I'll post some pics tonight when I get home. In running multiple G29 commands the numbers are up to 0.1mm different. It could be the inductive sensor that is not being consistent. I have ran with out bed leveling but still see inconsistencies.

 

I'm curious how @CapnBry is getting prints to turn out with that same setup.

Manual leveling on the cbot works great because the xy gantry is so stable in z, no need for leveling sensors.

I'm curious if your Z motor has fine enough resolution, maybe its settling in between two incremental angles

 

Might be worthwhile to check for skipped steps as well.

FYI - I run a 300x300mm cantilevered sandwiched bed with a 6mm aluminum slab on top, then heater, silicon insulator, 12mm of cork and 6mm of plywood on bottom. That all sits on lead screws front and back each with a stepper. I believe @AKEric inspired this setup. Overkill perhaps but I'm running over 630mm in the vertical so prints could get heavy. In my testing I've had great success with this setup and when motors are powered down, a slight touch starts the z axis moving downwards. The front / back screws also result in zero deflection which I really like.

 

Here are some pictures of the monster...




Note - The wheel is in the groove. Just the way the picture came out makes it look like it is not.

 

The cable management looks great! Nice looking printer.... I need to step up my game.

Would the mid point for the two lead screws from front to back lead to a pivot point? I would think the back would have a tiny amount of slop regardless of how tight it was. Couple that with a pivot point and the leverage of the bed itself and I think you will always have deflection? Eg; pushing on the front edge lifts the back because of the mid point mount of the screws?

 

Thanks. I am kind of proud about the wiring. Given most wiring I do is a mess.

I'm not quite sure what you are referring to. I'm thinking something about there will still be some torque around the lead screw connection point. I am expecting that, but sometimes feel there is just too much much deflection. I'm probably being overly sensitive about it. Used to the bed on my Printrbot Simple Metal being rock solid.

 

Yeah I turned a simple question into an overly complicated one....

 

Well, been doing some attempts at printing here tonight. Leveled the bed manually and tried printing with and without ABL. Right now my conclusion is the extruder is not working right. I have calibrated it and had good flow coming out of it but now, it is not flowing that well at all. Going to have to try calibrating it again later.

 

Can you make a video of it printing?

Edit: I'm in full on fixit mode... obviously ignore this if you're not asking for help.

 

Well, just picture the hotend moving around with nothing coming out. I'll see if I can get something here in a bit.

EDIT: And no, there is not a jam.

 

Just ran some tests measuring filament being feed vs what was requested. It looks like there is a lot of slippage going on right now. Never been a big fan of these smaller MK8 drives. They just seem too small. A while back I was having issues trying to get the filament to feed at a higher speed but it could never keep a good enough grip to push it through.

 

I had poor extrusion and i switched to a much more rigid extruder spring and now the extruder engages very well.

 

I got that spring pretty much collapsed from tightening the wing nut. Will have to see if I can find a stiffer spring somewhere.

 

Before and after, with the old spring no matter how much I tightened it there still wasn't enough engagement with the gear.

 

I had been talking to a co-worker about the problem and we came up with the idea of spreading the wheels apart too. Since you have already designed the part, will give that a try. Might also take out the second wheel while I am at it.

 

Where did you get your spring from?

 

A Home Depot multipack for about $4

 

alright guys, so update on my huge version of this great printer. ive decided on a bed size to fit what i want to do with it, 406x406mm [16"x16"], and got most of the parts ordered, but the build volume i need requires i buy 1000mm lengths of v-slot for the 4 vertical legs, i need 560mm build height minimum for this project.

now since i have to buy 1000mm length anyways...why not make it 1000mm tall? well nearly anyways. it requires the same materials be bought for the frame, and the only other difference is longer lead screws [no biggie] and perhaps some more modification of parts.

my real question is this, how rigid is this frame as i approach such great heights? and more importantly are the 20x40 extrusions rigid enough over nearly 40" or should i switch the vertical legs [or possibly just 2 of them] to the square 40x40 extrusions from openbuilds?

i would love to hear some thoughts on the rigidity and stiffness of the frame. i think im going to try to go that height anyways, since i already have to buy the same amount of extrusion.

 

I am looking at the same route on my Core XY since my ramps died. Working in it now. I think it will be a great setup.
By the way does anyone know a good step setting for a Radds/Due/Raps128 setup. I would suspect a 32 or 64 might be a good sweet spot but not sure?

 

My setup works great! I get decent repeatability in my configuration with the two side leadscrews driven by one motor, but there may be some differences in our designs.

