Quite an Unusual one

[Bart]

Hi,
my first helping post here but I was reading for quite some time...
silyavski
here is part of my excel spreadsheet that might be useful for you- - just type in your variables in green boxes and you should get all the date you need.
Attachment 11071
I do not guarantee correctness of the results but I'm fairly confident that they are correct.
It's slightly more complicated then most spreadsheets that I've seen here so if you have any questions ask here.

[Boyan Silyavski]

Hi,
my first helping post here but I was reading for quite some time...
silyavski
here is part of my excel spreadsheet that might be useful for you- - just type in your variables in green boxes and you should get all the date you need.
Attachment 11071
I do not guarantee correctness of the results but I'm fairly confident that they are correct.
It's slightly more complicated then most spreadsheets that I've seen here so if you have any questions ask here.

Thanks!
P[W] stands for calculated power per motor for X or for both motors?

[Boyan Silyavski]

Some updates:

Motors:
Thanks for the help! Now things are more clear there.

The main option i will go most possibly is 4 servos x 400w or 2x400w +2x750w.

Obviously from the calculations if 2:1 then 2x200w+2x400w will be sufficient, but as the price difference between 200w,400w and 750w is merely 5-10 euro, i dont see a reason why not going properly bigger.

The Hybrid stepper option i discarded due to price similar to servos.

DC Servos and motors from Leadshine are almost the price of AC servos and motors , so 220v seems a lot better choice

Steppers are still an option, except for the long axis that moves the gantry. However i would like the Z also to be closed loop, due to the vibrations. Plus the price of decent driver and motor and PSU is almost as the price of AC servo, hence the servo decision.

Another point there is i am starting to doubt about the cheap servos, so i am trying to get for the same price 4 x ACH750 Leadshine AC Servo motor drives + motors. Bargaining with Chinese people takes time :-)

The Z axis

The single screw design i am almost 99% sure will be without a problem. Hoewver i decided not to risque due to the impact hammer head and changed the design. Lost something of the beautiful simplicity and acquired annoying amount of pulleys and idlers, but i could not design it better for now. Best would be with 2 stepper motors on 1 drive, i know,not a very good idea, but works/my flimsy cnc is that way on the gantry without any problem, but is flimsy, not rigid like this design/
So, for now that's how it would be:



Rotating ball nut
At the end i found somebody help me with making it. Jeff, from the forum, who happens to live very near, here in Spain. Wow, what a work shop and machines he has, especially compared to my garage.

Now as i decided on Servo, may be even will go with double ball nut/all over the machine also/. 1.450kg said Fred yesterday, weights the 2510 double nut. I wonder what the inertia will be, he he.

I thought of integrating it into the gantry, but at the end decided to fix it aside, due to the possibility to lower significantly the screw length+ avoiding an accidental hit of the gantry to the screw mount




Breakout board
-ESS and PMDX126 seems to be the first choice. What i don't like of this combo is the fact that i have to buy additional spindle control board

So i investigated quite a bit even looking at some second hand Galil motion boards on ebay.

Another good option seems the KFLOP. In fact it seemed ideal/8 axis they say +usb/ until i found that i have to know C+ and that half of its IO are 3v so i have to spend another 240$ for accompanying IO board.

What i need is very simple: cheap ethernet digital 8axis board

A question ?????
There is something i don't understand about boards and servos. Why all speak of the encoders to go in the BOB? Dont they go to the servo drive and the servo drive controls the closed loop? I read at Galil and KFLOP that the BOB closes the loop? Or am i mistaken?