4x8 router build, 387oz steppers enough?

[jbluetooth]

Hey guys, I'm about to start building a 4x8 table router for my dad. It will use rack and pinion x and y, ball screw z. I want to be able to rapid accurately at 200+ ipm (300+ would be great) and cut at 100+ ipm with a Portercable 3 1/4 or maybe 1 3/4 hp router at first. I know I'll have to gear the motors down for the racks, that's fine, so assume proper gearing, maybe 3-1 or 4-1 or so. I want an all together plug and play package setup. I've read lots of good things about the G540, just wondering if the Keling 4 axis package will be enough, or if I should go for something bigger:

G540 4 axis package (One G540 + Four
KL23H284-35-4B (1/4” Dual shaft with a flat) 387 oz-in + one KL-600-
48 48V/12.5A 115V /230Vpower supply): $624.95

Any recommendations?

Thanks
Jesse

[jbluetooth]

Should have mentioned, will be cutting wood, 4x8 sheets of plywood, MDF, and hardwood planks.
thanks
Jesse

[stevespo]

What is the gantry made of? How much weight are you going to be pushing around? How many TPI on the R/P?

Properly geared, it might be possible - but... my gut feeling is that you're going to be a lot safer and happier with some NEMA 34s. Even 200 IPM rapids are going to feel very slow when you're homing on that 8' table. For a table that size, I'd definitely consider servos as well.

Are there any DIY examples here of a big table, R/P and similar steppers? I can't imagine there are any commercial machines using motors that size - but I could definitely be wrong...

Steve

[jbluetooth]

gantry will be a 3060 piece of aluminum extrusion, precision rails. I was thinking nema 34s might be a better bet, is there a package deal someone sells, or a proven combination of power supply, drivers, motors, bob, whatever is needed, that is simple, or plug and play? Or can you reccomend a simple Servo setup? Budget up to about a grand I guess for it all.

How is this Keling kit:
2: NEMA 23 Servo Motors 4 Axis CNC Kit: $1120.,84

A: 4 PCS Geckodriver G320, 80V/20A

B: 4 PCS KL23-130-60 (NEMA23) Dual Shaft, 350 oz-in Peak 60V/20A

C: 4 PCS AMT102-V Optical Encoder +
4PCS AMT102-V Optical Encoder CABLE, SHIELLD LATCH 5PIN 24
AWG 6

D: 1 PCS KL-600-48 48V/12.5A 110V/220V

E: 1 PCS C10 Breakout board, E-Stop or Limit Switch can be wired

Or would I want to do nema 34 servos?

How about this kit?
4: NEMA 34 640 oz-in Steppper Motors 4 Axis CNC Kit: $889

A: 4 PCS KL-5056, 24- 50VDC, 5.6A Driver

B: 4 PCS EMA 34-640 oz-in Stepper Motors

C: 1 PCS 48V/ 12.5A, Power Supply

D:1 PCS C10 Breakout board, E-Stop or Limit Switch can be wired


I don't want to have to mess with trying to do a lot of tuning and adjusting or trying different equipment, just a proven combination, preferably plug and play. Obviously there will be some Mach setup either way.

[ger21]

Spend some time at the mechmate forum to see what they're doing with a similar size machine. www.mechmate.com.

Imo, those motors are too small, and If possible, you'll want to rapid faster than 300ipm. It'll take 20 seconds to move from one end to the other at that speed.

[jbluetooth]

When you say "IMO those motors are too small" are you talking about the 387s or the other 2 kits? or all?

[ger21]

387's

[ger21]

Originally Posted by jbluetooth I don't want to have to mess with trying to do a lot of tuning and adjusting or trying different equipment, just a proven combination, preferably plug and play.

What works on one machine may not work on another. There are many more factors than just motor torque. Machine weight, and gearing play a big part. Typically you design for a certain max speed. Motors and gearing need to work together to achieve that speed. Figure out how fast the motor will spin, while still having enough torque to provide the force you want, and then gear accordingly.

A lot of motor manufacturers have motor sizing applications that can help you pick a drive system.

There's some good info here.
http://cnczone.com/forums/showthread.php?t=17419

As well as on Gecko's site.
http://www.geckodrive.com/support.aspx?n=181822

[stevespo]

Gerry is absolutely right. When you design/build your own machine, there's no 'plug and play' - every machine is a little different. Doing the research, calculations, making educated guesses, will all improve your chances of success. Overbuilding doesn't always work because the bigger motors have different velocity/torque characteristics than the smaller models and may not give you the performance you're looking for. It's a balancing act.

The other option is to copy a proven design (like the Mechmate). If I was building a big machine, I would be very tempted to do this - but it may not fit into my budget or skill set.

They've already done a lot of the hard work figuring out motor specs, gearing ratios, etc. They appear to recommend a NEMA 34 stepper with 640 - 800 oz/in of holding torque, with either a direct drive approach or different gearing schemes to increase torque and resolution.

http://www.mechmate.com/forums/showthread.php?t=1114

So, the 640 oz/in Keling kit is probably a good match. Hard to say for sure. It really depends on your R/P, gearing ratios, desired speeds, etc. I didn't see any mention of servos in the above thread, the there is probably a never-ending discussion on that topic as well.

Steve