General 3D Printing Thread


 
Question for those that have a C-Bot / D-Bot.

I'm building a D-Bot & I'm to the Z-carriage installation and the wheels won't roll. Only 1 on each side rolls, the others slide. the carriage moves smoothly, just the wheels aren't spinning. I think I've got 1 or both of the problems below.

When I bought my wheels from open builds, I misplaced the precision shims. So I printed the shims that came in the file.
The bearings were from Amazon & don't roll as smoothly as I'd like, but I don't think that is the issue. The wheels don't roll nicely on a bolt with any pressure on them, I think the printed shims are the issue. I found the metal shims - but so far I haven't been able to press the bearings out of the wheels (advice?). Since the wheels/bearings are a significant expense on the printer, I don't want to just re-order them yet. I clamped them in a vice w/washers on each side & it improved the rolling, but not enough to fix the z-carriage issue.
Also,
I'm not sure I have enough clamping force from the z wheel mounts to the vertical member. There's contact and no play, but it doesn't seem like there is force on the wheels, except the top/back wheels from the torque of the cantilever. The thickness on the z-wheel mounts seems to be more than other parts, can't loosen bolts much at all before the nuts fall off & was very hard to install onto the rail. I could sand a little off the mating surface, but I want opinions before I do that. Everything else has fit really well.

I'm going to post this on the google group thread, but I get good advice here on most things.
 
Yeah those little wheels are surprisingly expensive and add up to a lot of money pretty quickly. To get the bearings out of one, use a small flat bladed screwdriver (~3mm wide tip or less?) and press through the center hole against the bearing the bearing on the opposite side. You gotta try to sort of get the blade between the shim and the bearing and push it out rather than try to pull them out.

I'm not sure what Z bar mounts you're using, they've changed a few times over the years. I have the kind that is sort of like the other axis where there is a plate on the outside to hold it all together, and I fiddled a lot with the wheels because I thought they weren't rolling well. That's why I eventually created my version that had the leadscrews halfway down the bed to take weight off the wheels. I'm not sure which wheels are "doing the work" of holding the bed up, all of them I can rotate with one finger pushing on them without any large amount of force. My Z bolts are plenty long to just come out the other side of the nut by about 1-2mm. Not sure if any of that helps, but at least it is information!
 
Thank you Bryan, your advise helped me get rolling. Now I need help with getting under power. I bought a cheap RAMPS/Arduino/A4988 kit off ebay for $20, figured that would get me going. Seems like it won't power the motors. I bought some motors on Amazon that looked like they'd work, but I'm not sure what spec I screwed up. The D-Bot BOM has a motor that's not available I can't pull the specs up. It says to set Vref to 0.55V. I don't get any movement at all under 0.8V & it will only move a little bit at 1.2V (the drivers get warm fast). They're 2A/2.8V 64oz-in motors & the closest I can find to the P/N in the BOM are 1.5A/4.8V 76oz-in w/higher resistance & inductance.

If I go by the pololu wiki, I probably need 1.6V Vref - but the drivers only go to 1.23V & I"m sure running them at max will smoke them eventually.
What should I look at first? Drivers or motors? I can't find anything that tells me what spec is wrong or really how to choose a motor for specific drivers. I just picked a decent deal on 64oz-in motors....
 
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I use Kysan 1124090 steppers for my two axis which are 4.2V 1.5A 2.8ohm 4.8mH, set to a current of 0.8A (320mV). They crank out a ton of power. I am almost certain that the chinacheap drivers still have the old 0.05ohm sense resistor on them and not the 0.068 resistors. With 0.05 sense, 0.8V is 2A which is way more current than you should ever be using.

I would think your motors should work though, the voltage is just the minimum voltage they need I believe and really the whole thing is driven by current. Are you sure that the wiring to the motors is right and the phases are not fighting each other or a poor connection on one wire is causing the whole thing to just sort of hang out at one step position?
 
thanks Bryan, I was assuming it was either I fried something or did something dumb, but I couldn't find a spec that was 'key' to choosing motors - I wanted to cross that off the list.
It was (partially) the latter. I wondered what the bag of jumpers was for when I got the RAMPS, but forgot all about them in the 3 months of procrastination. Now I know....

