Yeah, I need to try to find a 3/16" single flute bit. I have 10 or so 1/8" single flute carbides, and they are working well in aluminum, I am currently trying to find out how fast I can cut which is why I’ve moved up to the larger bit. The adaptive cut I am running is from fusion 360 and has a constant engagement, similar to the trochoidal cut. This cut starts on the outside of the material and engages only 1.9mm at any time throughout the cut, I will probably have to reduce that amount to keep the bit from pulling out of the collet.
Amazing build, I love it.
I just have one remark: You strengthened all the axis, except for the Z one… Problem is, the main issue from my experience with the MPCNC is the strenght of the Z axis. And it is not only for the MPCNC by the way, I also have a 3040 full aluminum mini CNC and the Z axis is also the one who has the less strenght.
You’ve made an incredible build, so, really, kudos on that. I suggest you push it a little further by adding 2 more Z tubes at the opposite sides of the current ones, mirroring them. This way you’ll have the spindle fully supported on all 4 corners, it would reduce drastically any kind of flex. You’ll need to add another motor for Z but this isn’t really a problem.
I planned to do that a few months ago, but I gave up because of other projects and the fact that it would sacrifice a lot of usable space which I need for big 3D prints.
The super loud noise means that your spindle is either not perpendicular to the work, or your bit isn’t adapted or your cutting speeds are off, or your rpm is in the range of resonance. When it is properly tuned and when everything is ok, it shouldn’t be very loud at all. Actually that how you know your settings are ok, when the cut is as silent as it can be and when your chips are consistent.
Again, kudos on your build and keep up the updates and pictures!
Great work.
Single flute didn’t work for me with the brushless spindle. Reason being the low RPM. I think it is perfectly suited for a Dewalt spindle who can reach 30K rpms, but not really for a brushell who only reaches 10-12K.
According to my tests, 2 flutes and even 3 flutes worked better than single flute on aluminum. Chatter was crazy with one flute.
[attachment file=49663]
You can see the results of 3 different bits on 3 different cuts I’ve made with the brushless spindle: Top left is one flute, top right is 2 flutes and bottom right is 3 flutes. 2 flutes was the winner, slightly better than 3 flutes. The cut with the one flute was horrible, I thought the machine would explode.
Dui,
Thanks, I am enjoying the build and experimenting, I just added homing switches (not the prettiest implementation), but I am hoping that will help with tool changes.
I have a lot more testing I need to do with aluminum to get it correct, and the noise really seemed to amp up after I added the steel coolant drain pan, I am looking into various ways I can dampen the entire system. My spindle is trammed and very perpendicular.
Currently, my Z axis seems to be a bit stronger than default just due to the way my Z axis bearings compress on the lower end of the spindle, it holds perpendicular very well for some ridiculous cut depths. Current tests in red oak hardwood are within 0.01 mm in X direction and 0.06 mm in Y direction at 3mm DOC (with a finishing contour pass). The X direction accuracy seems to back up your idea that 4 tubes would help, since the existing tubes are parallel to the X axis.
I really would like to get to a 4 tube solution, in fact I already have the tubing and extra motor ready. My plan is to get it cutting good enough in aluminum and then mill the parts out of some aluminum plate, it’s the only way I can think to reduce the overall size of the gantry, I lose 4 inches in X and Y due to the extrusion frame around the spindle alone. I may end up ordering some linear bearings to make it more compact.
Great note on the end mill flutes, your single flute results look similar to mine, although I at the time I was thinking it was due to the 1/8" end-mill bending under load. The 3/16" two flute bull nose I am using now definitely cuts better, I just need to tune out the harmonics.
Tuning steps/mm:
Making a box for my ER11 collets:
Testing Op 1 of 4 for a custom set of dominos:
Domino jig, this didn’t end up holding the pieces as accurately or as tightly as I need, so I will have to come up with another solution:
Setting up for Op2 to take off the remaining stock:
Op 3, engraving and chamfering. This was the impetus for adding homing switches, but I also need some better endmills for engraving and for chamfering. Will be trying this again using some different work-holding, probably after the holidays.
