[louieatienza]

It's a Sherline Industrial Headstock. I modified it a bit to be able to mount it flange style. spindles

I've seen some pretty badass router/mill builds that use the aluminum extrusion parts as frame members. They all seem to be more capable than mine though. Here's one that inspired me:
http://www.cnczone.com/forums/diy-cn...82294-cnc.html

His can tear through aluminum parts, if you look at the videos he's posted. His other youtube videos show it blasting through no problem. I think I should be able to get that kind of performance out of this machine.

While you maybe able to generate 1HP, I would venture the electric spindles in katran's machines have more torque. They are also capable at generating that power at 20krpm-24krpm. The Sherline spindle's bearing are only rated to 10krpm max, and that's with very little to no preload on it. There is a company out there that rebuilds Sherline spindle heads to super low runout (.0005" TIR or so) and ups the max speed to about 20krpm. Or you could just get a Chinese made water-cooled spindle. Katran's machine I believe also use servos, have thicker-gage wall extrusions as well.

[ihavenofish]

I'm not sure spindles need to be that powerful. In my case I was able to maintain RPM while cutting, and the motor only drew 100 W. That was a surprise to me, but the data is there.

its not the power, its the structure. sherline spindles are very light duty with raidial bearings and little or no preload.

[G59]

Small spindles all suffer from lack of inertia. Basically, no flywheel effect. No mass to absorb vibrations and less than adequate bearing size and support for steel or even efficient aluminum machining. In other words too light.

[wizard]

It's a Sherline Industrial Headstock. I modified it a bit to be able to mount it flange style. spindles

That is a problem then. The spindle isn't really designed for this sort of usage. In a nut shell it is light duty.

I've seen some pretty badass router/mill builds that use the aluminum extrusion parts as frame members. They all seem to be more capable than mine though. Here's one that inspired me:
http://www.cnczone.com/forums/diy-cn...82294-cnc.html

It doesn't really matter what you think about other machines at the moment. The problems you are having are on your machine and it has a lot of problems. Those problems exist from end to end. Everything from the lack of a frame for the Z / table, to the light duty spindle is a problem.

You can certainly improve this machine SOME but I wouldn't bother, Use this machine instead to build a much stiffer machine.

His can tear through aluminum parts, if you look at the videos he's posted.

Well we all have different expectations. In any event bandwidth limited at the moment.

His other youtube videos show it blasting through no problem. I think I should be able to get that kind of performance out of this machine.

Not a chance without an overhaul.

[rogue-insight]

This guy is using the same spindle I am, and it seems to tear through brass well. He is running at super high RPM though:
https://www.youtube.com/watch?v=32j3S4PWSpg

[rogue-insight]

While you maybe able to generate 1HP, I would venture the electric spindles in katran's machines have more torque. They are also capable at generating that power at 20krpm-24krpm. The Sherline spindle's bearing are only rated to 10krpm max, and that's with very little to no preload on it. There is a company out there that rebuilds Sherline spindle heads to super low runout (.0005" TIR or so) and ups the max speed to about 20krpm. Or you could just get a Chinese made water-cooled spindle. Katran's machine I believe also use servos, have thicker-gage wall extrusions as well.

Torque RPM and power are all related. Power is RPM*Torque. Torque only matters when you can't produce enough of it at a certain rpm to maintain that rpm. I think it makes more sense that the housing of the spindle is wimpy, since I cut off some of the sides. Also, this spindle is beefier than the one they put on their little cnc mill and lathe.

[rogue-insight]

Not a chance without an overhaul.

I think I have the same overall structure as him. My machine is smaller too, I'm not convinced the extrusions are the culprit. There are a lot of extrusion-based machines that seem to do well with metals. The fact that it's a high-pitched resonant mode that's being excited leads me to think it's something with the bearings. It's also possible my feed and speed is simply in the wrong place. Maybe if i move up in RPM all this would go away. My attempts thus far have been at 3000-4000 rpm.

[Tkamsker]

Hi Rouge i also cut alu in an extrusion Based machine it is a Heiz 400 t i agree with Most the People already have stated but extrusion yes but much thicker z support much stronger uprights must be connected and i would eventually also use you rails 90 degreees different maybe a kress 1050 would be a Start For your spindle issue but
I would Start with connecting your upright s together and change the spindle Then use your machine and get experience and Then make decisions


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[louieatienza]

I think I have the same overall structure as him. My machine is smaller too, I'm not convinced the extrusions are the culprit. There are a lot of extrusion-based machines that seem to do well with metals. The fact that it's a high-pitched resonant mode that's being excited leads me to think it's something with the bearings. It's also possible my feed and speed is simply in the wrong place. Maybe if i move up in RPM all this would go away. My attempts thus far have been at 3000-4000 rpm.

Your RPM determines your federate. If you're using a 1/4" 2-flute cutter in aluminum, using a low-end .0027" chipload per flute, at 4000rpm your federate should be around 21.6ipm. Your aDoC and rDoC will depend on machine rigidity and spindle HP.

As to the machine - aside from the two dangling masts, you have the two long-axis ballscrews hanging in the air, waiting to vibrate. They really should be supported at the free end. You can make free end bearing supports pretty easily with a bearing ID that fits over the screw and a bore that allows a slip fit of the OD of the bearing.

As to the high-pitched whine - I don't think that has to do with high resonant modes. The heavier the structure, the higher the resonant frequency. What vibrates the easiest in the machine is the lightest component. Which just happens to be those darn extrusions. You can test this by filling them with lead shot or sand and see if the problem still persists.