My CNC Bender Build - Page 4


Page 4 of 6 FirstFirst 123456 LastLast
Results 61 to 80 of 117

Thread: My CNC Bender Build

  1. #61
    Registered
    Join Date
    Jan 2006
    Location
    USA
    Posts
    2985
    Downloads
    0
    Uploads
    0

    Default

    Sounds Good.

    Keep us updated.

    Matt



  2. #62
    Registered
    Join Date
    Jun 2005
    Location
    Indianapolis, IN, USA
    Posts
    91
    Downloads
    0
    Uploads
    0

    Default

    Question:

    The quad. encoder to RS-232 adapter comes with a short serial cable that is permanently attached at the adapter. It will hang 1 foot down from my computer. The wire for the encoder isn't quite long enough. Can I use Cat5e cable to extend the 8 wires coming from the encoder? The encoder has the wires soldered to the board; there is no connecter to unplug. With the Cat5e will I run the risk of noise?



  3. #63
    Registered
    Join Date
    Jan 2006
    Location
    USA
    Posts
    2985
    Downloads
    0
    Uploads
    0

    Default

    If you are using the differential signals, it will be more resistant to noise so it might be ok to use cat5. If you are concerned, you can use cat6, which is shielded, or just get some 8 conductor shielded wire from a local place, even lowes or home depot should have something that would work.

    Why not just increase the length of the serial cable and put the converter within reach of the cable. You can get a DB9 extension cable pretty easily. Then you don't have to fool with the wiring on the encoder.

    Matt



  4. #64
    Registered
    Join Date
    Jun 2005
    Location
    Indianapolis, IN, USA
    Posts
    91
    Downloads
    0
    Uploads
    0

    Default Updates, Finally!

    I finally have updates! I turned down the die center pin to accommodate for the rotary encoder. The rotary encoder has a 8mm hollow shaft. The center pin had to be turned down to 8mm (0.3150) +0.015/-0.000. Unfortunately the only lathe available at the shop was a fairly large one. The jaws would barely hold onto the shaft because they were so big.

    To force the center pin to move with the die, I drilled and tapped two 1/4-20 holes in the die for two set screws. I haven't bent any tube yet, but I might have to machine a flat in the center pin.

    I mounted the rotary encoder with two 6-32 button head socket cap screws. I managed to break two 6-32 taps in the bottom of the tube bender. There was barely any room to use a t-handle. I welded the tube bender to the stand a while ago. I jumped the gun on the welding; I never considered the troubles it would bring. I used two of the twist style taps. I never have much luck hand tapping with them. They seem a lot easier to break than standard taps.

    Set screws in the die:


    Center pin mounted:


    Turning the pin:


    Die center pin:


    Die center pin with encoder mounted:


    Center pin bender frame engagement:


    Mockup:


    Drilling and breaking taps:


    Encoder mounted:




  5. #65
    Member
    Join Date
    May 2004
    Location
    Australia
    Posts
    600
    Downloads
    0
    Uploads
    0

    Default

    Supahonkey,
    As I've stated before, I've enjoyed following this thread. Your objective from the beginning was to make a cnc controlled bender. That being said however (and don't take this as a criticism as it not meant to be one), your machine won't advance the tube to do the next bend and I'd imagine that the only reason you need it cnc'd is so that you can measure an angle that is required and then go and produce that very angle with a tube. This makes me wonder whether it would be much easier and cheaper to buy (or make) and fit a degree wheel (I think the tube bender manufacturers even sell them for this purpose) and you fit a limit switch and an easily adjustable stop that runs in a slide around the perimeter of the degree wheel. Dial up the angle you want, flick the go switch, tube gets bent until it hits the limit switch, system stops.
    Admittedly it wouldn't have helped your uni thesis, nor would it have been as much fun either! Anyway, as I said earlier, I've enjoyed following the thread.

    Last edited by skippy; 12-21-2008 at 12:57 PM.


