Hi guys. The prints are coming out pretty good so far. I'm still having issues with overhangs, bridges I just use support in Cura and then cut them away. Recently I started to notice that the spot where the head STARTS and STOPS the most outer layer (the one visible/outside one) it makes a small little "blob" that sticks out from the part. It doesn't do it all the time but sometimes it does it multiple times in the row. I will post pictures when the part is done. Any idea what is causing it???
it makes a small little "blob
Because of the springiness of the bowden and delays and such sometimes you get blobs - but usually at the *end* of a line segment - not the begining. Anyway - anywhere it pauses it can happen. The usual fix is to just slow down some more which reduces the pressure in the nozzle. For extra beautiful prints I've been doing 220C, 30mm/sec, .1mm layers.
But please, post a picture!
Ok here they are. Notice on the edges of this pyramid some layers have these "blobs" and some don't. Sometimes its few in row. Also what freaks me out when the printer starts to print the brim, it skips some lines. You can hear the feeder for PLA on the back sounds like skips and then I can see that the filament is not coming out and after a whole line it starts again and it does it couple of times during the brim (20 lines for brim). I definitely need to practice my overhnangs. They look horrible. Currently printing at 30mm/s 0.1mm layer at 220C
On top of that the tip of that pyramid looks like a blob of melted PLA....
The skipping on the first layer is almost certainly because the head is too close to the bed in some/all places. The plastic can't get out fast enough through the reduced gap, so the pressure in the head builds up until the extruder can't fight it anymore and it skips steps.
The tip is melted because the plastic doesn't have enough time to solidify before the next layer goes on top - or alternatively, if you are using a 'minimum layer time' setting the head is slowing down so much that it jsut sits over the part dumping heat into it, and keeping it molten.
The way around this last part is to be sure and set a minimum layer time of say 5 seconds, and then either a) to enable the cool head lift function in expert settings (which moves the head away to wait for the cooling time to elapse), or b ) print two or more parts at once, so the head can go do something else while it waits.
Thanks illuminarti. Note taken on that. So if there is too much pressure in the head then it will retract the material correct? How do you set it up in cura so it prints lets say two of the same parts layer by layer on both instead whole one part and then the other. Yes i noticed that at the very tip the head slows down quite a bit. What about these tiny blobs that stick out a tiny bit from the part when the layer is finished. I posted the picture. Thanks in advance.
To print multiple parts "all at once" you can set the gantry height to 0 in machine settings. That's a quick way.
The cool head lift is a very nice option for fixing the top.
One way to fix the bottom brim is to move the head a tiny tiny tiny bit away from the glass. Another way is to maybe print the bottom layer thicker. I usually print bottom layer .2 or .3 and the rest thinner. Did you do that? This can help a lot with that extruder slipping on the bottom layer.
Now finally - the blobs on the corner. Not certain how to fix that. I think it's probably caused because it slows down quite a bit at each corner from 30mm/sec along the edge to about 10mm/sec at the corner but the extruder still has pressure. Really not sure what to do. You could lower the speed to 10mm/sec of course but that just seems silly. Maybe lowering the acceleration to around 1000mm/sec would do it? And hopefully not slow down the print as much as lowering to 10mm/sec would! Raising or lowering temp might help: raising because pressures won't build up so much, lower because built up pressure is less likely to force out too much pla. Not sure what will happen.
Good morning guys. So the next print I will move the plate a little bit away. Also I have enable cooling of the head for the top layers. I have the top/bottom layer same as the shell @ 1.2 and the initial layer @ .2 I kept on printing on 60C bed and 230C head and the blobs just started showing recently. I will lower the acceleration speed from 5000 to 2000 and we will go from there.
So after changing the settings I did not noticed any difference. I was printing a different part that did not have a pointy tip so I can't comment on that. Still having these "blobs" when the layer is finished. I didn't see them on older prints and I didn't change anything...hmmm weird.
I was doing some more research for past few days. I'm really thinking about getting my own 3D printer. I don't want to spend 2 or 3k on it. I found a Reprap Prusa 2 that is below 1k and its a open project, lots of upgrades etc. Do you have any feedback about it? mostly about quality of the print. From the specs looks like it can do 0.1mm layers so thats what I'm doing on the UM2 now. Could I expect the same or close results with Reprap???? thanks
People say the quality of the UM machines is far better than repraps but I don't know if this is true. Prusa is a good design - very popular among reprap people.
go to meetup.com and look for reprap meetings and attend one. Check out their quality. There is one in the boston area once every 6 months or so - they are looking for a location for the next meeting. Also consider going to the NYC printshow next week. I will be there along with a few other's on this forum. And some Ultimaker people will be there. Check meetup.com to see if there are other reprap or 3d printing groups meeting in your area or between NYC and Boston.
$35 if you go only Saturday. Printrbot will be there - they make very inexpensive printers. Probably other's also. And you can introduce yourself to me. Pikey is going Saturday. Illuminarti and I will be there the whole time.
Tom, what were your settings on the simple planetary gears set?
thanks
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It took me few times to put it together with the right spacing between the modules. It's all together now and works flawless.
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