lars86
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Posts posted by lars86
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Also, your pulleys could have runout.
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So I managed to get it working, the problem was indeed the bearings getting pinched. However, I now face my next problem. The holes are not round when it prints circular items. Any ideas on what could cause this? The old setup printed perfectly round holes.
I have never tested it, but I would imagine that having mismatched X and Y acceleration settings could do this. Worth checking if you have changed them.
What is your print speed?
You could try slowing the print down to like 20 mm/s and see what the result is.
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It sounds like the bouncing over sparse infill is a result of the force generated between the molten filament leaving the nozzle and the printed part. If the printing speed and infill spacing set up a frequency that resonates in the bed assembly, it could definitely be amplified. In that case, stiffening the bed will change the resonant frequencies and could help the issue. It is not going to help the collision with a curled up, cooled portion of the print, so that is probably solved best in its own thread.
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Am I crazy, or is there no way to edit a post via mobile browser?
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To me it seems more like the bottom of the nozzle going over the print of the plastic itself... Sometimes with a lot of retractions etc it creates "hills" on top of the print that are a bit higher than where the head is positioned at. If it moves over it bounces the bed up and down.
I'd have to hear the actual sound being made to compare it to what I've experienced a multitude of times, but it sure looks the same visually.
If you are experiencing the bed bouncing during feed moves, you are over extruding.
This bouncing motion in my video is purely a result of Z layer change motion.
I do think it is possible to have a bed supported at both ends and achieve a high level of quality. It's a bit more complicated than its worth though, I think.
Simply stiffening the platform is pretty easy.
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No one else has an opinion?
Ooze is definitely time dependant, and since rapid travel speeds are fixed and known, you can just evaluate the length of the rapid move, and apply a variable retract distance which ensures the retract move is completed within the rapid move.
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Here's a quick video I shot in super slow mo, that shows the judder in the bed during a layer change:
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I don't like to contradict @lars86, you may have your reasons, but i didn't faced that problem and I think the only reason to tighten your screws that much is the fear that the screws could loose more and more. in that case I would suggest spring washers, as - in my eyes - everyone should use at moving parts.
Too many variables to just say you can or can't fully tighten the bolts on a clamp style XY block.
Even if you are printing the exact same model as someone else, the calibration of the extruder, XY steppers, flow rate, filament size, etc, means that the size of the bore you print will vary. It's possible that the XY block halves seat against one another before exerting much force on the bushing. It is also possible that the bore touches the bushing first, in which case, a large force can be put on the bushing for a very small torque on the bolt (this is why we love threaded fasteners!)
What can be said without question, is that the bushings are extremely prone to deformation and binding (even the amount of force needed to compress a spring washer). It is an easy test to loosen the bolts and look for an improvement in the force needed to move the print head.
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Also, having the 6mm rods out of square with the 8mm's will cause bind.
Try out my squaring arms: https://ultimaker.com/en/community/view/15770-lars-xy-axis-square
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Well, I spent all afternoon on this. So, first problem...the rods i bought are a different size! They are I think h6, 8mm. So the bearings etc take some force to get on. I got past that however. The bronze guide bearings seem ok, still pretty loose. However, on assembling it all with the new xy blocks, its all super stiff...cant move properly. I'm trying to troubleshoot now. If I loosen the 6mm rod points on the XY blocks, it gets much easier to move around. Maybe its an alignment problem on the print head. The old system was maybe more forgiving?
Macua, the bronze bushings are super prone to being distorted by the XY blocks. If they involve a bolt that clamps the XY block together, it needs to be almost finger tight. I ended up adding some super glue to restrain the bushing while avoiding any real clamping.
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I decided to whip up a Solidworks static simulation to illustrate the concept. I used the STP file for the build platform from the Github repository and applied 6061-T6 as the material.
Here is the intended modification. Twin .75"x.75" aluminum angle, bolted to the underside:
For the simulation, I simply fixed the linear bearing mounting features ( a simplification, but a good representation), applied gravity, and applied a 1lb point force near the front of the bed.
