Fan Shroud Printing Problems

[ebasch]

I have Printrbot Simple Metal with a heated bed (put together form a kit) . I have been playing with it for a few days with only a little bit of success. I finally was able to print a decent 3mm box with help from Printrbot support in the form of an ini file for Cura. The problem I am having is printing the fan shroud. The base prints well but the layers don't seem adhere to each other as the layers go up.

I am using Cura. I am brand new to 3D printing, so I don't have any gcode or slicing experience. I am simply using the provided .stl file from the printrbot site with the settings that worked for my test box.

I am printing at 220 with the bed at 70. I thought this was pretty hot but it was what was suggested and it printed the box well. I have set my z axis but have not made any changes to x and y. I got a perfect print of the 3mm test box.

Does anyone have any ideas of what I should try? I am so frustrated!

IMG_20150317_174215862_HDR.jpg

[SpannerHands]

Repeat the set-up process (the M501 command stuff) with and lower Z another 0.1mm looks to me that your running a little high of the bed....

[ebasch]

Do you typically have to change the Z depending on the print? I am asking because the small test square seems to print well...then....
also, does Z tend to shift after 5-10 prints where you have to reset it?

[SpannerHands]

[ebasch]

I feel like I am never going to gt there. Still holes. I guess all there is to do is continue to lower Z by .1 each print until I can see that it adhere....right? I guess if it does not, then I have another problem?

So, it is just the overhang since the other side which isn't at so much of an angle looks really good.

Thanks for being patient with me as I learn.

[RetireeJay]

There are lots of posts about bed adherence. Be sure your surface is clean, clean, clean; invisible fingerprints will ruin the adhesion. Wipe down the surface with isopropyl alcohol and let it dry before printing.

It looks like you may be under-extruding a bit; you may need to work on your calibration. The calibrations for X, Y, and Z should be correct from the factory, but you should check your extruder calibration (steps per millimeter) (there are plenty of posts that say how). Also, measure the actual diameter of your filament with a digital caliper and use that in your slicer. Note that filament is generally not perfectly round, so measure both the smallest and largest "diameter" and take the average.

[ebasch]

IMG_20150318_171547698.jpgOk, so here are the starts of the fan shroud with changing the Z axis to be closer to the bed by .1 for each print. If anytihng, the -.6 looks better than the -.8. I am not sure if I should go any lower.....Maybe higher. Maybe thicker walls?

There were printed at at .15, shell thickness .8, 30 print speed, temp 210 and 70 for the bed.

I can look into callebrating the extruder. I have increased the tension on the aluminum bearings and nut...but that is it. I put this together over the weekend...so it did not come assembled from the factory. The filament is indeed. 1.75 I am using Cura and not Repetier with a separate slicing. I couldn't figure how to get that to operate my printrbot. Cura seems easier.

Did any of you out there have success with printing the fan shroud and if so, what were the settings in Cura?

[SpannerHands]

Have a look at this:

http://help.printrbot.com/Answers/View/ ... +with+Cura

[PxT]

Are your prints adhering well to the bed and then only failing once you get to the higher layers? If so, I think the initial Z height is probably fine. Pretty much the only thing that is going to affect is how well the first couple of layers stick.

I agree with RJ, start with your extruder calibration and make sure that is dialed in -- i.e. when you manually extrude 30mm via software has 30mm of filament actually entered the top of the extruder? Make a mark on the incoming filament and measure the distance to it before and after from a fixed point. You should use a pair of digital calipers for this if at all possible. You can get a cheap pair for $10 - $15 online or at somewhere like Harbor Freight, they will be plenty accurate enough for our purposes and can be used to measure your filament diameter as well.

Also 220 is on the high end for printing PLA. Which brand are you using? I might go down to around 185 - 190 to start. Try extruding a few tens of millimeters and see if it comes out clean & smooth. Increment up by 5 degrees at a time if your extruder seems to be struggling. The tension on the bearing should be set so that the top of the nut is right at the top of of the cutout - see picture #2 on this page: http://printrbot.com/shop/assembled-simple-metal/

Let us know the results of your 30mm test.

