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Author Topic: CNC KNEE MILL ATC HELP!  (Read 6039 times)

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Offline mike^3

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CNC KNEE MILL ATC HELP!
« on: February 07, 2015, 08:21:52 AM »
  ;D

Hello, I am retrofitting a cnc knee mill with a tool changer that has some kind of switched logic, can anyone help me figure it out?

It is basically like a rotary encoder with logic from the switched that indicate tool position, there are 24 tools...

here is a small video I made https://www.youtube.com/watch?v=OsBAYHpI6es

thanks for any help!

Offline BR549

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Re: CNC KNEE MILL ATC HELP!
« Reply #1 on: February 07, 2015, 02:47:05 PM »
That style tool changer with Dark logic encoding with SWITCHES will make you pull your hair out handfulls at a time (;-).  Trust me on that (;-)

I would remove the old Drive motor assembly  and switches and run the tool changer with a simple stepper motor . PUT 1 home switch in to set the Tool Changer HOME position, normally the  tool #1 position.

Is that a single arm changer that changes one tool at a time OR is it  a Hot Swap where it removes 1 tool and installs another in the same cycle. I can't tell from the Video what you have.

IF it is a HOT swap then you will have to develope the Macro Logic to do the Hotswap. (Remove 1 tool from the carasel slot and install a different tool back in the same slot.

Could you show some more video of the change arm and spindle area ?

(;-) TP

(;-) TP

Offline mike^3

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Re: CNC KNEE MILL ATC HELP!
« Reply #2 on: February 07, 2015, 04:19:02 PM »
Hi! Sure I can take some more video tonight, I think the operation of the tool changer is. Z to tool chage position(switch to indicate tool change position) then run swing arm motor till a switch is triggered, then stop tool changer motor arm, then activate tool changer fingers extension, then activate air cylinder that lowers arm (pulls out tool) then activate tool changer arm motor (moves to tool changer carousel) then de activate arm lowering cylinder (pulls tool into carousel) then deactivate fingers (restracts) then spin carousel to new tool, then reverse the previous steps.

I do also think it would be a lot easier to mount a stepper motor on the bottom with a home switch (one of the pre existing switches at the top! Lol), but the problem is that I have a csmio A driver for analog +-10 volt drives, which means I have to buy amother drive and motor :( just for the tool changer, I have a ton of steppers laying around, maybe a gecko drive and keling servo would work...?

Offline BR549

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Re: CNC KNEE MILL ATC HELP!
« Reply #3 on: February 07, 2015, 05:06:32 PM »
If you are running the machine with the CSMIO then you cannot run the LPT driver so you have no where to hook another drive.  You will have to run the Tool Changer servo from the CSMIO as well.

The other option would be to run a stepper from a PLC. BUT that can be as expensive and a lot harder to do(ladder logic) as the NEW driver/servo route.

(;-) TP

Offline mike^3

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Re: CNC KNEE MILL ATC HELP!
« Reply #4 on: February 07, 2015, 05:34:06 PM »
Could I just use 24 inputs? One input per tool position, then just run the tool changer till it hits the right input, the initiate tool change?

Scratch that only got 24 inputs :(

Offline BR549

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Re: CNC KNEE MILL ATC HELP!
« Reply #5 on: February 07, 2015, 11:28:09 PM »
Having a tool changer on a knee mill is a blessing I would spring for a new drive and servo to run it. A good tool changer can be your BEST FRIEND spend a little cash on him he is worth every dollar. (;-)

(;-) TP

Offline mike^3

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Re: CNC KNEE MILL ATC HELP!
« Reply #6 on: February 08, 2015, 07:06:19 AM »
Thank u ;), any idea where I can get a good servo and drive that talKS +-10 volts for input? I

Offline Hood

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Re: CNC KNEE MILL ATC HELP!
« Reply #7 on: February 08, 2015, 07:53:32 AM »
The original turret and toolposts on my lathe worked in a similar manner with regards the tool signals, ie there were 3 limit switches and depending on their sequence you knew which position it was at.
Mine was only 6 pos for the turret and 4 pos for the toolpost hence only 3 switches on each required for the position.
They were hydraulically driven so that side was a bit different but it worked extremely well with the exception of it having to lock at each position before unclamping and moving to the next before eventually getting to the desired position. That was because of the hydraulics as they were rack and pinion driven, so that would not be an issue with your setup.

I used a PLC as it is a lot quicker than VB and also because Ladder Logic is much easier for me than VB :)

Another option is to use an Indexing Servo drive but if going down the servo route, and as you have an IP-A,  then I think just using a normal +/- 10v servo would be best.

If  its a choice between a servo and a PLC then probably the Servo is the best option and you can usually pick them up on eBay at a reasonable cost second hand which will likely work out cheaper, or as cheap, as a PLC.
I have used Allen Bradley DSD drives, they can be used in Step/Dir or Analogue and if the Sercos or Indexing drive then can additionally be used as indexing drives. If going that route just make sure you get a motor and drive that are matched.

Hood

Offline BR549

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Re: CNC KNEE MILL ATC HELP!
« Reply #8 on: February 08, 2015, 12:45:54 PM »
YEP on what HOOD said. 

(;-) TP

Offline mike^3

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Re: CNC KNEE MILL ATC HELP!
« Reply #9 on: February 08, 2015, 02:36:11 PM »
My thoughts pretty spot on! :)

I would like to first try the VB, then if that doesnt work then just get a servo, the issue is that I love retrofitting machines, and always buying and putting servos on the tool changers are not always possible without heavy modification.

What size servo do you think I would need to move the umbrella? I was thinkinkg like a 200 watt motor? the current motor is a single phase motor with a gear reduction,