Hi Salah,
I had planned on doing the same for my lathe, but after doing my VFD conversion (https://www.hobby-machinist.com/thr...tronic-components-pm1440gt-vfd-3-phase.95058/) I have gotten busy with other projects and have hardly spent any time doing metal working. I spent too long on the TPI Excel workbook then got busy with non-HM topics!
What motor did you purchase for the Z-axis. I suppose you had to change the amplifier from the stock that came with the factory CNC, but maybe you already had done so when you did the conversion?
I will be interested in what you might come up with for supporting the 940M head. I went through a number of concepts, but never built any of them. Getting some of the weight off I think would also improve the z-axis performance in terms of head knod and backlash. I slowly came to the conclusion that the geared head is so heavy that it actually causes flexture in the vertical way width! So I started to counter balance with weights or springs (coil spring was the best approach, but these all effectively add more weight on the vertical column), then the air gas spring/struts concept but I did not figure out a way to fasten them nor did I find any that were long enough. (The pushing struts are available in longer lengths than are the pulling versions.) I tried out both concepts of pushing and pulling struts, but never liked my designs. My more recent concept is to use two pushing struts in series, a pair on each side for a total of 4. One goes from the mill base to a custom machined part that fits on the ways and lifts/slides the part along the way as the head goes up and down. The other, goes from the machined part on the way to the center of gravity on the head at an angle. At the head's lowest position both are compressed. As the head is lifted the strut going from the way to the head would first expand to lift the head and to keep the head from torquing on the ways. When it reached its maximum extension then the second strut takes over to lift the custom part which is mounted on the ways. This would all seem to fit on the mill and would not require some contraption over the top for a counter balance approach. It should work, but would it be stable or have its own problems? TBD.
One has more projects than he can get done. I also wanted to facilitate a power tap system. For what I do with the mill this would be more important to me than other tool changing systems. I purchased the 4th axis CNC and find I do not use it much so I was thinking about using it on the spindle for power tapping. It would require some custom G code.
Oh well, back to my work projects.
Dave L.
I did that when I made the caster mounts for my PM1440GT. It was messy, but I built a plexiglass box around the table and the vice and attached it to the front and the back of the vice while resting on the table. I then attached adjustable cardboard, via bolts, at the front, back and ends to allow me to run it right up to the lowest mill head position I was going to use to prevent over spray. I lined the box with heavy Al foil to cause the oil to drain on to table to then drain back to the coolant pump. It all worked ok and the mess was pretty much contained. I have my equipment in the basement of a 1930s house and put all the metal working equipment in one small room. One of the advantages of having the mill on casters is that I could roll it out. I then put down rubber, bathroom shower rubber which you can get in 6 or 8 foot widths. This protects the unsealed concrete a bit. Then I put down big pieces of scrap card board to catch any drips..... the 940 drips from a lot of places anyway. The thought was that when the cardboard got dirty I would just switch it out. However, ti have found that while it has a few stains for the most part it does not get to dirty.
I had planned on doing the same for my lathe, but after doing my VFD conversion (https://www.hobby-machinist.com/thr...tronic-components-pm1440gt-vfd-3-phase.95058/) I have gotten busy with other projects and have hardly spent any time doing metal working. I spent too long on the TPI Excel workbook then got busy with non-HM topics!
What motor did you purchase for the Z-axis. I suppose you had to change the amplifier from the stock that came with the factory CNC, but maybe you already had done so when you did the conversion?
I will be interested in what you might come up with for supporting the 940M head. I went through a number of concepts, but never built any of them. Getting some of the weight off I think would also improve the z-axis performance in terms of head knod and backlash. I slowly came to the conclusion that the geared head is so heavy that it actually causes flexture in the vertical way width! So I started to counter balance with weights or springs (coil spring was the best approach, but these all effectively add more weight on the vertical column), then the air gas spring/struts concept but I did not figure out a way to fasten them nor did I find any that were long enough. (The pushing struts are available in longer lengths than are the pulling versions.) I tried out both concepts of pushing and pulling struts, but never liked my designs. My more recent concept is to use two pushing struts in series, a pair on each side for a total of 4. One goes from the mill base to a custom machined part that fits on the ways and lifts/slides the part along the way as the head goes up and down. The other, goes from the machined part on the way to the center of gravity on the head at an angle. At the head's lowest position both are compressed. As the head is lifted the strut going from the way to the head would first expand to lift the head and to keep the head from torquing on the ways. When it reached its maximum extension then the second strut takes over to lift the custom part which is mounted on the ways. This would all seem to fit on the mill and would not require some contraption over the top for a counter balance approach. It should work, but would it be stable or have its own problems? TBD.
One has more projects than he can get done. I also wanted to facilitate a power tap system. For what I do with the mill this would be more important to me than other tool changing systems. I purchased the 4th axis CNC and find I do not use it much so I was thinking about using it on the spindle for power tapping. It would require some custom G code.
Oh well, back to my work projects.
Dave L.
