The Z-rails at the back look good, that's what I would do in this configuration as well. The outer Z bracket dimensions also look good, enough to compensate for slight rail miss-alignment but still stiff enough. What print speeds are you aiming for? If it isn't super fast, the moving mass of the XY is more of a red hearing if your linear guides are stiff enough.by gmedlicott - General
Flanged bearings work better than (cheap) pre-made idlers but not because the bearings are better quality. The idlers have the two bearings pressed in with the outer races contacting the idler, but the inner races free. When you tighten the bearing axially, the inner races load up and make it hard to turn. Flanged bearings can be stacked with a small washer in between (contacting inner races),by gmedlicott - Mechanics
Looking good! The 2 rail, 3 lead-screw Z axis is a popular arrangement that seams to work well (still over-constrained in multiple directions, but the Z should travel and build plate should always be perpendicular, so less of a concern). I like the maglev 2020 X axis! When you do mount it to the rails, use plastic (3d printed or machined) to take up the slight possible Y axes out of parallelby gmedlicott - General
QuoteMKSA Quotegmedlicott The printed parts are very rigid, and are designed so the bearings have a light pre-load. It takes an accurate printer, and measuring the extrusion dimension to make it work. . They don't look rigid at all and in fact luckily they are not as the whole set up would have the bearings eat in the Al extrusion or bind. The X, Y connecting part is particularly flimsy. Thby gmedlicott - Extruded Aluminum Frames
Quotethe_digital_dentist If I were contemplating enough production to justify a printer farm, I don't think I would rely on bearings held in printed plastic mounts. I think I'd end up spending more time repairing the machines than printing. Would it really be difficult to make the part from a drilled piece of metal? Having come from a background of designing parts for CNC machining, plastic (pby gmedlicott - Extruded Aluminum Frames
QuoteFA-MAS Those steel bearings are going to start eating away at the softer aluminum they’re riding on. Another concern I'm looking into, though the bearings in this setup have a light preload (20N maybe for the X&Y, 50N for the Z) and have purely rolling motion vs rolling-sliding as found in V-wheels. Also aluminum extrusion is anodized which increases hardness. Even so, I'm working onby gmedlicott - Extruded Aluminum Frames
Quoteo_lampe How do you adjust the bearing clearance? Using eccentric screw posts or do you add some tensioners in the brackets? The printed parts are very rigid, and are designed so the bearings have a light pre-load. It takes an accurate printer, and measuring the extrusion dimension to make it work. Quoteo_lampe Most people would be afraid of the noise coming from naked bearings on extrusioby gmedlicott - Extruded Aluminum Frames
A while back I designed a printer that was to be the base for a printer farm after trying to use a upgraded Folger FT5 for that purpose. The printer is designed to be easily extendable in the X (or Y) dimension. It uses 623zz bearings that ride on the extrusions for all motion constrain. I finally wrote up a blog post here: https://www.tolen3d.com/blog/designing-a-printer-farm-unit I'm in thby gmedlicott - Extruded Aluminum Frames
Quotethe_digital_dentist I came up with the kinematic mount because the bed gets hot and the carriage plate, on which the levelers mount, does not. That means that when the plate heats up it pushes the levelers sideways which makes things (usually the carriage plate) bend. The kinematic mount allows the bed plate to expand without creating any bending forces. The plate can expand in X or Y atby gmedlicott - Extruded Aluminum Frames
QuotecharlieRC I am building this printer... I will check out the cast/tooling plate. If you're building a printer and want to use a rigid 1/4 bed, a printer with the bed only traveling in the Z is the better option I think. For Prusa style printers with a bed moving laterally, bed weight should be light as you mentioned. A 1/4 aluminum bed on a 1/8 mounting sheet is close to 2.5kg which is aby gmedlicott - Extruded Aluminum Frames
Hi o_lampe, Can you post more pictures of the contact between the outermost bed end and the uprights of your parallel bar method. Is the bed contacting the uprights with a slightly compliant joint (i.e. printed) to stop radial movement about the singular linear rail?by gmedlicott - CoreXY Machines
Nice job on the write-up, it reads like a book! That is a unique printed carriage design for the extrusions. One thing that caught my eye, It looks like the lever arm for the belt connection is fairly far away from the rail (15mm or so)? Given the friction of sliding parts, I would do everything I could to try to minimize the belt to rail distance. This will help with lowering friction, asby gmedlicott - Delta Machines
I've used a couple of the TE (Tyco or Potter & Brumfield) SSRT-240D25 relays, good for 25A. They can be had used or NOS on ebay for $10-$15 (I think I paid $15 for two). I would only trust genuine name brand stuff for high current applications.by gmedlicott - Reprappers
What firmware are you using? There is a Z-offset height for homing that you can adjust to clear taller clamps.by gmedlicott - General
