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Discussion in '3D printers' started by CoreCube3D, Jan 4, 2019.
Discussion in '3D printers' started by CoreCube3D, Jan 4, 2019.
Building a CoreXY based 3D printer using primarily parts from China on eBay. Large 500mm frame.
CoreCube3D published a new build:
Read more about this build...
Great idea adding the microfit 3.0 terminals into the v connect head!
I have this mounted on the X axis now and will give it a first test tomorrow. It looks like it will work pretty well. I spent yesterday wiring up all the connections. I have 2 x 6pin micro-fit, one for each head in a dual head config. And also have a 2500mW laser head ready to go (only uses one connector). I hope to test that within a day or two. I have some photos I'll upload in a few minutes.
I'll upload the design files on thingiverse.com (user: neocogent) after I've had a chance to test them and make final fixes.
What is the size of the print surface (Usable)?
I think I have it set for 360x372x360mm right now. It may be possible to squeeze slightly more out of it. I had to reduce it a bit when I set it up for the dual extruder heads. So actually both heads cannot reach that full area. I've never tried using the full space yet.
The problem isn't really making the machine bigger as the t-slot bars are cheap enough but the build times get ridiculous. Even doing a modest sized build can get into multiple days and I think trying to print something as big as this machine could handle may take weeks. However, it is useful for long thin parts without large volumes. I made it big because I wanted to print some struts that wouldn't fit on a smaller 200mm bed.
ever since I saw a 3D printed violin, I have wanted to build a larger printer than my RepRap one and have been studying builds on here. As my knowledge grew, I thought of extras that I wanted such as a easily exchangable head for different nozzle sizes (changing the whole head quickly rather than faffing with unscrewing the nozzle), which also led to thinking about engraving and routing heads. My downfall is that I have concentration problems and cannot get my head around CAD software. Your Build is practically exactly what I have envisioned in my head but have failed to achieve. You are a beauty! I may have to pinch the plans and save up to make one! Well done mate
Thanks for your comment.
A number of things I'm still fine tuning but once I get there I'll upload files for printing parts. I think the total parts cost ran between $400-500 Australian dollars. That was only possible because most of the stuff came from China. Local prices are generally at least double for same items.
I've been swapping between the dual head and laser daily lately. It's quick and works but I have some connection issues and I'd like to reprint the head-connector part to get a better fit. It's been running around the clock the last week as I'm currently printing all the parts for a Root 3 CNC machine.It has about a dozen 8 hour prints plus many shorter ones. I'm happy with the parts it's making though. I'll probably post the CNC machine on here later when it's running.
BTW I've been using Blender (free open source) for creating things and editing parts I find. It's not quite as technical as CAD software but it still has a steep learning curve due to many tools for modelling. Just about everything I know about using it has been found by googling what I want to do.
Ta for that, I shall download it and have a go, I have onlybeen able to create very basic models using TinkerCAD so far and it was the main chassis I couldn't work out how to design as every time I moved one of the struts it would split into its component lines and only shift one of them.
There's a bunch of fairly decent Blender for 3D printing tutorials on youtube. That helps with setting up a good initial workspace as it can be used for different purposes like animation an video as well. I find the actual controls non-intuitive for me but once I got the hang of the weird way of doing things it becomes second nature and only a problem if I haven't used it for months. After that and some basics I just found I could google some question like "blender cut hole in block" etc. and find usable tutorials.
I really like this design and am particularly interested in what you did with the Z axis. Can you please post some more photos or maybe a video that pans around the whole thing? If you made a CAD model for it, that would be great too. I have a Frankenprinter in progress that started life as an Acro 1010 and is now an Acro mounted inside a giant Core, but the Z is going to be big and heavy and I wasn't sure how to do it. It looks like you may have solved that.
I'll try to post more photos soon and hope that helps. This was my second attempt at Z axis and I have some ideas for changes still. It works quite well - better than the first, which I copied from another design here. The first I cut and drilled aluminum L and box sections to make a platform and raised it with a linear rail at back. I found it resonated too much during some print patterns (fast fills back and forth) and also had a stutter in the Z direction that caused ridges in the print.
So I redesigned with a second attempt. I saw one other design which used wheels on the Z axis but they had separate Z rails and wheels on opposite sides of rail (like X and Y axis). That looked like it would still have resonance issues. So I had a go at putting wheels on the frame as then it's supported and dampened at all four corners. This design is very straight forward and works well. The only slightly tricky part is making a long belt loop. I tried my best at hacking something and it seems to work. I cut one end's teeth off to make a thin flat section. Then I trimmed off some backing on the other end to match and sewed (with a needle by hand) between the teeth to join the two layers. That worked well but I'm still suspicious of the slight thickness change causing a bump in each full loop pass. That would be about 7cm Z height but I have not yet noticed any effect. I don't print that high very often anyway.
The eccentric spacers on the wheels give enough adjustment to get them snug against frame. The only real thing here is you need to get the frame as square and parallel as possible. I had no problem with that as the T-slot pieces were all very close in length, keeping them equidistant, and I had already made the frame as square as I could.
Changes I may make are to print the corner brackets rather than use aluminum. Originally I printed in PETG (on hand and wanting to use up) but found it very flexible and they twisted too easily - not good. So I had aluminum on hand and hacked up some pieces to test. Much better rigidity. I think possibly a thicker PLA corner may work and would be easier for future builds. The corners attach to a sub-frame made of 5 T-slot pieces (in my case 2x500, 2x450, 1x400) and I don't think I even had to cut them, though I may be forgetting now. I also may reprint the Z-axis bearing holders to be only attached to frame rather than resting on table. I don't think the current design is good if you want to move the printer as they go unsupported (hang). It should be feasible to make a rigid side support piece instead.
My original intent was for the sub-frame to be on one level but I found the bed was too low to place well with the head. Seems my calcs and measuring were off. So I raised the cross bars to sit on top the side ones. It doesn't need to be like that. Anyway that works fine.
The lead screws are 8mm dia. 2mm pitch, 2mm lead but I guess others will work too. For the weight of the frame being moved I think the lower 2mm lead needs less torque (though is less efficient overall). Many lead screws have 8mm lead (more rise per turn) and may require a Nema23 motor. Not sure. I ended up using 20 tooth main pulley and 16 tooth on each axis. In that case you have to allow for difference in calculating steps per mm when putting values into firmware. It'd be easier to use same teeth on all pulleys. The motor can be moved along frame to tension the belt. For assembly, try to get both axis adjusted so platform is level and then slip belt on (motor one last), then tension up.
If you want some blender design files for the various pieces I can post an archive here. Actually some parts aren't that great and I'll most likely improve them at some point. Maybe they can be a starting point.
Most the these parts were bought at Banggood.com. Their prices for t-slot were best I could find.
Photos being uploaded now are of PETG parts. I'd recommend using PLA instead and maybe even heat annealing (have to adjust sizes first to allow for shrinkage). You can see wobble in my parts from the original Z-axis stutter. That is completely gone on this new Z-axis.