04 #83444
by tommylight
Replied by tommylight on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
How many wires do motors have? You need that info before buying drives as there are unipolar and bipolar motors and drives.
If they have 5 wires, they are unipolar and the only way to use them with bipolar drives is to open the back of motors and rewire.
If they are 6, or 8 wires, they can be used as bipolar and unipolar.
In case they are 4 wire ones they can be used only as bipolar.
The older drives were unipolar, almost all new ones are bipolar.
If they have 5 wires, they are unipolar and the only way to use them with bipolar drives is to open the back of motors and rewire.
If they are 6, or 8 wires, they can be used as bipolar and unipolar.
In case they are 4 wire ones they can be used only as bipolar.
The older drives were unipolar, almost all new ones are bipolar.
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29 Nov 2016 19:44 - 29 Nov 2016 19:47 #83447
by frecel
Can you recommend a breakout board I could use?
I would love to use this www.buyapi.ca/product/raspberry-pi-cnc-board/ since it has all the features I need and I've used RPi in previous projects so I am familiar with it but unfortunately I can't find drivers compatible with that board that are capable of delivering 6A
All of them have 4 wires
Replied by frecel on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
Consider buying a cheap breakout board and running with the parallel port just to get the machine moving. But don't reckon on running production with that setup.
Can you recommend a breakout board I could use?
I would love to use this www.buyapi.ca/product/raspberry-pi-cnc-board/ since it has all the features I need and I've used RPi in previous projects so I am familiar with it but unfortunately I can't find drivers compatible with that board that are capable of delivering 6A
How many wires do motors have?
All of them have 4 wires
Last edit: 29 Nov 2016 19:47 by frecel.
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29 Nov 2016 20:16 #83450
by andypugh
Replied by andypugh on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
I would avoid the Pi for this application. It doesn't have the CPU / graphics to give a responsive user experience (even though it does the realtime motion control moderately well)
Do you have a generic PC available to load LinuxCNC onto?
Do you have a generic PC available to load LinuxCNC onto?
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29 Nov 2016 20:20 #83451
by frecel
Replied by frecel on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
I have a laptop I could use.
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29 Nov 2016 20:32 #83452
by andypugh
Replied by andypugh on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
Laptops are not generally recommended, they tend to over-think power management.
What external interfaces does the laptop have?
What external interfaces does the laptop have?
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29 Nov 2016 20:44 #83454
by frecel
Replied by frecel on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
It's a Dell D630, I keep it around pretty much just because of the DB-9 port on it. I could just buy a dedicated machine for this it really isn't a big deal.
As far as power management goes I guess there is nothing you can't fix by changing a few config files.
As far as power management goes I guess there is nothing you can't fix by changing a few config files.
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29 Nov 2016 21:00 #83455
by andypugh
Replied by andypugh on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
My preferred solution for machine controllers (this makes it sound like I have done many of them, but it's only my own three machines) is to put a bare 12V-powered Mini-ITX board in the same case as all the other boards.
One example here: goo.gl/photos/db7xcXPsCjbLG17X6
That's a PC motherboard and a collection of Mesa interface cards mounted on an aluminium plate.
One example here: goo.gl/photos/db7xcXPsCjbLG17X6
That's a PC motherboard and a collection of Mesa interface cards mounted on an aluminium plate.
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29 Nov 2016 21:03 - 29 Nov 2016 21:07 #83456
by BigJohnT
Replied by BigJohnT on topic Help needed: Retrofitting a CNC plasma table with new drivers and controller
This is a real machine and you will want real hardware. I have a plasma table so I know.
You will need a real PC not a laptop and starting from the control end a 5i25/7i77 PNG Kit will get that wrapped up. You will need a 24vdc power supply for field voltage so if you go the Antek route get one with 5v and 24v as well. If you can't find drives that take 120v then a good power supply like an Antek (note not Antec) and some good drives like Gecko GM215 that takes 80v input. For torch height control a THCAD card will take care of that. I sell the Mesa cards.
JT
You will need a real PC not a laptop and starting from the control end a 5i25/7i77 PNG Kit will get that wrapped up. You will need a 24vdc power supply for field voltage so if you go the Antek route get one with 5v and 24v as well. If you can't find drives that take 120v then a good power supply like an Antek (note not Antec) and some good drives like Gecko GM215 that takes 80v input. For torch height control a THCAD card will take care of that. I sell the Mesa cards.
JT
Last edit: 29 Nov 2016 21:07 by BigJohnT.
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