Lathe turret tool changer

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02 Aug 2020 21:15 #176943 by eegleston
Hi there,

I have been working on retrofitting a Dyna Myte 3000 to linuxCNC. I'm using a mesa 7i76e board and gecko GR214V drives with steppers on the x and z axis and the tool changer. So far, I have the x and z axis working and the tool changer partially working.

I have implemented a version of ToolChanger.comp, from the linuxCNC wiki, and I believe it is working as intended, however, I am stumped on how to move the tool changer manually. I can enter Tx M6 in the MIDI command line, and the tool changer moves roughly to the desired tool, but I need some method for manually moving the turret so I can fine tune the turret position and automate the homing process of the turret.

I would greatly appreciate advice on how to implement the following.

a. I would like to add a pair of jog buttons to the UI so that I can fine tune the position of the tool changer.

b. My tool changer has 3 indexing disks that can be used to readout the tool positions. I've combined the signals from the disks in a custom.hal file to give me an index pulse at tool 1, but they could also be used with a look-up table to identify each tool. At the least, I would add a "home" button to the UI that uses the tool 1 location.

I'm pretty sure I can figure out the UI part of these tasks, but I would be grateful for some help on how to get a command to ToolChanger.comp tomove the tool changer manually. I'm starting to think that structurally there may be a better (or more up-to-date) way to do this, but since I have a lot of this configuration working, I thought I would reach out with what I have.

I've attached my configuration files - they are still in development form, so I apologize for all the commented out sections. Many thanks to all who contribute to this forum. I could not have made it this far without the help I have received just from lurking!

Best regards,
Erik
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02 Aug 2020 23:03 #176957 by cmorley
Replied by cmorley on topic Lathe turret tool changer
A picture description of your toolchanger would be helpful.
A list of all input and output related to the toolchanger hardware would be nice.

I see jogging code in your toolchanger.comp so can you explain what the manual toolchange problem is?

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03 Aug 2020 02:33 #176990 by eegleston
Replied by eegleston on topic Lathe turret tool changer
Thanks for the reply - I've attached a picture of the tool changer. It has a ratchet pawl, so I set the move values high enough to go past the pawl and then back down onto it. My issue is dealing with the backlash in the gear mechanism. I think I can use the "fudge_factor" to deal with this, but I need to be able to get the changer into the correct starting point.

From the hardware side, the tool changer has connections to the stepper from a gecko drive. There are 3 proximity sensors on the three position disks which sense gaps in the disks. These sensors are connected to my mesa card, but are not (yet) used by the configuration files beyond the custom.hal file. This file does correctly combine the sensor input to provide a single signal that senses position 1 on the tool changer. If I understood how to command the tool changer to jog until this signal switched to true, I could home the tool changer.
I am not sure of how to trigger ToolChanger.comp this beyond calling Tx M6 - my issue is likely just a lack of understanding of what the code can do. Can you describe a bit more about how to trigger the jogging code?

Best regards,
Erik
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03 Aug 2020 07:10 #177008 by cmorley
Replied by cmorley on topic Lathe turret tool changer
Thank you for the details.
Is there away to detect when the tool is 'parked' or do you just move backwards till the motor stalls?

Seems like setting toolChanger's HAL pins would make it move.
You could run these commands in a terminal while linuxcnc is running:

halcmd setp ToolChanger.jog_move 10
halcmd setp ToolChanger.jog_forward true
to stop:
halcmd setp ToolChange.jog_forward false

or omit the 'halcmd' and add them to the HAL file (but then it will jog continuously)

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04 Aug 2020 00:44 #177138 by eegleston
Replied by eegleston on topic Lathe turret tool changer
I appreciate the help!

Right now I am backing on to the pawl and stalling the motor. I don't think the position disks are precise enough to get the changer parked, but it is a good idea since stalling the motor causes step count issues.

jog-move appears to set the speed of the jog, and jog-forward triggers the stepper to move. I will work with what I have learned a bit and report back when I have a working setup, or more questions!

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05 Aug 2020 06:54 - 05 Aug 2020 06:55 #177353 by mydani
Replied by mydani on topic Lathe turret tool changer
Did the toolchanger have a stepper motor before or was it a DC motor?

Regards
Last edit: 05 Aug 2020 06:55 by mydani.

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05 Aug 2020 12:25 #177388 by andypugh
Replied by andypugh on topic Lathe turret tool changer
You might prefer to use the "carousel" component (2.8+ version) which is designed to control this type of tool changer (amongst others)

No real advantage over a random comp from the Wiki, except that it's an officially supported part of LinuxCNC.

linuxcnc.org/docs/2.8/html/man/man9/carousel.9.html

(The only complication is that you will have to compile the 2.8 version if you are using LinuxCNC 2.7 still)

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