CNC Knee Mill Control Conversion

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Re: CNC Knee Mill Control Conversion

Postby rrnut-2 » Mon Jul 24, 2017 11:55 am

After looking and talking with Centroid about the motors, I decided to go with the "All-in-One" board. The whole system seems to be a lot simpler to install and set up. I am able to convert the SEM motors to a new encoder with a lot less machine work, than trying to adapt the AC servos to this old Bridgeport Interact.

On the SEM motors, I had to disassemble the motors and machine the tachometer/encoder shaft from 17mm to .5" for the new encoder. One motor done, two more to go.

Jim B

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Re: CNC Knee Mill Control Conversion

Postby Marty_Escarcega » Mon Jul 24, 2017 12:07 pm

I think you will be quite pleased with your choice.
Have you had a chance to check out my YouTube channel, documenting my conversion using the All in One DC? martyscncgarage
http://www.automation4less.com/encoders.htm is a good resource for encoders. You can contact them with your needs. Most times you can get an encoder in metric to fit most shafts.

Marty
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Re: CNC Knee Mill Control Conversion

Postby rrnut-2 » Mon Jul 24, 2017 12:31 pm

No, I haven't checked out your video. I will when I get home.
I had decided to buy their encoder and cable to see what they are supplying. I thought the cable was pricey at $165. I can get the material and build them myself. The encoder was about the same as anywhere else. I did look at automation4less and have done business with them in the past.
I still have two more encoders to buy. I will try to make a video of the install on the motors.

Jim B

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Re: CNC Knee Mill Control Conversion

Postby Marty_Escarcega » Mon Jul 24, 2017 12:51 pm

I bought their encoder cable and power cable. I have the part numbers. Nothing special, most of their dealers don't buy the cable from them either.
I have used Cat6E stranded for encoder cable. 14 gauge shielded with drain wire works well for power wire. Never again will I buy their cable. :-)

I hope you will learn a lot from my videos on the AIO DC. Its what I hoped to accomplish.
Marty
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Re: CNC Knee Mill Control Conversion

Postby LIALLEGHENY » Wed Jul 26, 2017 6:42 am

So here's my predicament.....1997 I bought a Brute ( Dahlih) CNC knee mill from the local college. (Paid $5000 for it which was probably to much.) It was built in1996 and had under a 100 hrs use on it. Delta 10 controls. It is a really heavy duty machine for a knee mill and has a NMBT40 spindle. It took me a while to get it running, I had to pull all the boards and clean contacts, etc and finally got it powered up. I left the shop for about an hour and when I came back the z-axis servo motor had over heated and burned up....it apparently sat there oscillating due to the drive being out of adjustment, or something of the like.
So off to the machine dealer who built/ sold it to the school, to talk to the tech. The z axis servo motor was outdated and unavailable, but they had a few used motors that matched the x, y motors that I could have for free and away I went. The original z-axis motor was smaller than the x & y motors being that it only was driving the quill, but the drives were identical. Problem was I had to modify the mounting bracket and spindle brake unit to fit the larger motor on the machine. Couple of evenings of work and i had it done and away I went or so i thought .....turns out that after playing with things for over a week trying this and that......none of the used motors I was given for free, worked.
So now it was time to look for another motor.....and with a price tag of $1500 for a new motor I decided to wait and see what i could find on Ebay. Month after month no motor ( they were EG&G Torque Systems motors) not very common. Finally in 1999 I ordered a New machine from the dealer and put the Brute on the back burner.....and someday would fix it.
Several years later I'm goofing off on Ebay one night, and stumble across a pair of used "working " EG&G motors that I picked up for $100. I figure I can finally get this machine running. At about the time the motors arrive I decide to move my shop to a new location and the project is on hold again. The rigger arrives , and in a flash I'm off to the new shop.
So now another couple of years goes by and it's time to make this machine run. ( When I moved the rigger told me that a few cables i had on top of the control cabinet, he placed inside the cabinet) So I remove the cables from inside the cabinet, install the ebay motor, look everything over quickly and power her up.....and poof , smoke comes out of the cabinet, and the monitor doesn't power up. As it turns out, there were a couple of allen wrenches that the rigger tossed in the cabinet as well when he moved the machine, and they shorted out the monitor board and something else.....I was able to get a good monitor and board for $25 but still the machine didn't run. Having paid to much initially, and spent way to much time on the machine, making modifications and repairs..... it has now been sitting for 20 years...with an outdated control unit that I could send out and have fixed, but for how much? and still it is outdated......
To add to the mix....how do you justify spending $7000 or so for a new controls with motors and drives, when you can purchase a VMC with a tool changer, cat 40 spindle, recent controls , larger travels, etc for less money? ( Last week I purchased a good running Cincinnati VMC 1250 with A2100 contols for $4300. ) So what do i do with this machine I have been sitting on for 20 years that is practically brand new, that needs at the least -controls & drives ? Convert it to a manual machine? such a waste for a machine with ballscrews.... or......


Nyle

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Re: CNC Knee Mill Control Conversion

Postby Dave_C » Wed Jul 26, 2017 7:55 am

I feel your pain!

