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PART CNC PART MECHANICAL
« on: April 10, 2012, 08:07:51 AM »
Hi All
My machine is a lathe set up with a quick remove vertical slide so I can use it as a 3 axis mill.
My question is:-
Is it possible to use Mach 3 some how with the motors disconnected and use conventional mechanical feeds and speeds and yet maintain the DRO display.
This occurs when I have to screw cut part way thro a job  as I do not have a pulse generator.
Alternative to this where can I find a laymans description of  conversion to cnc screwcutting with a list of parts.
Graham

Offline Tweakie.CNC

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Re: PART CNC PART MECHANICAL
« Reply #1 on: April 10, 2012, 09:30:03 AM »
Hi Graham,

This may be a good place to start http://cnccookbook.com/

Tweakie.
KEEP SAFE !
Re: PART CNC PART MECHANICAL
« Reply #2 on: April 10, 2012, 10:20:39 AM »
it would be easier to ge a pulse signal and get mach to do the threading

Offline RICH

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Re: PART CNC PART MECHANICAL
« Reply #3 on: April 10, 2012, 09:28:19 PM »
Alternative to this where can I find a laymans description of  conversion to cnc screwcutting with a list of parts

Would seem rather dificult to provide any type of specific list of parts for a machine which we know nothing about.
That said and think what your are meaning is what is required to convert a lathe to cnc.
There are a few threads on lathe conversions worth having a look at on the site.
You basicaly need to provide a screw which is rotated using a stepper or servo motor for the Z and X axis along with the appropriate controller.
RICH
Re: PART CNC PART MECHANICAL
« Reply #4 on: April 11, 2012, 11:16:16 AM »
Hi Rich
My Colchester master lathe is already converted to cnc but as a 4 axis mill i.e x,y,z,a using a vertical slide as y.
What I wanted was a simple explanation and possible parts to graft onto my BOB 6560 to make it more flexible and multipurpose.
Graham
PS I ask because I am not an electronic expert having bought a bob, power supply, and motors off ebay.
Re: PART CNC PART MECHANICAL
« Reply #5 on: April 11, 2012, 07:29:52 PM »
I think what you want is a rotary encoder to take the place of a stepper or servo keeping track of your conventionally turned screws on the DRO, much like any manual machine. The question is how do you feed that back to Mach as an input elctrically? Am I undestanding you here? That brings up the question other than a pulse generator is there an interface/input to make the DRO work based on position that is not tied to a motor but the axis turning. That could be an interesting feature for Mach if you wanted to kick into conventional mode for certain jobs.

Robert
Re: PART CNC PART MECHANICAL
« Reply #6 on: April 12, 2012, 05:01:42 AM »
ALLSTAR1
Yes thats what I was asking.
At the moment I disconnect the x axis stepper and have a prog that adds the correct amount to the side feed for a given cut and work the x axis manually.
Thats why I want to fit a pulse generator as well.
All part of the never ending story.
Graham
PS Just fitting new ballscrews to eliminate backlash had up to .015" on the old ones.
Re: PART CNC PART MECHANICAL
« Reply #7 on: April 12, 2012, 11:24:56 AM »
Gray

When I started with Mach, one of the first thoughts that popped into my head was how could I use it as a low cost DRO without having to turn/power the stepper motors. I guess when your trasitioning from conventional to CNC a part of your machining background keeps you thinking traditional. There may be an easy way to implement this concept, but like you I am no electronic/computer whiz however I like your thought process.

I am also working on backlash issues as well so I can relate.

Robert
Re: PART CNC PART MECHANICAL
« Reply #8 on: April 13, 2012, 04:41:27 AM »
Robert
Got the z axis backlash down to less than  0.0005" which I believe is down to machine flexing. I am happy with this.
Now for the x axis which will require a lot of modification but if I get the same results I will be very happy as it is currently 0.007"
Have you any experiance with this new? software MSM from Calypso that works with Mach3?
Graham

Offline Hood

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Re: PART CNC PART MECHANICAL
« Reply #9 on: April 13, 2012, 10:38:34 AM »
I am messing around with the pokeys at the moment hooked up to the encoder outputs from my servo drives. What I am planning for is to be able to update machine coordinates from encoder position when I bring Mach out of reset. It is working well so far, just need to get the zeroing of the encoder working right and it should work well.

Hood