@chrishamm Thanks! Updated. I'll let it run for a while and see how it goes. I do run a VPN on the computer that is accessing the Duet board. I'll try switching that off and see if it behaves differently.
Posts made by mrehorstdmd
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RE: Note on updating firmware in older boards- check ajax retries!
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RE: Where to source reliable GT2 30T 10mm belt width pulleys?
My experience with cheap pulleys sourced from China is that the holes are either too large or off center resulting in unwanted motion of the printer mechanism. Idlers that have built-in bearings typically have very small, low quality bearings that won't last, and are likely to have the same off-center hole to mount the bearings. Filastruder sells Gates pulleys that are properly drilled for about $5 each.
If I wanted a toothed idler I would probably buy a Gates pulley, insert a shaft, and mount it in an assembly that uses larger ball bearings. Otherwise, if you don't need toothed idlers, stacked F608 bearings make great pulleys for 10mm belt. They are cheap and will probably last forever in a 3D printer. I've been using them in my printer for 6 or 7 years and they show no signs of problems.
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Note on updating firmware in older boards- check ajax retries!
My sand table uses a Duet2 wifi board. For a long time it had problems maintaining the wifi connection on multiple wifi systems using different routers. It couldn't stay connected for more than about 1 minute and 7 or 8 seconds. I decided to dig into it again and found mention of the ajax retries in the wifi troubleshooting wiki. I found that setting ajax retries from default 2 to 5 fixed the dropped wifi connection problem.
Yesterday I was commissioning a "new" (version 1.02 hardware) board for a new project and wanted to update the firmware from 2.05.1 to more recent stuff. I got it working on my network, and like the sand table, had to set ajax retries to 5 to get it to stay connected. I went through the recommended sequence on updating to 3.0, then 3.3, and finally 3.4.6 and found that when I updated to firmware 3.3 the ajax retries got reset back to 2 which caused the connection to drop every 1 minute and 7 or 8 seconds until I set it to 5 again.
My current network uses a mesh router that includes sandboxed 2.4 GHz IOT network that I was connecting the duet2 board to, so the router shouldn't be trying to tell the board to reconnect on a 5GHz network.
Is there some reason the default ajax retries is 2 and not some higher number, or is my situation somehow very different from typical?
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RE: how to join wires together?
@achrn get something like this to hold the wires as you hold the soldering iron with one hand and the solder with the other.
I typically put a single bend in each wire and hook them together, squeezing the bends tight, then solder, then shrink the tubing over them. Never fails.
Wagos are great, but they're big- not the sort of thing you want dangling from your extruder carriage. They are great for wiring the rest of the printer...
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Arrakis 2.0 Sand Table programmed for cat entertainment
My coffee table, aka Arrakis 2.0, is a servomotor powered coreXY mechanism that is normally used to magnetically drag a steel ball to create pretty patterns in sand. My cat enjoys chasing the ball, especially when the table is running a spiral erase pattern at 1000 mm/sec.
I decided to try to create patterns that she might like, so I wrote a spreadsheet that generates random motion of the type that attracts her attention. I enter the table dimensions, the desired speed range, and desired dwell time range and the spreadsheet creates gcode that causes the ball to move in random directions at random speeds and then stops for a random amount of time, before darting away, sort of like a small animal might behave. Ms. Kitty loves it!
The spreadsheet generates 500 lines of gcode that typically take about 16 minutes to run on the table, about 3x longer than Ms. Kitty's attention span.
More: blog post
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RE: Weird extrusion issue
@LeonMF It looks like both the extruders you mentioned are dual drive type.
Have you seen this: https://youtu.be/32dTLRNIYmw?si=d5yZB3FCSG-k59EY ? -
RE: Chamber circulation fan control
@travasky said in Chamber circulation fan control:
@mrehorstdmd how are you getting around the fans turning off / pulsing when the chamber hits the target temp? In the original machine fans were on 100% of the time the machine was on. In my case I'd like the ability to control them if I decide to print a material other than ABS for example. I added a heated bed to give me flexibility on materials instead of the plastic build plate that was passively heated on the original. Seems like a shame to not be able to use or not use the fans at will.
I don't. The fan turns on and off with the heater. The printer is tall and the heater/fan located at the bottom of the machine. I only heat to 50C when printing ABS and don't want a lot of air movement at the print, so for my printer, it's fine that the fan is low powered and doesn't spin continuously.
