Railcore II ZLT Stepper motors - advice please
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In the BOM it lists these Stepper motors.
https://www.omc-stepperonline.com/nema-17-bipolar-09deg-44ncm-623ozin-168a-28v-42x42x47mm-4-wires-17hm19-1684s.html?search=17HM19-1684S
for the X, Y and Z but also in the BOM it notes this - 'XYZ steppers (A decent torque 1.8 can be substitued for the Z)
I presume it means 1.8deg step angle.
Would this be suitable for the Z axis?
https://www.omc-stepperonline.com/nema-17-stepper-motor/nema-17-bipolar-59ncm-84ozin-2a-42x48mm-4wires-w-1m-cable-and-connector-17hs19-2004s1.html?mfp=149-step-angle[1.8]%2C184-frame-size-mm[42x42]%2C183-body-length-mm[48]%2C71-single-shaft-dual-shaft[Single Shaft]%2C148-bipolar-unipolar[Bipolar]%2C24-no-of-lead[4]Thank you. Paul.
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I don't know the Railcore, but that motor looks OK to me.
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Bear in mind that if 1.8deg steppers are used for Z, I believe the leadscrew pitch will need to be changed as well, to achieve the correct stepping. I don't know the exact pitch to use, but a web search should get you the answer. Perhaps @kraegar or @jstevewhite (co-developers of the RailCore) will jump in with the correct value.
I do know the BOM uses a particular 0.9deg & leadscrew pairing, while the ProjectR3D kit uses 1.8deg steppers with a different leadscrew pitch to achieve the same 0.01 stepping.
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the blv cube build (https://www.thingiverse.com/thing:3382718)for example recommends the 2A motors from omc
https://www.omc-stepperonline.com/nema-17-bipolar-09deg-46ncm-651ozin-2a-28v-42x42x48mm-4-wires-17hm19-2004s.html/?tracking=5c7cdef6c9645and these for z (same ones you found)
https://www.omc-stepperonline.com/nema-17-bipolar-59ncm-84ozin-2a-42x48mm-4wires-w-1m-cable-and-connector-17hs19-2004s1.html/?tracking=5c7cdef6c9645 -
For 0.01mm full step layer height ( "Magic Number" ) you need either 0.9º steppers with 4mm lead (2-start T8) leadscrew or 1.8º steppers with 2mm lead (1 start T8). That said, 0.9º steppers work fine with 2-start T8; you get lower vertical speed but a full step height of 0.005mm. You can find this information here:
https://railcore.github.io/hardware/leadscrews.html
As far as motors go, the Z axis is heavily reduced (in the sense of mechanical advantage), so torque is almost irrelevant. If you need high jerk or accel on Z - like if you want high speed moves on Z in the case of a ZLT - you'll want beefier motors. But be careful; a failed probe can break stuff!
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Thanks all.
I have ordered TR8*2's from RepRap World as it is the only place I can seem to find them on this side of the world and the brass anti backlash nuts. It then matches the BOM apart from the Delrin bit.
Did not fancy paying $50 just for shipping from the states!.@jstevewhite TR8*8's were all I could find in the UK and I did not understand all of the numbers, how much one thread pitch could vary and what it would affect in regards to quality etc.
Even reading the link people had posted here and in the FB forum to the Leadscrew page I was lost as there were to many decisions, for me!So to recap, I now know I am going to need 2 x 0.9 for the X and Y and 3 x 1.8 for the Z's
as I do not need 0.005 resolution!
Thank you all again, it is appreciated.Paul.
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Note that with TR8*8 screws, your "magic number" (Full step height) will be 0.02. All this means is that for best print quality, your layer height should be a multiple of 0.02. So rather than printing at 0.15, you'll want to do 0.16 or 0.14 instead.
I ran the original non-ZL RailCore 2 with this configuration for quite some time (until December of last year) and was quite happy with the prints.
Just remember you'll need to change the configuration for Z steps per mm from the default.
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@jstevewhite Thank you for the extra info. I remember CHEP doing a youtube about magic numbers for Ender3. 0.04 they were.
So with a 0.01 is better I presume, as everything is divisable with it.Thanks again.
