Centroid CNC Acorn

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Marty_Escarcega
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Centroid CNC Acorn

Post by Marty_Escarcega » Wed Dec 13, 2017 7:36 pm

Centroid Acorn is doing well...I wanted to post a couple of recent videos from Centroid on a bench top Techno Isel CNC lathe. It is running open loop steppers (Acorn will control closed loop steppers, AC servo drives like DMM DYN2 and DYN4 [Doing and Emcoturn 120 with those now] any motor driver that can take step and direction inpu) and Gecko G540. It has a TRUE spindle encoder on it. This video shows how well it does with the encoder on it. Threading, rigid tapping, true constant surface speed are all demonstrated here:


The encoder can be put on a mill and with the right software package could do rigid tapping as well.

I have been Beta testing Acorn for Centroid since its inception. The most exciting thing, is that both the hardware AND software come from the same manufacturer, who has been doing industrial CNC control for over 30 years. The same software is used on their higher end motion controllers, OAK and All in One DC (I'm doing my second retrofit using All in One DC now on a Supermax YCM-40 CNC Knee Mill) Centroid has very vested interest in making sure the software is solid as well as the hardware. They have thousands of heavy machines running in the field and the absolutely have to run correctly.

More info on Acorn: http://www.centroidcnc.com/centroid_diy ... oller.html
Acorn user forums (feel free to ask questions before you buy or read up): http://centroidcncforum.com/viewforum.p ... acf0dc4f08

Marty
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Dave_C
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Re: Centroid CNC Acorn

Post by Dave_C » Wed Dec 13, 2017 8:05 pm

Yup, I'm sold! I bought my Acorn board last night so I can install it in the mill control panel. I will order the computer and the PRO mill licenses later after I get the machine a little further along.

I've had Mach 3 for about 4 years but it has too many limitations for me. IE: Non standard G-Codes, can't run CSS and Feed Per Rev at the same time, CAD-Cam Post processors need lots of editing to work and so on.

I'm really enjoying the Centroid forum as well as Centroid's documentation of the product and how to wire things up.

Really looking forward to this product!

Dave C.
I learn something new every day! Problem is I forget two.

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Re: Centroid CNC Acorn

Post by BClemens » Thu Dec 14, 2017 5:37 pm

I'm so impressed that I'm considering 'upgrading' this fully operational machine to Acorn. Hate to throw in the towel with Mach but features and stability make a considerable and enticing desire to convert - again. The research and decision to do so will involve what must be replaced electronically with a system with fully functional mechanical systems - servos and servo drivers by Gecko - there's no mention of this...basic step and direction..

BC

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Re: Centroid CNC Acorn

Post by Marty_Escarcega » Thu Dec 14, 2017 5:52 pm

You can use the Gecko 320x servo driver with Acorn...basically any motor driver that can take step and direction input will generally work fine with Acorn.
Marty
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Re: Centroid CNC Acorn

Post by Dave_C » Thu Dec 14, 2017 6:03 pm

Not sure who added the note to my post about the encoder but YES, that is in the plans and I already have it figured out. I use Automation Direct all the time, just got an order in today!

The short of it is this. The belt drive pulley on my spindle has a hub that hangs down below the pulley about a 1/2". It is about 2.5" in diameter. So I will buy a pair of matched timing belt pulleys large enough to fit over the pulley hub after I bore the center. Then I will press it on to the pulley hub and the other I will mount on the encoder with a proper mount. This will give me a 1:1 ratio and should let me do ridged tapping.

Party on!

Dave C.
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Re: Centroid CNC Acorn

Post by Marty_Escarcega » Thu Dec 14, 2017 6:06 pm

Dave_C wrote:Yup, I'm sold! I bought my Acorn board last night so I can install it in the mill control panel. I will order the computer and the PRO mill licenses later after I get the machine a little further along.

I've had Mach 3 for about 4 years but it has too many limitations for me. IE: Non standard G-Codes, can't run CSS and Feed Per Rev at the same time, CAD-Cam Post processors need lots of editing to work and so on.