Y movements now work as expected. X movements sometimes work (X+ seems to always work, X- & homing sometimes don't - quiet whine when it doesn't work vs normal stepper music). Z tries to work, but doesn't seem like it's getting enough power (quiet whine again). Need to take the bed off & see if it's 2 motors in parallel (1 motor on the table seems to work ok & has enough torque that I couldn't get it to stall). I tried swapping drivers around & upping the current, no changes - almost acts like I still have no jumper installed. Still haven't figured out why X- works sometimes & sometimes doesn't (seems to be tied to something with Z, but I haven't found a connection).
I swung for another RAMPS (not the cheapest possible one this time) - just to compare & make sure I didn't fry anything.
 
Hey guys, I think I am going to go ahead and build a corexy, leaning towards the J-Bot which is really a D-bot but the print bed is supported on the front as well as the back. I have a couple of questions for you (the first one is really for the D-Bot owners):

1. Where did you get your printed parts from? There is a guy on ebay selling the complete printed parts kit for a D-Bot for $110. My small Ordbot Hadron is in pieces right now and I am not sure I want to put the effort into getting it back into printing shape and the print all of the D-Bot parts (there are quite a few).

2. What extruder/hotend combo are you running?

3. Are you using any kind of enclosure? I have seen some pretty nice prints by people on here that I could never achieve with my Hadron.

Thanks
 
I made my printed parts for my C-bot variant on my MakerFarm i3, so I am not much help in that department, but I can help with the other two questions.

2) I was running the "direct drive" carriage, with the motor on the top and an E3D volcano hotend on the bottom with a 0.6mm nozzle. It worked very well although at low layer heights (0.15mm and below) I had issues with the extruder not putting out enough plastic to get a good bond. It was like it took too long for the small amount of plastic to start flowing so everything was a little wispy. I don't usually print this fine though (usually 0.2-0.3mm) so I never spent any time trying to get it to work. There are some really decent E3D V6 clones out there now too so if price is an issue, you can always go with one of those (look for the kind with the PTFE inside but it only goes a little into the heatbreak). I recently switched to an E3D Titan Aero and can't tell the difference, but haven't tried printing smaller layers yet.

3) I have enclosures on both my printers which gets up to 50-55C and definitely makes a difference in reducing ABS warp on parts like the 4.3 case. This can be as simple as finding a large enough box to put over the printer. My C-Bot has a wooden dowel frame with cardboard panels cut to fit and a lexan front. Note that it doesn't need to completely enclose the printer, just pretty much from the bed up and the smaller the enclosed space the better. Don't waste your time coating the cardboard with mylar space blankets like I did as thermal imaging measurements show that it doesn't affect the temperature by more than 2C.


If you plan to print in PLA don't even bother with the enclosure, it makes no difference.
 
Thanks Bryan for all of the great info!! I do have an E3D V6. In reading through everything you wrote, I will most likely order a .6mm nozzle for it since I ordered it with a .25 and I think it might have contributed to some of my issues. I will definitely fashion some sort of enclosure to help with the warping. I might just go ahead then and try to get my Ord Bot back online to print the parts for the D-Bot. Did you design your own Z-Axis part to hold the belt tensioner? I searched Thingiverse but could't find one that looked like yours.

Thanks again for your answer!!

Troy
 
Ooh yeah that is a pretty small nozzle. All my prints are utilitarian so I don't need any fine details so the larger nozzles are great for great for making a nice solid 2.5mm thick wall in four quick passes. The C-Bot on the left has the Volcano with 0.6mm nozzle and the i3 on the right has an E3D V6 with a 0.5mm nozzle. The C-Bot can push 12mm3/sec and still get 98% of the requested material, and the i3 can do about 8mm3/sec. That's with printing at the high end of material temperatures (250C for ABS, 230C for PLA). I'm not sure how anyone can print at like 70mm/s at 190C in PLA and actually get the right amount of material laid down. For testing, I used a 50g scale and extruded 300mm of filament at various feedrates and temperatures, weighing the amount of extruded plastic.


My Z-Axis is a unique beast! I've got a 20T gear on the Z motor (which is the standard Z motor mount) and 40T gears on my leadscrews which are sitting in flanged bearings with my own mounts. The 2:1 gearing means I get 0.02mm per full step on the Z motor with twice the torque and no worries about the Z screws getting out of sync. Placing both Z screws at the center of gravity of the bed didn't work very well, as the bed could slightly teeter back and forth due to vibrations while printing and left artifacts on the print. Now they are placed slightly heavier on the front so it is always teetered in the same direction. There are a few closeups of them in my 3D Printing album. The model I used I sent back to Carl and he made an even swankier version I posted to the C-Bot thread. The model name is "Z bearing mount carl" if you need to google it.
 
