yea ive been considering it, but it would require a large change plus i already had the 2 lead screws to begin with so i wanted to make it work.

this brings another question to my mind though, with the 2 lead screw setup, thats 2 screws but also 2 motors
with 3+ screws, i have to back it down to 1 motor. is that going to actually change the load capacity? even though im adding another screw, im still subtracting a motor.

that being said, how often to the two motor setups get out of sync? could i go 4 lead screws and have 2 motors that drive two screws each?

side note, your 3 screw setup elmo, is amazing. and its absolutely my reference point for that kind of thing

 

I think you have my build confused with another one. I have a 2 screw/1 motor setup. Adamcook seems like the goto guy for the 3 screw setup. He did a build based on that... Triple C-Bot | OpenBuilds

 

oh youre right, i was actually referring to your build, but the 3 pulleys, for some reason in my mind, got confused for 3 screws. I definitely have images of your build in my mind when i think about how to setup multiple screws on a single motor. elegant tensioning is elegant.

 

Thanks, but I can't take all the credit. Mine is based on what several other people had done in here.

But be careful about modeling after my printer. It is cursed. Every time I get it working and do a long print, something breaks. It's a running joke at work. The day after I say it's working, the next day they ask what broke.

 

a while back in this someone mentioned running a belt between 2 motors wired to the same stepper, couldn't you use a similar set up with 3 screws and 2 motors? run the one belt across the two motors and around the last screw, it should help to keep everything synced together from what the earlier posts said, you'd just lose a bit of usable space from the addition of the pulleys on top of the couplers

 

If you look at the kit that I linked you'll see it's a bit more.... brutal. It's meant to be chucked in a drill.

 

Sorry I forgot to reply! The GT2-40 gear is held on to the lead screw by the set screw in the gear itself. The fit of the gear on the lead screw is incredibly tight. I actually put the lead screw in a drill and ran it on a sanding block for a little bit to lightly shave it down so I could get the gear on at all / into the bearing. The bearing just sits in the mount from the weight of the system, then I have a precision shim, then the GT2-40 gear and the lead screw just slide into the whole thing.


When you do this, don't be a dummy like me. Make sure your lead screw only comes up as high as it needs to / flush with the build plate. Mine comes up high enough that if the extruder is at the X=0 position, the fan shroud can ram into the leadscrew, so I have my X axis endstop about 10mm in to prevent that. The easiest way to do this is to just insert the leadscrews far enough through the gear / bearing so that it is the proper height and you won't have to cut the leadscrews.


EDIT: It appears imgur's thumbnailing has gotten wonky so medium thumbnails instead!

 

Here's the EAGLE 6.6 file, along with a text BOM file, OpenSCAD source, and compiled firmware hex file. You'll need to print out one of the supports and attach it to your hotend then measure and update the overall length of the mount to suit your hotend height. Mine is slightly longer than most because the trauma it has endured has made it so that it doesn't thread all the way into the heatsink any more. There's also some additional information in the BOM file where to get the source code and some further reading on the operation.

 

hey quick question, do you have those mount files that i could snag and print?
and also, what model/size bearings are you using for this? they look like flanged bearings, is that working out better for you than standard ones?

and would you instead recommend these?
http://www.amazon.com/Inner-Mounted...d=1460477741&sr=1-3&keywords=8mm+bore+bearing

 

Just a general question so, it doesn't require a precise answer: I'm in the midst of my build but am waiting on my order for GT2 belt, otherwise I'd just see for myself but, how much is this puppy gonna shake? lol
I entered 320x350x500 into the build calc and had those lengths cut. Although not belted yet, the XY gantry system is assembled and I've noticed that it has a fair bit of moving mass. I went with the direct drive extruder option and chose a Nema17 that was a bit lighter (300g) than the rest of them. I'm just wondering if this thing is going to dance off the table the first time it does some infill! lol

Experiences? Videos? Suggestions?

 

Oh yes they are flanged bearings, F608Z. I wouldn't recommend pillow blocks, they're not designed to rotate axially. Well I guess 608 bearings aren't made to resist lateral force either, but it isn't like we're moving them all that much. I remixed that mount from Carl's mount, which he remixed into a much sexier looking version that I would use if I were doing it again.

STL and 123dx attached.

 

My experience is that as a unit its pretty stable, however with direct drive and the rear mounted lead screws the front of the bed easily shakes ~1mm when the gantry really gets going, I think this is a weakness in the way the bed is attached to the z-gantry with just those 4 x 90degree mounts. I ordered some aluminum ones from OpenBuilds to play with, and I am considering going to Bowden until my Flex3Drive shows up in the next couple weeks.

 

If you're referring to the mounts I think you are, then I might try that. I'd ordered a dozen or so cast corners for the rest of the frame but was unable to used them as I needed low profile M5s because the socket cap ones wouldn't fit. Since then, I have a few of the low profile ones on my belt order as well.
I chose to use an offset dual screw design. I haven't gotten that far yet in assembly so my photo doesn't show that.

