Tuesday, April 6, 2010

CNC Milling Machine

Here is a picture of my CNC mill.

CNC Mill

In the Beginning...

It started off life as a small manual Sieg X1 Micro Mill bought from Harbor Freight (discontinued now)

Then it got CNCed...

CNC is accomplished by NEMA23 Stepper motors from Keling and Stepper Drivers and 2 parallel port breakout boards of my own design along with a custom 42V switching power supply.  One parallel port didn't provide enough inputs and outputs to control the 3 stepper motors, home / limit switches, spindle encoder, touch probes, and flood cooling.

The motor mounting brackets and spacers were all made on the mill itself when it was still a manual mill.  The solid couplers were made on a manual mini lathe.  Not fun and I'm glad I will never have to make anything manually on this mill again.

The mill runs a closed loop spindle so the spindle speed can be set from GCode programs.
The mill uses dynamic tool sensing so everytime a tool is changed the length of the tool is measured on a touch off plate automatically.

Software for controlling the CNC mill is EMC2 available at LinuxCNC

When everything was first put together and nicely maintained, the X and the Y would do 60 IPM rapids all day long with no problems.  Sadly after a few years of just enough maintenance to keep it running for one more job and not having the time to really take the mill apart and clean and realign everything performance has dropped down to 30 IPM rapids.

Then it got upgraded...

Along the way it got upgraded with these parts from LittleMachineShop

And then I went nuts with flood cooling...

It has a plastic enclosure surrounding the mill with doors.  The mill has flood cooling which pours a continuous stream of coolant at the cutting tool.  Before flood cooling the mill really struggled to make good clean cuts at any decent speed.  Heavy cuts would make horrible noises and it felt like the machine would shake itself apart.  With flood cooling, cuts with end mills come out very nice and machining speed has drastically improved with very little noise.  The belt drive and cutting at 6000RPM helps immensely also.  I do most of my milling in aluminum and the coolant helps carry away hot chips and keeps them from welding to the end mill especially at high RPMs.

Protip:  Never ever ever do high speed machining and flood cooling without an enclosure.  Coolant ends up sprayed all over the room.  Don't ask how I know this...

One day I was at Harbor Freight and there was a clearance sale...

I was at harbor freight to pick up some tools and noticed they were clearing out all of their MT2 drill chucks for something like $10 each.  I bought all they had left.  You can see them neatly arrayed in the tool holding rack on the right side of the picture along with a bunch of end mill holders.


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