Wow! Nice work. Thanks Bryan for taking the time to give me the info. I just ordered .6mm and .8mm brass nozzles. The E3D v6 came with a .4mm brass nozzle so I should have a good number of nozzles to try out once I get the Ordbot back into shape. I really never quite fully understood the relationship between what is expected and what is extruded was so high based in part on the very small nozzle size.

I really like your z axis setup and will shoot to mimic it on my D-Bot I will build. I really like the 2:1 gearing for the Z motor! Did you print your C-Bot structural pieces at 100% infill? i had read that suggestion by the author on the Thingiverse D-Bot model page.

Thanks,
Troy
 
Thanks! On my i3, the two Z motors would need to be reset every few days because they would slowly drift away from being equally high so when I designed my Z setup, I wanted to be sure there was no way that would happen any more. It is nice because I can loosen the front motor and slide it to the middle and the belt is then loose enough that I can turn either leadscrew (with a little elbow grease) to get the bed arms level, then just side the Z motor off to the side to tighten the belt back up. Another nice thing is that the leadscrews have can be inserted far enough through the pulley to adjust their height. Right now my volcano head can run into the leadscrew tops if it goes off the side of the bed, but next time I need to take the bed off I am going to loosen the set screws on the 40T pulleys and slide them down a little further to make them sit below the bed height. It is a lot easier than cutting a hardened steel leadscrew!

I printed my parts with 40% honeycomb infill. 4 perimeters, 4 top, 4 bottom layers, 0.24mm layer height. There's not much infill in them though, because between the perims and layers it fills most of the space solid anyway. Slic3r has the new "cubic" infill as well now, which is supposedly stronger than honeycomb for shear strength so that might be a better option.
 
Those print settings are good to know! Is your build including the parts you used documented anywhere? I don't want to keep bugging you but I like a few of your mods and wouldn't mind replicating them.

1. Did you use the BOM specified Z-screws and motor?
2. Are your modified X-Y motor mounts posted anywhere? I saw how you adjusted them for a little extra room away from the frame. Seems like a nice mod.

BTW, thanks for your service. What branch were you in? I retired from the USAF in 2008.

Troy
 
I sort of documented what I did along the way in the OpenBuilds forum C-Bot thread, but stopped when they moved to a Google+ group because that is pretty unusable as a way to share information. I started with the original C-Bot BOM and started putting it all together but just kept changing things along the way as I saw things I thought could be better. It is pretty disorganized, I have mods done in 123D, Fusion 360, and all my custom from scratch stuff is done in OpenSCAD. I had to search around just to figure out where the XY Motors were (they were in both 123D and Fusion!). I am happy to answer any questions you have though, you can even email me directly heatermeter@capnbry.net if it is more convenient, it makes no difference to me.

1. Yes I used the OpenBuilds 8mm lead screws (250mm length) if that's still what is on the BOM. My X Y and Z motors are all the Kysan 48mm long steppers which I think are specified in the BOM. I run the X and Y at 0.7A and the Z at 0.5A.
2. I moved the motors out just a bit so they weren't pushed up against the frame in any way and thickened the support fillet to offset any detrimental effects of having the motor just dangling. I use Astrosyn dampers on the XY motors which also makes them much quieter. The E and Z I tried and didn't hear any significant difference so I removed them. The part is available shared in my Fusion 360. Let me know if that link doesn't work or if you just want STLs, I've never shared anything through Fusion so don't know if I am doing it right.

No, thank you for your service. The Captain in CapnBry has to do with a charterboat license (OUPV) which I think we can all agree is far less beneficial to the country, but a fun way to make a little money moving boats around Florida back in college. What did you do in the Air Force? I had high school dreams of being a naval aviator and went through all the interviews, physicals, fitness tests, and academic testing to try and get into Annapolis but ultimately did not make the cut and settled for the private sector.
 
I figured you used the BOM for as much as would work and then just modified after that. I am glad the BOM uses a ball lead screw. My current Ordbot just uses a regular non-ball lead screw (threaded rod, Lol!). I should be able to take those motor mounts off of the Fusion360 and pull them into solidworks. Thanks for the link!! I also like those Astrosyn dampers. From your graphs it looks like the do quiet down those motors quite a bit.

The Charterboat license would be cool and very fun!! I was blessed enough to get to be a pilot in the USAF for 17 of the 20 years I was in. I had loved planes since I was old enough to walk!

Thanks again!

