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V-slot Z axis on i3 variant

Posted by NinthDimension 
V-slot Z axis on i3 variant
December 02, 2018 01:51PM
I have a Folgertech 2020 i3 that I intend on and already have begun modifying beyond recognition. It is constructed using 2020 T-slot extrusions for the frame and all axes move on smooth rods with belts except the Z-axis which uses a pair of 5mm threaded rod with nuts and top-mounted stepper motors. I am planning on doing V-slot upgrades to both the X and Y axes and I'm considering also upgrading the Z-axis to V-slot. My question is, should I change the Z to V-slot? Whether I do upgrade or not, I intend on replacing the 5mm threaded rod with an 8mm lead screw but the question is whether or not I should replace the 8mm smooth rods on the Z-axis with V-slot rails. If I do switch to a V-slot Z-axis, would a belt driven Z-axis make sense or should I stick with lead screws? Also, if I use lead screws, whether with smooth rods or V-slot, should I mount the steppers on the top or bottom?
Re: V-slot Z axis on i3 variant
December 02, 2018 02:52PM
One issue with belt driven z-axis is it drops on power cut or machine shut down. Ideally you' used braked steppers with the brake releasing with the associated stepper drive enable signal. If left to drop the back voltage geenerated by the steppers could cause issues.
Re: V-slot Z axis on i3 variant
December 02, 2018 04:56PM
Yeah, okay well I just bought a pair of 8mm lead screws with 2mm pitch so belts are now out of the question, I'm still not sure if I should stick with 8mm smooth rods or go with V-slot for the Z-axis though.
Re: V-slot Z axis on i3 variant
December 14, 2018 04:12PM
What is your current print quality? Do you have problems with layer registration? If it ain't broke, don't fix it!

Belts work well, just check out the digital dentist.

If you use screws I highly suggest pairing them to one stepper motor with a belt, not two.

Belts and screws are both very viable, it really depends on the implementation.
Re: V-slot Z axis on i3 variant
December 16, 2018 10:56AM
I use vslot and leadscrews on my corexy build z axis with a single stepper motor and a closed loop belt, and works very well. I used tr8x8 though, i've found they provide plenty of resolution. The layers are very consistent. Minimum layer height is 0.04mm per full step and use layer heights that are a multiple of that number, usually 0.32 or 0.2mm depending on the level of detail required.

Since you'll need 3 vslot wheels you'll probably need longer extrusions. Also make sure you've got the correct type of extrusion, the openbuilds type with slots with 45 degree angles into the slot. There are more common rounded edged ones that won't take vslot wheels. I used a delrin anti backlash nut block. The leadscrew is fixed on one end only to prevent it being overconstrained. The vslot keeps everything locked in the xy direction while being very smooth in the z axis.

Edited 1 time(s). Last edit at 12/16/2018 10:57AM by imqqmi.

Kind regards

NFAN CoreXY printer:
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