madoverlord

Interesting. Another possible approach would be a small printed duct that deflects the airflow into the lee. That might get you more airflow where you want it. But quite frankly a fan would be about the same weight and give you much more cooling air.

@fns720: I only print in PLA.

fns720 -- looks lovely! I've been lurking in this thread for a while because I've been hideously busy with a KickStarter project but it is of great interest to me. I'm glad to see this topic is heating up again :cool: Perhaps the solution to the issue of uneven cooling in the "lee" of the printhead where it blocks the airflow is a small fan on the printhead that blows directly downwards. So the setup would be that the fan is on the left side (the reverse of fns720's setup) and the fan is mounted to the printhead on the right side, blowing directly down, perhaps with a duct. My current setup has two fans on the printhead, one in the standard position and one blowing down vertically as described above, and seems to work well. You can see it here: http://www.thingiverse.com/thing:164499 It is an accessory mount ring for the hot-end that makes it much easier to mount things to it, and it was designed with fans in mind.

Using the Cura infill to collimate the airflow is elegant; well done!

I'm going to get on the bandwagon and start experimenting with this. With regards to the side panels, probably the easiest construction method is going to be 4mm corrugated plastic sheet (basically plastic cardboard!) plus some small neodymium magnets located at the bolts; they should just pop on and off. I may play with some custom mounts so I can inset the panels.

Update: rebooting my machine fixed the mouse actions issue. Very strange.

Ah, well part 1 of the problem is fixed; somehow it decided I was using a UM2 instead of a UM1. Now the basic UI is working but I still can't select any objects on the printbed to move/rotate/resize them. All the other mouse actions (like changing the viewpoint) work fine.

No matter how I adjust the tension spring/bolt in my Ultimaker extruder, the filament is getting ground up, and plastic dust is getting drawn up into the bowden tube, resulting in an eventual jam. I've backed off the bolt so that the distance between the blue plastic block and the washer at the other side of the spring is 12.39mm and it's still happening. When initially feeding the filament (before it gets to the hot end, so no resistance) I can see very small dimples in the filament caused by the knurled bolt. What should I try next?

I am running OS X Mavericks. Cura 13.12 shows only Print speed under the Speed and Temperature part of Full Settings / Basic. I can't set the temperature. Also, I can't select objects once they are loaded. I went back to 13.10; it lets me set temperature but popups like Platform Adhesion type are stuck and don't work. I had to go all the way back to 13.06 in order to get a version where the UI worked for me. Bizarre! Any suggestions?

I've had good results with small drillbits -- mcmaster.com is as usual the place to go for stuff like this.

Nick, I'd suggest that you remove some of the insulation higher up on the hot end, so that some of the cooling air can get in there and mitigate any thermal creep. You might even want to heat-sink that area. One of the issues I ran into with the thermal sock was that it was too effective and extended the hot zone, leading to clogs. I had to redesign the sock so that it left the area above the hot-block exposed, and that eliminated the clogs.

You should just be able to print a passive duct/hood that modifies the airflow. It's won't have to get close to the hot-block to do the job. One trick I've used is to apply foil-tape (basically, aluminum foil with adhesive on one side) to the sides of the ductwork that face the hot-block. The foil reflects a lot of the IR, and conducts heat away from the parts closest to the hot-block (and into cooling airflow in this case). You can get within a few mm of the hot-block without issues. Not to mention my hot-end sock reduces heat-flow considerably. It will get up to full hot-block temperature eventually but it is so non-conductive that you can touch your finger to it for a second or two before it becomes uncomfortable.

Given that the hot-block doesn't block that much and is in any case moving (and usually diagonally), I doubt this is a significant problem. There might be some marginal improvement to be had by putting a passive duct (perhaps with a small fan) on the hot-end that redirects some of the air from above the plane down behind the hot-block.

Looks very interesting. Checking out crossflow fans has been on my todo list for a while, but I've been busy with a KickStarter. My mold for a standard hot-end thermal sock may come in handy...

Holy crap, that's an awesome idea! I will be updating my mold in a few days so that it doesn't cover the top of the hot block. The current design was reducing the temperature gradient too much, resulting in increase clogs. You can simply cut that area of the silicone away from the current version of course.

I'm sorry I was not clear. I was not talking about retracting the hot end, but moving the feeder up, so that the path from it to the melt chamber was increased, and thus the filament was sucked up. In other words, one solenoid is a ratchet that does the normal feed, and one solenoid quickly retracts the filament -- not the hot end.

Rereading this thread, a fairly insane idea occurred to me: how about a dual-solenoid system -- a solenoid-based feeder that pushes filament into the hot end, and a solenoid that retracts the entire feeder (!) to handle retraction. I'm thinking there may be mass issues, and also reaction forces when the retraction solenoid fires. But perhaps this will inspire someone.

I tried the cornstarch method and found it reduced the surface quality a bit. I also did a lot of experimenting with injection ports (I actually made a threaded port that fit the silicone tube) but in the end found it wasn't worth the complication. I tried cooking the mold at about 110F to speed up the cure and while that does worth, the increased rate of acetic acid release during curing can cause delamination of the mold -- you get plastic flakes adhering to the silicone that are a pain in the ass to remove. If you find the part hasn't fully cured when you open the outer mold, just reassemble it and wait. You can fix any surface imperfections later by just adding some new silicone.

Yes, it just locks naturally into place. I went through a bunch of iterations to get it to be a nice fit.

I got my Ultimaker in the spring, so v2 I would suppose.

I apologise for the delay in posting this, but I ended up doing all sorts of experiments before finalizing the design of the hot end thermal isolation sock. Here it is: http://www.thingiverse.com/thing:165750

Side note, I just published a hopefully useful hot end utility mount that does not interfere with either the sliding blocks or most existing fan mounts, and lets you mount things on all 4 sides of the hot end -- in particular, it makes it easy to mount vertical 40mm and 50mm fans. http://www.thingiverse.com/thing:164499

I've actually found them to be fairly accurate, especially when you have a load in the circuit. If you want to get things a little smoother, just put a ceramic cap in parallel.

Interesting. I put a voltmeter on the fan supply and to my surprise it provides 18v. I was under the impression it was a standard 12v supply. This means that the standard 50mm fan is being overvolted. To get 12v you set the fan speed to 150.

You should have no problems. I have a .55A (6.6W) 40mm fan that I have used in tests -- alas it screams like a jet engine.