I'm really enjoying the Centroid forum as well as Centroid's documentation of the product and how to wire things up.

Really looking forward to this product!

Dave C.
Dave, PLEASE try and fit an encoder to your spindle, Its always tough on a knee mill type setup, but we've yet to have someone get it setup so we can demonstrate rigid tapping. Automationdirect.com is your friend:
https://www.automationdirect.com/adc/Sh ... -SH2500-VD
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Re: Centroid CNC Acorn

Post by Marty_Escarcega » Thu Dec 14, 2017 6:09 pm

Whoops! That was me Dave. I fixed it.
Can't wait to see your mill rigid tapping with Acorn! :D
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Re: Centroid CNC Acorn

Post by Dave_C » Thu Dec 14, 2017 6:28 pm

If I'd thought for just a minute I would have know it was Marty, LOL.

One of the reasons I bought the mill I bought was because I could see a way to add the encoder. Most of the other mills I looked at would have to have the timing pulley added to the top of the spindle pulley and it would have to be much larger. The mill I bought also has a 1:2 motor to spindle pulley setup and making it a 1:1 is a piece of cake. Just change the motor pulley to match the spindle pulley. One set screw and they put the set screw on the keyway, not on the shaft so there is no mark on the shaft to make it bind. So I plan on having a low speed and a high speed on the spindle. Low speed will be 200-2250 rpm and high speed will be 400-4500 rpm. That should make some chips!

I have to reprogram the drive and add a braking resistor. Right now it takes 5 seconds to accelerate and decelerate, In order to do rigid tapping I'll have to get it down to something like .5 seconds or less. Anyone have any experience in that area? Thoughts...

Dave C.
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Re: Centroid CNC Acorn

Post by rrnut-2 » Fri Dec 15, 2017 12:15 pm

"I have to reprogram the drive and add a braking resistor. Right now it takes 5 seconds to accelerate and decelerate, In order to do rigid tapping I'll have to get it down to something like .5 seconds or less. Anyone have any experience in that area? Thoughts..."

As long as your VFD for the spindle will allow you to add the braking resister, you will be able to get to the de-accel that you want. I do this now on my manual BP so that I don't have to reach for the manual brake. All the resistor does is to drain the excess buss voltage to a safe level, because the motor acts like a generator on de-accel and will raise the buss voltage to an unsafe level for the VFD without it. The faster the deceleration the higher the voltage.

Jim B

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Re: Centroid CNC Acorn

Post by Dave_C » Fri Dec 15, 2017 1:07 pm

Jim, Yup, that is all correct and exactly what I did on my Lathe conversion! This new VFD does have the ability to add the braking resistor. It calls for 100 ohm and 100 watts but the manual says if you plan on "rapid" starting and stopping to go to a higher wattage resistor. So I bought a 100 ohm 300 watt braking resistor from Automation Direct.

Now I need to play with the timing to make the drive happy and see how fast I can actually go from forward to reverse without any over voltage issues. I suppose I could look at my program in the Lathe setup as it does a real nice job as programmed.

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Re: Centroid CNC Acorn

Post by Marty_Escarcega » Fri Dec 15, 2017 1:22 pm

Dave, I can't remember, did you switch to Acorn on your lathe?
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Re: Centroid CNC Acorn

Post by Dave_C » Fri Dec 15, 2017 3:05 pm

No, but I gave it some serious thoughts! I'd have to abandon some of my external function buttons as they would be replaced with the virtual panel in the Centroid screen.

Not a big deal, it just leaves some buttons in the panel I made being non functional.

But we will see after I get this mill done. It would be nice to have the rigid tapping feature on the lathe and then just have one control program and deal with one set of post processors. Of course there is a bit more to it as I will have to replace my computer and screen as the one I use for Mach 3 doesn't meet the requirements for Acorn.

Dave C.
I learn something new every day! Problem is I forget two.

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