aviphysics

Being 429 columns wide, the "machine_start_gcode" is a little difficult to read. Can Cura handle line continuations in this script?

Well, 16 € + domestic shipping as I'll be in USA in two weeks ;-) Great. Please PM me the payment details and shipping cost. PayPal is probably the easiest.

What tip for the Merlin are you using there? Also, I have found that the Merlin tip is very sensitive to crossflow fan airflow during the first millimeter of the print. Have you noticed this and if so, what work around have you used. The tip is my own design. A workshop made me a batch with 0.2, 0.4, 0.6 and 0.8 mm (which can be drilled to 1.0 mm). If you like to try they are 4 € / piece. I didn't notice the sensitiveness so far. But it makes some sense as the heated mass of the nozzle is so low. However, I always tried to extend the heating block isolation thing some mm downwards to reduce the airflow hitting the nozzle. I bet replacing the steel tip with copper or brass probably also helps. Otherwise been really enjoying this hot end. Bridging and overhang performance is downright fantastic. How much for a full set of tips shipped to California USA?

Made a hardware work around for the low initial voltage problem for my crossflow fan. Now I am wishing that I could set a custom fan ramp curve, as the crossflow fan airflow is a lot more focused during the first few millimeters (when the platform is there to contain the airflow.

What tip for the Merlin are you using there? Also, I have found that the Merlin tip is very sensitive to crossflow fan airflow during the first millimeter of the print. Have you noticed this and if so, what work around have you used.

That could help, but some fans simply don't run below a certain threshold.

Time to maximum fan speed would be nice. I feel like the ramp rate for fan speed on a lot of my prints are due to how quickly the hot end can adjust to the increased airflow/cooling. This seems more layer than time dependent. Also, being able to set the minimum percentage for the fan to start spinning would be helpful.

Bug? Is the fan speed supposed to go up and down every few layers? Edit Nevermind: I had just inverted the fan min/max speed settings. Woops.

What happened to the ability to alter the start and stop gcode? It is kind of necessary if you are using a custom extruder and need to change the initial extrude or retract settings. Also, on some prints I prefer the printer to not cool everything down right away and with my current print head, I find it necessary to add an extra pause for the head to fully come up to temperature. Edit: I found what appears to be the start and stop g-code in "C:\Program Files (x86)\Cura_15.06.01\resources\settings" in the *.json files; however, when I created a printer with a custom name, it didn't create a new file in this folder, so it seems like this might not be the file to edit. Is there another folder somewhere with the stored settings?

Ok I wasn't able to get the original modular Merlin mount to work, so I just designed one with the correct dimensions and that part is taken care of. However, It seems like the hole in the top cap of the merlin hot end is a little to small to fully retract the filament through. Currently I have to unscrew the plastic part and clip off the melted portion before I can retract the filament back through the cap.

I made an adjustable mount for the papst QG030 series fans. It is a little rough and heavy handed, but seems functional. https://www.youmagine.com/designs/umo-papst-crossflow-adjustable-mount

Heating the aluminum part was a good idea. I had tried heating the plastic and pressing against the aluminum. Seems like heating the aluminum would be better.

Was trying the Merlin was the modular printhead and it doesn't seam to fit the groove profile. My Ubis Hotend perfectly fits the Ubis version, which I printed at the same time. I also found that the groove profile in the Nema 8 worm gear version is slightly different and seems to fit correctly. I am wondering if there was a change in the Merlin mount profile at some point. BTW, for I have also found that the Merlin Hotend needs a little extra time for the tip to come up to temperature, after the thermistor is up to temperature. Seems like the start code could use a 1 or 2 minute pause before printing.

I made some "C" shaped spacers. They seem to work great and you don't have to take much apart to install (I did have to loosen a bearing on one side to squeeze the second spacer in.) Sorry, I didn't publish them just because I am not using the normal sprockets and didn't want to confuse anyone. They are pretty simple to make.