  6. #66
    Registered
    Join Date
    Jun 2005
    Location
    Indianapolis, IN, USA
    Posts
    91
    Downloads
    0
    Uploads
    0

    Default

    Yes, my machine won’t advance the tube. My original plan was to implement a system which did just that. After doing some research, the area in which the positioning system would use is far too large. It would also be difficult to actually move tube through a JD2 bender. They have a sloppy setup. Once pressure from the die is relieved, the tube isn’t support in the die. There is also a large bolt that keeps the tube against the die. I wouldn’t be able to use the positioning system.

    My project is meant as a segue into a more complex bender. I built such a large stand in anticipation of bender where the actual die itself moves about its center rather than with arms. That is the only setup worth creating a positioning system. Of course, a positioning system in itself would be insanely expensive. Imagine the cost of a ball or lead screw that is about 10 feet long!

    I know I could have simply made a mechanical stop attached to the degree ring that came with my bender. By doing that, I wouldn’t have gained the knowledge of implementing a CNC system. My next project is rebuilding a Bridgeport II Proto-Trak mill. Knowledge gained from this project will come in handy for the next.



  7. #67
    Registered
    Join Date
    Jun 2005
    Location
    Indianapolis, IN, USA
    Posts
    91
    Downloads
    0
    Uploads
    0

    Default

    I managed to brush up on my VB this weekend. I made a program to control my tube bender. I wasn’t able to work with my encoder yet as I don’t have the RS-232 adapter. The program has 3 buttons: extend, retract and pause. I now have wireless control of my bender with a wireless number pad. It’s very satisfying wirelessly controlling my bender with software I wrote. Its very cool pressing a button on my computer and watching my machine react. The real struggle will come when I get the RS-232 adapter.

    Essentially I must store the desired angle (input from the user) as a variable. I then must setup a loop that checks the desired angle with the current angle (from the encoder). Once they are equal, I want the computer to set pin 3 to low (pause). If I like the angle, I want to hit retract on the number pad.

    With a lot of testing, I want to have a drop down box to select material type and size. This will account for spring back. The screen will also have a read out for current and desired angle. I would appreciate anyone chiming in on anything programming related. Thanks for your interest in my project.



  8. #68
    Registered
    Join Date
    Jan 2006
    Location
    USA
    Posts
    2985
    Downloads
    0
    Uploads
    0

    Default

    I think you will need a limit switch to use for alignment purposes. The encoder has to know where 0 degrees is before it can go to 73 (or whatever) degrees accurately. I think the code could go something like this:


    Code:
    // homing sequence
    
    // this would make sure the angle was greater than zero
    
    ram(extend);
    wait 1 second
    ram(pause);
    
    // find the limit switch which would be zero degrees
    ram(retract);
    while limit switch not pressed
    {}
    ram(pause);
    encoder_count = 0;
    
    // now you have the encoder zeroed at zero degrees
    
    // load your tube after the zeroing routine
    
    //now you enter your desired angle and material for springback correction
    desired_counts = angle + springback
    ram(extend);
    while encoder_count < desired_counts
    {}
    ram(pause);
    
    //now you should have your bend, held at the correct angle.

    If you want to have the tube advance, a rack and pinion setup would be much more cost effective than a ballscrew. You also need to be able to spin the tube to change the plane of the bend. The ultimate would have 3 axes of control: advance tube, bend, advance, rotate to next angle, bend again.

    Matt



  9. #69
    Community Moderator Al_The_Man's Avatar
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    24216
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by keebler303 View Post
    I think you will need a limit switch to use for alignment purposes. The encoder has to know where 0 degrees is before it can go to 73 (or whatever) degrees accurately.
    Another possibility is to output a retract signal and a software loop waits for no, or appreciably no encoder movement for x secs/msec.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


  10. #70
    Registered
    Join Date
    Jan 2006
    Location
    USA
    Posts
    2985
    Downloads
    0
    Uploads
    0

    Default

    That would work too and you wouldn't need the limit switch. But then you also need an offset for zero as the limit of travel is probably not exactly 0 degrees.

