Conversion of Tormach PCNC 770 to Centroid's Acorn

[briuz]

Thanks for the feedback on LInuxCNC. I briefly considered using it instead of Acorn as I didn't want to have to get another PC....only to have to get a PC (Intel NUC) for Acorn. lol

Open Source solutions like LinuxCNC are serious contenders and not to be taken lightly.

Also, if you are outside of the US, there are export laws involving 5 axis systems. LinuxCNC may be a way to get around this if you want to do something with 5 axis.

The Centroid Acorn is a very nice alternative for a retrofit to a Tormach or any machine for that matter. Another alternative is Linuxcnc. Tormach themselves decided to go with Linuxcnc (they call it pathpilot). I have used Linuxcnc for many years now after ditching Mach3 and never regretted the decision. Linuxcnc is even more versatile than the Acorn and its capabilities are amazing. Linuxcnc can do everything discussed in this thread and lots more, as well as being free. Have you seen Skunkworks thread on here boring hex shaped holes with a boring bar on a lathe? Only downside is that LInuxcnc has a steeper learning curve, the Acorn is plug and play for those either not capable or unwilling to learn Linuxcnc.

Its nice to see the Acorn out there as a alternative. For me at least, Mach3 (or4) would be my absolute last choice and that comes after using it for many years.

[polaraligned]

Have you seen Skunkworks thread on here boring hex shaped holes with a boring bar on a lathe? .

I don't think this is a LinuxCNC specific thing, but rather just a matter of programming. Same program would probably run on Centroid.

[Sparky_NY]

I don't think this is a LinuxCNC specific thing, but rather just a matter of programming. Same program would probably run on Centroid.

Probably not. It requires considerable math/trig NOT done in the gcode program and also the ability to coordinate movement in the X/Z and spindle axis. Linuxcnc has a very powerful HAL (hardware abstraction layer) that is fully configurable in the config files. This deep level of configuration is not normally available in controllers. This is why pretty much any hardware can be used with Linuxcnc.

You would have to be pretty familiar with using Linuxcnc to appreciate the power it has. I have used it hands on for many years with a few different machines. Its NOT your typical controller.

One example would be something I implement, closed loop PID spindle speed control. It takes the encoder feedback from the spindle, with the commanded speed and processes these through a PID loop to modulate the 0-10V control signal to the VFD. This gives commanded speed vs actual within a very very close tolerance AND greatly reduces any speed bog down under varying loads, such as peck drilling. Normally to accomplish this you need a very high end VFD that has encoder feedback directly into the VFD.

Another example would be a onscreen spindle load meter, in the form of a bar graph green/yellow/red with the actual spindle current digitally overlaid. In linuxcnc its just a simple matter of taking the current output pin of the vfd and running it into a analog input, scaling it with some math, defining the bargraph etc. Same can easily be done for servo loads if desired.

How about controlling a hexapod type machine where multiple servos must be coordinated to produce movement in a single axis direction using kinematics? Then apply linear and angular compensation to each motions controlled by each servo? No problem. https://www.youtube.com/watch?v=51jICcUkhhM

These are just very simple examples that barely touch on the power of Linuxcnc. As mentioned, there is a steep learning curve with all this power and the Acorn serves most hobbyist needs much simpler. There is a market for both.

[skunkworks]

As sparky has said.. For basic 3 axis machines - almost anything will work. You have a lot of options out there..

Once you get above that (tool changer, rigid tapping, pallet changers, actual machining centers) the playing field gets smaller.

We have 3 basic mills at work that all have centroid controllers on them. the guys love them. I have not used them so I have no opinion. Again - the acorn is a very good option - it has rigid tapping and threading that usually doesn't work or work well on hobby grade controllers...

One of linuxcnc's strong point (and what a lot of people don't understand) is that the motion controller is in the computer. It isn't some expensive external magic box. Because the motion controller is in the computer - the external interface devices are simple and inexpensive. I am running a small mill that can rigid tap, realtime spindle speed control, Load monitoring, and even spindle controlled motion - all with a $89 mesa ethernet interface card.

we also have a hmc that has
Pallet changer
60 tool random tool changer with barcoded tools
16 speed hydraulicly shifted gear box..
40 amp servos for each axis.
temperature compensated spindle.
4th axis table indexer.

this is all done within linuxcnc. It has an integrated plc that is also realtime.

It is similar to centroid - you can use the same interface on all your machines... (just a lot less expensive.. :P)

[polaraligned]

As sparky has said.. For basic 3 axis machines - almost anything will work. You have a lot of options out there..

Once you get above that (tool changer, rigid tapping, pallet changers, actual machining centers) the playing field gets smaller.

And Centroid is probably the biggest contender for 4, 5, 6 or more axis machine retrofits. Their All-in-one and Oak controller will easily handle a tool changer, rigid tap, pallet changer, etc. Of course I am not speaking of the Acorn crap. That is just a hobbyist controller as it is not closed loop.
Free is good, but for someone (or company) who just wants their machine up and running without the learning curve, the price of Centroid is very reasonable- and there are a number of guys out there who make a living doing Centroid retrofits for companies. I paid about $2500 for my DC3IOB + MPU11 from them about 10 years ago, and I have 5 axis DC servo control. After dealing with Gecko and Granite drives, getting the Centroid drives was the best thing I did. Their MPU11 is a dedicated motion controller and it operates flawlessly. It opens the computer up for doing complex contouring and digitizing. Only thing I hate is that their latest software release is only supported on Win 10 which is the crappiest OS ever, but it does work. Unix was the best real time operating system ever, and it's child, Linux is derived from it. Centroid at one time operated on Linux, but for some stupid reason they dropped it.

