Chips

Finally, my first cuts in Aluminum and success.

Cuts were made in the aluminum mentioned in the previous post using a 1/8″ two flute endmill purchased from  drill bit city.  The design was drawn up in CamBam and for some reason I could not get the holes that were in the drawing to port over to EMC.  To continue the process and not fight with the software, the holes were omitted.  In retrospect this was probably lucky, as the holes were the size of the endmill and there is a good chance trying to plunge the endmill straight down through the aluminum would have resulted in a broken bit.

The aluminum block was held down on the machine with super sticky double face tape, that I purchased at Lowes building supply.  It seemed to hold the work very well, so well in fact it was hard to pry the finished piece off the table with a screwdriver.

Initial spindle speed was set at 5000 and feed rate at 10 inches per min, the aluminum would be cut dry and from everything I could find on line this was a good starting point.  It took quite a while to line up the spindle with the work.  The probe worked very well for finding the top, however aligning X and Y meant quite a few trips from the computer to the machine to jog.  I am thinking laser spot for this step and or remote pendant in the future.

As the spindle plunged into the work I could hear it start to cut and then kind of bog down, after that I wasn’t sure if I could hear the spindle motor any more.  It ran like that for a short while, “milling” out the pocket on the hexagon.

Nerves sat in and I stopped the process, raised the spindle and had a look.  Unfortunately the brush blocks all view of the cutter while its working, so, you can’t see chips, or the cutter.  Its good for vacuum and chip removal, but bad for observation.

Inspection showed a very gouged up mess, the cutter tip was still in tact but the spindle speed seemed way off.  Actually, after investigation, what had happened was the spindle motor fuse blew!  The spindle was not running at all and the machine was just gouging the tip around in the aluminum.  Turns out there was a 32V fuse in spindle fuse holder instead of 250V one.  After it was replaced and the spindle speed increased to 12000 everything worked fine.

I kept the cutting path lubricated with a little Zoom Spout oil and it progressed very smoothly.  The bit did not seem to burn or jam, however the plunging sounded fairly rough.  In the future I’ll ramp down into the work, rather then just plunge.  Holes I’ll drill by hand for now, until I figure out more about the process.

For now, I will call it a very happy success!

Heat Sink on the machine table, still held down by tape.

Close up of finished piece.

Finished Piece removed with pencil for scale.

EMC window showing the tool path used to cut out the piece.

Files used for the piece:

CamBam File for the Luxeon Heat Sink

Gcode File for the Luxeon Heat Sink

EDIT:

Here are some shots of the finished heat sink mounted with LED and driver circuit.  Turned out very nice, however I think I will add some slots on the next version so that there is more surface area and it can dissipate more heat.  It does get pretty hot.

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