[ebasch]

You are all awesome....!

So, I am back to -.6 or -.7 because I think I get the best base prints of the shroud from that. Layers stick together, no curling good bed adhesion.
I am NOT having adhesion problems at all. So I htink that settles the z question.
I do think I am having an extrusion problem.

I have increased the flow % to 105 and it looks a lot better.I had the friction nut as high as it could go but now I loosened it a little thinking I would get more filament. I don't know if that is correct. Would more tension be MORE or LESS extrusion. I would have thought LESS....but maybe that is wrong.

I am printing at 210 with the bed at 70 but if you think changing that would make the walls of the shroud stick together better, I am all for that. I am using the prinrbot filament that came with my kit. I measured it and it looks to be correctly 1.75

The finished print that I did of the shroud with 105% flow and LESS tension on the spring came out with many fewer holes

I reset the tension it as shown in the picture and did the 30mm test...It looks like it extruded a little more than 30mm (like by 2-3mm...maybe). Do you know if the flow % is used at all when you do a manual extrusion? Changing the position of the nut in the channel for the filament tension did not have any affect on the amount extruded...which seems weird.

I will try the print again with a highter flow % and see what happens. Is there some other hardware on the extruder to play with to change the flow?

[RetireeJay]

The intent of the design of the extruder is for it to deliver a consistent quantity of filament based on the diameter of the shaft with the sharp "gear teeth." It can't possibly deliver more than what the shaft calls for (circumference of shaft = mm of filament delivered per turn of the shaft). If it is delivering less, then you have the teeth slipping on the filament, and that won't be consistent. So the bottom line is, don't try to tweak the flow with mechanical adjustments.

Do make sure your slicer is using 1.75mm as the filament diameter.

If your extruder is delivering MORE than the requested amount, then it's curious why you have seeming under-extrusion.

Am I correct that your layer thickness is 0.15? You might try a little more, like 0.2 or 0.25. And can you tell if Cura is generating more than one shell trace per layer? 0.8mm shell would be awfully fat for a single trace. I use Slic3r, so I'm a little unfamiliar with how Cura works.

[ebasch]

Ok, here is the deal... I have decided that I do NOT have a problem with my printer extrusion (or anything else). I think the problem lies in the design of this particular shroud. Why printrbot has decided to point to this one of the first things to print for people brand new to 3d printing is beyond me. The angle is just too steep to print without supports (in my opinion). After at least 20 attempts with different settings, clearly, I can't do it... and it is ridiculous that I wasted so much time thinking the problem was mine. I have downloaded a different shroud (forum won't let me post the link) and I am currently printing it out ...lesson learned ....I will happily post my pic once (if) it succesfully completes. Thank you all so much for your patience and suggestions Keep your fingers crossed for me!!!

And Here It is, no holes, no problems!!!!!!!!!!

[PxT]

[ebasch]

Thank you. I just heard back from printrbot support and they said it could be a challenging print because of the angle. I am going to try to print some other prints before coming back to this. My settings for this print were the same as the ones for the original print so, other than the steep angle, there is not a good explanation, i will do the extrusion test again..maybe with better calipers. I may not have been off....a couple of mm is hard to tell the way i was feeling yesterday. The value for the extruder stepper is the correct default for this hardware. I did check. Do you think it be worth changing it just to see what happens? Thank you for your help. My next print is an iphone holder for the car. We will see how that goes.

[PxT]

Yeah, I would say now that you have some success maybe just run with it and see what happens. If you do make changes only change one thing at a time, then do a new print to see the results.

The E calibration is a little bit black magic. There is a hardware default, but unlike the other axes that have fixed and predictable movement, it can require some adjustment. I have found that different brands of filament and sometimes even different colors within the same brand require some slight tweaks because they feed slightly differently even with a constant spring tension.