[Overtorque]

Hello,

I am considering converting a knee mill to CNC using the quill as the Z axis.

How would I handle things if I needed more that 4.5" of Z movement? I know that I could move the knee and reset the tool height, however I am unsure how well this would work with complex parts.

Is this commonly done, and how well does it work for more complex pieces?

Also, how does one program for it (in Fusion 360)?

Thanks in advance.

[awerby]

Do you really think you'll be machining all the way through pieces of metal that are more than 5" thick? Most things are going to be a lot thinner than that - what are you planning to make? The knee will go down to accommodate larger pieces; you just won't be able to machine all the way through them - but the tools won't be long enough for that anyway. I'd say go ahead with your conversion, and be able to make the 99% or so of the parts you'll actually be dealing with. Leave the monsters to the monster machine you build next.

[Overtorque]

Do you really think you'll be machining all the way through pieces of metal that are more than 5" thick? Most things are going to be a lot thinner than that - what are you planning to make? The knee will go down to accommodate larger pieces; you just won't be able to machine all the way through them - but the tools won't be long enough for that anyway. I'd say go ahead with your conversion, and be able to make the 99% or so of the parts you'll actually be dealing with. Leave the monsters to the monster machine you build next.

Thanks for your response. I understand that 4.5" is a good amount of travel. It's more of a "what if" type question.

[109jb]

Do you really think you'll be machining all the way through pieces of metal that are more than 5" thick?

Simply switching from a drill mounted in a chuck to an end mill in an end mill holder can eat up all of his 4.5" of quill travel.

Way back a long time ago, I used to run an Excello CNC knee mill with the Z-axis on the quill. The knee had a single axis digital readout and we would use the DRO to move the knee for tool height compensation during a tool change. It worked but wasn't ideal. Today, I would say to just make or buy an electronic tool setter and break your programs up by tool with a tool setting routine with automatic touch-off.

[dnldfte]

Where I used to work they had a Bridgeport with a fagor/servo2 conversion that had a large servo motor on the knee. Much more robust than the mill conversion where z was on the quill like a dynapath I used at a later job.


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