Quite an Unusual one

**Boyan Silyavski** · 20-12-2013

Now back to reality. I need some help here please! With motor calculations. I read numerous threads here and at the zone, have done numerous calculations as far as i could but will shamelessly ask here again as i am stuck.Almost finished the drawings. The Z looks quite nice and now i am sure its possible, though some blocks will look like cheese due to the ridiculous hole placement

I though i had everything clear until yesterday i calculated the weights.

The Z weights 32kg and the gantry in total 120kg

Part of the problem lies that i don't know what exactly i want

as till now i have experience only with small weak machines.

1. I would like the gantry and the Z to be rigid as they are in the drawings
2. I would like the machine to be in the middle between resolution and speed. What i am not sure is what speeds i want/not rapids-cutting speed/. I will cut wood and aluminum on that machine. I chose 1610 to move the z left right and 2510 screw to move the gantry. I thought of 1:1, now i am thinking of 2:1, otherwise not only i am jumping in the so called "servo territory" but will have to jump in the "expensive big servo territory"

I have decided on the 3kw spindle. I am not sure but i believe i will be happy with sturdy heavy machine that could do 250IPM /6350mm per min/- cutting in wood at good if not full cutter depth. The weight should help with the depth and i assume with the aluminum finish. Aluminum i will be happy if i do it at flute diameter depth. It seems the machine will be sturdy enough for this, having in mind the very extremely low overhang with my design, enclosed frame spoindle and strong gantry +the quantity of bearings.

3. I thought of driving the Z with hybrid closed loop Leadshine Nema 23 3Nm, same the Z left right and 2x the same that move the gantry.

That was when i did not know about the actual weight.

Now the question is:
-do i make my machine smaller / which i would not like much, cause the money will be almost the same and missing eventual job on the long run could be very undesirable/

or

Keep it like this and figure how to drive it.

So definitely i need some help in this mess in order to evaluate options and make no mistake here.

The servos i am looking at are these: my friend Fred's BST store
He seems to have the lowest priced servos and drivers around and as i will buy the rails and screws from him, seems quite logical choice

Questions:
having in mind that i don't want to compromise one axis due to small savings of $ and ruin the integrity of the machine. Obviously on the long axis i will go with servos. And here BST store llloking at the prices of servos i am almost ready to fit servos on all axis, as they are almost the price of the Leadshine closed loops

1. The Z weight will stay the same. 10kg spindle + some aluminum, there is nothing more to do except lower the weight about 5-6kg which i believe is not worth it . That is clear. RM1605 screw . Should i stay with 3Nm leadshine Nema 23 closed loop motor 1:1, change the relation 2:1, or upgrade the motor to servo?
If servo, what reduction and how big the servo motor?

2. Z weight again same. RM1610 screw. Should i stay with 3Nm leadshine Nema 23 closed loop motor 1:1, change the relation 2:1, or upgrade the motor to servo? If servo, what reduction and how big the servo motor?

3. Gantry 120kg

, 2510, rotating ball nut both sides.
options i see:

- drive it with 2 servo motors, one each side. I am lost what power i need here. According to what i calculated if i am not mistaken could go with 2x 6N.M 1.8KW 3000RPM 110ST AC Servo Motor 110ST-M06030 + Matched Servo Driver / 310euro each . i am not sure though if the reduction here should be 2:1? Or if with 2:1 reduction i could go with smaller servos like the 4N.M 1.2KW 3000RPM 110ST AC Servo Motor 110ST-M04030 + Matched Servo Driver, where the price is 304euro, so as you see there is almost no price difference .

-drive it with 1 big motor and 25mm belt which i am almost sure i can fit to pass through the gantry beam
for a motor i believe the 130ST-M10025 servo motor and servo driver system 2.6KW 10Nm 2500rpm 10A / 375 euro/ would be ok. Again not sure if the ratio should be 2:1 as i assume.

4. Or i stay with closed loop steppers, but they arent cheap, i almost decided on servos.

5. I can not find what size in Nema are these servo motors so i could continue with the drawings, in fact no info on these cheap servos

PS. Found the documents at last for the servos PDF specs
it seems they are Xinje Servo drives and motors here PDF for the drives