Belt Driven CR-10 Dual Z using a single stepper motor

thingiverse

This is my first try at posting a “thing” on Thingiverse so hopefully this will be useful to some. I have a CR-10 and had ordered the “Dual Z” modification kit which came with a second stepper motor. Before I installed it I heard of instances where the separate steppers could get out of sync. I also had come across several examples that used a belt to drive a second Z instead of a second stepper motor. I liked that idea so I decided to design some parts that would utilize the factory Z screw mount (for the second Z side) but use a belt instead of the second stepper. This is what I came up with. It has been working well for me but I took the time to make sure that both of my Z lead screws were as straight as possible and everything is properly aligned. Anyone is free to download and use these parts for your own use but you use these at your own risk as I take no responsibility for any problems that could happen. Installed correctly, this should work fine for you too. Parts needed in addition to the printed parts: (If not in a hurry, order parts from China.- Much cheaper. Ebay, Aliexpress.com, Banggood.com, Gearbest.com) 1 – 852mm x 6mm closed loop GT2 timing belt https://www.amazon.com/Uxcell-a16031400ux0530-PRINTER-Closure-Circumference/dp/B01ER9GFHG 1 (2nd is optional) - 8mm - 24”/600mm Screw Rod for Z axis https://www.amazon.com/gp/product/B01DXBMGIG 2 - Aluminum GT2 40 Teeth 8mm Bore Timing Belt Pulleys https://www.amazon.com/gp/product/B071W6CHN9 2 - 8x16x5mm Flanged Precision Ball Bearings (or similar) https://www.amazon.com/gp/product/B01A1ALUCA 1 - GT2 20Teeth 5mm Bore Aluminum Timing Belt Idler Pulley https://www.amazon.com/gp/product/B076D2GWZR 2 - GT2 20T 5mm Bore Aluminum Toothless Timing Belt Idler Pulley https://www.amazon.com/gp/product/B076D52NHB 6 - M4 x 10mm Button Head bolts and (optional) washers 4 - M4 x 35mm Hex Head bolts 3 - M5 x 50mm Hex Head bolt 3 - M5 Nylon Lock Nuts and M5 washers 10 - M4 “T” nuts https://www.amazon.com/gp/product/B01D83H10W OPTIONAL (Sliding “T” nuts in place of regular “T” nuts) https://www.amazon.com/50pcs-Aluminum-Extrusion-Profile-Sereis/dp/B01GCDG2RI M3 x 10mm Flat head screws https://www.amazon.com/gp/product/B01DIL1KDS 2 - Black Oxide Steel Shaft Collars, Metric, 8mm Bore, 16mm OD, 8mm Width https://www.amazon.com/gp/product/B0063KWI42 General alignment information for your consideration (not part of the installation instructions): First the lead screw needs to be as straight as possible........I laid mine out on a flat counter top and rolled it. If it rolls smoothly, it is straight. If it wobbles or doesn't even want to roll easily then it needs straightening. If it needs straightening, usually you can roll it until both ends are touching (on a FLAT surface, such as a counter top) and the middle is slightly elevated. Then you need to try to slightly bend the screw rod to eliminate the center portion being high. Keep doing that until it rolls as smoothly as possible. If you screw rod is bent too much and you can't get it rolling smoothly, you may need to get another screw rod. Once you have a straight screw rod the rest is easy. You need the top flange bearing, the X axis brass screw fitting, and the bottom coupler to be in perfect alignment so that as the hot end/extruder is raised from 0 Z to the 400 Z position, there is no binding at all (even with the small screws around the brass fitting tightened). This can be accomplished by loosening up the top black flange bearing guide and then lowering the screw rod down through the brass screw piece (the tiny screws can be loose at this point), and then down to the coupler hole with the X axis resting on some supports about midway up (200mm/7.5 inches high). Move the top flange bearing (with the brass screw piece loose) until the screw rod goes dead center into the top coupler hole without having to force it. Hopefully you don't have to loosen the coupler itself to get this to happen (but you might). Once you have the straight screw rod able to glide into the coupler hole easily, you have everything aligned and you can tighten the coupler (if you had to loosen it to move it slightly), then tighten the small screws in the brass screw guide. Turn on the controller and do the “Auto Home”. Then MANUALLY raise the hot end (by increasing the Z value) until it is all the way at the top (400 Z value) then tighten the top black Z screw flange bearing holder to the cross extrusion. If done right, now the X axis/hot end will be able to move from top to bottom with no binding at all and with those small screws next to the brass screw piece tightened. I know a lot of people think that those screws have to be loose to prevent binding but I can tell you that is not necessarily true, if everything is aligned correctly and the lead screw rod is straight. Dual Z single stepper installation instructions: Before starting, do the “Auto Home”, then manually move the Y axis to 150mm and then the X axis to 150mm (centering over the middle of the bed). Next, raise the X axis up to about midway and place something under the X axis extrusion to support it (under both sides – MUST be the same height) and then lower the X axis so it is close to resting on the supports. Leave the control box power ON for testing after the install. Next you will have to replace your original Z screw rod with a longer one (21.25” to 22”) to allow for adding the 40 tooth pulley at the top that will drive the second Z screw rod with a timing belt. Hopefully you know how to do this but if you don't, here is what you need to do. Loosen the top of the stepper coupling so that the Z screw rod is free to turn without the coupler moving, then manually turn the screw rod until the X axis is resting on the previously placed supports. Unscrew the 2 small screws in the top black Z screw rod guide so that the flange bearing will be free when you remove the bearing cover. Then you will be able to turn the Z screw rod manually (by hand) and remove it from the top. Replace it with a longer Z screw rod. NOTE: I replaced the factory top black Z screw rod guide with one of my own (like what will be on the other side) and I also installed a shaft collar (optional) just under the bottom of the top Z screw