    Matt



  11. #71
    Registered
    Join Date
    Jun 2005
    Location
    Indianapolis, IN, USA
    Posts
    91
    Downloads
    0
    Uploads
    0

    Default

    Wow Matt, thanks for your help. I never considered having to zero the bender out. A homing sequence would be a necessity. The bender doesn't actually start bending until about 25 degrees of travel from full retraction of the cylinder. It will be somewhat difficult to determine the actual start of bend (0 degrees). I guess I will have to do a lot of tests to determine encoder readout and actual bend.

    I keep forgetting about a limit switch. I bought two limit switches made by Omron. They are small optical switches that close a circuit when something breaks the beam. I will put one at true zero and one a few degrees before max travel. Max travel simply activates a relief valve. Unfortunately the relief causes a lot of stress on the hydraulic system. Because my valve blocks ports A and B and dumps to tank, if I activate the relief valve, once I reverse flow, the valve reacts violently and the hoses shake really hard. I know this can't be good for the system. I can adjust relief valve activation, but I want to do it when I am actually bending tube, not when the system is absent of load.

    As Al said, I believe I could get by without limit switches by using software and the encoder. Unfortunately nothing can replace a limit switch that is dead accurate every time. I use OMRON limit switches at work on part marking machines and they haven't failed yet.



  12. #72
    Community Moderator Al_The_Man's Avatar
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    24216
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by supahonkey View Post
    I believe I could get by without limit switches by using software and the encoder. Unfortunately nothing can replace a limit switch that is dead accurate every time. I use OMRON limit switches at work on part marking machines and they haven't failed yet.
    With a on/off hydraulic system, I would be inclined to use coming up to a stop and registering that as zero as opposed to the limit switch which although it may be possible to capture the limit at high speed, if the cyclinder is in motion, there may be overtravel when the valve is de-energised, this can vary with oil temp etc, if you read the switch when the cyclinder at the rear stop, its the same thing anyway?
    On servo systems that use a limit, the axis generally goes in to creep mode when seeking the edge.
    I am not sure what the purpose of the relief valve is?
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


  13. #73
    Registered
    Join Date
    Jun 2005
    Location
    Indianapolis, IN, USA
    Posts
    91
    Downloads
    0
    Uploads
    0

    Default

    Al,

    The relief valve is built into the motor/pump/reservoir unit. If I reach full retraction or extension, the relief valve kicks in and dumps to tank. I need to set the relief valve activation pressure to just above the required bending pressure for the largest material I will bend.

    I never considered over travel once the valve disengages. It might not be necessary to consider as I am just bending tube, not machining aircraft parts. I will definitely look into it, I won't skimp just to avoid extra work.

    Today will be spent programming the min and max travel limit switches. I haven't tested input capabilities with the inpout32.dll file I am using to access the DB25 ports. I have only tested output capabilities.



  14. #74
    Registered
    Join Date
    Jan 2006
    Location
    USA
    Posts
    2985
    Downloads
    0
    Uploads
    0

    Default

    The dead stop would be more accurate, but I don't think the switch would be a problem either. You can write the code so it is capturing the encoder count and then actually stopping the valve. If it overruns, its not a big deal because the encoder knows how much past the switch it went. Dependent on the speed of the encoder converter, you should be able to capture the position in less than a millisecond, which I would think would be more than enough for what you are doing.

    I don't think limit switches are that important as long as the stroke of the ram cannot pull apart the machine. It shouldn't harm it to stroke in or out completely. The only time I could see the limit switches being necessary is if you didn't zero the encoder or something and it tried to get to an angle greater than it is mechanically capable. The software would think it never got to the desired and keep the valve on. Again this shouldn't hurt anything but it might not be ideal.

