Upgrade of Sequoyatec RichAuto to Acorn CNC

Post your completed retrofits for the world to see.

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robertallenpayne
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Joined: Sat Sep 12, 2020 3:48 pm
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Upgrade of Sequoyatec RichAuto to Acorn CNC

Post by robertallenpayne »

We are Twin Cities Maker, a non-profit, volunteer driven community of artists, engineers, and makers. Together, we operate a shared community workshop where you can build nearly anything you can imagine. We want to share the story of upgrading a CNC router from RichAuto to Acorn from Centroid CNC.

Non-profit organizations often find that money is tight these days. But one of the top community requests was that we acquire a four foot by eight foot CNC router. We found one that met our budget requirements. It is from Sequoyatec. While we were pleased with the build quality of the machine itself, we were not satisfied with the RichAuto operating system. We wanted to give our users an upgraded experience, and Acorn CNC allowed us to do that.

Before we get into this, please understand that this post cannot possibly cover all the necessary safety aspects. These types of changes are relatively simple. But if you are not comfortable working with high voltage, then get some help doing this. Never open the electrical cabinet when the power cables are connected to power. Always make sure the on/off switch is off and the E-stop has been triggered. Lastly, follow lock-out/tag-out procedures. No one’s health and safety are worth swapping out the brains in a CNC.

We began by reading all the documentation we could find on both the RichAuto system and Acord CNC. It is important to have a rough idea of how the two different systems operate before attempting to swap one for the other. And if you haven’t done it already, please download the Acorn hookup schematics. They are super helpful. At the time this post was written, they could be found at https://www.centroidcnc.com/centroid_di ... matics.zip.

We also photographed everything and created wiring maps. If you choose to upgrade your CNC router to Acorn, you can follow these basic steps to help insure a successful transition. It isn’t a hard thing to do.

But please understand. Even if you purchase “the exact same CNC” that we did, please create your own photos and wiring maps. We do like the Sequoyatec. But it is a relatively inexpensive, imported machine. While all the wires were well labeled, there were some things that made us think that their quality control may not be on point. There were simple things like the installation of the DIN rails that components were mounted to. Some were not secure. Some were cocked off at odd angles. Nothing major. But they also used an electrical bus bar for the important connections. We have engineers on staff who design PLC systems. When they saw these things, they were very concerned. All in all, the electrical control panel had the feel of something that had been wired “as you go” with no real plan in place. If that is the case, it is entirely possible that you could purchase the same machine and find it to be wired in a completely different manner than what we describe here. So please, take pictures and create wire maps.

To create our wire maps, we simply listed each component we would be changing. Under each component, we listed each wiring terminal.
Although we didn’t change anything about the Power Filter, it only has a few terminals, so it is easy to show how the mapping works.
In the left column we list the terminals on the component. In the right column we list the terminals that are connected to the left terminals.

So, “Load P” on the Power Filter is actually connected to the “L” terminal on the Variable Frequency Drive (VFD).

Likewise, “Line P” on the Power Filter is where the ‘positive’ power comes into the power filter and that is connected to the “2T1” terminal on the thermal relay.
001-Wire.png
001-Wire.png (10.85 KiB) Viewed 123 times
We created wire maps for the following components:
1. RichAuto Control Box
2. X Motor Driver
3. Y1 Motor Driver
4. Y2 Motor Driver
5. Z Motor Driver
6. VFD
7. Front Bus Bar
002-4.png


You can see from the photo of the bus bar that while every wire and every terminal block is labeled, there are four sets of connections that are identically marked. This is not a big deal on the upper terminals because it is easy to trace those wires through the cabinet to their location. And, at least in our setup, the bus bar connections were X, Y1, Y2, and Z from left to right. But the bottom set of connections go out to the CNC platform. They all run through a conduit and if you don’t have them labeled and they come loose or otherwise get disconnected – well, good luck with that. ;) I think you can see what we mean when we say we think they wired it as if they had no real plan.

All we are saying here is that you should know where the wires are supposed to go, and make sure you have it written down so when you come back to it after taking a three-week break, you won’t be totally lost.

Now, the nitty gritty. What did we change?

