Z-AXIZ weight

[signIT]

HELP!

How much is the maximum weight for a Z axis in this project!.

The stepper is heavy about 1.5 kilo, my idea is to use a trapetzoid screw TR18 x 4 and two THK HRW27 320mm, this will be mounted on a X axiz with two THK HRW27 640mm long.

The case is that I have bought three steppers that are very big by a mistake I forgot to ask the seller about weight so... I have to use them in this project, the router will be rather small but uses very robust THK rails the measure of the X,Y table is about 640mm x 640mm.

My problem is the Z-Axiz can this project be relevant or should I buy a smaller stepper to drive the Z Axis.

If I build this monster it may be strong enough to carry a heavy router like Makita or Bosch.

At a loss!

[balsaman]

Should be no problem. How many oz-in is the stepper?

Eric

[signIT]

This is what I can find on the label
Astrosyn Stepper
IBM P/N 6851910
EC NO. A 83331
TYPE 34PN-C102-02
3.0V/PHASE SER. NO 26-92
MINEBEA CO., LTD
Made in Thailand

[jstuedle]

Just a thought from a newbie. But could you use a air cylinder like those used to hold up the hatch or hood of a car? I would think this would counter balance the extra wieght.

[svenakela]

There shouldn't be any problems at all, specially if you really are going to use 18mm screws which probably is a lot more than you'll ever need. Besides that, the bigger stepper the stronger it gets, as an example, what is the z-axis weight on a milling machine?
If it can't keep the spindle up, just gear it down.

Cheers,
Sven

[chuckknigh]

I was at Home Depot, the other night. They have those wonderful panel saws, with the linear rails, and what appears to be a fairly heavy saw mounted on it, so I asked if I could look at the back. My first thought was a spring loaded counterweighting device, similar to the torsion springs on a garage door. Instead, they came up with a beautifully simple solution.

All they did was use a counterweight and a cable slung over a pulley, to effectively negate the weight. The counterweight? A brick.

It didn't have to be high tech, to work. This is an elegant solution, for their problem.

-- Chuck Knight

[balsaman]

Yes, you can use a cylinder similar to those found on a hatch back. Or a spring will work. A counterbalance weight can work too but it doubles the weight of the assembly, which sometimes must be considered. On a gantry for example.

Eric

[ger21]

You might want to look at a constant force spring. Kind of like a tape measure. McMaster-Carr has them.

[signIT]

Hmm...! I think that my monster steppers will manage to lift the Z-axis if I build it as light as possible but yet strong and stiff enough to carry an ordinary wood router.
My idea is to use this cnc machine to cut hard wood and soft metal like aluminum and brass it will be a rather small machine with a heavy Z axis about 4 kilo, it seems to overkill but I have those X IBM steppers.
This project will start in october and will be finished befor X-mas.

Products like wood fly boxes and front panels for electronics will be produced at high speed.

I own a Zoltar from the Netherlands CNC@Home it is a nice machine cheap and easy to manage I have done a couple of cuttings in MDF it is just Ok.