[cyquant]

Hi, I have a tray that is 17" x 14" and have several parts placed on the tray which do a certain task. The tray needs to travel on a vertical type CNC along the 3 Axis(X,Y,Z) in front of a 16X16 matrics placed on a vertical surface(like a wall). The tray weighs 20 pounds and I am thinking to mount the tray on a Cross X and Z axis and then have the whole setup including the X,Z axis and the tray placed on a Gantry type Y axis which will need to raise and lower this heavy weight which now including everything it must be about 50 pounds.
What type of Nema motors will I need for this setup? I appreciate your help and advise. Thank you and Happy Thanks Giving.

[joeavaerage]

Hi,
a stepper is just a motor, so it will not 'lift' anything...as is. It needs to be connected to some sort of linear motion actuator.

If you want precision and reliability the ballscews are the way to go. On Ebay and other places you can buy C7 grade rolled ballscrews including support bearings for say $100 each for
16mm diameter, 5mm pitch and say 700mm long. C7 screw are +-50um per 300mm and 30 um cyclic....is that accurate enough?

You can get ballscrews in 10mm and 20mm pitch, and they travel very fast but with less thrust. 5mm pitch screw travel slower but have more thrust. With 5mm pitch screws matched to
(low inductance) 23 or 24 size steppers of say 500oz.in you'll move your 50lb easy, and at considerable speed and repeatability.

Craig

[cyquant]

Hi Craig,
Thanks for the responce, that's what I meant to use the necessary parts and all so in a way it would be a CNC router type of a machine with all the needed hardware and your info on the ball screw iand the motors are very complete and accurate and solves that problem for me. Thanks so very much.

Cy

[joeavaerage]

Hi,

Nema 34s with 650 Oz holding Torque?

I think that is over the top, 23 size steppers of 200 oz.in I suspect would be ample.

Lets do a rough calculation:

Assume 1Nm torque (approx 190 oz.in)
16mm diameter ballscrew =0.016m or 0.008m radius.
5mm pitch =0.005m

Mechanical advantage of ballscrew = 16mm * Pi / 5mm =10

Force acting at 0.008m = 1N / 0.008=125N
Thrust ( at stall) = 125N * 10 =1250N or 125kgForce....is that enough?

Remember that is just one 200 oz.in motor, if you have two ballscrews and two motors you'd end up with double the thrust.
You will have to consider that the torque diminishes with speed and this rough estimate is at zero speed or stall.
With decent low inductance steppers and good high voltage drivers and supply you could rely on 50% torque at 500rpm, but that should still be plenty.

Craig

[cyquant]

Craig,
Thanks again, the formula you have given solved a lot of problems for me and saves me a lot of $ , I had ordered 34s which I now cancelled and will go with 23s of 200oz with plenty of good deals on them and since using 2 for the Y axis raising and holding the tray I will be more than OK.

Happy Thanks giving

[cyquant]

Just found this great deal and bought it it should be enogh I hope:

Package Included:---1* CNC V3 ?1* Control Board ? 4* TB6600 ? 4* Limited Switches ?4* 23HS5628 Motor with 30cm wire
Twotrees CNC Controller Kit with Nema 23 Stepper Motor 8.0 mm shaft?TB6600 Stepper Motor Driver,GRBL CNC Shield Board?Switch Endstop $110