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19-06-2016 #31
Hi PotatoMill your math certainly is correct but it doesn't account for the full picture. I use Kollmorgen MOTIONEERING to calculate more precisely what kind of motors are required, it's a little tricky to understand in the beginning but sticking with it pays off massively! http://www.kollmorgen.com/en-us/serv...eering-online/ here's the link to their site. I use their older application at the bottom of that page, it looks like they have a new online tool available now.
Kollmorgen have a huge range of motors available and the MOTIONEERING app helps point you to which is suited for your machine, I just use the data from that motor to base my search for a cheap servo / stepper system off of.
Also always remember that steppers holding torque is not the same as a servo rated/max torque.
A good rule of thumb that I use (though I'm not entirely sure it's correct) is that a 3Nm stepper is roughly equal in power to a 100W Servo.
Hope this helps!
Fenza
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19-06-2016 #32
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19-06-2016 #33
It would probably be best to make a 3:1 gearing to utilize the holding torque best. Or is it possible to get cheap ballscrews with shorter than 5mm lead?
Last edited by PotatoMill; 19-06-2016 at 06:29 PM.
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19-06-2016 #34
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19-06-2016 #35
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19-06-2016 #36
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19-06-2016 #37
With steppers? No, not really.
What do you mean with a corner speed?
Here you can see a torque curve for both. You can calculate with a 0-500rpm range.
Unfortuantely it is Hungarian, but here you can see my calculation for my X axis with servo. This is the optimal for a dynamics, but I chosen 2.5:1.Last edited by remrendes; 19-06-2016 at 08:54 PM.
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19-06-2016 #38
Here is some info on corner speed. https://www.google.no/url?sa=t&sourc...JAddXnAgnBfq5A it's more apparent on these speed torque curves http://www.sanyodenki.eu/IMG/pdf/Ste..._06.12.N_e.pdf
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19-06-2016 #39
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19-06-2016 #40
Hi PotatoMill, I see you specced 10m/s^2 acceleration. Now I'm not too experienced with routers and steppers (Mills and Servos is more my thing) but 1g is kind of a lot! I did a quick calculation and a 20mm ball screw 1,200mm length 5mm pitch with 40kg load will require over 3Nm of torque at the shaft to accelerate all the moving parts at 10m/s^2
Cutting forces are only small but the force required to overcome inertia and accelerate a 40kg load is great!
I believe 2.5m/s^2 would be a good target to try and aim for, though It would be nice if someone experienced with steppers and routers could chime in and advise. I believe 50in/s^2 is considered not too shabby in Mach3 which would be 1.27m/s^2
Hope this helps! That Kollmorgen app really is a great tool once you get used to it
Fenza
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