Could Linux CNC reasonably be made to work in a prototrak type mill?

I have an old Bridgeport mill that I am considering doing a cnc conversion on.

The catch is that I would still like to be able to use it as a manual machine as well. (like a protrak/ez-trak mill)

This would require a closed loop setup, which I know is possible with linux cnc.

The tricky part would be making linux cnc act as a DRO. This would require cutting power to the servo/steppers, but still registering feedback from the encoder ( or a glass scale / seperate rotary encoder ) without linuxcnc attempting to make "corrections" or having some other kind of error.

I understand that anything is possible, but is this something that could be done reasonably?

I just deleted the reposts.

It sounds like the most difficult part will be getting the encoders to work correctly than? Thanks for the input, I think this is the route I may go.

Another option is to have two linuxcnc configs.
One is the CNC controller
The other is a HAL only DRO made with GladeVCP.

The only real difference is The DRO could have operational zero/offset buttons which would be harder to do with the (turned off) machine controller.

Chris M

I would think (though I am not certain) that the issue with that would be losing your position when switching between configs. Ideally I am looking to fairly seamlessly switch from manual to cnc without needing to return to some set zero point every time.

I am going to have to setup a controller so I can start learning more in depth.

Are you wanting to 'feel' the cut? If that isn't a big deal - use jog wheels. One for each axis. Most people that think the want to keep 'manual' control quickly find out that cnc control is much nicer.

I want to have the bridgeport remain a true (as in still having handwheels) manual machine with cnc capability, mainly for doing hole patterns in large plates. It will be x/y axis only.

I have a tormach 1100 to use as a designated cnc mill, but some of the work I do is simply easier and far quicker on bridgeport.

I’m thinking of doing the same thing and I’m putting together a component list. It seems like there are two basic configurations:
1: analog input amplifiers with encoder feedback to linuxcnc, PID tuning happens inside linuxcnc.
2: digital servo drives with encoders feeding back to the digital drive. PID tuning is done inside the drive. Linuxcnc passes step and direction to digital drives.

It seems like option 1 would work to run in DRO mode like what was suggested i.e. disable drives and encoders keep feeding back to LInuxCNC. I don’t know how option 2 “step & direction” would work without encoder feedback to linuxcnc. Any thoughts

My understanding is the 2nd option would create a "closed loop" entirely outside of linux cnc. If you wanted to do this you could buy the off the shelf clearpath motors, though as you stated, Linuxcnc gets no direct feedback, and therefore could not be used as a DRO for manual work.

I have an old Bridgeport mill that I am considering doing a cnc conversion on.

How much of your mill is CNC ready? The quill feed can be a tricky retrofit if your machine is all manual.
Okay, just saw your post on the machine being 2 axis.

I pondered over how to keep my machine manual and CNC and spend too much time making my old anilam quill drive detachable so I can use it manually. It has come in handy a few times such as for power tapping but I mainly use the machine in CNC mode. The way I look at it is, if it takes longer to get the machine to a manual ready state than booting up the pc and homing then it's not really worth it.

If you want to do drill patterns etc, it's actually faster rapiding to that position than manually cranking the handles.
But if you want to do it manually its no problem reading in linear scales or rotary encoders for position. In my config,when I switch over to CNC I do have to home the machine 1st.

For jogging around I would suggest getting a good quality MPG. I wore out the spring on the detent mechanism on a cheap ebay one within a couple of months.

I also would recommend fold up safety hand wheels over the stock handles and spend the time balancing them!