Here is a video of my Core bot with an RGB lighting strip, the color can be controlled with G codes while printing.

 

Great stuff @sheffdog !

 

Are the large heated pcb beds such as 8"x12" and 12"x12" performing well enough regarding heat up time and meeting goal temp? Has anyone tried a 120v silicone mat heater?

 

I just made a picture of these (as part of my blog), see attached:

 

I've ordered the 750W 120V version I'm going to drive with a SSR. I'd imagine the 8x12 and 12x12 beds heat around as fast as an 8x8 would with a regular PCB heater, right? The wattage should increase with the size of the heated bed, but I don't know that for a fact. All I know is that stepping 120VAC down to 12VDC then trying to run like 15 amps to power the bed and then having to wait 10 minutes to heat up is just silly. You'd get the same heating from just 1.5A of AC power, which is peanuts!

@Carl Feniak - Is there a structural reason the back left and right vertical legs (that the z axis rides along) are turned that way and not so that the Z bar ends ride similar to the XY bar ends? You wouldn't need the 60mm bolts and 25mm spacers if it rode on the thin edge of the extrusion. I know someone earlier posted some XY Idlers that used 20x20 extrusion, but I'd prefer to use 20x40 for everything. I was considering rotating them 90 degrees and revising the parts but if it serves a structural purpose to have them that way I wouldn't want to weaken the structure.

It is fun to me to design the different 3D parts based on your design, but buying 25mm spacers from McMaster at $1.80 a piece, or cutting 40mm spacers down does not make me happy at all!

 

@CapnBry Wattage is a function of voltage/current (and resistance). While you may only be 1.5A with AC (V*I=W or 120*1.5=180W), running 12v at 15A produces, the same wattage and is using the same amount of power. There is extra power used in converting AC to DC so it is not identical. Whether using AC or DC, a 180W heater will heat at the same rate. BTW, your 750W AC heater is going to be drawing around 6.25A.

 

I ended up running 24v through the 12v circuit of my heater. Doubled the wattage and it heats up FAST! (And yes, it is okay to do this. The maker of the heater even suggests doing it).

 

Oh yeah I'm totally familiar with how power works. I was saying that pushing 15A at 12V is silly because you can't ran that sort of current through a RAMPS controller (especially not a 1oz copper pour PCB that you'd get from a China eBay special). The Bed MOSFET would also probably catch fire, so you're going to have to use an external SSR to switch it. For that current level, at least 12 gauge wire which can be a real pain to solder to the bed. My point was that 180W (AC) is not equal to 180W (DC) just due to complexity of having to move that much DC current.

Regarding the bed size / PCB power, I assume that if the 8x8 PCB heater is 2 ohms, the 12x12 would be designed to be 0.9 ohms to maintain the same watts per square inch. However, now looking at the math that would be 13.5amps and I'm wondering if that's what they do.

On my i3, I have the 12V power supply cranked up to 14.5V just to get that extra power to the bed heater and heat up faster. Actually, doubling the voltage quadruples the wattage as the wattage is the square of the current.

 

Wait, you mean I can use a 3D printer to... create things?! haha sometimes I forget the easiest solution is the easiest solution. I'm going to start printing parts tonight, still waiting on a whack of parts though.

I just got my MIC-6 12 x 12 x 1/4" aluminum bed yesterday. Holy smokes, this thing weighs exactly what I calculated it out to be, which is 3.6lbs. Cripes! Hopefully it will be flat enough I don't have to cover it with 3mm borosillicate and add even more weight.

 

Thanks Carl, but I can handle that. I have no problem with basic modeling, and can make some pretty great stuff in OpenSCAD. I've modeled that spacer in 123D, which I haven't used since the first Betas came out and it was a crash-monger. I spent some time playing with your Z-bar end model adding extruded tubes like your Spacer model but man that is so frustrating for me. "Just sketch there. not there. no what are you snapping to? ARGH!" As a software developer I much prefer to describe my solids with math instead of trying to draw them.

I appreciate the offer though.

 

I added a post about how I added RGB lighting to my c-bot. I thought some of you may be interested. http://mason3d.com/blog/?p=35

 

This is great Elmo, how fast does your bed heat up now? My 12x12 is such a pain to wait for, it currently takes about 7 minutes for me on 12v.

 

It goes from room temp to 80C in a minute or so. Haven't actually timed it but it is fast.

 

Got most of my parts printed out, apart from the carriage and the extruder. (Gizmo Dorks Fluorescent Blue ABS)


Also my parts from the OpenBuilds store came today too so I can get started. The 1/4" spacers that I got are actually #12-1/4" (3/8" OD) spacers so they need the shims. They're the exact same size as these 1" spacers I found on amazon for the Z ends. I just thought I'd let folks know to definitely buy shims from OpenBuilds because otherwise the spacers rub the bearings.

 

That's a really nice color. The other option is to print these spacers from Carl: http://www.thingiverse.com/thing:502734 The end of the spacer is the size of the shim so you could potentially not need to buy spacers or extra shims other than the shims that need to go inside the wheel between the bearings.