Being a person who enjoys taking manual machines and converting them to CNC I came to much the same conclusion as what you have just stated. By the time I spent money for "good" ball screws and "Good" motors I was close to a Haas machine which has a better frame and a better control system.

When I say "close" I figure if I spend over 50% of the cost of the new Haas to convert a manual machine then I just as well stop and wait until I can get the Haas machine.

But then I don't get to have all the fun of designing the parts and all that other stuff.

So you have to decide what you like to do. Are you needing the machine to make money or do you just like doing conversions. If it is to make money, then just buy the new machine and sell the left over stuff. After all, time is money! I like to tinker and design stuff, but that's me.

Dave C.
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Re: CNC Knee Mill Control Conversion

Postby Marty_Escarcega » Wed Jul 26, 2017 8:20 am

I'm in the same camp as Dave_C. I like to tinker with machines and controls.
If the "iron" is as nice as you say it is, then it might be worthy of the upgrade if you are going to use it. If you have found something else, then pass it on, at a loss I know, but the real estate space it takes up has to be worth something. Painful part is that around here there are few that are willing to take on the project. Here's what I would do if it were me:

You could go to DMM Technologies and buy their DYN4 and AC Servos for all three axis.
Centroid is supposed to release their ACORN Step and Direction Motion controller VERY SOON, pair them up and you have a nice functional machine again. Search Centroid Acorn and you should be able to find information on the board You should be into the conversion for about $3k.
ACORN Step/Dir Ethernet Based Motion Controller about $300
3 DMM 750W AC Servos $250 each, $750
3 DMM DYN4 AC Servo Drives $220 each, $660
3 Sets of Motor and Servo Cables $300
Figure $500 on misc parts (If you can reuse terminal blocks you might some money here)
Email the folks at DMM tell them what you have, the ballscrew size/pitch you have, and if you know the pulley reduction.

You will need to add in the cost of a 2.9GHZ or better CPU computer. Look at the Lenovo Tiny M92E on Ebay. They can be had for about $200
Then buy a TOUCH SCREEN ASUS Monitor, about $200
NOW, this all assumes you have some basic electrical/electronic skills and you can do the conversion yourself!

This would not yield a totally closed loop servo system. The motion controller would not "know" where the table is BUT the loop is closed by the servo drives/servo motors, so its a nice cost effective compromise and it will make use of your machine again.

Just my .02
Marty
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Re: CNC Knee Mill Control Conversion

Postby Dave_C » Thu Jul 27, 2017 8:43 am

Marty,

Is that $300 number a typo? (I hope not)

That beats the Mach 3 conversion I did on my Lathe. I paid $150.00 for Mach 3 license, then about $150.00 for a CM-126 breakout board and then added an Ethernet smooth stepper at $300 or so. So I am at $600.00 and I don't have the centroid software which in my opinion is a much better control system with much more useful conversational.

Or is the Centroid version a stripped down version?

Dave C.
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Re: CNC Knee Mill Control Conversion

Postby Marty_Escarcega » Thu Jul 27, 2017 9:28 am

It is NOT a typo. They are keeping the price low by having peer based support via their support forum. They have different levels of software, shown right on that page and what functions and it IS the same software used on their higher end controls. (Same software that runs their 5 axis machining centers (with the software options of course) Did you note a REAL encoder port for the lathe?

DB25 happens to be pin compatible with the Gecko G540 and many other breakout boards. Yes, if they can keep the price down, this is going to be a game changer from a company that has been doing CNC motion control for YEARS. Hardware AND software from the same company. No finger pointing.
Just watch that page for updates and its release. I can't say anymore than that. If you want to upgrade from Mach, then this is going to be the board in my opinion.....
Marty
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Re: CNC Knee Mill Control Conversion

Postby rrnut-2 » Thu Jul 27, 2017 10:04 am

LIALLEGHENY, here is the other option. One set of three Delta AC, 1Kw servo motors and drives, get Centroid Oak board and convert the machine that way. Depends on how much machining that you would have to do to adapt the motors. Drives and motors...contact me. Too bad that you aren't closer, but that's a long drive to get out to the island and ya I know, there is the ferry.

Jim B

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Re: CNC Knee Mill Control Conversion

Postby DICKEYBIRD » Sat Jul 29, 2017 8:31 am

Dave_C wrote:Marty,

Is that $300 number a typo? (I hope not)

That beats the Mach 3 conversion I did on my Lathe. I paid $150.00 for Mach 3 license, then about $150.00 for a CM-126 breakout board and then added an Ethernet smooth stepper at $300 or so. So I am at $600.00 and I don't have the centroid software which in my opinion is a much better control system with much more useful conversational.
Exactly! I'm REALLY hoping the Acorn & software will truly be available at that price. The mill that's coming (slowly) together in my shop is patiently waiting for it. I'm SO ready to experience the serenity of working with hardware & software designed from the ground up to play nice together! :D

Assuming the results with an Acorn are as good as I hope they'll be when I'm done with the mill, I'll be saving up for another one to put in my Mach-equipped lathe as soon as possible. Hoo-rah, an ENCODER on the spindle! Real CSS & threading too! :shock:
Milton in Tennessee

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