Need Help! Tool changer (lathe)


Results 1 to 19 of 19

Thread: Tool changer (lathe)

  1. #1
    Member GuntisK's Avatar
    Join Date
    Mar 2007
    Location
    Latvia
    Posts
    84
    Downloads
    3
    Uploads
    0

    Default Tool changer (lathe)

    Hi everyone! I have an old cnc lathe to rebuild. It has a turret that handle 6 tools. At the beginning I wanted to use EMC2, but then I change my mind because TCNC is more compatible with old system.
    Could someone explain me how exactly automatic toolchanging can be done in TCNC? Did TOOL TURRET INDEX send a number of pulses of a tool? For example: when instruction M06 T4 is executed, there is a 4 pulses on TOOL TURRET INDEX pin or what? Need a help here.
    Guntis

    Similar Threads:


  2. #2
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    There is only one pulse from TCNC. You can set how long this pulse is going to be though.

    So if you want to change tool, you will either have to place the next tool to use on the upcomming slot, or write several M6 commands. I'm trying to place the next tool I'm using in the next slot. If thats not possible, I will just have to repeat the M6 command a couple times..

    I have been toying with the idea of making a separat tool changing computer (just a microcontroller with LCD display and a simple keypad) which keeps track of what tool is to be used next and so indexes to this tool. My tool changer is already controlled by a microcontroller, so adding a feature like this should not be too hard.



  3. #3
    Member GuntisK's Avatar
    Join Date
    Mar 2007
    Location
    Latvia
    Posts
    84
    Downloads
    3
    Uploads
    0

    Default

    Mmm! Thanks The Blight! So that signal just means: change to the next tool. I thought about using of a PLC here. Logic for that toolchange is this: PC gives a signal to change to Tn (n is a tool number), from another pin there goes PLC handshake signal that tell PLC to switch on a motor, instrumental disc is moving. Position is controlled by six magnetic reed switches, when there is the right tool for example T6, switch with the same number gives a log.1. to PLC, PLC gives a signal to reverse motor to lock instrumental disc, then the shaft press a microswitch, again the logical.1. signal goes to PLC input, PLC send signal to pin "PLC handshake sense". Tool is changed, everything is ok, TCNC can execute next line of program. This would be ideal for this purpose.



  4. #4
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    Sounds good enough. I use stepper motors for my tool changer. The only problem with this system is that if one of the motors loose a couple steps, you can end up with a machine trying to take a cut that is not locked in place, or take a cut with the wrong tool.

    I was thinking about another method on how to tell the controller what tool you want to use. Connect another axis output where you can write the tool number. On the controller for the ATC, you can check this line for which tool to use next. The bad side of this would be that you can't use the T word. In my eyes that would be too messy. I like a clean code, so I'm just setting it up to use the next tool in line.



  5. #5
    Member GuntisK's Avatar
    Join Date
    Mar 2007
    Location
    Latvia
    Posts
    84
    Downloads
    3
    Uploads
    0

    Default

    I got an idea. You said that Your tool changer use a stepper motor. I know that in TCNC there can be set an axis which use angular positions so called A, B, C axis). For example we have 4 tools. 4 tools = 360 degree. So the stepper motor should rotate every 90 degrees to change to another tool. Just write a simple code in the line and You got it! At this moment it seems to be a simplest solution for this. Sad, that I cant use it in my system.



  6. #6
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    I have set my changer up as a linear axis at the moment going from 1 to 4. I think I have set it as the Y axis (lathe), and if I type G00 Y1 it goes to tool pos. 1. First I have to release the locking pin, which is axis A. So G00 A1, G00 Y1, G00 A0 is a tool change. I just need to hook up the new microcontroller so that it takes care of the whole tool change with offsets for the locking pin and a home position sensor.

    How does your tool changer work? Got any pictures?



  7. #7
    Member GuntisK's Avatar
    Join Date
    Mar 2007
    Location
    Latvia
    Posts
    84
    Downloads
    3
    Uploads
    0

    Default

    Hi! Sorry for my late answer.
    This one works exactly I explained in my previous post where I mentioned PLC- except is that there is used special electroautomatic control board instead of modern PLC. I found very interesting homepage where is explained how to build simple PIC based PLC : http://getok.net/plc2pic/index.php?next=index . Maybe it is worth to build one? Another idea is to change TCNC code in a way that TCNC gives in output a number of pulses equal to number of tool. T4 for example gives 4 pulses on some LPT pin. This would be more and more easier than it is now...
    Aaa-and here are some photos:

    Attached Thumbnails Attached Thumbnails Tool changer (lathe)-toolchanger-jpg   Tool changer (lathe)-toolholder-jpg   Tool changer (lathe)-korpuss-jpg   Tool changer (lathe)-tmotor-jpg  

    Tool changer (lathe)-turret2-jpg   Tool changer (lathe)-magnsens-jpg   Tool changer (lathe)-controlswitch-jpg   Tool changer (lathe)-painting-jpg  



  8. #8
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    Looks like a nice project, and a beautiful cleanup so far.

    That PLC circuit looks simple enough, and it should work just fine if you can hook it up. Do you know how to program in turbo pascal? If you get around to do some changes in TCNC, please share. I tried to get into programming pascal, but I gave up shortly after.