Power Supply

The power supply that came with the Sequoyatec converted 240 volts AC to 24 volts DC. And that was fine for RichAuto. But our motor drivers require 5 volts DC. RichAuto handled that conversion internally. Acorn may or may not. But Acorn provides a power supply that accepts either 120 or 240 volts AC and outputs both 5 and 24 volts DC. So we swapped those powers supplies.

VFD Control

The Variable Frequency Drive (VFD) controls how fast the spindle spins. The model supplied with our CNC was the Best FC300-3.0G-3S-B4CF. Yours may be different. So just make sure you check the wiring.

RichAuto was configured to only allow three spindle speeds: low, medium, and high. The VFD is capable of a lot more. Originally, there were connections between VFD terminals X2, X3, and X4 and RichAuto Output Signal Jack terminals Y2, Y3, and Y4 respectively. Here is where we took advantage of the documentation for the VFD (which you should find on-line or from the supplier) and for Acorn.
005-6.png

Acorn provides a hook up schematic for a generic VFD. We didn’t use all of these connections, but we did use the 0 to 10 volt signal from Acorn to allow very fine control of the spindle speed. The hookup schematic S14983-ACORN_rev4_GENERIC_VFD.pdf is your reference sheet for this. It shows a connection between Acorn CNC jack H8 terminal “AN OUT” and the 0-10 volt DC terminal on a generic VFD. It also shows a connection between Acorn CNC jack H8 terminal “AN GND” and the 0-10 volt DC common terminal on a generic VFD.

On our Best FC300-3.0G-3S-B4CF VFD, the 0-10 volt DC terminal was marked AVI. And the 0-10 volt DC common was one to the right of that terminal and was simply marked COM. These connections are highlighted below.
007-Acorn.png
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008-VFD.png
008-VFD.png (7.73 KiB) Viewed 123 times

If you are curious how this simple two wire connection controls the speed of the spindle, it is relatively straight forward. The AN-GND to VFD-COM connection is just a common wire. Sometimes it is called a ground, but this is misleading. A ground provides a way to drain electricity from a system in order to prevent harm in the case that something goes wrong. But a common just provides a path for the electricity to return after doing its work. It isn’t an “emergency” thing – it is a “complete the circuit” thing. But it definitely shouldn’t be considered a ground.

The AN-OUT to VFD-AVI is where the magic happens. The Acorn can create and vary a voltage between 0 and 10 volts DC. At 0 volts, the VFD does not spin the spindle. At 10 volts, the VFD will spin the spindle at the maximum speed. At 5 volts, the spindle is half of its max speed. At 7.5 volts, the spindle is three-quarters of its max speed. In this way, the user can optimize the spindle speed for the material being processed.

Motor Drivers

Our version of the Sequoyatec CNC came with LeadShine drives. This is where it is important to have the 5 volt DC power supply. RichAuto seems to have a 24 volt DC to 5 volt DC converter built in to it. Acorn does not seem to. That’s not a bad thing. It’s just a thing. So the wiring on this is a little more complicated than the last section. Fortunately, Acorn provides a schematic (S14974-ACORN_rev4_MULTIPLE_LEADSHINE_CS-D1008.pdf) that spells it all out. You could also follow S14976-ACORN_rev4_LEADSHINE_DM_856,870,1182_&_2282.pdf perhaps. Our drive model was the LeadShine DMA860H. Since there wasn’t an exact diagram provided from Acorn for this, we just elected to go with S14974 and it worked out great.

We purchased a DB25 breakout board (you can get them from Acorn or get them from Amazon and many other places). Some of the connections to the drives were made through the DB25 connector. Some were made directly to the Acorn jacks.

As you get into the conversion, you will notice that the Y axis outputs from RichAuto are split into two sets of wire bundles to service the Y1 and Y2 drives. So be aware of that. You will probably not be able to use the wiring bundles provided with the equipment. Do not be afraid to make your own bundles. We used 18 gauge wire rated for 600 volts – which is pretty common.