• My Z endstop is a hall effect sensor which triggers 5mm or so away from the end position, then I add a Z offset in the homing routine. The offset it dependent on the bed temperature.
• My bed is on springs on clips which grip the edges of the plate, which I think is where I get all of my variability from. If I wrestle with the bed too much when removing a print or cleaning the glass, I can compress one of the edges and have it not spring back fully, which you adjust for, then later it pops back and you have to readjust. I don't think your mechanism would have this problem.
• My bed's center of gravity is behind the z screws (closer to the Z rail) so the front of my bed is higher than the back. Yours appears the opposite but there's no reason this should make any difference because it is a constant.
• I don't have double sets of wheels on the Z axis, just the one pair per side per side. Yours should again be more stable than mine.

We both have that 2:1 gearing on our leadscrews to double the precision of the steppers there so we should have the same "microstep slop". My fast homing speed is 5mm/s, back off 2mm, then slow home at 1mm/s. However, I run smoothieware so the response time of the endstop hit to stop might vary.

But for sure that is an amazing wiring job you did there. I am definitely going to borrow some of those ideas.

 

I just wanted to say, as many have before, thank you to everyone that has contributed to the development and refinement of this project! I found my way to this forum by initially stumbling on trublu832's remix on Thingiverse while looking for something interesting to print. Of course the "need a new printer.. yes another one" bug had recently bitten me, so I was intrigued and found my way here. I have 80% of the parts and I am just waiting on the China express to get the rest to me over the next couple of weeks. This will be printer #4.

The first was a cheap-o QUBD 2-UP printer kit, but it was enough to get my feet wet. Lots of issues with those MDF frame printers, but TLC and perseverance made it a very reliable, though slow, machine. My second was born out of frustration with the 2-UP for being so flimsy and slow. I tore it up and salvaged the electronics and hardware, tossing the MDF in the fire pit. Ended up reborn as a box monstrosity with 8020 frame and aluminum heated bed. She is slow, but rock solid and prints like a dream. Next was a Folger Kossel Delta. Delta's are a different creature altogether, but a good challenge and a great printer nonetheless.

Now I want something bigger and faster. The weak points on my other printers are the small build volume of the Kossel and the moving Y build plate in the other limiting speed (that and the crappy 8mm smooth rods are not ideal in my opinion). I have always liked the CoreXY concept, so this printer will be the culmination of many desires and a fun project I am looking forward to like a kid on Christmas Eve. Thanks everyone!!

 

Are you doing any fun variations? extended build size, dual extruders, direct drive, etc?

 

Yep. I am raising the Z height to 18" for starters. I'll begin with a bowden single extruder, but plan to change it over to direct drive in order to print flexibles. I have a couple of rolls of NinjaFlex that I have not been able to use and many plans for them! Another mod is a funny coincidence. While reading the forum from the beginning and seeing all the talk about direct vs bowden an idea popped into my head. Oddly enough, a dozen pages later you mentioned it! I have a Dremel with a flex shaft and the thought occurred to me to design some sort of hybrid drive with the motor mounted to the frame coupled to the flex drive terminating in the filament drive gear. I was even looking into a more industrial flex transmission solution with 5mm female connectors on the ends which would mate with the stepper and another shaft on the other end with the drive gear. Just need a simple mounting plate to adapt the flex drive end to the stepper mount on the extruder. Not 100% sure I will still do this, but it was a fun thought exercise. I still have doubts on the spring play in the shaft during retractions, which may end up making it as bad as a bowden config in that regards.

Things evolve in my mind at the speed of thought, so I'll likely come up with other ideas as I build!

 

The commercial version of that concept is called the Flex3drive

 

Yeah, I saw that. It is funny to have an idea I thought was so original and innovative one minute, just to find out a few days later its been thought of and done before. Still, was a fun mental exercise and something I may still try on my own just for kicks. I like weird solutions to problems.

 

Yep, I'd definitely try to get as many diagonal cross-members in there as possible to strengthen the frame: Need to triangulate those suckers and make them strong, so you don't get any deflection at that size. That would be my biggest suggestion.

 

I just set that up myself (although I'm using SD6128 drivers): I set mine to 1/32 microstepping based on suggestions of the forums. The thought is humans can't notice much past 1/16th, and the higher the microstepping the less torque you have. The drivers I got were all set to .55v by default: I pushed them up to 1v (since the safe range was .8-1.2v I think?), and nearly melted my stepper brackets after 5 minutes of usage (steppers got super hot). Put them back to .55 and the printer has been doing just fine.