Issues with warping.

I am getting some pretty amazing prints from my "trusty" Robo printer. The only issue I seem to have is warping at the ends of a longer print (over 4" long). If doesn't matter what material I use, and the part is stuck hard to the Boro Glass, but the ends will warp up tremendously. I was wondering how to adjust for this. My first thought is to increase the flow so as it cools, It doesn't pull tight, but I think this will lend itself to other problems (calibration, size, etc….). Anyways, I am seeing a lot of warping with both PLA and ABS (although ABS seems to be worse). One further sign I may need to fix/adjust/clean something, is when I am at idle (nozzle heated up), I get oozing from the tip (servo not turning). The very first print I did, the printer started in the upper left corner (0,0) and drew a line right from the start. Now, it takes it almost a 1/4 of the way around the first loop before material starts to lay down. After that, I do get pretty good prints.

As far as keeping the part to the glass, I have found that a good cleaning with soap and water between prints, and a light to medium layer of Aquanet hairspray…. Seems to do the trick, although "first layer height" seems to also be a strong key to success.

and one last question,… What is the fan for? Should I be using it? if so, when and where.

 

Fan is used to keep the hot end temperature regulated. Repetier will automatically turn it on depending on hot end temperatures.

For warping a mod you could do is a part fan where you have a fan blowing cool air on the printed part. The faster local cooling should help prevent warping. I get the same thing where my nozzle takes about 1/4 of the first skirt to start flowing. This is why I do 2 skirts.

I don't bother cleaning the hairspray off between prints. I do quite a few just spraying a bit more down each time. Maybe scrape it every 2-3 days or so.

 

I'm the same way Mike. I'll make sure to get the major of the offensive plastic up, but in general I only do a full clean the glass every few prints.

I will note that I don't think Repetier is turning on the fan by default unless you tell it to. So as it stands it just sits there. Even at that if it is designed to cool the hot head it really is spilling over the print a lot which has made my nerve to actually try and work it into my prints. I've not seem to need it so far.

 

Thanks so much for the quick response guys. I have seen (on thingiverse) different models of a fan shroud for this very purpose. I just thought it was for nylon printing.....

 

Thanks! What temps can I experiment with? I currently have my bed start at 110c and drop to 90c after the first layer.

 

reading your lot about warping gives me hope as having had my printer for a month I am still to get a print off complete with 1. difficulty getting it to stick, and two when I do it warps itself off the bed. I am using 210/85degrees for extruder/printer as advised, have tried hairspray, abs juice and both on glass with NO traction and after several attempts with tape found a load of abs juice (abs & acetone) I do get traction but only for 3-7slices by which time it warps off the heatbed. It reads as if i need to bump the temp a lot higher -100? I have stuck with Robo emails for advice BUT IT IS NOT WORKING......... small scream of insanity inserted 'here'. All feedback welcome.

 

Matt, after venting my frustration with 'youall' I lifted the heatbed to 100 up from 80 and excellent stick and print completion. phew! Tape and abs slurry for traction. Now some technical issues .....I start should start a new thread?)..... thanks

 

Matt, my relief was short lived as I cannot repeat my one-off success. Excuse my training wheels but how does one 'do' a raft? And the fan can be turned off from manual controls if turned on at manual controls however it (the fan) operates independently apart from that - or mine does. I was going to print the world today and have a buckets of scrap to show for it. I am using ABS Reprapper because I picked up half dozen rolls well priced at auctions, not being aware PLA is a learners preference. Gold mining requires some heavy digging - spade in hand!

 

the raft is turned on under "support material" on the slicer tab. I had to use it today for the first time myself printing a part with a very small, staggered base area. It creates a material "shadow" under the part. You can increase the levels to raise it up more. It also makes breaking the part off the bed substantially easier as you aren't worry about damaging the part, just the raft.

You can turn the raft on without turning on supporting material btw. I found this out about an hour into a part, realizing I just wasted 20 minutes doing nothing but printing worthless filler.

 

In no way am I to be portrayed as the expert in this field..... But here is what I have found to work the best for me.

First of all, you MUST" get the "Z" height set correctly. Without this step.... Nothing will stick.
For me, this was a little confusing at first... So after I figured this out, I thought I should share my results.... I am getting fantastic prints.... With one exception..... when I go high (tall prints), it appears to me the printer shakes too much up there....and the print quality goes down......making me realize the vertical rods need support......

Back to setting your "Z" height correctly.

1. First of all, understand that there is two vertical threaded rods inside our printer, one on the left, and one on the right.
2. Home your machine (all axes).... The carriage will be on the LEFT. Push the "+100" button on the X axes button TWICE (moving it 200mm to the right side). Leave it there for the moment.
3. Remember, you should "ONLY" ever adjust the left threaded rod manually, and "ONLY" after you have the right side set correctly.
4. Behind the right rod, there is the "Z" height adjustment screw. If you turn it counterclockwise, you will LOWER the nozzle, and if you turn it clockwise, you will RAISE the nozzle.
5. Hit the "Z" axes Home button (not the home all button). Your printer will jump up and down slightly.
Try to slide a sheet of thin paper (I use a sticky note, which measures about .13mm (.005")) under the nozzle. It should go under, but not easily. if it is too tight, screw the "z" adjustment screw clockwise approx 1/5 of a turn and try again (turn counter clockwise if it is too loose). REPEAT the HOME Z AXES after each adjustment BEFORE you try your paper fit. Once you have it set so a thin paper will go under without moving the print head, but a thicker piece of paper will not, you are close.
6. Once you have your "RIGHT" side automatically set (it gets set properly via Homing).... THEN move your carriage all the way to the left side (you can hit the -100 button twice, or hit the Home only the X axes button)
7. Using the same paper, try to get it under your nozzle on the left side. if it is too loose, MANUALLY turn your threaded rod counter clockwise (if it is too tight, turn it clockwise) until your paper is set to the exact same way.
8. Your printer is now level. your printer will now home one more time once you hit the "RUN" button and should print really good. you should NOT need to adjust this unless your printer crashes....etc...
9. Now for the sad part... you will have to do this often....at least set the right side with the setting screw (the left side should follow). Almost every time you decide to use your printer..... because the homing switch isn't perfectly accurate.

One other note, as Mike Kelly, and Ben Lindstrom pointed out, there is a very important trick (second and third post in this thread). Don't, clean your class between prints, only once in awhile. Scrape off any plastic, and then spray more hairspray, turn your heated bed on (if you have one) for 3 or 4 minutes, only to dry the hairspray. When you do clean your glass, do this a couple of times before printing (2 coats). I can print really well, with NO warping with PLA this way. As far as ABS.... the verdict is still out.... I am interested in trying the new bed temps mentioned here, just haven't had a chance yet.

 

one additional ting I forgot to mention:

I print at .2mm, but as you may have already read, the "DEFAULT" setting for repeater for the first layer is .35mm. You MUST set this to the same setting (in my case .2mm works really well, and probably should be even a little less because of "Squishing of the first layer). It isn't really clear here, at least not for me initially.

 

I also find these items at thingiverse really helpful as test prints.

First is the bed leveling print:
http://www.thingiverse.com/thing:15709

This prints a single layer print. You can look for warping and check the height of the first layer.

Second is the Circles Calibration print
http://www.thingiverse.com/thing:12259

It prints 3 circles. One fully hollow, one hollow but with a top and a third solid. Since it's three objects in one it also tests bridging.

Last is the Hollow Calibration Pyramid
http://www.thingiverse.com/thing:8757

It'll show you how well overhangs do. The top is tricky since it's so small. My understanding is pretty much no one prints it perfectly but you can get darn close.