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Bridgeport Knee Mill Millpwer and Prototrak CNC Retrofit Swap

M.B. Naegle

Feb 7, 2011
Conroe, TX USA
I know lots of guys on here understandably don't care for CNC retrofitted knee mills, but we like ours and it has it's place BESIDE (not in place of) our VMC's, so I hope this thread doesn't devolve into the typical "don't waste your money on those things" thread.

We have an early 90's Bridgeport knee mill with the 2J variable speed head, ball screws, and 30 tamper quick change tooling. Great 'Merican bones with little wear and the 30 taper spindle means we can hold onto any 30 taper tool we want with the right drawbar. It has a Prototrak Edge CNC kit installed, which is a simple 2 axis conversational control with Z axis DRO on the quill and some DXF file interpretive function. Great control if you're used to doing it all manually, kinda like having a 3 axis DRO that will take over turning the cranks for you when milling around parts.

An opportunity arose to get a newish (grey paint, not white) Jet knee mill with a 3 axis Acu-rite Millpwer CNC control. It looks to have an R8 spindle which I don't care for, same with the Jet iron, but I've read good things about Acu-rite's Millpwer control and like the idea of adding another axis to our knee milling capabilities (via the quill), even if it's just stepping a mill path or pecking a drill. Again, we're not looking at competing with a 3 axis VMC, just getting the most out of a 2nd op knee mill.

My question is: how much of a project would it be to swap the CNC retrofit packages between these machines? Is anyone familiar enough with the Trak Edge and Millpwer controls if they are simple bolt-on conversions where I could put the Millpwer package on our Bridgeport to keep and put the Trak package on the Jet to pass on to someone else? How much of a BP clone are the newer Jet knee mills? Do they both use the same ball screws and same end bracket hole patterns? How does the Millpwer Z axis interface with the quill?
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Both controls are new and simple (not bad simple) enough you might be lucky and just swap controller, the original motors/drives stay. Step and direction input.
I would like a detail picture of quill drive, it is the biggest frustration other than me on my mill.