Even a Taig works with the Acorn

[Richards]

After bench testing three Acorns for an inordinate length of time, I decided that, as interesting as bench testing is, that using the Acorn with a machine, even a little Taig should be the next logical step. Taig has a CNC ready mill, the 5019CR micro mill. It needs motors and a control system, so it is a perfect match for the Acorn and motors from my test bench. I first wanted to use the Teknic ClearPath servos with the Taig, but I ordered the ClearPath motors with the 0.375" shaft. The mill comes with 0.250" motor connectors, so I decided to start with some surplus Oriental Motor PK268-02A motors and Leadshine DM542 stepper drivers along with the V.3 Acorn that I bought about a year ago.

This morning, I ran my first test in 6061 aluminum. I was amazed. The last aluminum that I cut was with my 60" X 120" Shopbot PRT-Alpha. The results from the Shopbot were okay, but far more crude that I had hoped. On the other hand, the Acorn equipped Taig did everything that I expected.

The first step was to create a spreadsheet to compute spindle speed, feed speed, and number of flutes to get the proper chip load. I started by looking up two things, the chip load for aluminum and the Surface Feet Per Minute for aluminum. As most of you know, the Internet supplies a lot of information that differs. It seemed that 0.002" chips with a 0.250" end mill was listed on some reliable sites. A SFPM of about 300 was also listed on some reliable sites, so I started there. The Taig uses a multi-position pulley system to change speeds. Instead of replacing the stock motor and pulley system with a VFD and 3-phase motor or using my DMM 750 motor with DYN4 driver, I decided to use a pulley setting that gives 4,200 RPM on the Taig. 4,200 RPM with a 0.250" end mill gives 275for SFPM. I thought that would be a good starting point.

Next step was to compute the feed speed. Since I was using 3-flute carbide cutters designed for aluminum, I plugged various values into the spreadsheet. Pushing a 3-flute end mill 25" per minute at 4,200 RPM told me to expect a 0.002" chip load.

The final step before running the test was to hand write some G-code. I used the jog buttons on the Acorn's VCP to position the axes, set the axes to zero and ran the program. The program ramped the end mill 0.025" into the aluminum, cut a horizontal groove, lifted the end mill and positioned the cutter for the next cut.

I made cuts at 15" per second, 25" per second and 35" per second. All cut perfectly. The 25" speed produced 0.002" chips. I ran one more test that added a 0.125" X-axis cut and then moving the Y-axis back to it's starting position and ramping it out of the material so that the edges of the cut would all be going in the conventional direction. Again, a perfect cut. It passed the fingernail test, i.e., the fingernail can't feel any ridge between the cuts.

Next step is to put the Acorn in a proper enclosure and then put the Taig to work.

[cnckeith]

Cool thanks for posting!