    Matt



  15. #75
    Registered
    Join Date
    Jan 2007
    Location
    usa
    Posts
    219
    Downloads
    0
    Uploads
    0

    Default

    What version on VB are you using to create this program?

    -Adam

    www.adambrunette.com - Converting My Harbor Freight X2 And My Jet Jvm-830 Knee Mill, As well as many other projects.


  16. #76
    Registered
    Join Date
    Jun 2005
    Location
    Indianapolis, IN, USA
    Posts
    91
    Downloads
    0
    Uploads
    0

    Default

    I am using Visual Studio 2008. I learned VB on VS2005 and I reference my 2005 book. So far I haven't noticed any differences.

    I am having a lot of trouble with the inpout32.dll file. I got my limit switches hooked up, but I seem to be taking the wrong approach. I am addressing the status ports as input ports. The inpout32.dll file uses the command input(Port Address, Pin). To make the valve pause, I use the command: Input(888,0). This makes the data ports (pins 1-7) go low. I want a simple if statement that states "if limit switch (pin 11) goes high, make pin 1 go low.

    If Input(889, 64) then Output(888, 0)

    889 = 0379 (status port)
    64 = 01000000 = pin 11

    888 = 0378 (data port)
    0 = Pins 1-7 low

    VB freaks out and won't allow the Input and Output functions. The output and input functions come from the inpout32.dll file. I must address the inpout32.dll file in the Public sub statement.

    Maybe I am taking the wrong approach. Should I capture the data received from the input and save it as a variable, and then compare the value?



  17. #77
    Registered
    Join Date
    Sep 2005
    Location
    united states
    Posts
    164
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by supahonkey View Post
    Of course, a positioning system in itself would be insanely expensive. Imagine the cost of a ball or lead screw that is about 10 feet long!
    I would build it with a shorter screw and use a number of advances to get the desired movement... Like an automatic feed bandsaw, it could even be hydraulic to a stop set by a smaller acme screw and stepper motor or servo. Backlash would be removed by the ram each time advanced. Just a couple thoughts.

    Danny



  18. #78
    Registered
    Join Date
    Jun 2003
    Location
    Monterrey, Mexico
    Posts
    91
    Downloads
    0
    Uploads
    0

    Default Mach 3 usage

    Hello,
    Dont know where you are on the control software, but i have a couple of suggestions that might help out using mach3 as your control software.

    1.
    use an encoder input, have mach3 read that possition and configure your pulses per degree information, this should be pretty straight forward as mach3 is already set up for this.
    Then you could set up a Brain in mach3, that will compare the encoder DRO with a user DRO where you put the desired angle. When the encoder dro reaches the user dro, retract the cylinder.

    2
    Second option is to use a Rotary one turn potentiometer, wire a 10v power suply to it and read the voltage trough an analog module on a plc, translate the voltage into position (angle) and compare that value to a user DRO using a Brain, when the value is reached retract the cylinder.

    Just my 2 cents

    Regards
    Fernando



  19. #79
    Registered
    Join Date
    Jan 2006
    Location
    USA
    Posts
    2985
    Downloads
    0
    Uploads
    0

    Default

    I have not really used visual basic at all. Maybe there are examples you could go off of? I have done a fair amount of programming in matlab and in C (for microcontrollers) and have learned most of it by picking apart examples. I would think there would be a pretty good online database of vb code. Beyond that, I would search out a vb forum and ask your questions or maybe you could find someone on campus who could help.

    Matt



  20. #80
    Registered
    Join Date
    Mar 2006
    Location
    .
    Posts
    48
    Downloads
    0
    Uploads
    0

    Default

    Hi, I have been following this interesting thread.

    Meantime, this youtube video ( ) of a cnc pipe bender made by a friend in Pakistan using modified Mach3 screen and macros should give you some ideas on what you can possibly make with Mach3.



Page 4 of 6 FirstFirst 123456 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

My CNC Bender Build

My CNC Bender Build