Strange Problem With First Layer??

Hi all,
I have a prusa i3 and have just switched from a jhead to the E3D hotend with the standard .4mm nozzle, im having issues with the filament not seeming to adhere to the bed and also the filament lines not merging with eachother.

As pictures speak louder than words i have attached 2 pictures. In the first picture you can see gaps between the filament paths as if the paths are to far apart and not sticking together. In the second picture you see 2 circles, the one on the left is the skirt and the one on the right is the circle itself, this was one print, i cant understand why the skirt is perfectly round and stuck tight to the bed yet the circle itself isnt actually a circle and didnt adhere to the bed, surely if the nozzle height is okay for the skirt the acutal print itself should stick and be round too?

ive calibrated the E-Steps so when i tell it to extrude 100mm it extrudes 100mm, i set the gap between the bed and the nozzle to 0.2mm, Im using repetier host 95F and printing at 0.2mm layer heights with the layer being 150% of that. im using slic3r 1.1.2 with the default extrusion width at 0.4mm and first layer extrusion width at 200%.

Ive even set a Z offset of -0.2mm in an attempt to get print to stick/have no gaps but it hasnt helped and im abit stuck with what to try next

I cannot really help you because I am in the building process and never printed anything yet

But for the circle problem I have a similar issue:

I draw my parts with Catia V5, in Catia my circles are round but when I export them to .STL the circles become multilines like you have on your bed. Haven't found a setting to correct this so far.

Hope you find a solution!

Have you made sure that your heated bed is level? Your hot end should be really close to the heated bed when it is at its lowest -- a regular piece of paper should tug a little.

You say that when you tell it to extrude 100mm that it extrudes 100mm. I assume you don't mean this literally. Extrusion is what comes OUT of the hot end. What you want is to measure 100mm on the way INTO the extruder.

Have you checked to see what your first layer height is? I usually do this by taking the skirt outline off of the bed, and measuring it with a caliper. To me it looks like the first layer is way too thick, which would explain why the extrusion width is too narrow.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

Quote
jbernardis
You say that when you tell it to extrude 100mm that it extrudes 100mm. I assume you don't mean this literally. Extrusion is what comes OUT of the hot end. What you want is to measure 100mm on the way INTO the extruder.

it is what goes in the extruder in fact that's how you calibrate the extruder which is a very important piece of the calibration process there are many posts on it

Edited 1 time(s). Last edit at 05/06/2014 03:56AM by cnc dick.

Hi all, thanks for your replies, to clarify, when i said i tell it to extrude 100mm and thats exactly what it extrudes i was referring to the filament going into the hotend and not the extruded material.

yanickr1973 , The model i am using is a cylinder that i downloaded and it looks perfectly circle when i look at it in repetier host

John de Michele , ive checked and my bed is level, i used feeler gauges to get the head gap to 0.2mm

manton, i havent measured the thickness of the first layer, i will try it when i get home, what is the ideal first layer thickness for a .4mm nozzle printing at 0.2mm layer heights? i have it set at 150% which would make it 0.3mm for the first layer however when i cancelled the print on the first layer and tried to measure the head gap it was over 0.5mm from the bed, something doesnt seem right somewhere

I wouldn't muck about with Z offsets - just set your nozzle gap properly and not 0.2mm but 0.1mm. Do this with the heat bed up to temp and the nozzle at or near print temp. A piece of copy paper should lightly drag under the nozzle as was rightly suggested by John D.

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_______________________________________
Waitaki 3D Printer

Hi waitaki,
I only used the offsets to see if lowering the nozzle helped with adhesion, i used feeler gauges to get an accurate nozzle height of 0.2mm, i even went down to 0.15mm and it made no difference. I will try going down to 0.1mm gap but i thought with a 0.4mm nozzle the gap was supposed to be 0.2mm? i am going to delete all my repetier host profiles and start from scratch (and remove the Z offset) just in case theres something wrong there. Im also going to decrease the first layer height abit, its currently set at 0.3mm when i print 0.2mm layers, im not sure what the rule is for determining the first layer height but i will try a lower number and see if that helps

Quote
waitaki
I wouldn't muck about with Z offsets - just set your nozzle gap properly and not 0.2mm but 0.1mm. Do this with the heat bed up to temp and the nozzle at or near print temp. A piece of copy paper should lightly drag under the nozzle as was rightly suggested by John D.

