The CR10 has a single Z axis leadscrew and I have no issue with this it really produces superb prints. From an engineering point of view a better idea would be to have a leadscrew at both ends. There is an upgrade kit available which uses a second stepper motor but I understand these can get out of sync when power is switched off and on and the bed must be re leveled every time.
My solution links the screws with a toothed belt and is driven by the existing single stepper. It cannot get out of sync.
All the parts cost less that £12.00 ( US $16.00) including delivery!
There is a bit of metalwork involved but you only need a saw. file and drill. If you really cannot do metalwork I have designed a printed bracket with the same dimensions. Be warned though this has not been tried out but it should be OK.
Parts needed include
600mm leadscrew and nut https://goo.gl/fM8znL
GT2 Aluminum timing belt pulley 36 teeth 8mm bore ( 2 required)
http://bit.ly/2DXpmch
GT2 852mm Timing Belt: https://goo.gl/iXa4sv ( be sure to get the correct length)
Flexible Shaft Coupling: https://goo.gl/qfUhEe
Bearings: https://goo.gl/HnzTqr
You also need
2 x M5 x 16 screws and Tee nuts.
2 x M3 x 16 screws and nuts.
A few washers.
2mm sheet metal for the bracket if not using the printed one.
Creality 3D printer: https://goo.gl/wXrkMi
Discount code 20%off for CR -10 3D printer: bg3dprinter
3D printer special page: https://goo.gl/xEdxVB (15%off coupon: bgprinter)
STL files https://www.thingiverse.com/thing:2569379
Video https://youtu.be/-ASBhJiU8NI
The existing leadscrew is replaced by a longer one so that a toothed pulley can be mounted above the printer frame.
The existing leadscrew is reused on the other side and a bracket added to connect the leadscrew nut to the right of the gantry.
The top bearing for the existing leadscrew is replaced by a new printed one. The ball bearing in this can be adjusted to line up with the screw and then locked in place.
A similar bearing block is printed to go on the right hand side.
The position of the leadscrew nut is also adjustable and is locked in place when everything has been aligned.
Print out the parts required.
The bracket is made to the dimensions shown below.
The 3 holes at the top are best marked from the printer itself as described later.
If you would like a full size copy of the plan send me an email.
Installation
It's worth checking if the Z stepper motor is correctly lined up with the leadscrew.
I found mine was not so I cut 2 strips from a plastic Clover spread container, punched 2 holes for the screws and fitted it between the yellow motor mount and the printer vertical frame. Now it lines up perfectly.
Undue the 2 screws securing the leadscrew to the flexible couple and remove it from the printer.
Shorten the new leadscrew to 535mm and screw it through the leadscrew nut and connect it to the flexible coupler on the stepper.
Assemble the new LH bearing block. The existing flanged ball bearing is reused and 2 nuts and screws hold the retaining plate in place. Move the Z axis fully to the top and fit the new block. The bearing can be adjusted so it lines up with the leadscrew by sliding it left and right along the frame and the moving the bearing in the block front to back. It is then locked in place with the 2 screws. Fit a pulley to the protruding leadscrew.
Fit the RH bearing block loosely in place and put the bit of leadscrew that was cut off into the bearings with a toothed pulley attached to it. With the belt fitted on the pulleys tension the RH block and tighten the fixing screws.
Fit the new bracket to the gantry with a washer over the wheel stud so that only the centre part of the ball bearing is clamped to the bracket. Check it is square to the frame and tighten up. At this stage the 3 holes in the bracket have not been drilled. Remove the belt and pulleys and using an 8mm drill through the bearing mark the hole position. See video.
Remove the bracket, drill the holes, paint and refit , this time with the nut and printed parts loosely fitted.
Fit the new leadscrew with a pulley on top and a flexible coupling, which is acting as a collar below the block. A washer is used on each side of the bearing. Also fit the belt.
With the gantry in the top position tighten the screws on the bracket printed parts to lock the nut in place.
Installation is complete.
Adjusting the axis
If you have a digital caliper this can be used to set each side to the same height. As the travel will always be up when making a print make sure the gantry is moved in the up direction before taking measurements. It's easy to move the Z axis now, just pull on the belt.
Measurements are taken from the extrusion the print head runs on (X ) to the printer frame front to back extrusions.
Start with a distance of about 125mm. Take an exact measurment from the stepper motor side and compare it with the other side.
If the dimensions differ slacken the screws on the right hand pulley and hold the pulley still whilst rotating the leadscrew to move the axis up or down as required and then tighten it up again. Check again by lowering the gantry and then raising it again.
If you have no caliper, use a length of rod, plastic metal or wood as a gauge to check the sides are equal.
All that's left to do now is to re level the bed and the job is complete.
