dwalton

I don't have white filament but gr5 helped me get my prints to this level with Colorfabb orange. You can see the thread at: http://umforum.ultimaker.com/index.php?/topic/3169-overhangs-sag-too-much/

I used gr5's trick to get better antennas and it worked. I had been wondering how to do this in Cura and thanks to gr5, I know how to do it. Here are the prints: Thanks again for all of the help!

I apologize for not being clearer. I was using Ultimachine filament, not Ultimaker filament. I don't know if Ultimaker gets their filament from colorfabb or not, but the colorfabb sure printed nicely: Here is the print profile I used: [profile] layer_height = 0.1 wall_thickness = 1.2 retraction_enable = True solid_layer_thickness = 1.2 fill_density = 10 nozzle_size = 0.4 print_speed = 25 print_temperature = 185 print_temperature2 = 0 print_temperature3 = 0 print_temperature4 = 0 print_bed_temperature = 0 support = None platform_adhesion = Brim support_dual_extrusion = Both filament_diameter = 2.84 filament_diameter2 = 0 filament_diameter3 = 0 filament_diameter4 = 0 filament_flow = 100.0 retraction_speed = 40.0 retraction_amount = 4.5 retraction_dual_amount = 16.5 retraction_min_travel = e retraction_combing = True retraction_minimal_extrusion = 0.25 bottom_thickness = 0.3 object_sink = 0 overlap_dual = 0.2 travel_speed = 150.0 bottom_layer_speed = 20 infill_speed = 0.0 cool_min_layer_time = 5 fan_enabled = True skirt_line_count = 5 skirt_gap = 3 skirt_minimal_length = 150.0 fan_layer = 1 fan_speed = 100 fan_speed_max = 100 cool_min_feedrate = 0 cool_head_lift = True solid_top = True solid_bottom = True fill_overlap = 15 support_fill_rate = 20 support_xy_distance = 0.7 support_z_distance = 0.15 brim_line_count = 10 raft_margin = 5 raft_line_spacing = 1.0 raft_base_thickness = 0.3 raft_base_linewidth = 0.7 raft_interface_thickness = 0.2 raft_interface_linewidth = 0.2 fix_horrible_union_all_type_a = False fix_horrible_union_all_type_b = False fix_horrible_use_open_bits = False fix_horrible_extensive_stitching = False plugin_config = (lp1 . object_center_x = -1 object_center_y = -1

I have this clip installed: http://www.thingiverse.com/thing:24363 I have it pushed to the second-highest setting and it seems to work OK. Is the one you mentioned better?

I had another breakthrough. You suggested I try another filament so I tried UM red and had the same problem, even when printing at 25 mm/s. The melted filament for the horns kept sticking to the nozzle. I even tried putting a little machine oil on the nozzle to see if that would make the filament stick less with no success. I also tried to make retraction occur a bit more often on the horns to see if that would help, but it did not seem to help much. I set retraction minimum travel to 1 and minimal extrusion before retracting to 0.25. I wasn't worried about grinding the filament since the robot does seem to cause much retraction. I then decided to try another filament: http://colorfabb.com/3-mm-filaments/stock-colors/2-dutch-orange-300-20.html It is pretty expensive and I don't use it often, but it made quite a difference. The stringing is gone and the horns look very good. I am printing a full robot and so far it looks almost as good as yours. I have been distracted by a plumbing emergency, but will try to get pictures of my experiments posted tonight along with my settings. I also measured the speed of air over the bed with the stock fan. It was between 1.9 and 2 MPH which I am certain is higher than the printed duct. I'll try to measure the wind speed with the printed duct as soon as I get a chance.

That is a great tip. I cut the bottom off like you suggested and tried prints at 185 and 181. When the temperature dipped below 180 briefly at the beginning of one print, the filament stopped coming out. I still got stringing, even with minimum layer time of 12 seconds and at 181C. I've been swamped today (and have a broken toilet that needs urgent attention), but will try to post pictures later tonight. I also tried a print with the cool head lift feature enabled, but that did not help. I suspect you are right that I have a cooling issue since the horns seem to stay pretty mushy as the nozzles runs in circles around them. I had a problem a while ago where the fan always ran and found the Darlington BJT that controls the fan had failed. The Darlington did not have any protection from back EMF (AKA flyback current) and I think that PWMing the fan (running at less than 100%) killed the transistor. I replaced the transistor and put a clamping diode in parallel with the fan to protect the new transistor. I'll check it with a scope to make sure it is working correctly. I am 95% certain that my repair will not alter the performance of the fan, but I can check the PWM signal with an oscilloscope easily enough. I moved the head around by hand. It is a bit stiff from the belt tension, but I didn't feel any backlash. I noticed that I could slightly tighten one of the pulleys that turned the y-axis. In my experience, the pulley set screws need to be really tight or they will slip. Otherwise, the belts sound tight when I pluck them like a guitar string. I might be able to get the left y axis belt slightly tighter. I have belt tightening devices on all of the belts. I bought a set of belts with 1 less teeth to make them tighter, but haven't seen the need to put them on yet (I was concerned the belts would get loose over time). Do you have any other ideas? Thanks again!

Here are some pictures of the duct repair: This shows what happens when your duct unfolds and hits the nozzle. This causes severe under extrusion and I decided to replace the duct. This is a comparison of the replacement duct with the original. The replacement duct ended up not working as well as the original. This is the repaired duct, reinstalled and taped so that it won't unfold.

