Thread: need help! choosing right kit
To reduce the risk i will reduce the overall machine size frame to 2000*1150*400 mm
X one ballscrew 2510 length 1750
Y one ballscrew 2510 length 950mm
z one ballscrew 1605 length 300 mm
i also plan to use design made from steel like this
X gantry using 50*70*3mm box
all bed made using steel
one central ballscrew 2510 for X gantry
That's because vendor wants you to buy the PSU he has on his site, the recommendation is meaningless as he doesn't know intended use.
Single ballscrew on that width isn't going to work, the gantry will rack and bind if you cut towards the edges.
Inertia of 25mm screw is too high for a 2.8Nm motor, you'll be severely constrained on feed rates as you won't have the acceleration to change direction quick enough. Unless you go with fixed screws, driven ballnuts.
You may well have made a usable machine before but from your description this is in a different league and needs much more thought and design. We appreciate your supply difficulties but you're wasting your money by rushing to buy the wrong kit.
i need advice JAZZCNC for ordering one Power supply 70V~90V 12A in this link
i already have 4 driver 80V 7.8A
and i hope this PS match The JK57HS112-3004 (NM 3 - 425 oZ 3A 6.8mh) with 2510 and 1610
is one enough for 4 nema 23 steppers
thanks irving2008 for reply i appropriate your effort with me thanks again
Single ballscrew on that width isn't going to work,
what is your opinion about the design of steel machine above
Inertia of 25mm screw is too high for a 2.8Nm motor
Ok well it,s been said but will say again to backup. Forget Single screw down centre gantry will twist at this width. Forget 25mm screws unless running nema34 with high voltage AC drives.
Now the sqrt(3.8 mh) * 32 is just a guide and in practice you can go higher without any issues or shortening motor life too considerably. (One thing to note because your in a Hot country I would consider putting cooling fans on the motors, PC CPU fans work well)
The PSU you linked too would work ok but first I would look into making your own.?
It's very easy all you need is toroidal transformer, 1 x brdige rectifier and capacitor/s. Obviously these need to be sized to give the output your require which we can help with.
You must have electrical component suppliers like RS components in your country so I would enquire about costs because Unregulated toroidal PSU is much better for CNC when your running near the drives Max voltage.
So Definately go with 2 x 3nm/1610 running 70V. Will warn thou that at 1750mm length with 16mm screws your at the point when whip at higher feeds can cause problems so you may still need to limit motor tuning to lower rapid speeds.?
Also the mounting and alignment will need to be perfect, which it should be anyway, but if your off just a little then this is amplified at this length which can introduce whip and resonance.!
So hopefully now you see why WE all have been asking you to slow down and think about it becasue so many things affect other parts of the machine and for good machine you need balance and components working in harmoney not fighting each other.!! . . . . In CNC we Make LOVE(chips) not WAR. .Lol
Last edited by JAZZCNC; 17-09-2014 at 08:43 AM.
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