If you check out the S15032 schematic, you will see that all of the “Enable” signals come directly from the H2, and H3 jacks on the Acorn board.
009-Driv.png

We will talk about the DB25 connections in a moment, but now is a good time to talk about the connections to the low voltage power supply provided by Acorn. In the diagram above, you will see that the output from the +5 volts DC does not connect to the Acorn itself. It connects directly to each of our LeadShine DMA 860H drives. Please understand that even though the diagram above only shows one drive, there are four of them. Acorn’s H2 jack EN1 terminal is for the X axis drive. EN2 is for both the Y axis drives. And EN3 is for the Z axis drive. This means you will have one wire in the EN1 and EN3 terminal. But you will have two wires in the EN2 terminal.

Now that we have the Enable circuits and the +5 volts DC sorted, it is time to deal with the DB25 connector breakout board. Your break-out board will indicate which terminal goes to which DB25 pin, so we won’t talk about the breakout board itself. The following diagram shows how the pins connect to the drives.
010-DB.png

Pins 2, 4, and 6 are for Step/Pulse. Pins 3, 5, and 7 are for Direction.

Pins 2 and 3 service the X-Axis. Pins 4 and 5 service the Y-Axis. And Pins 6 and 7 service the Z-Axis.

Simply wire Pin 2 to the “Step/Pulse-” terminal of the X-axis drive. Wire Pin 3 to the “Direction-” terminal of the X-axis drive. Then move on in a similar way to the Y and Z axis drives.
011-Bus.png

You may find that one or more of the motors do not move in the direction you are expecting once you start testing out your changes. We found that when we wanted the Z-axis to move down, it actually moved up. And vice-versa. That’s an easy thing to fix. If you encounter this, just find the particular axis connections for A+ and A- on the bus-bar in the front of the cabinet. Swap those two wires, and you should be OK. You could also do this on the High Voltage outputs on the axis-drives, but it’s just a matter of preference. You may find also that one Y axis motor moves the gantry forward and the other moves it backward. This is the same situation. Just swap one of the sets of A+ and A- for the Y-Axis. If you are like us, you will change the wrong one and the gantry will move back when you want it to move forward. In that case, just go back and this time swap both sets of A+ and A- on the Y-axis.

Touch Probe

The CNC also came with a touch probe. It is a simple setup. All it does is allow a circuit to close when the bit in the spindle comes into contact with the touch plate.

Acorn CNC implements this in a manner that is not ideal in my opinion. It may not even be to code. But being low voltage, I don’t think anyone is worried about it. And most importantly, it gets the job done. Acorn provides a generic schematic for touch probes (S14957-ACORN_rev4_HOMEBUILT_CONDUCTIVE_PROBE.pdf). Take a look at the document. You will see that there is a single wire connected to the Acorn’s H1 IN7 terminal. They rely on the machine ground to complete the circuit when the bit touches the touch-plate.

This probably should have a dedicated common instead, but we are grateful that Acorn did this. This brought to our attention the fact that while the electrical cabinet of the Sequoyatec CNC is grounded, the bed and spindle really are not! There is no dedicated ground between the electrical cabinet and the machine itself. This is so out of Code it isn’t even funny. But somehow, we missed this important fact until we got to this point.
012-Touc.png
012-Touc.png (93.5 KiB) Viewed 123 times

Our system was wired with the two connections on the far right of the bus bar controlling the touch probe. One wire was labeled 0V and the other was marked with Chinese characters. We confirmed electrical connectivity between the 0V terminal and the metal on the CNC bed. So this wire can serve as the grounding wire. The problem is that it was not wired to electrical ground with the RichAuto setup. It was wired to a ground terminal on the RichAuto module, but if there were stray high voltage from the CNC bed, rather than harmlessly earthing itself through a proper ground, it would have earthed itself through the RichAuto module – which likely was not designed for high voltage grounding. Fortunately, the solution was simple and we simply connected the 0V terminal to the electrical ground in the cabinet. And since Acorn is also tied to that ground, we are still able to get a touch probe signal. This is something we would like to see changed in future releases of Acorn, but it certainly met our need.

The last lead with the Chinese characters is simply connected to Acorn’s H1 IN7 terminal.