 

Had to share my first print... a 1cm calibration cube:

That's a 1mm volcano nozzle printing at 500micron layer height.
It 'just worked' on the first try, pretty impressive. Next up is to clean up all that wiring.
But I'm pretty excited that a months worth of work has paid off to this point

 

FYI
If u r using Slic3r and have not upgrades to 1.2.9 stable yet - do it.
It solved an issue I thought was my printer and settings with thin wall prints.
Slic3r wasn't filling the gap between the walls.

 

You think that color is awesome, it also is UV reactive! Like a techno rave all up in this, giving @sheffdog's LEDs a run for his money


I've run into a couple of problems. #1 the Z motor mounts are 4mm thick so M3x10mm screws don't go all the way down. The kysan steppers I have specify "min 4.5" as the depth for the M3 holes and so even with the M3 washer there's a mm left. I have some knurled M3 cap screws where the cap is about 0.5mm smaller so they're even worse. Not a big deal to pull the face, but I will have to reprint the motor mounts. Might want to consider increasing the thickness of that part to 5.5mm or 6mm.


My bigger worry is that my Z axis in the back has a some play in the v-wheel to 20x40 extrusion and I'm not if it is too much play. Most of the v-wheels are tight against the slots, with a good amount of friction. but some are barely touching. Is there a good way to make sure they're set properly apart from just loosening the bolts on the angled side of the connector, squeezing them, and re-tightening?

EDIT: They should rename t-slot into "you-never-put-enough-tnuts-where-you-actually-need-them slot"

 

@CapnBry : I had a similar issue mounting the z-steppers, although in my case one washer was enough to pick up the slack. Maybe you can just add a couple more into each if you don't want to reprint it?

I also had a lot (relatively speaking) of wheel slop on my rear 20x60 z-gantry in: My wheels weren't all connecting how I'd like: I had my son lift up lightly on the HBP to remove that torque, while my wife held a wrench on the nuts that hold the wheel assemblies in: From there. I'd loosen one wheel assembly at a time, "pinch it in" to make the closest possible contact with the slot, then tighten it back up. Doing that my issue was solved. I just needed two extra hands in the process

 

Thanks for the tips everyone, all my rollers have just the right tightness now and I ended up just sticking extra washers in the extra space which was a lot easier than reprinting all the motor pieces.


I was a couple of t-nuts short in a couple places and had a few extra in other places. I spent the afternoon taking the whole thing apart and back together again. It goes together a lot more quickly the second time around! While I had it mostly apart, the whole thing was overly wide by about 35mm on the left and right so I took the opportunity to shorten the cross beams by 50mm. I chickened out on doing the full 70mm... then 60mm... down to 50mm. I think cutting 60mm out would have been fine, 70mm would have started to get tight. It's a 10% reduction in width so it's pretty significant. I figure the smaller size might possibly reduce twisting an insignificant amount.

I was planning on cutting the extrusion with a hacksaw and a miter box but I am sure glad I didn't because that would have taken forever. I borrowed a miter saw and bought a $22 80 tooth saw blade which made great cuts that didn't even need cleanup and could cut through all 4 legs at the same time. Much better than the $50 diablo saw blade (at least on price).

I also spent about an hour trying to figure out why my XY bar was hella-crooked. The frame is so dead square yet the bar was angled pretty badly. I loosened ends and made gaps in the extrusion to make it unsquare but it just would not get straight. Then it dawned on me that I only had installed one belt and the belt tension has to be equal in order to keep it square. 5 minutes later I had the second belt on, pulled them both tight, and now it is perfectly straight. I really slapped myself on the forehead when I realized it and hopefully that might help someone else.

Wow so much cleanup work left to do, and I am still waiting on my bed heater which hasn't even left China yet, two weeks later. This thing is so wicked fast, I've got 3x the acceleration and 2x the speed of my i3. It's really great how well this all fits together, thanks for sharing the design, Carl.

 

Looks great, even with the tangle of wires. I see you went with the leadscrews centered on each side, did you try to put it near the center of gravity? Does it roll up and down smoothly? looks like you're the guinea pig for that method I posted earlier.

 

Yup, I said I loved your idea and I wasn't kidding. I've tried a couple different placements of the Z motors so far but haven't done a full evaluation. If I placed them where the bed was neutrally balanced, there was a little bit of teetering because the Z bar can slide up or down just a very small amount as the bed rocks on the leadscrew fulcrum. You can probably take this slop out by really cranking down on the Z axis wheels but I just pushed the motors back a bit so there's some weight loaded on the bar at all time. Sort of like Carl said, you want some amount of weight pushing it on one direction or the other so any amount of looseness always leans in the same direction.

My 12x12 bed takes ~8lbs of force to hold steady using my super-accurate luggage scale (sarcasm) but the two motors running at 0.5A can move it at F500 (8.33mm/s) with 1000mm/s^2 acceleration. I'm not sure how that compares with the original design. I have tried 15mm/s but there's something holding it back because it still takes the same amount of time to move, despite the max feedrate being set high enough.

 

Here's some pics of my nearly finished bot: I got the final wiring complete this weekend. Other than a tray for the power supply and a case for the LCD, it's complete (well, except for the filament coolers I still need to print). Been an awesome project, and a huge shoutout again to @Carl Feniak for the design and @sheffdog for all his help along the way!