Tool changer (lathe)

[GuntisK]

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!

[The Blight]

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).

[GuntisK]

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

[The Blight]

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?

[GuntisK]

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.

[jasminder]

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

[The Blight]

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