rod guide, as insurance against the Z screw rod trying to move vertically. This is optional and was done more for the looks than anything else. Next (for the second Z screw rod mount) you will need to install the black metal Creality factory Z screw rod part that attaches to the X axis extrusion by way of the three “V” wheels. You can find instructions on Youtube. The bottom Z screw rod stabilizer for the second Z screw rod is optional. If you want to utilize your original Z screw rod which is regular length, you can leave the bottom of the second screw rod hanging free. If you get a longer 24” (cut to size needed) Z screw rod, you can utilize the bottom Z screw rod stabilizer if you choose to. It is held in place by “T” nuts and can be placed as needed, just not too high, so that the extruder/hot end can get down to the bed height. I mounted mine about 1/4” from the bottom. If you are going to use a longer 24” Z screw rod for the second Z side you can cut it (but don't have too) so that it fits down into where you placed the bottom Z screw rod stabilizer. I made mine 23”. Remember, you can reuse the original Z screw rod that you took from the other side if you want, but then you won't be able to use the bottom Z screw rod stabilizer. Go ahead and mount the top Z screw rod guide (for the second Z screw rod) using “T” nuts. Leave out the flange bearing and cover for now. NOTE: I used sliding “T” nuts in the place of the regular “T” nuts. If you are going to use the bottom Z screw rod stabilizer part, after you drop the second Z screw rod through the top Z screw rod guide, then a shaft collar, and then the through the brass fitting on the black metal CR-10 factory Z screw rod part, you will need to slide on the bottom Z screw rod stabilizer flange bearing COVER and then install a flange bearing onto the bottom of the second Z screw rod before you guide the Z screw rod into the bottom Z screw rod stabilizer part. NOTE: I had to take some fine sandpaper to the end of the Z screw rod to get the flange bearings to slide onto the screw rod. If needed, sand just enough to slide the flange bearing on. You DO NOT want it loose though. It should be tight enough to stay in place. Tighten flange bearing cover with 2 small screws (similar to the top black factory guide). So now you have the second screw rod going through the top stabilizer/guide, a shaft collar, the brass fitting on the black metal CR-10 factory Z screw rod part, (and if using the bottom guide) the bottom flange bearing cover, a flange bearing, and into the bottom stabilizer/guide. Next, adjust the height of the second screw rod to match the screw rod on the other side (the one with the stepper motor) and install the 2 small flat head screws to secure the bottom flange bearing cover. Next, install the top flange bearing to where it is down inside the top stabilizer/guide and then install the cover. Slide the shaft collar up to the bottom of the top stabilizer/guide and secure. This is just insurance against the Z screw rod trying to move vertically. Hopefully you have a straight Z screw rod and all 3 parts (bottom, middle, and top) are aligned and straight. I visually checked to make sure that the screw rod was in line vertically with the frame. It should not be leaning to the left or right when looking at it from the back of the printer. Now, you are ready to install the 40 tooth pulleys on both Z screw rods and the middle pulley parts and belt. This is fairly simple. Just keep all of the pulleys at the same height so the belt is level. Two M5x50mm long bolts go into the 2 side (left and right) pulley parts, down through the toothless pulleys, then a small 2.5mm spacer, and into the parts. A nylon lock nut and washer goes on the bottom. Tighten until snug, but you want the pulleys to spin freely without binding. Use the other M5x50mm bolt on the center sliding part, installing the toothed pulley in the same manner. NOTE: I used M4 washers on all of the M4 bolts/screws. This is optional. The 2 side parts install to the top cross piece fairly easily using “T” nuts (or sliding “T” nuts). The center sliding part goes between them (of course) but it is a little trickier to install. You have to drop the “T” nut into the channel and then line it up with the top hole (since the sliding part slides onto the top cross piece) and then install the M5x10mm screw (I used washers as well but that is optional). The bottom hole is similar. You have to slide the “T” nut in place after you have the center sliding part in place and the top bolt installed. Patience, you can do it. NOTE: I used SLIDING “T” nuts instead of regular “T” nuts (in many places). I liked that they will always hold the screws/bolts secure, without worrying if they have turned the 90 degrees to hold (like a regular “T” nut needs to). To do this you have to temporarily remove the 2 hex head nuts in the top cross frame on one side. Then you can install(slide in) 5 sliding “T” nuts in the top channel and 1 sliding “T” nut into the bottom channel (of the top cross extrusion/cross piece). Now you can install the 852mm timing belt, slide the 2 side pieces against the center piece and tighten them in place. Slide the center piece out until there is good tension on the belt and tighten the top and bottom screws. Place the 8mm end caps on top of each Z screw rod (if desired). NOTE: Before you install the timing belt, the X axis extrusion should be resting on the 2 supports that you place under it at the beginning. Those supports should be the same height, holding the X axis parallel to the bed (level). Double check everything to see if you forgot to tighten any screws and you should be ready to test the Dual Z – one stepper mod. Remove the 2 supports that you initially place under the X axis. Then manually (using the control box) move the Z axis from the bottom to the top a little at a time making sure that there is no binding. (If it binds, refer to the General alignment information posted earlier.) Then lower it as well. If everything was aligned properly it should move up and down with no problems. Now you can move the X axis back to the top and then use the “Auto Home” to do a final check. (If it binds – it shouldn't – turn off the control box and double check for problems). Congrats! You're done.