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RE: Chamber circulation fan control
@travasky I use one 500W Stratasys heater in my printer. I have the fan wired in parallel with the heater so that when the heater turns on, the fan runs. Those heaters will get scary hot without the fan(s), but you don't need a lot of air speed over them to keep them at safer temperatures. I used a 220VAC fan and run it from 117VAC. It turns slowly and quietly and moves just enough air without causing a hurricane inside the printer that might mess with the print.
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RE: Large 3D printer build! Hardware discussion and ideas
@Danny-Jay You haven't said how large the bed plates are, but 300 mm plates expand by about 0.5 mm when heated from 25 to 105C (ABS print temperature). The underlying support frame will not be as hot so it will expand much less. That's going to force something to flex, and that will move the bed plates in Z.
If you put each plate on a kinematic mount, and put the reference points at the center of the group, the plates will expand outward. The kinematic mounts will allow that expansion without forcing anything to flex. The spacing between the plates will remain almost exactly constant. You will need a hole in each plate at the reference adjuster and a short slot at the pitch adjuster aligned parallel to the X axis of the printer, and a screw that touches the bottom of each plate at the roll adjuster point. You'll also need springs to hold each plate down on the pitch and roll adjuster screws.
With this arrangement, heating one or two of the plates for a small print won't create any problems.
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RE: Large 3D printer build! Hardware discussion and ideas
@Danny-Jay I used 60 tooth drive pulleys for the Z axis in my printer which yields 20 um per full step, and I slew the Z axis at 15 mm/sec (I think it could do 20). Using 30 tooth pulleys would take that to 10 um per full step and slow it down a little. My printer uses two belts to lift the Z axis and measurements show belt stretch is inconsequential. If you use 4 belts instead of two you can expect less stretch. I haven't tested the limits, but I suspect that motor, running at 80% of rated current, could lift 30-40 kg without problems.
I don't think using flexible stud mounts for the bed plates is a good idea. If the studs flex, the plates will move in Z. It would be more stable to put the plates on kinematic mounts. They will be able to expand without bending anything and maintain constant Z position regardless of temperature. If you put the reference adjuster positions all near the center of the 4 plates, the plates will be free to expand outward. I would use kinematic mounts even if you plan to use bed flatness compensation.
In the pages linked above there are some updates- be sure to check them out as some changes were made after the original blog posts.
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RE: Large 3D printer build! Hardware discussion and ideas
@Danny-Jay said in Large 3D printer build! Hardware discussion and ideas:
brakes are an absolute necessity on this scale, the bed will crash down no matter what as soon as power is cut to the motors.
Have you considered using a belt lifted Z axis? I used a 30:1 worm gear reducer to stop bed movement when power to the z axis motor is cut. It's very simple- no brakes, no external motor drivers, and no fancy configuration are required. I run the motor at 1A (driven by the driver on the Duet 2 controller board) and it has no trouble lifting 7.5 kg (that's as far as I have tested it.). Running the motor closer to rated current will probably allow a very heavy load to be lifted. If you use 30 tooth pulleys you'll get 10 um movement per full step from the motor.
When power is cut, the bed doesn't move. It might jump a tiny bit when power is restored, but you should be able to resume prints with a minor z artifact at the point where power failed and was restored (assuming the print remained attached to the bed, and that you used a single motor to lift the bed).
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RE: Belt/idler issue and motors temperature
@Arminas Printed motor mounts and pulley blocks have a tendency to flex when you tension the belts. That can cause the motor shafts and pulley axles to tilt a bit, and that can cause the belt to miss-track. I can't see what everything looks like, but as a general rule, don't stand pulleys up on posts, especially if the posts are in plastic. Also don't design motor and pulley mounts to look like they are made of bent steel sheet. I design them starting from a solid block and remove only enough material to allow assembly, tool, and belt access. Make sure pulley axles are supported at the top and bottom.
If the printer is large, the belt tension can cause the frame to flex, too, especially if it is made from small cross-section t-slot.
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RE: Fast print results, what can I improve?
@claustro I'd check the drive pulleys to make sure they're firmly screwed to the motor shafts and then grab the hot-end and try to wiggle it. I should be pretty solid- if it wiggles easily that may be the source of the line pairs. It could be the way the hot end is attached to the extruder or the way the extruder is mounted on the carriage, or the carriage bearings on the X axis guide rail.
Under extrusion can be just slicer settings, or it could be you're trying to print too fast for the hot-end to keep up. What's the hot-end heater power rating?
The wavy perimeter lines could be a symptom of the underextrusion problem or could indicate some mechanical issue.
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RE: Fast print results, what can I improve?
