Discussion in '3-D Printers' started by ddmckee54, Apr 27, 2018.
Keep the updates coming Don. I'm finding all this very interesting as well.
I stumbled across an interesting video Tuesday night, but I couldn't find the link today to save my soul. The video was the first part of rebuilding a Creality Ender to rival a Prusa Mk3 using a Duet board and other parts. That in itself was interesting, but the really interesting part was he redesigned the filament cooling fan shroud and how he tested it. He used a shallow pan of water on the print bed and brought the nozzle down low enough to see the air flow pattern in the surface of the water.
Well I said I was going to do some experimenting, so last night I did. My cooling fan shroud used to look like this, with the axial fan at the back of the printer.
I switched to this shroud when I got the blower to use instead of the axial fan. Again, the blower is on the back side of the printer just like the axial fan was.
As I said earlier I found that I had plenty of air movement, too much of that air was directed at the extruder hot block. In fact so much air was hitting the block that the heater couldn't maintain extruder temperature with the fan speed set at 60%. I had to lower the fan speed to about 10-15% in order to maintain extruder temperature.
When I first tested the shroud with the pan of water, I found that I also had plenty of air hitting the surface of the water. Unfortunately where the air streams hit the water was about 6-8mm away from the nozzle on all sides. Out came the aluminum foil and the masking tape and I started blocking off parts of the shroud openings. Bottom line, I've blocked off the entire opening on the back side of the hot block and I've blocked off all but about the from 8-10mm of the openings on both sides of the shroud. This gave me two indentations in the water about 6-8mm long on both sides of the nozzle, about 1-2mm away from it. Sorry, didn't think that I should have gotten some pictures of that until I was typing this - but I promise it did actually happen. (The checks in the mail too - just in case you're wondering.) I did find out that with the discharge blocked off as it is now I can maintain extruder temperature, even at 40-50% fan speed.
Anyway, this is what the next iteration of the filament cooling shroud will look like. I left the walls on both sides of the openings plenty thick and solid, about 1.5-2mm. Just in case I need to get out the file and do some more "adjusting" to the air flow later on.
We'll see if this works.
I changed the fan shroud over the weekend and repeated the water test to check the airflow with then new shroud.
I'm halfway there, the air from the right-hand discharge is hitting right where I want it to hit - at the tip of the nozzle. The left-hand side is still hitting about 6-8mm away from the tip. I can maintain extruder temperature with the fan running at 60% constantly and I can bump the fan speed up to 100% temporarily for bridging, just like you're supposed to do.
Definitely making progress, along with a bunch of junk prototype parts - but that's another topic.
I use foxit reader which has a beta program for showing 3d pdf files, I can rotate it but only see a solid black image.
I use Designspark for my 3D work, the price was right - free - so I'm not too sure about the "quality" of the PDF file that it generates. I'm able to "see" the file on several machines using the freebie Adobe runtime package.
I've been threatening to devote the time to learning Fusion but just haven't done it yet.
Been thinking about the checkering on the grips of the PPK and how I could 3D model/print that. While I was printing a part for another project I had a epifany, epipheny, brain fart. I got to wondering what a part that was printed with cubic infill would look like if you printed NO top layers. I whipped up a quick test part, 40mm X 40mm X 5mm with a 3.5mm dia. thru hole.
The attached file is is what I got. The best description I can think of is that it's kind of an inverted checkering. It's a crappy picture, and this was the BEST of the bunch. I covered part of it with a green highlighter to try and get a little better definition - didn't help THAT much.
I printed this with a 0.4mm extrusion width, 0.2mm layer thickness, 6 bottom layers, NO top layers, with 10 perimeters. This SHOULD give me about a 4mm border around the part, never did measure it to verify that. I don't think I could use this trick on any part that didn't have a flat top, at least not with my current Slic3r. I think that you can print multiple parts simultaneously with Simplify3D and use different slicing settings for each part. If you can print a solid part with infill, NO perimeters and NO top - this might allow you to sculpt the top of the infill.
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