Orac homing

All info relating to the Denford ORAC CNC lathes

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Handy8000
Posts: 1
Joined: Thu 24 Aug , 2017 10:20 am
Hardware/Software: CNC Routers and converted Denford Orac

Orac homing

Post by Handy8000 » Thu 24 Aug , 2017 10:39 am

Hi All,

First post :D

I have an orac that has been modernised (original steppers and spindle motor, new stepper drivers , connected via b.o.b to parallel port, and an inverter for the spindle motor) and using linuxcnc as the control software.
I'm a newbie when it comes to cnc lathes but have experience with cnc mills / routers.

Now for the question..
Where on a cnc lathe is the home position?

i know that the orac comes with 2 switches on the (x) cross slide at the inbound end and a plunger at the chuck end (z).
Does it make sense to use these sensor position to home the lathe?
As doing so would mean that if something stops the program half way through a job the work would need to be removed from the chuck to re-home the orac.

And does that position make sense when using cad / cam programs?
cheers.

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Lone_Ranger
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Posts: 220
Joined: Mon 01 Oct , 2007 15:23 pm
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Re: Orac homing

Post by Lone_Ranger » Fri 01 Sep , 2017 22:39 pm

Handy8000 wrote:Hi All,

First post :D

I have an orac that has been modernised (original steppers and spindle motor, new stepper drivers , connected via b.o.b to parallel port, and an inverter for the spindle motor) and using linuxcnc as the control software.
I'm a newbie when it comes to cnc lathes but have experience with cnc mills / routers.

Now for the question..
Where on a cnc lathe is the home position?

i know that the orac comes with 2 switches on the (x) cross slide at the inbound end and a plunger at the chuck end (z).
Does it make sense to use these sensor position to home the lathe?
As doing so would mean that if something stops the program half way through a job the work would need to be removed from the chuck to re-home the orac.

And does that position make sense when using cad / cam programs?
cheers.
The switches you refer to are axis limits that stop the lathe going overtravel, the Z axis should have an adjustable block on the bed that can be set to stop the machine driving a tool into the chuck.

The Orac doesn`t normally have any "Homing" switches, if you want/need that facility then you will need to fit a couple of switches at positions on the X and Z axis where you want the Lathe to Home to and wire them into inputs on your BOB and also configure LinuxCNC accordingly.

Homing isn`t really needed on a Lathe as the tools are usually "touched off" on the X axis (Diameter) and Z axis (Z Zero) and cutting is done from those coordinates :D

To use Cad-CAM software to generate G code you will probably need to set a Z axis Machine Zero point at say the face of the Chuck or similar face that is never likely to be moved/changed, that position can then be used to draw from in the Cad-CAM eg "face of chuck + height of jaws" = 30mm + length of part would be where you would draw the Z Zero of the part from, that is just one method, there are others but that is usualy the simplest as it means that all the tools in the tool library (Assuming they are set correctly) will automatically follow the correct paths to cut the part without ever having to use the "touch off" method for every different part, many people prefer the "touch off" method though, all down to personal preference on how you like to work :D :D

Hope that is of some help to you :D

Regards
Rob

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