First of all, let me introduce myself, as this is my very first post here! I'm an electrical engineer and software engineer from Spain, but I really like all kind of tecnical challenges. My 3D printing adventures began almost 2 years ago, with a Tevo Tarantula (I said I like challenges, didn't I...?). It kind of printed ok-ish after assembly, but it had an awful lot of limitations. As any unexperienced thingiverser out there, I printed all "improvements" I found, sometimes for the better, sometimes... not, but I learned A LOT in the process. Thing is that some months ago I completely redesigned my printer, up to the point it was no longer a Tarantula anymore: I made a sturdy bolted 2020 structure, dual 12mm smooth rod bed support, linear guide X and double linear guide and double leadcrew Z, almost everything bolted metal or metal supported. I've managed to get a very good quality and layer registration up to 0.08mm layer height, so 0.2mm printing is near flawless. But the speed is not so great, moving a heavy bed at more than 60mm/s (and 30mm/s perimeters) shows more ringing that I'd like, and I have to keep acceleration below 1000mm/s. So be it called the "3DEgon 1". Now I'm aiming to an all new config for "3DEgon 2", and CoreXY is the architecture I gravitated to.
The issue I had the hardest time with was Z axis. The original Tarantula had a single leadscrew cantilevered X gantry with wheels on T-Slot, 4 wheels each side. It never worked really good, tried custom 4 and 3 wheeled gantries, more/less tension in the wheels, dual leadscrew, oldham couplers... Nothing worked to get good quality, so for my redisgn I aimed to dual linear guide and holy cow, that thing was a game changer! Once aligned, it was ultra-smooth but also ultra stable and had no play at all. Regarding the motor, my first design was a two-leadscrew with single motor and closed belt. And the problems began. My leadscrews weren't chinese, but from a german store, www.motedis.de, 400mm TR8x1.5, with nuts. I set it up, but the result was not so good: I had some mild Z wobble.
The reason was multiple: the pulleys were not perfectly concentric in the leadscews, one of the leadscrews was slighty bent, the belt was bowing lightly the leadscrews, and the less tension, the less wobbling, but the less tension, the less precission too, so was a no-no. I finally ditched the leadscrews, and bought 2 motors with integrated TR8x2 leadscrews, then connected them in series. It works flawlessly, but now I live with the fear of desync. I can daily print over more than a month without releveling the bed, but I don't feel comfortable with the chance of desyncing. I suppose the it works so well because I have quite a heavy X gantry (dual extruder chimera with extruders mounted in a 2020 gantry) and everytime the power goes of both motors go to the lower fullstep, but who knows...
So, right now, I wonder which approach should be better for my new CoreXY bed motion. I plan it to be 300x300mm size, and I'd really like to keep a single Z motor, and I definitely want to use linear guides (my experience with unsupported smooth rods, even at 12mm, is that I cannot stop them vibrating when the bed moves a large span, and the Y wall texture is not as perfect as X texture). So my first idea is something like 2 linear guides, each one at the middle of bed's left and right sides, and a single 1204 ballscrew in the middle back side. Do u thing it would be stable enough? Should I try a 3 ballscrew setup with a closed belt?
Thank in advance for your thoughts!
The issue I had the hardest time with was Z axis. The original Tarantula had a single leadscrew cantilevered X gantry with wheels on T-Slot, 4 wheels each side. It never worked really good, tried custom 4 and 3 wheeled gantries, more/less tension in the wheels, dual leadscrew, oldham couplers... Nothing worked to get good quality, so for my redisgn I aimed to dual linear guide and holy cow, that thing was a game changer! Once aligned, it was ultra-smooth but also ultra stable and had no play at all. Regarding the motor, my first design was a two-leadscrew with single motor and closed belt. And the problems began. My leadscrews weren't chinese, but from a german store, www.motedis.de, 400mm TR8x1.5, with nuts. I set it up, but the result was not so good: I had some mild Z wobble.
The reason was multiple: the pulleys were not perfectly concentric in the leadscews, one of the leadscrews was slighty bent, the belt was bowing lightly the leadscrews, and the less tension, the less wobbling, but the less tension, the less precission too, so was a no-no. I finally ditched the leadscrews, and bought 2 motors with integrated TR8x2 leadscrews, then connected them in series. It works flawlessly, but now I live with the fear of desync. I can daily print over more than a month without releveling the bed, but I don't feel comfortable with the chance of desyncing. I suppose the it works so well because I have quite a heavy X gantry (dual extruder chimera with extruders mounted in a 2020 gantry) and everytime the power goes of both motors go to the lower fullstep, but who knows...
So, right now, I wonder which approach should be better for my new CoreXY bed motion. I plan it to be 300x300mm size, and I'd really like to keep a single Z motor, and I definitely want to use linear guides (my experience with unsupported smooth rods, even at 12mm, is that I cannot stop them vibrating when the bed moves a large span, and the Y wall texture is not as perfect as X texture). So my first idea is something like 2 linear guides, each one at the middle of bed's left and right sides, and a single 1204 ballscrew in the middle back side. Do u thing it would be stable enough? Should I try a 3 ballscrew setup with a closed belt?
Thank in advance for your thoughts!