Finally, the Homing Sensors

Homing is very simple to connect. As always, Acorn provides a schematic. S14955-ACORN_rev4_LIMIT-HOME_NPN_PROXIMITY_SENSORS.pdf did the trick for us. The good news for us was that the power and common leads were already taken care of by Sequoyatec. We didn’t need to do anything with them.
013-Home.png
013-Home.png (10.84 KiB) Viewed 123 times
All we needed to do was connect “the black lead” from each sensor to the Acorn. On our bus-bar, each black lead from the NPN sensors came back labeled as X0, Y0, and Z0. These were connected to Acorn’s H4 jack terminals IN1, IN2, and IN3 respectively. And we also connected the power supplies 24 volt DC to the H4 24 IN terminal.

And that was the end of it. Conversion done.

Acorn’s hookup schematics are highly useful. At some point in the future, we will probably implement other features available on the Acorn. The first is probably to add the ability to turn on the spindle cooling pump. And adding tooling coolant pumps or air blasters would be fun too.
But for now, this implementation has allowed us to provide our community with an upgraded CNC experience from the one that came in the box. We hope that by posting this document we can help the broader community too.

Centroid CNC – thank you for producing such an excellent product.

And as we say at Twin Cities Maker, be excellent to each other.
Robert Allen Payne
Minneapolis, MN, USA
Member of Twin Cities Maker and CNC Fan Boy
cnckeith
Posts: 2931
Joined: Wed Mar 03, 2010 4:23 pm
Acorn CNC Controller: Yes
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MPU11 & GPIO4D -w/ 3rd Party Drives: Yes
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Re: Upgrade of Sequoyatec RichAuto to Acorn CNC

Post by cnckeith »

Wow, great post. please post some overall machine photos. thanks!!
When requesting support READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043

Please ALWAYS post a FRESH report. To make a report: https://www.youtube.com/watch?v=Ecvg0VJp1oQ.

(We pride ourselves on providing timely solid technical support but, without good information we may not be able to help and/or reply until such information is posted.)
cncsnw
Posts: 1605
Joined: Wed Mar 24, 2010 5:48 pm

Re: Upgrade of Sequoyatec RichAuto to Acorn CNC

Post by cncsnw »

robertallenpayne wrote:The AN-OUT to VFD-AVI is where the magic happens. The Acorn can create and vary a voltage between 0 and 10 volts DC. At 0 volts, the VFD does not spin the spindle. At 10 volts, the VFD will spin the spindle at the maximum speed. At 5 volts, the spindle is half of its max speed. At 7.5 volts, the spindle is three-quarters of its max speed.
The analog speed command should, as a rule, be used in combination with a digital "run" signal (or, on machines which need to run the spindle in both directions, separate "run forward" and "run reverse" signals). Do not count on a VFD to actually power off and free the spindle just because the analog reference is at minimum.
essbend
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CNC11: No
CPU10 or CPU7: No
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Re: Upgrade of Sequoyatec RichAuto to Acorn CNC

Post by essbend »

Some more photos...




BEFORE:

AFTER:

BEFORE:

AFTER:
essbend
Posts: 5
Joined: Sun Dec 29, 2019 5:15 pm
Acorn CNC Controller: No
Allin1DC CNC Controller: No
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CNC12: No
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: none

Re: Upgrade of Sequoyatec RichAuto to Acorn CNC

Post by essbend »

cncsnw wrote: Sat Nov 21, 2020 5:23 pm
robertallenpayne wrote:The AN-OUT to VFD-AVI is where the magic happens. The Acorn can create and vary a voltage between 0 and 10 volts DC. At 0 volts, the VFD does not spin the spindle. At 10 volts, the VFD will spin the spindle at the maximum speed. At 5 volts, the spindle is half of its max speed. At 7.5 volts, the spindle is three-quarters of its max speed.
The analog speed command should, as a rule, be used in combination with a digital "run" signal (or, on machines which need to run the spindle in both directions, separate "run forward" and "run reverse" signals). Do not count on a VFD to actually power off and free the spindle just because the analog reference is at minimum.
That's good to know. I hardwired the digital "run" signal to always on, but yeah now that you mention it that sounds like a bad idea. I'll get it fixed ASAP.
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