Daid's duct blows down a little bit more than the stock duct. I noticed more air blowing in parallel with the bed with the stock duct. I have an anemometer and will see if I can measure the difference. The duct was all I changed since going to 1.2 mm walls. I even used the same g-code files for the prints. I would turn the HB on and off using the Ulticontroller. I am using the silver filament from Ultimachine: https://ultimachine.com/content/pla-3mm-silver-1kg-spool Here are some earlier prints: Here are some images of the improved prints: The left arm is still a little warped but the back and the keychain hole on the head are dramatically improved. Thanks for all of the help!

That is a good idea. I cut three pieces from 1/4' foam insulation used on houses, taped them together and cut out slots on the left for the power and USB cable. I can set that on the printer and quickly insulate the chamber on large prints where I am concerned about warping.

I had a breakthrough! Repairing the original fan duct with Kapton tape dramatically improved the print quality. It is not as good as your print, but it was nearly as good as the print from Erik. My first print with the repaired duct got knocked loose towards the end of the print, but the results are very promising. I'll print again and upload a comparison of the last few things I have tried. I attached a thermocouple to the print head with Kapton tape and attached it to my multimeter. It looks like the aluminum block is a few degrees cooler on the outside, but I think my temperature is pretty accurate. I think the problem was that the printed fan duct is not nearly as good as the original. My heated bed is 1/4 inch thick. When I print on a cold bed, I can see the temperature of the bed go up by a degree or two as the bed is heated a little by the hot filament and the bed's temperature sensor is in the middle of the bed (where I am printing). I originally used a reprap PC board heater, but that took too long to heat up. I replaced it with this one: http://store.qu-bd.com/product.php?id_product=61 It takes about 5 minutes to heat up, even with the thick aluminum plate. I used my laser cutter to create a plywood board that holds the pad against the plate. I tapped holes in the plate and sandwich the heater between the underside of the plate and plywood using screws to draw it together. I have been thinking about insulating parts of the plate to see if I can get it to heat up faster.

Does anyone know about the fans that cool the nozzle on the UM2? I would like to retrofit them to my UM1 and document the results so others can also try the retrofit. From looking at the schematics of the UM2, I can see that the fans are still driven by Vcc/2 through a low side switch for PWM control. I like the addition of the clamping diode. I added one to my UM1 when the darlington BJT driving the fan failed. How big are the fans? Are they 40 x 40 x 10? Thanks for making great products and for your commitment to open source hardware!

That sounds like good advice. I'll have to see if I can resurrect the duct with the tape. I tried another duct from thingiverse and the results were disappointing: http://www.thingiverse.com/thing:21182 I didn't even bother finishing the print because the overhang was so bad. I put Daid's duct back on and am trying another print with blue tape over the Kapton and the heated bed turned off and the temperature reduced even further. I'll post pictures when it is finished. It looks a little better, but the left arm rings still curve up and the back overhang looks a bit rough. The print was soft, even near the head (well away from the heated bed) so I am thinking I may need that second fan. Is your bad aluminum or glass? I ended up having to wipe the blue tape with alcohol to get the PLA to stick to it. I was wondering if my aluminum bed is conducting heat away from the first layer faster and if that affected it's ability to stick to the tape.

I'm open to putting blue tape on the heated bed for a small print. I only really need the heated bed when printing large things. I'll also try a print with a layer cool time of 10 seconds. I am going to try the robot again with a modified fan duct as well. I'll post the results when the prints are complete. My fan duct is Daid's replacement for the stock duct and it is pretty close to the original. Unfortunately, the original unfolded and touched the heater. It melted where it touched the heater and was blowing on the head, causing it to cool and under extrude. If I can find some plastic of the right thickness, I might cut a new folding duct on my laser cutter, but ordering a new duct from Ultimaker is a bit expensive. I really appreciate your help. Thanks again!

I changed the wall thickness to 1.2 and this improved the print quite a bit: I also included a picture of the "Alien Landing Zone" lighting system. It really helps me see what the printer is doing, especially when making sure the first layer height is correct. The prints are better, but still have room for improvement. The front looks much better, with very little sagging. The left arm rings are still warped up a bit. The back is better, but there is still pronounced sagging. I watched the print and noticed that the plastic moved a little while the printer moved over it. It was as if the whole model was still soft. When I was having under extrusion problems, the fan was blowing on the nozzle and was cooling it. Now I think the fan is blowing down too much and is not getting enough air on the recently printed layers. Thanks for suggesting the video on the belts. I think mine are reasonably tight. It is funny that you mentioned the Maker Faire. I was at the Bay Area Maker Faire this year and spoke with Erik. He was great to talk to and I was excited to see the new things coming from Ultimaker. He gave me one of the Ultimaker robots he had printed at the Maker Faire and I have been using that as a reference to which I compare my prints. Do you have any other suggestions?

Thanks for the fast response! I was hoping from help from either gr5 or illuminarti and am grateful for both of your answers. illuminarti, The fan is definitely blowing air out of the duct onto the extruded plastic. I have not timed how much it slows down, but it gets pretty slow when printing the horns. I'll time it tomorrow and reply. gr5, Thanks for catching the odd wall thickness. I am still trying to figure out how you got the amazing prints in this thread: http://umforum.ultimaker.com/index.php?/topic/3038-can-your-ultimakerultimaker2-print-such-quality/ I'll try the print with 1.2 mm wall thickness and cleaned the kapton tape with alcohol. I forgot to add brim, but I expect the warping will be minimal with clean kapton tape. The filament is definitely the silver PLA from Ultimachine. I didn't correct the white balance for the lights I used for the pictures. I have white LED light bars surrounding the top of the printer. My wife calls it "The alien landing zone" since it seems to be lit like the ones you see in movies. It is great for seeing what the printer is doing, but not so great for capturing colors accurately. In any case, I have started another robot print and will let you know how it turned out when I get up tomorrow. Thanks again!