Agree. .2mm is too much distance between the nozzle and heatbed.

If possible, manually adjust the threaded Z-rods while printing the perimeters until you have correct adhesion.

Aboput printing circles, you might want to read this:

[hydraraptor.blogspot.com]

I usually use 0.2mm for a first layer height with a 0.35mm nozzle. I would not print with a first layer height higher than this. Generally you want the first layer to be lower than normal, not higher, as you want the extrudate to squish into the bed. If you go to high, you won't extrude wide enough, and if too low, you will put too much plastic down. Somewhere between 0.1 and 0.2 should work really well. If your bed is not perfectly flat, and level to the nozzle, you will have problems with 0.1mm layer heights though.

If your layer height actually was 0.5mm, I wouldn't expect it to stick at all, since the is larger than the nozzle diameter.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

.2mm is too high, lower it closer to .1mm

If 0.2mm is too high, why does it work so well? I always print at 0.2mm, and it is very rare that I have adhesion issues. I've had far more problems printing at less than 0.2mm. That being said, I am not printing on glass directly. If printing with PLA, dilute white glue works well, ABS works well on kapton tape, both on a heated bed. Lately however, I've had good success with both material types printed on Ultem PEI.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

Quote
manton
If 0.2mm is too high, why does it work so well? I always print at 0.2mm, and it is very rare that I have adhesion issues. I've had far more problems printing at less than 0.2mm. That being said, I am not printing on glass directly. If printing with PLA, dilute white glue works well, ABS works well on kapton tape, both on a heated bed. Lately however, I've had good success with both material types printed on Ultem PEI.

Are you talking about 0.2mm Layer height set in your slicer or is that the height you manually set the nozzle to when calibrating?

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_______________________________________
Waitaki 3D Printer

I'm talking about the first layer height set in the slicer, which is what I understood we were discussing. You certainly wouldn't calibrate with 0.2mm, unless you were using a feeler gauge, as that would be too high for a piece of paper.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

Mike,
Can you tell me where you got your Ultem, what grade it is and how thick? I'd like to try it out.

Thanks

This is the stuff I used: Ultem 1000. I bought the 0.030" thick stuff, but it actually measured 0.040" thick. I used a sheet of 3M MP468 transfer tape to glue it down to a sheet of glass, but others have used high temperature silicone to glue it down, which may be a better way to go. I ended up with some visible small bubbles in the bond line, but it still seems very flat.

It has a shiny side, and a matte side, so you can pick the surface finish you would like to have on the bottom surface of your parts. I used the matte side, and it is very nice. Alas, if you mark the surface at all, it will show on the finished parts. Someday I'll figure out how to clean up the surface again so it is more even.

It does not have the greatest thermal conductivity, so I don't think you will want to go too thick.

Clean it with alcohol only, and make sure you don't touch it with your hot end, as it will leave a mark. Parts come off pretty easy once the bed is cool, though ABS is more difficult to remove.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

Ok, thanks. I looked at that link and they only listed one item for several hundred dollars. I assume you can get cut pieces at various thicknesses elsewhere?

If you print ABS on it, does the shrinkage cause the ultem to pull away from the glass? (Ie., does the tape keep it in place?) do you have to heat it to print PLA?

I'd like to compare it to the plates I sell on my site at PRINTinZ and see how it does. I've heard a few people say they really love the PEI.

Wayne

I'm not sure what you are seeing, but the first item in the list is a 12" x24" piece that is 0.030" thick for $40.68. Further down there is a 12"x12" size for $26.29. Also listed as customer also viewed items is the 468MP adhesive. I got the part number wrong earlier on that one.

I haven't had anything pull it away from the glass. That transfer tape is really strong glue. I'm sure it would be extremely difficult to get it off. The glue is rated for the temperatures that we run our beds at too. Be careful when sticking it down though, and make sure you have cleaned the glass and the PEI with alcohol to remove any fingerprints. Initially I just tried it with binder clips holding it to the bed, and it worked ok, but I'm sure ABS would cause it to lift and bend without the glue holding it down.

I heat the bed to 70C for PLA, and 100C for ABS. I'm not sure if it would work well cold, as I haven't tried it.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

I see it now. Sorry. I looked at it on my phone and for some reason didn't get the table of sizes.

Thanks for the info.