Here are the displacement charts with a 50x exaggeration and equal color scaling:
Original:
Braced:
The braces reduce deflection by nearly 90% in this situation. Are these numbers directly applicable to printing? No. Is a stiffer platform going to give you more consistent prints? Yes.
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Have you guys scrutinized the concentricity of the pulleys? That is my biggest concern, because once fastened to the rods, if there is any eccentricity to the cogged surface, the print head motion will have sinusoidal accel / decel instead of constant velocity.
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I'm not sure that there is a problem. The bed holds it's position for months of printing without needing re-leveling even though sometimes I have to wack the parts off the bed using my palm as a hammer and a putty knife to apply the pressure with enough force to slide the printer a foot across the table.
So, you are describing the repeatability of the leveling system / support springs. The 4mm platform is the base for that, so yes, it can stand up to a beating without plastically deforming, but that doesn't speak to its dynamic stability.
When we are trying to print say a 0.1mm layer height, how much of a deviation in Z height of the nozzle do you think it takes to either swell or contract the width of the bead you are laying down? I would guess that even a 25% change would produce a visible artifact. That is only 25 microns, or around 0.001" for us yanks.
Not only do you have an interaction between the nozzle/filament bead and the part/bed which can cause movement, or excite vibrations, but also the rapid changes in Z height from layer change or Z hop moves. To a lessor extent, you even have the printed part's weight increasing throughout the print, and adding to deflection of the bed.
The temptation is to print right at the front of the bed, in the middle... which is literally the worst place to print for machine rigidity. The best bet would be at either back corner, where deflection of the bed, lash from the Z bearings, and flex of the 8mm and 6mm rods is minimized.
Here is a quick video to illustrate specifically the cantilevered deflection of the bed platform. I'll check again after my modifications sometime next week. (I'm going to the RAPID conference in LA early next week, woohoo!!)
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I ordered 2 ft of each to test out.
Right now I'm actually running a very short, over-head extruder drive setup. It has many benefits, but is a little tricky to execute. I'm having trouble mounting the drive in a way that allows enough movement as the print head tracks around, without allowing too much.
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Hi guys,
Has anyone experimented with different types of tubing for the bowden?
Both of these look like they could be good alternatives:
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Yeah, just got my quote today. Shipping is a little high.
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Probably the biggest shortcoming I've found so far is the bed platform's bending stiffness. 4mm aluminum plate cantilevered out 12" just isn't up to my standard for stiffness.
Luckily, it's a pretty easy modification with the way it is designed.
I'm thinking about mounting two pieces of aluminum angle stock on the underside, so that it spans from a front corner, to the inside edge of a linear bearing. This will really improve the stiffness.
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My bed is holding a steady temp, so I'm not too concerned about running autotune now. It sure takes a while to hit 90* though!
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- I know that the latest Cura has a compatible firmware build, but was wondering if using this builder would be equivalent: http://marlinbuilder.robotfuzz.com/
I have a few other tweaks; custom extruder drive, direct drive XY, and a bunch of custom parameters for accel, jerk, etc.
The best thing you maybe can do is to download the UMO HBK Marlin version from the Github repository and modifiy the configuration.h file with your tweaks. Then you can directly build and upload the firmware with the Arduino Software. In order to find out how you have to modify the configuration.h file you can download the zip file of your current configuration from Robotfuzz-Marlinbuilder which also includes a configuration.h file. But you cannot use this file directly out of the same reasons you already figured out.
If you are working with Windows I can recommend Winmerge for comparing the two configuration.h files and move information/settings from one to the other.
Agreed. I went ahead last night and modified the new official release. It's really not bad at all, thanks to the write-ups by members of our community. Thanks GR5!
I tried to do a PID autotune on my bed last night and ran into two issues. First was a timeout. It was definitely heating, but seemed to struggle to hit the commanded 90* from ambient. I immediately restarted the processes and it seemed to be working.