Looks nice.

So, it worked for around 30 seconds. Then I think it basically started to melt. Also, when a used a reamer to widen the bearing holes, I think I got them a little to far to one side. It seems like filament drive gear is a little too far away from the hole, Basically, I think my part failed in almost every way it could have; however, from the brief period it was working, the potential of the design looks amazing. Time to go back and reprint in a higher temperature material. I also found that coating the purchase for the spring in epoxy helped give it a little more durability. Going to make some small changes to the design while I am at it.

Finally finished assembly and briefly test the extruder. It seems functional. I accidentally cracked the main body of the assemble, but it seems structurally stable. Going forward for now and will reprint later. Still need to figure out a filament guide.

Never mind about the cotton. There seems to be a risk of ignition as low as 210 C. Wool is just slightly better. Seems I need to drop by the hardware store for some fiberglass.

The insulation sock slipped off during an unattended print and then filled up with PLA. On top of that, the filament seems to have been overheated and isn't softening in boiling water (which normally PLA seems to do quite nicely. Two things. 1) How necessary is the insulation sock and what would be a suitable replacement? Maybe a strip of an old 100% cotton sock secured with heat shrink? 2) The overheated plastic seems to be super strong. I wonder if there is any way to heat treat printed parts without completely melting them.

I have some PETG from Gizmodorks that I was thinking of trying. I also have some ABS, but I was waiting until I can dedicate a hot end for it. Don't want to deal with some of the fowling issues that people reported happening when you change from a high temp to low temp filament.

I increased the stand off distance, which seems to have helped. I also added some aluminum foil across the top of the plastic body, where the motor mounts, to reflect some of the radiant heat and distribute what heat comes through the 2mm screws. The initial results look okay. The plastic still gets a little warm, buy does not seem to soften too much. Not sure if it will hold up in the long run.

I got around to hooking up the 0.8 Amp Nema 8 stepper today. The assembly seems to work, but the stepper motor started to melt the PLA, despite the 2 mm nuts I was using as standoffs. I will try cutting back on the current some, but I think the design either needs a higher temperature plastic, or needs a fan. I have some alternative plastic on hand, but don't know when I will get around to trying it. For now, will just try adding a fan.

Hi Jason I haven't had time to test out my configuration and I think it will need a little work. There was talk of switching to 1.75mm filament, which would require less force and thus smaller gear ratio. It might be worth working on that or waiting for a design revision. I will say, I recommend a larger diameter axle. The 3 mm rod seems to have a small amount of flex. 4 or 5 mm is what I plan to use in my next design.

I think it used to happen only when the head was moving. Now it happens with the head just sitting there. The problem has been slowly getting progressively worse for a while, until today when it seems to have completely failed. I will have to try your test later. With the thing not working, I decided to take off the hot end and finally give the UBIS a try. The UBIS is working really great. I setup the UBIS to run on the same cables that the stock hotend did, so it seems like they aren't the problem. As a side bonus, it seems like this was also probably the source of my stringing issues. I am guessing that the hot end was probably running way too hot, due to the malfunctioning sensor. I had previously noticed buldging in the last 30 mm of filament, when I removed it from the hot end (which had also been getting progressively worse), which I am guessing might mean the stock hot end is somewhat wrecked.

The temperature sensor on my UMO seems to have given out. It uses the sensor the the TC2 board. The sensor will hold for a minute at 180 C (the set point) and will then begin to fluctuate, until the fluctuations get so big that the I get a max temperature error. From what I can tell by looking at the filament, the actual hot end temperature is not running high. I tried separating the thermocouple wires from the hot end and fan wires, as much as possible. This had no effect. I tried reseating the connectors and the thermocouple wires. This had no effect. I inspected the sensor for poor solder joints. It looks fine, though I haven't used an iron to reheat and reseat the joints. My guess is that the thermocouple wire is broken some place, though I am not sure how that would cause a reading to go high. What do I need to do to fix this?