I guess open source has a lot of potential power, but how many people out there really have the ability to take advantage of it, or for that matter really need that ability? I had considered it before I purchased the Centroid, but it seemed it wasn't worth the learning curve to me.

[Sparky_NY]

And Centroid is probably the biggest contender for 4, 5, 6 or more axis machine retrofits. Their All-in-one and Oak controller will easily handle a tool changer, rigid tap, pallet changer, etc. Of course I am not speaking of the Acorn crap. That is just a hobbyist controller as it is not closed loop.
Free is good, but for someone (or company) who just wants their machine up and running without the learning curve, the price of Centroid is very reasonable- and there are a number of guys out there who make a living doing Centroid retrofits for companies. I paid about $2500 for my DC3IOB + MPU11 from them about 10 years ago, and I have 5 axis DC servo control. After dealing with Gecko and Granite drives, getting the Centroid drives was the best thing I did. Their MPU11 is a dedicated motion controller and it operates flawlessly. It opens the computer up for doing complex contouring and digitizing. Only thing I hate is that their latest software release is only supported on Win 10 which is the crappiest OS ever, but it does work. Unix was the best real time operating system ever, and it's child, Linux is derived from it. Centroid at one time operated on Linux, but for some stupid reason they dropped it.

I guess open source has a lot of potential power, but how many people out there really have the ability to take advantage of it, or for that matter really need that ability? I had considered it before I purchased the Centroid, but it seemed it wasn't worth the learning curve to me.

Agreed, the Linuxcnc learning curve is the biggest drawback. Centroid is a better option for a commercial shop that depends on outside support if something goes wrong. There is a fringe benefit to Linuxcnc and doing a retrofit with it, if something breaks down the road you can fix it yourself, quickly and cheaply, a big plus for hobby users and some commercial users.

Gecko and Granite drives are hobby aimed servo drives. With linuxcnc you can use pretty much any drive out there. I used Advanced Motion Controls (AMC) BE25a20AC drives for my bridgeport, 25amp/200V commercial drives with built in AC power supply, I got 5 of them for $150 on ebay. Another retrofit was a commercial lathe which I reused the original drives. You are NOT limited to only hardware that the control manufacturer supports. A good example is those inexpensive wireless pendants with MPG, plug and play with linuxcnc but not a option with a commercial controller, you have to buy their big buck offering.

I still believe the Acorn is a great option for those wanting a inexpensive retrofit without much of a learning curve for a common 2/3/4 axis mill or lathe. Not much electronic/electric knowledge required either.

[polaraligned]

Wow, you got a screaming deal on those drives Sparky. I would never get so lucky...

The Centroid Oak controller offers control of 3rd party drives supporting position feedback right to the controller. I went with their DC servo drives because it was the easiest path for me and they are built solid.

Also, there are a lot of guys using generic wireless MPG's with the Acorn, some even using X-box controllers... So you are not committed to a "big buck" Centroid offering, but frankly their wireless MPG at $299 is not a bad deal. My background is in electronics and having studied their offerings that I own and I can tell you Centroid only uses very high quality components. From Nichicon capacitors to as much Made in the USA parts as they can get, with exceptional build quality. They really do make quality items in Howard PA, but they cost more than cheap china imports. You get what you pay for.

I purchased their KP-3 probe and for $725 it is accurate and high quality. They machine the probe on a Hardinge lathe right in their facility in PA. No regrets. Others are using surplus Renishaw probes with their Centroid, and they work fine. I just couldn't find a surplus Renishaw that was less expensive and was tested working. Centroids automatic tool setter is a bit pricey, so I purchased an import on Amazon for $69 and it works fine with the Centroid.

So you are not committed to the Centroid "add-on's".

Centroid also repairs all their products. The price is not cheap for repairs, but at least you can get your controller fixed with a fast turn around time. I bet a lot of these other drives become throw away once they fail.

That said, if I ever blew up my controller beyond repair, I would again consider LinuxCNC probably with AC servos this time, but I do love the Centroid interface.

[burdickjp]

The Centroid Acorn is running on a Beagle Bone Black, which is an interesting piece of hardware for doing real time stuffs.

A LinuxCNC fork called machinekit was developed for the beaglebone black:
http://machinekit.io/

[Wirecutter]

Thanks for the feedback on LInuxCNC. I briefly considered using it instead of Acorn as I didn't want to have to get another PC....only to have to get a PC (Intel NUC) for Acorn. lol

Open Source solutions like LinuxCNC are serious contenders and not to be taken lightly.

Also, if you are outside of the US, there are export laws involving 5 axis systems. LinuxCNC may be a way to get around this if you want to do something with 5 axis.

I would not recommend any Intel NUC. We've used them at work. Yeah, they're cute and small, but they're also pricey, and the reliability is a real disappointment. 4 of the 5 of these that I've worked with have given me problems. I've had to re-flash BIOS on several of them after they decided not to boot, and one just died completely.

FYI, we run Ubuntu Linux on them and use them to provide USB JTAG and serial connections to evaluation boards over a network connection. We are not doing particularly fancy I/O with them, such as spindle or stepper motor control. We have had much better luck with outdated laptops we beg from our IT department, but just about any old PC will do.

To be fair, Intel makes some good stuff, much of which we use in our products. The NUC just doesn't seem to be one of them. IMHO.

-Mark

[RB211]

Only looked at the pictures. I am a Centroid Acorn user myself, but isn't the Tormach controller a fully featured Linux CNC based affair? Was it really an upgrade or a lateral move into something you had more control over? You also could of went pure Linux CNC

[kf2qd]

Having worked with Steppers and Servos... I would like to upgrade my system, but I think I could get much higher performance using any of the brushless servos in their positioning/stepper mode. Much faster and smoother motion. More expensive...