I am building a large CNC for Plywood and maybe Aluminium if it works. (1.8x1.5m - effective 1.5x1m) Got the frame all sorted, now I only need the electronics.
I have no applicable experience with lead screw machines, but would offer the following comments.
Question1 - Not clear what you are using for a spindle. You'll need a lot of torque to make cutting speed in plywood, for sure in Al. Torque generally translates to mass, which raises the question of strength of the X Axis cross member.
Questions2 - Your description translates to likely long runs due to relatively slow lead crew movement, for sure in AL. Longs runs translate to potential heat build-up in the drivers. I have seen references suggesting that higher voltage (I believe it is 36V max) is better under high load conditions. I'd search about, hopefully someone with applicable experience will stop by and comment. Be mindful of your thermal design.
Question3 - Yes, some form of computer will be required to continuously stream the GCode. TinyG has a limited code buffer.
Sounds very interesting, be sure to post a picture when you are done!
I meant torque to move the axis not for the spindle. The axis are very strong and rigid. Will the steppers be powerful enough with the given current to drive the axis?
Thermal control shouldn't be a problem. I plan to measure the stepper temperature during use and maybe will add mini fans.
Spindle; I don't think my machine is in your league, but find the DW660(my spindle) to be a relatively large mass for the X Servo to control. It also puts a good twist load on the axis member, but you seem to have that covered. If you had an even larger router, controlling/moving that mass could be a challenge, mitigated of course by the torque gain inherent in the screw based design.
Stepper power - that will depend a lot on your stepper to lead screw ratio, or do the steppers directly drive them? And, obviously, the efficiency of / drag on the screws from the movable elements.
Thermal - actually, I was worried more about tinyG thermal management.
The router is a big woodworking router. It weighs 3.5kg. So its quite heavy. If I can't cut aluminum, so be it. I would only work on palm size pieces anyway. But would be nice to have the ability. Main use will by plywood.
The leads crew will be this one. I´ll make some anti backlash nuts from Delrin. The steppers will be directly connected.
So it all comes down to: Have the steppers got enough torq with the current provided from the board without extra stepper drivers. (4x drivers add quite a bit to the costs.)
http://imgur.com/XiTfKPG I took the 222N from a CNC forum which is a guestimate that other people use.
According to this, one motor will not be enough. I could use 2 Nema 24s for the Y-Axis (left + right) And then Nema 34s for the X and Z axis with separate drivers right?
This topic is from the original forum (May 2014). Your reply starts a new discussion linked to it.
