[DannyR]

Well my collection of components just got serious last week. I think I may actually have to stop looking and start building my dream machine. Some of the components I've salvaged (all freebies) include:
Frame
- 2 ea: 750 lb. steel frames, with 72" Linear slides and 42" Ball Screws for the "Y" axis.
- 1 ea: Aluminum slide, (24" Linear slides with mounting plate) for the "Z" axis.
Servos:
- 3 ea: Parker Superior Servos; KMT093F10C5, 3.21 vdc, 5.1 amps, 200 Steps/Rev. 500 PPR Encoders ("Y&X" axis).
- 2 ea: Parker Superior Servos; KMT092F07C5, 3.48 vdc, 3.25 amps, 200 Steps/Rev. 500 PPR Encoders (just one for the "Z" axis).
-2 ea: 12" linear servos actuator which I don't know if I'll need (1 on the "Z" Axis?)

Due to the availablity of these frames and wanting a 5'x8' router table, I'm drawing up a design that would require a rather long gantry (100") for the "X" axis. I plan on purchasing 2 additional Linear Slides and use a helical rack & pinion drive. With this weight, I'll also be using dual servos/ball screws drives on each side of the short "Y" axis.

A few of the MANY Questions to come:
1. Are these servos adiquate for this large of a router (to be used for case work and 3-D carving).
2. Any recommendations on an overall electronic "package" design, including servo controllers? I want to get a controller to test and learn or play with ASAP.
3. How do I determine axis speeds. Ball screws are set up for direct drive but I havn't yet measured In/Rev. of the screws.

Any thoughts would be greatly appreciated. Have pictures to upload but can't seem to lower the the picture resolution (you know, sometimes I really hate computers) and will try again.

[ger21]

1) Those are steppers, not servos. Whether they are adequate depends on a lot of factors, one of which is how fast do you want to go?

[DannyR]

Yes, your right. TMI leads to overload and had Servos on my mind. They are steppers with encoders. At this time, processing speed doesn't concern me as this will be my first design and used for prototyping and some very light manufacturing. I would guess 800-1200 In/min. would be more that enough to start.

[ger21]

I'd say you'll need at least 1 inch/turn screws to get 800ipm, and I don't know if those motors are powerful enough. Most machines in that speed range use servo's, and or rack and pinion drive. With steppers and 1tpi screws, you're limited to .005 inches per step resolution.

[DannyR]

Gerry, I checked the ball screws and they are 1/2"/turn. Increased torque but decreased speed? If servo's will be better suited for this design, I do have another source. Can you recommend a servo size?

As I stated and hope you'll see in the photos, the current screws are a tad short of the min. 52-62" of travel I would want for the size of slides that I have. So upgrading to R&P on the 2 "Y" axis is not out of the question.

[paulC]

Steppers are good for about 900rpm
900rpm x 1/2 inch =450IPM
That is quite fast. You will never cut at that speed, just use it for rapids.
Question is, will you have enough torque. You may have to gear it even slower to use this stuff.
I would seriously think about what speed you actually need before going any further.
Bear in mind that most of the hobby machines are running around 80 - 100 IPM.
I'm really envious of your freebees.
Paul

[DannyR]

Ah, freebies are good... I've was at the NCExpo show looking a CNC equipment (Flexicam, Thermwood, Komo, etc.) where speed is a givin along with the equally impressive high $K price tag. So even though a slower speed is more that adiquate for my applications, 450 ipm sounds REALLY SLOW. In reality, for my first build, would targeting 250 IPM and investigate adding gear reduction be adiquate to maintain torque? Slower speed would definately help in simplifying final contruction.

Any suggestions on controllers and electronic system designs? Gecko's sound like the way to go.

FYI: For the torque discussion, I plan on doing the initial test cuts with a 3 1/4hp router, then I'll start looking into a 5 to 10hp industrial spindle. I also have a 4'x8' CNC Laser on order (delivery due on 5/22) so these two projects will keep me busy for a while.

Thanks for the assistance

Danr