Then I decided that I wanted to preheat the nozzle while that was happening, so on the UC, I turned it on. The set point showed up but the nozzle didn't begin to heat, seemingly from a conflict with Pronterface having control. The Bed autotune continued for a couple minutes, but then gave me a heating failed error, which also showed up on the UC display. Not sure if that was my fault.
Also, during the autotune, the bed temp display in pronterface didn't update in realtime like it has with the nozzle in the past. Not sure why.
Man, I forgot how aggressive the stock XY accel settings are! The Z accel of 100 is pretty soft though, and 300 has worked well so far.
- I know that the latest Cura has a compatible firmware build, but was wondering if using this builder would be equivalent: http://marlinbuilder.robotfuzz.com/
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It's a little more clear in the readme:
For gen6/gen7 and sanguinololu the Sanguino directory in the Marlin dir needs to be copied to the arduino environment.copy ArduinoAddons\Arduino_x.x.x\sanguino \hardware\Sanguino
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Maybe you could also help me better understand adding the files to the Arduino environment.
Install the arduino software IDE/toolset v23 (Some configurations also work with 1.x.x) http://www.arduino.cc/en/Main/SoftwareDownload the Marlin firmware https://github.com/ErikZalm/Marlin/tree/Marlin_v1 Use the "Download Zip" button on the right.
For gen6/gen7 and sanguinololu the Sanguino directory in the Marlin dir needs to be copied to the arduino environment. copy ArduinoAddons\Arduino_x.x.x\sanguino \hardware\Sanguino
Start the arduino IDE. Select Tools -> Board -> Arduino Mega 2560 or your microcontroller Select the correct serial port in Tools ->Serial Port Open Marlin.pde
It just says copy the files. Copy them where?
I have this similar folder: Program Files (x86)\Arduino\hardware\arduino\avr
But copying the files there would overwrite boards.txt
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robotfuzz is incompatible with the pt100 found in the heated bed. However you can use this marlin builder:
Unfortunately it has MANY fewer options :(
To make a dump of your current firmware you need to know what version it is. I don't remember if you can determine it on the ulticontroller. You basically have to know where the hex file is that created it. You can get tons of old firmware versions from all the old curas here:
Thanks gr5!
Unfortunately, I just found that out on my own
The control gave me a max bed temp error and showed the wrong idle temp.I flashed the stock firmware via Cura, and everything looks good, bed heats... I just can't use it because of my direct drive.
How does that builder compare to the official firmware base? Would I be better off editing the official? It's been forever since I compiled a firmware build and remember very little.
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Some questions:
- I know that the latest Cura has a compatible firmware build, but was wondering if using this builder would be equivalent: http://marlinbuilder.robotfuzz.com/
I have a few other tweaks; custom extruder drive, direct drive XY, and a bunch of custom parameters for accel, jerk, etc.
- Is there a way to make a dump of my current firmware as a backup?
Anyone?
- I know that the latest Cura has a compatible firmware build, but was wondering if using this builder would be equivalent: http://marlinbuilder.robotfuzz.com/
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There is definitely a decent amount of backlash in the lead screw.
Yes, you have gravity working to help take up backlash, but giving it a bit of help is good insurance against forces that would exploit the backlash, like the linear bearings sticking on reversal (which mine do).
Official Heated Bed Upgrade Kit: Ultimaker Original
in Third party products & modifications
Posted
Yes, those settings are available to tune during a print, but really they would be just a bandaid for the real issue: a lack of platform rigidity.
Z jerk, accel, and velocity should be tuned in order to give clean crisp motion without missing steps or causing the print head to dwell long enough to scar the print.
The platform should be stiff enough to accommodate the tuned Z motion without excessive flex or resonance.
I used to have a big chunk of weight glued under my original bed to lower the resonance. I actually think that the original platform was stiffer despite being wood. It had a FAR taller aspect ratio.