Wayne
PRINTinZ.com

I have ordered the Ultem and am going to try it adhered with high temp silicone. I'm wondering if it would be best to use a laminate roller to press the Ultem to the glass to make it as flat as possible and eliminate bulges of silicone? Would such a method leave enough silicone between the two materials for good bonding? It might not be good to starve the joint.

I think you will want as thin a layer as you can get. Someday I will glue mine down, as I have a fair number of air bubbles in the transfer tape layer, and I think that is causing some vertical changes with temperature. But, the transfer tape has done well as far as keeping the Ultem adhered to the bed.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

Quote
Garry Bartsch
I have ordered the Ultem and am going to try it adhered with high temp silicone. I'm wondering if it would be best to use a laminate roller to press the Ultem to the glass to make it as flat as possible and eliminate bulges of silicone? Would such a method leave enough silicone between the two materials for good bonding? It might not be good to starve the joint.

If I was trying this, I would probably put the Ultem face down on a surface plate, apply silicone and glass/bed, and then squeeze out as much as possible. Using a roller should work well. Then I would leave a heavy weight on it, until it all sets, ideally a second surface plate would work well as the weight. The advantage to the surface plate is, it is perfectly flat, and the silicone will then be allowed to fill any gaps due to uneven surfaces, or thickness in the Ultem. You could probably use a really thick piece of glass instead of a surface plate.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

Hi Mike, Thanks for those ideas.

I had planned to put the silicone onto the glass and then put the Ultem on top and roll the Ultem since I assume it would be slightly flexible? More so than the glass? But I'll consider your plan once I see the Ultem. And yes, then I would put a few layers of glass on top followed by big hardcover book with a bunch of filament on top of that. I don't really have any large enough dedicated surface plates.

I don't really have any trouble with getting PLA to stick but I am really eager to see how Ultem works with ABS. Ultem seems like such a clean/simple way to go.

PLA onto PVA glue on glass would be a close second to Ultem. ABS on Ultem is actually difficult to get off at times, as it really sticks well. You will want to wait until the bed is cool before removing it, and often you will need to use a knife edge to get under it. Alas, the Ultem does not help with the stress fractures in ABS while printing...

I glued my Ultem on with the shiny side down, so that I have a matte finish on the bottom of my parts. I think it is really nice like this.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

I tried some Ultem taped to a piece of perf board this weekend and had poor results. The 3m tape I used is rated for higher adhesion and temp resistance than the 468 tape, but when it got hot it released from the Ultem. (After it cooled off again it was really stuck - couldn't pull it apart hardly. But at 100C it didn't stick.) The ABS print didn't stick to it either in the area where it separated and warped away from the bed. I think sanding the surface of the ultem would definitely help make the tape stick though. If it stayed stuck it would have stayed hotter and I expect I would have had better adhesion. Not sure. I will try again.

After I tried the Ultem I printed on a PRINTinZ printer plate. Same part, same filament, same everything. Much better results. I'll attach photos of both. If you aren't printing enormous ABS parts, you might find these printer plates will work well for you.

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Wayne
PRINTinZ.com

Did you clean the Ultem, and mating surface with alcohol before applying the tape? Also clean the surface with alcohol before printing. It must be clean. I've never had the 468 adhesive give any signs of letting go, even at 100C.

I do print on the matte side of the Ultem, so maybe that makes a difference. Your Ultem picture doesn't look like mine. Mine looks like an opaque amber color.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

Yes, I cleaned the surfaces thoroughly with alcohol first. I also let the plate sit overnight. (VHB tapes cure over 72 hours but reach most of their strength in 24). The ultem is the .03" thick found on amazon and it's amber colored. It's smooth on both sides. There is a forum on SeeMeCNC where this is discussed as well and people have received both smooth and matte finishes via amazon for some reason.

I have a contact at 3M who suggested sanding it to rough up the surface before using the tape. They also have a primer you can use. I have a can so maybe I'll try that too.

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Wayne
PRINTinZ.com

My Ultem came from Amazon, with one side shiny, and the other side matte. How thick is the VHB tape? AFAIK VHB tapes are usually foam core, whereas the 468MP is a transfer tape, with only a glue layer. It looks like the max rated temperature for any of the VHB tapes I could find is 120C, and that is dependant on the tape used, and the substrates it is bonding. The 468MP tape is rated for up to 204C, so that might be a lot of your problem.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]