@claustro The top of the cube looks under-extruded. Notice the lines are in pairs with wider gaps between pairs than between the lines that make up the pairs. That indicates there is some backlash or other mechanical problem.
The side of the cube looks a little rough. That may be due to a dual drive extruder in which the drive gears don't mesh properly.
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RE: Help for heated printing table
@bernardomattiucci Here's a company that makes good quality heaters- they sell via ebay, amazon, ali-express, etc.: https://www.keenovo.com/ They supply heaters with and without adhesive sheets. Get one without adhesive and use silicone to mount the heater on the plate.
Build-tak probably expands more than the aluminum when heated, and if the aluminum is thin it might cause it to bow if the build-tak is glued to the aluminum. A thicker aluminum plate would be less likely to have that problem. How are you attaching the 4mm plate to the thicker plate? Large prints stuck to the build-tak will shrink, even during printing, and may pull up the edges and corners of the 4mm sheet.
I would be very careful about operating the heater without it being pressed/glued into intimate contact with the aluminum plate. Any air between the heater and the aluminum may cause dangerously high temperatures to occur and burn up the heater.
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RE: Help for heated printing table
@bernardomattiucci Is that 8mm plate cast tooling plate? Regular aluminum sheet is rolled/extruded and will not be flat like cast plate. What will hold the 4mm sheet on the 8mm plate?
Is the 4mm sheet aluminum or steel? If you're thinking of flexing the 4mm sheet to release prints, you may have problems if it is aluminum- the first time you try to flex it, it may just stay bent. 4mm steel may be too thick to flex much.
I use an 8mm cast tooling plate bed on a kinematic mount with a 750W heater and 0.7mm PEI sheet glued to it. ABS, PLA, TPU, and PETG (haven't tried anything else) stick. I release prints (usually) after the plate has cooled using a sharp scraper and a few drops of IPA dropped along the edge of the print. I've been using the same PEI sheet for about 6 years, regluing it every few years. When I did the most recent reglue I sealed the edges with silicone which may prevent having to reglue it again.
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RE: Help for heated printing table
@bernardomattiucci This site will give an accurate estimate of heat-up time based on plate size and heater power: https://jscalc.io/calc/uS8JYjYISgIvzJ1x
While it seems wasteful to power the whole bed even for small prints, keep in mind that the bed runs at full power only until it heats up and then it starts turning on and off to maintain the set temperature. While it might run at 1200W for 10 minutes or so to get to print temperature, it probably only requires a few hundred watts to maintain that temperature. Slicers normally put prints at the center of the bed because it's the most evenly heated part of the bed where you can count on relative flatness and good print adhesion.
As @jens55 pointed out, if you heat a small part of the bed, the whole thing is going to warp. Make sure the bed is at print temperature before you probe and run mesh compensation.
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RE: Help for heated printing table
@bernardomattiucci The plate acts as a heatsink for the heater. If you don't attach it well at every point - i.e. no big air bubbles - the heater is liable to burn up.
I agree with @droftarts on using thick tooling plate. It is rigid, flat, and distributes heat well. The extra thermal mass will take longer to heat and cool, but you won't have to worry about Z artifacts due to rapid bed temperature changes. Use PID, not bang-bang, to control the bed temperature.
The heater should be the same size as the plate if possible. If you use a small heater, the cooler edges of the plate won't expand as much as the hotter center and the bed may bow unacceptably when heated.
Mount the heater on the plate using high temperature silicone so it won't detach after repeated heating and cooling. Mount a thermal cutoff on the heater (not the plate) to protect against fire if the if the adhesive lets go and the heater falls away from the plate.
A bed that large will expand about 1 mm when heated from room temp to 100C. Using a kinematic mount will allow the bed to expand without forcing it, or the support structure, to flex.
X axis sag will look like the bed has a hump on the mesh map. Make sure the X axis is rigid over its span.
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RE: dimensional inaccuracies in printed parts
@R006 If the belts and pulleys are not properly arranged you can see distorted prints. Does the distortion get worse when prints are near corners of the bed plate? Can you post a picture of the XY stage belt arrangement looking down on the machine?
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RE: Linear Rail X Gantry Support (MGN12)
@Dizzwold Thanks! Page 63, bottom right - smooth idlers should have diameter equivalent of the pitch diameter of a 40 tooth pulley. Page 18 shows the pitch diameter of a 40 tooth pulley (for 2mm pitch belt) is 25.46 mm. So the 608 bearings are a little small at 22 mm, but I haven't seen any issues with them.