Nice! I've been following your blog for a while now, I like the novel ideas, especially the max flow using a diamond hot end with simultaneous filament feed.by gmedlicott - Developers
Thanks for the handy spreadsheet DC42! For the belt section, while textbook correct for a two spring + mass arrangement, I think in practice you can only use the belt doing the pulling to determine resonance frequency. Reasoning being our 3d printers have belts that have very little tension to the point of having slack, so when one belt applies force in the opposite direction of travel the beby gmedlicott - Mechanics
QuoteBlisk What is my major concerne is that movable parts have almost none tolerance, of shaking and vibrating. Are you concerned with frame/bracket stiffness, or linear slide stiffness? For Z-axis frame stiffness, supports are an easy solution: Z-Braces Re-designed brackets could easily be made stiffer as well.by gmedlicott - Mechanics
I've bought a 1000mm+ closed belt from Amazon vendor '2GT Timing Belt Closed Loop', BEMONOC branded. The largest they list is 1524mm in both 6mm and 9mm. They have a wide selection in the 900-1000 range, maybe two belts would work? Also, the Amazon vendor 'FidgetFidget' has a dropdown list of all the common sizes of belts, looks like 1524mm is the max.by gmedlicott - CoreXY Machines
E3D swears by the Gates name brand belts for their tool-changer printer. Gates GT2 vs GT3 Anyone have any experience with GT3 2mm belts (Gates or other)?by gmedlicott - General
I have the Bondtech QR extruder that was running a bowden setup, but i'm switching to the arrangement you have here. It will work, it is just heavy. The extruder housing has a grove for the E3D heat-sink. I can send you the Fusion 360 file for the model I made (I might have a Solidworks file as well), or a STEP file if your using a different CAD program (if interested PM me your email addresby gmedlicott - General
If the cable is slipping on the rubber shaft, you could increase the rubber diameter for more cable wrap length (2x?). The shaft as shown is pretty small in diameter, smaller than a 12T GT2 pulley it looks like. At the risk of making it over complicated, you could add a second set of idlers at the corners and replicate the setup for double the cable wrap. That could possibly be less conducivby gmedlicott - Extruded Aluminum Frames
I'll write a blog post for my DIY printer, and and post on this forum as well once done. So much to do, so little time. 10mm belts with higher tension might help with ringing. How long are your longest unsupported belt runs?by gmedlicott - CoreXY Machines
Is the nozzle placed far from the linear rail on purpose (for counter-balancing the extruder)? I'm always fretting about reducing the lever arm/distance from the nozzle to the rail to try to reduce high acceleration artifacts, though your video of 200mm/s speed looks impressive for a large machine.by gmedlicott - CoreXY Machines
QuoteEd3D My fear exactly - would two central rails (like in the images) work ok? Im concerned about the bed tilting either way! Is thermal expansion a major concern though? I will be printing mostly PLA and not in an enclosure! Like The Digital Dentist mentioned, one linear rail per side can be sufficient. If you're using one lead-screw per side as well and are concerned about end table flex,by gmedlicott - General
Nice design! Looks like many hours of milling there. My DIY printer is somewhat similar with the two 20x80mm upright supports. I found i needed diagonal cross-braces on the exterior of the frame when printing at higher speed to keep frame flex at bay. Your test print looks good, so maybe you're alright there. Quoteimqqmi Overall the bed is now within 0.15mm level. It's hardly ideal but it'by gmedlicott - CoreXY Machines
Interesting indeed. What material is on the shaft for friction grip? It looks like the pulleys are different heights, any issues with the cable touching and rotating? And what cable are you using? Sorry, a unique design spawns many questions!by gmedlicott - Extruded Aluminum Frames
77slevin, How do you like the Lokbuild print surface? Have your tried Buildtak or PEI prior?by gmedlicott - Prusa i3 and variants
Nice bracket designs! What material are you printing them from, plain PLA? Quoteo_lampe Also the brackets for the idlers look like they could suffer from layer separation one day. Is there a chance to change print orentation? I second O_lampe's comment on the layer separation. They would be strongest if printed in the orientation they are mounted. You would also get a tighter tolerance holeby gmedlicott - CoreXY Machines
QuoteBjoern The Lead screw are 8mm diameter, 2mm pitch, 8 start , which gives a lead of 16mm. 8 start, nice, they do look really aggressive, and geared up, sounds like the X-Y could move quite quickly in theory. What travel speed are you printing at? And what problems do you notice, ringing from mass/backlash or other? QuoteBjoern About the Z axis, i was actually in doubt if this design wouldby gmedlicott - Reprappers
Great unique printer! I have a friend who is very keen on an all lead-screw printer; i'll point him here. Are the X-Y lead screws 4-turn? My DIY printer has a very similar Z-axis arrangement including bed mounting (with two extrusions along the center plane and two lead screws). Looking forward to more updates.by gmedlicott - Reprappers