Electronics Shopping List Approval Needed

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  • #6027
    spoonr778
    Member

    I am building a large CNC for Plywood and maybe Aluminium if it works. (1.8×1.5m – effective 1.5x1m) Got the frame all sorted, now I only need the electronics.

    Controller: TinyG V8

    Motors:
    http://www.ebay.de/itm/German-Ship-Promote-3-pcs-Nema-23-Stepper-Motor-3A-425-oz-4leads-dual-shaft-/281295712688?pt=Motoren_Getriebe&hash=item417e87f1b0
    Plus one extra for dual gantry drive.

    Drive: Lead Screw

    1. Does this combination work? Do you think its powerful enough?

    2. Which power supply would you recommend?

    3. Does my computer need to be connected while cutting?

    • This topic was modified 10 years, 5 months ago by spoonr778.
    • This topic was modified 10 years, 5 months ago by spoonr778.
    #6030
    cmcgrath5035
    Moderator

    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!

    • This reply was modified 10 years, 5 months ago by cmcgrath5035.
    #6033
    spoonr778
    Member

    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.

    #6038
    cmcgrath5035
    Moderator

    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.

    #6039
    mcgyvr
    Member

    yeah hard to answer any of those questions with the details provided.

    but yes you will ABSOLUTELY need a fan to blow on the tinyg board with 4 x Nema23 @ 3A..(50+ cfm blowing directly on the bottom)

    #6040
    spoonr778
    Member

    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.

    http://hfbshop.de/product_info.php?info=p3003_trapezgewindespindel-2000mm-rechts-tsr-tr12x2.html

    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/XiTfKPGTorq Calculations

    • This reply was modified 10 years, 5 months ago by spoonr778.
    • This reply was modified 10 years, 5 months ago by spoonr778.
    • This reply was modified 10 years, 5 months ago by spoonr778.
    • This reply was modified 10 years, 5 months ago by spoonr778.
    #6045
    spoonr778
    Member

    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 reply was modified 10 years, 5 months ago by spoonr778.
    • This reply was modified 10 years, 5 months ago by spoonr778.
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