6040 7i76 Conversion

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11 Apr 2023 16:47 - 11 Apr 2023 16:49 #268832 by spacestate1
I want to get feedback on converting a Chinese 6040 'SXCNC' machine over to a Mesa 7i76 board. It came with a control box that works good with LinuxCNC, but I want the ability to control the spindle speed from LinuxCNC and eventually, I want to add probing and possibly a tool offset sensor. 

Here's a basic diagram of what I'm thinking. I'm not sure how exactly to wire the power to the stepper controllers,
does it need to go through the 7i76?
What micro-step settings are best for the TB6600 controllers?
Not sure if I should buy a new VFD, or just use the one it came with.
Also I'm not sure my breaker sizes are correct or if they are in the right places.

Any feedback is appreciated.

 
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Last edit: 11 Apr 2023 16:49 by spacestate1. Reason: ACSII didn't format correctly

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11 Apr 2023 21:59 #268841 by andypugh
Replied by andypugh on topic 6040 7i76 Conversion
I don't think that you should try breaking the 36V DC, unless you get a DC-rated breaker. Best to break on the AC feed side to the PSU, I think.

Of course, you could just use a fuse, that would probably be fine.

The 36V (Or whatever) power supply for the stepper drives does not go anywhere near the 7i76. That runs from its own logic power supply, derived from the "field power" input and also generally from a 5V supply .
You show a 7i76, but that requires something like a 5i25 to connect it to the PC. Maybe you meant the 7i76E which connects to the PC via ethernet?
The 7i76 has a DB25 connector, but can't be connected to a conventional parallel port.

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11 Apr 2023 22:38 #268849 by spacestate1
Replied by spacestate1 on topic 6040 7i76 Conversion
Should have specified, it's connected to a 7i76E, and I'm buying DC breakers. I guess the part that I'm unclear on is how to connect the Field Power. does the filed power get all of it's power from the 5v supply ? from what I've seen, I think it does ?

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11 Apr 2023 23:01 #268852 by andypugh
Replied by andypugh on topic 6040 7i76 Conversion
No, field power (often 24V) is used for the sensors, limit switches etc. Logic power for the smart-serial part of the system is derived from the field power.
I think that there are jumper options to use the board 5V supply for field power, but it is generally wise to use a higher voltage for field IO as it adds a bit of noise resistance.

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12 Apr 2023 01:18 #268861 by spacestate1
Replied by spacestate1 on topic 6040 7i76 Conversion
Thanks again, I'll post some photos once the build ins underway. But this is a good start.

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10 May 2023 00:37 - 10 May 2023 01:04 #271076 by my1987toyota
Replied by my1987toyota on topic 6040 7i76 Conversion
Some things I would caution you on one stay away from the TB6600  they are too small of a stepper drive except
for the smallest of the nema 23 stepper motors . I went with the DM556 after running into cooling problems with
the TB6600 on a 3040 router stepper motor. The TB6600 also has the cheapest and worst cooling path for
for a drive . Sometimes they use heat transfer tape and thermal grease and I had one that bareilly had any
thermal paste at all between the chip and the chunk of aluminum the manufacturer used as a thermal bridge
and the heat sink. ( it would shut down randomly due to thermal overload )

When I am setting up a screw type of machine be it leadscrew or ballnut I go with 8 microstep

With the spindle motor control  it is highly dependent on what the motor driver is . If it has the usual
0 to 10 volt dc 3 wire potentiometer setup ( red, yellow, and black wires ) you can control the speed
directly with the 7i76E. Maybe add an enable relay for added safety. if the driver has a low voltage
On/Off switch ( I.E. 24 volts ) Pictures of the spindle drive will help immensely.

as far as wiring with the 7i76E the below PDF should help in your endeavor
 

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Last edit: 10 May 2023 01:04 by my1987toyota. Reason: adding information

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10 May 2023 12:45 #271106 by spacestate1
Replied by spacestate1 on topic 6040 7i76 Conversion
Thanks that's awesome, I'll need to see about those stepper controllers. I got a good deal on three TB6600s, but I can live  without them.

I need to figure out the best way to wire an E-stop, I've seen some posts on here that show how to do it.
 
Also does anyone have any recommendations for a power supply for the steppers? 
attached is a photo of progress.
 
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10 May 2023 18:35 - 10 May 2023 18:46 #271121 by my1987toyota
Replied by my1987toyota on topic 6040 7i76 Conversion
STOP !!!!. I thought you said you had a 7i76E. Your picture is of the 7i76 with a 7i92.  The wiring is different.
You will want to put a 24vdc power supply in the system to power TB1 field power. DO NOT put more then
5 volts dc into TB3 logic power. On that note though you should be able to supply the 7i76 with the 5 volts
from the 7i92 DB25 connector but I don't know the exact pin out and jumper settings maybe PCW could chime
in on that one.
 
Last edit: 10 May 2023 18:46 by my1987toyota.

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10 May 2023 20:56 #271128 by spacestate1
Replied by spacestate1 on topic 6040 7i76 Conversion
It's just 5v going to the 7i92. There's two 5v power supplies because I didn't realize the 7i76 can get power from the 7i92. As far as I can tell the stepper pins for TB2 are the same between the 7i76 and the 7i76E correct ?

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10 May 2023 21:00 #271129 by PCW
Replied by PCW on topic 6040 7i76 Conversion
To power 7I76 5V from the 7I92T:

7I92T W4 "UP"
7I76 W2 "LEFT"

Nothing connected to 7I76 TB3 pins 21..24
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