Troy
 
Hi Guys,

I am getting my Hadron OrdBot setup to print again, mainly so I can print my own parts to build a 300x300 corexy D-Bot printer. It has been a couple of years since I was printing anything and it seems there have been some advances in filament and hotends. I was wondering if people would mind sharing a few details about their setups.

1. What type (ABS, PETG, PLA, etc) and Brand of Filament do you use? I have printed w/MakerGeeks ABS in the past. It seemed ok but it would not fully dissolve in Acetone so I don't know if it had some fillers in it. I also ordered a couple of spools from them last year and it took almost 3 months for them to ship it. I am thinking about trying the PETG from Matter Hackers.

2. What Extruder/hotend combo do you use and what size nozzle?

3. What print bed/heater are you using?

Thanks in advance for your details.

TRoy
 
1. I use ABS for things I expect to get warm, including dark colored items for use outdoors as the sun can easily heat parts to deformation temperature. PLA for everything else just because it has fewer warp issues. I'm trying to find myself a new plastic supplier. I used to use ProtoParadigm for everything I could (all PLA), as their filament was consistent in tolerance, roundness, and color between orders. However, it takes about 2 weeks to get an order from them if they had the color in stock and recently everything was out of stock for weeks at a time so I couldn't count of them to keep me stocked up. For ABS, I go with eSun and haven't had a problem. Supposedly Inland filament is also made by eSun which is stocked at MicroCenter retail stores. Hatchbox is good too, but the price varies on Amazon from like $20 to $50 a spool for no good reason. I've started using a lot of MakerGeeks, but their ABS tends to be "moist" for some reason and prints like garbage no matter how long I keep it in desiccant. Their PLA is good but I don't like that they don't describe the colors on their product page so you may be surprised with what you get (like finding out that "gray matter" is translucent and not solid gray). They have shipped my 4 orders within a day each time though.

2. For extruders, the Titan Aero is nice but a bit on the expensive side. Just a direct drive MK8 hobbed gear is good if the tooth profile is cut well (many eBay sellers send a gear with just some scratches in it, which can't push anything), the "hobgoblin" is E3D's drive gear if you don't mind spending a couple extra bucks. The direct drive has a hard time with low layer heights (0.10mm and below) where it starts having a hard time putting out so little plastic. The hotend, I like the E3D V6 or Volcano. The only problem I've ever had with it is when the heatsink/heatbreak didn't have thermal compound in them and would jam randomly. They have since started including a packet of compound to alleviate this. If you're looking to save money, you can find really good clones of this now if you just compare the E3D official mechanical drawings to the eBay listings. Nozzle size depends on what you are printing. 0.4mm is a standard, but I prefer a little larger because I mostly make mechanical parts. I have 0.5mm on one printer, and 0.6mm on my main printer.

3. MIC6 aluminum plate with a 120VAC silicone heating pad stuck to it through a SSR. Trying to drive like 10A+ of 12V power just to try to generate heat is a waste, and larger beds can take forever (15-20 minutes) to heat up and cause problems with cheap chinese controller boards which really shouldn't have so much current running on them. My 300mm 1/4" aluminum bed can heat to 105C in about 3-4 minutes. I have a sheet of PEI stuck on top but it grips too well, sometimes ABS sticks so well I destroy the print taking it off despite the Z height being perfectly calibrated. My favorite is borosilicate with a light wipe of hairspray or thinned out gluestick which I will switch back to when I get enough time to remove the PEI stickum.
 
Plastic PET
Nozzle size .25mm
Print duration about 50 hours, I may run out of plastic before it's finished lol

What I'm I printing well it's to see if I'm able to print it. It's a proto part from work in which I thermoform PET and PP plastics into container for plants and this particular print is a tray call the 1006 seedling tray

http://myuds.servebeer.com
 
Whoa nelly, that is one heck of a long print. Looks good and I think it is coming to the top! I think I am actually more concerned about something going wrong with my 3D prints when I go to bed than with me BBQ. Too bad failed 3D prints don't still taste good too :(
 
Its on about 250 of about 440 layers, so it still has a while to go.

The first go at it failed fairly quickly at 5 to 6 hours. The support was not enough to support PET and I was trying to cheat the width and height to get my .35mm nozzle extrusion small enough to do the walls.

This print , I thought I was going to lose it about 5 hours ago when I saw the support get hit from build up on the nozzle. I was able to minimize the damage and it continued on.. it left some missing layers on the outer wall but it should be ok, I hope.

It won't be done until Monday, I believe, lol. I bought another roll of the Esun silver PET, just in case I don't have enough.
 
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