  9. #9
    Member GuntisK's Avatar
    Join Date
    Mar 2007
    Location
    Latvia
    Posts
    84
    Downloads
    3
    Uploads
    0

    Smile

    A good friend help me a lot in programming. Now we are trying to make TCNC multilingual (english, latvian and russian languages in one program, later maybe some other). If everything goes in a good way, then TCNC will became as a special OS for cnc machines. Of course I will share with the results. I must say many thanks to Dave Kowalczyk for this great program and his efforts to write it. It is really great and easy to use program.
    The Blight- can You show a pictures of Your toolchanger?



  10. #10
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    TCNC is really easy to use, and it has lots of functions. I think it's a great piece of software, and I don't think I will change. Dave has started working on it again it seems. I hope he fixes some of the bugs and adds a couple new features.

    The ATC is for my mini lathe (which I also have built myself), and it's for taking light cuts. I have taken 2mm cuts in brass, and it doesn't complain. I get some vibrations when using a 2mm parting tool, but it does work.








  11. #11
    Registered PEU's Avatar
    Join Date
    May 2005
    Location
    Buenos Aires - Argentina (I like Ribs)
    Posts
    925
    Downloads
    0
    Uploads
    0

    Default

    wow, very nice ATC, I would like to have something like it for my Syil C6, do you know where can I find ready made ATC like the one you built?



  12. #12
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    I think Enco have one, but I don't know how much it costs. There is lots of plans out there on how to make one. The problem is doing just that. I have heard some talk about using a rotary table to hold the tools. Might work if there is no slop in the system, or if you find a good locking system.



  13. #13
    Member GuntisK's Avatar
    Join Date
    Mar 2007
    Location
    Latvia
    Posts
    84
    Downloads
    3
    Uploads
    0

    Default

    Ok-some more progress on this thing (highschool takes a lot of time... Ehh! ). After some thinking I ended up with this design which uses a M71 and M70 commands. All electronics contains a couple of relays and some simple logic IC (SN74xx series). When it came to replace a tool (M06 M71 Txx command) TCNC make defined LPT port output active which enables toolchanger logic. In next step we need to enter a tool number from keypad-it starts an asinchronous motor to move an instrumental disc. If position is the same with choosed tool, circuit reverses motor spining direction. When disc became fixed it push the end switch- it disable motor spining. Thats all folks! Tool is changed and we can push the button OK and lathe can continue work. You can see a concept of the circuit in attached picture (circuit is done in simulator so it is slightly simplified). I hope that I will make a PCB this week. Cant wait to see it working!

    Attached Thumbnails Attached Thumbnails Tool changer (lathe)-instrumentaalis-jpg  


  14. #14
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    The M6 command also has an output that can be enabled (a single pulse that comes on whenever the M6 command is issued. It stays on for a fixed amount of time). The manual states that the M6 command sends out a number of pulses equal to the tool number, but this is not correct. It sends out one pulse no matter what. I'm using the M6 command for toolchange, and the M73 to check for PLC input (when the ATC is done, it will tell TCNC that it can continue with the program).



  15. #15
    Member GuntisK's Avatar
    Join Date
    Mar 2007
    Location
    Latvia
    Posts
    84
    Downloads
    3
    Uploads
    0

    Default

    Offtopic: The Blight-I noticed that You have a very nice DIY cnc lathe. How about some video?



  16. #16
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    Hehe. I didn't have time to take a video of it today as I was configuring the offsets for the machine. I'm also rewriting some of the code for the ATC, so I will have to change the chip tomorrow. If I can remember to bring the camera, I will be sure to upload a video.

    Have you gotten your machine to work?



  17. #17
    Member GuntisK's Avatar
    Join Date
    Mar 2007
    Location
    Latvia
    Posts
    84
    Downloads
    3
    Uploads
    0

    Default

    Not yet actually... There is still a lot of work to be done. This lathe is a project Im working on from time to time. Now I will got more spare time and I decided to do some really serious work on this project.



  18. #18
    Registered
    Join Date
    Jul 2008
    Location
    india
    Posts
    199
    Downloads
    0
    Uploads
    0

    Default diy lathe turret and the macro to run it

    Quote Originally Posted by The Blight View Post
    I have set my changer up as a linear axis at the moment going from 1 to 4. I think I have set it as the Y axis (lathe), and if I type G00 Y1 it goes to tool pos. 1. First I have to release the locking pin, which is axis A. So G00 A1, G00 Y1, G00 A0 is a tool change. I just need to hook up the new microcontroller so that it takes care of the whole tool change with offsets for the locking pin and a home position sensor.

    How does your tool changer work? Got any pictures?
    hello blight,
    i really liked your idea of using the a axis and y axis for moving the locking pin and the stepper motor. But i am wondering that how did you manage the tool offsets and m6 command?
    any help will be appreciated as i am building a turret too( same as yours).

    regards,
    jasminder singh

    It is better to die for something than to live for nothing.


  19. #19
    Registered
    Join Date
    Sep 2006
    Location
    Denmark
    Posts
    607
    Downloads
    0
    Uploads
    0

    Default

    Well, I bought a license for tcnc, and reprogrammed the M06 command (and made several others for calibration), so I don't really use the axis commands any more. The M06 commands works kind of like the M10 command (I think thats the one) with a parallel 4 bit bus that tells the tool changer what tool to load. The rest is handled by a micro controller that controls the steppers in the tool changer. I have also set up a handshake line, and a start line. The 4-bit bus is also used for jogging and calibration.

    So everything is handled by the microcontroller, and the software is just telling it what to do.

    Oh, and if I could do it again, I would have made the turret differently with a better locking system



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

Tool changer (lathe)

Tool changer (lathe)