 

I started with offset but was having some issues with my z-axis sliders (too much play) that I attempted to resolve by going to the rear mount. I may or may not go back to offset or front/back depending on how well these brackets work. The brackets I am referring to are the ones connecting the bed support rails to the z-axis gantry

 

holy cow i just had a thought! skateboard bearings have an 8mm bore and [being of the youth i was] i have a ton of those laying around, even extremely high strength ceramic ones which are sure to be (at least marginally) stronger than regular shielded bearings! awesome!

 

Awesome, much appreciated. It looks like a fun project!.

 

These are the ones I printed off (reworked STLs)

 

Honestly they are probably still a BIT weak. I would say the best bet for these would be something that has a vertical component that braces against the z-axis gantry (Somewhat like the stepper motor mounts do on the frame) with triangles etc.., not sure you would even need the bottom piece then. Also it could be that using a bowden setup or a lighter stepper motor would be sufficient too.

 

Awsome! thanks for the detailed explanation.

I was just worrying that the weight of the entire z platform might be a little stressing for the 4 set screws, since it is pushing downwards and it might slips over time. But again the sanding idea sounds great as it provides holding, i shall give it a try Thanks!!

 

It seems like with a few mods you could extend the bed and add a second Z bar that would go in the front.. Then maybe shorten the sides such that the lead screws could be mounted directly to the side extrusions. I imagine that would solve a lot of the weight distribution problems..

 

I'm not sure what you're hoping to see in a video, but I made a video of my 300x300x300 C-Bot printing with a direct drive extruder with a lighter NEMA 17 motor as well. In the video it is printing at 60mm/s perimeter, 75mm/s infill. I do have the nice rubber feet on the bottom like Carl has as well.


@Carl Feniak: to answer your earlier question, there doesn't appear to be any rounding of corners that I can see, although I use a 0.6mm nozzle so my corners aren't exactly sharp as a tack to begin with. I was going to say that the idea was terrible because my last prints were ruined, but turns out when I reassembled the frame I apparently torqued it so my diagonals were 670mm and 676mm. +/-3mm and none of my parts fit together any more! I loosened everything up, straightened it, and retightened this morning and it's working perfectly again now.

You might notice in the video that the fan in everyone's favorite standard 12V 30A power supply is MUCH louder than the printer itself now.

 

That's great CapnBry! Thank you for doing that. Gives me a good idea of what to expect. For some reason I just had it in my mind that it would be something different like watching my Kossel do honeycomb infill at high speed. I was getting concerned ... lol
Belts arrived today. Now just waiting on endstops (i have some regular ones but nothing with a switch soldered to a mini board) but it seems that my heatbed and volcano are being held up in Canadian Customs .... not fun. I'm excited about this build so it's hard to be patient. I did pick up some feet for mine too; just the vinyl springy ones with the hole through them from Home Depot. They might be a bit too springy so we'll have to see. I'll post a pic when the frame is assembled.

 

Motion on the XY axis! :-D
Yay!

Just a few movements here and there. That's about all I could to as I have no endstops in place. Z slider is in place but the beams are not as I've run out of t-nuts. Lol

26332721732_16c11f2362_k by wackocrash5150 posted Apr 14, 2016 at 9:07 AM

** forgive the background mess. We're remodeling our kitchen and the shop seems to be a dumping ground for everything.

 

Hi All,
I have been following this forum for a while and would like to thank Carl and the rest of you for an inspiringbuild.
here's my variant:
It is not quite finished yet, there are still things I'm going to try out but it prints well

And single lead screw and reverse x axis (move the hotend to the backside of the x axis, to move the bed back)

C-bot/D-bot by Carlsen

 

Hey for those of you who, like me, bought a Keenovo silicone heater thinking they were ideal, keep an eye out for smoke! I was firing up the printer this morning and cleaning off the build plate when I thought I saw a wisp of smoke catch my eye. For a moment I assumed it was just my bleary morning eyes playing tricks but another wisp floated across the build plate and into the LED lights. It seemed to be coming from under the build plate where a small light brown patch had developed in the heater so I busted out the FLIR and here is what I saw


I let it cool down and fired it up again to get some better pictures. The spot in question seems to have all of its heating strips in place, I expected to see a short, and it lags behind the temperature of the rest of the pad, then overtakes it as the build plate reaches temperature (heating to 100C)




Supposedly Keenovo has a 12 month warranty on their products for defects in workmanship so I am going to email them, but I don't have much confidence that they'll do anything about it.

EDIT: Ah! It makes perfect sense. The adhesive on the back is failing so at that point there is an air bubble which prevents the heater from transferring its heat to the aluminum plate and therefore overheats / cools quickly. Welp at least the heater is still good?

EDIT2: I think we can see what the problem is here! I'm not sure if this developed an air bubble or always had it. I am 99% certain it was perfect when I installed it. Clearly it has NO gription now. The scorched area isn't even slightly tacky to the touch.