First print failed need advice

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danmr
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First print failed need advice

Post#1 » Sun Nov 03, 2013 2:58 pm

My first first print failed, mainly because it didn't stick to the build table ( I found the first round bases floating around later). here is a few things that I did and notice:
-Use 1:1 red/cherry mix and Justin's settings from post "verdict after two months"
- Sliced at 50xy and 31.7 on z
-print was estimated two hrs but I stopped at 1hr as no object was growing.
-This I notice from the get go, calibration grid was ON and being projected on the vat the whole time, is this normal?
-Also I pour the recommended amount of resin at the beginning, but I noticed some bubbles form outside the build area and they start forming closer to the objects being built, so I pour a little more and the bubbles stop forming.

Any advice?
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Billions
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First print failed need advice

Post#2 » Sun Nov 03, 2013 3:09 pm

I'm certainly not an expert on all those troubles, but I can tell you that the grid stays on during my outputs as well, and I've done several prints over the last few weeks, so it seems to be normal.

Looking at your pic, if that was my set-up, I would have put more supports on it. It seems like a pretty heavy model for the four supports. Every time I have a failure like you describe, I rebuild the layout with more supports, and it's helped every time.

Also, seeing how you said you ended up getting disks floating around, with no real build happening, it seems we can conlude that the support bases didn't adhere to the build table as well as they need to - make sure you get your build table flat on the surface of the VAT window. I think it's somewhere in the directions, where with the screws loosened, you send the command to the B9 to calibrate the table to the PDMS vat window surface with a "g" command. Not sure about the order of things but you probably know what I'm talking about.

With the four screws loose, and the build platform raised and above the higher window build side of the vat, send the machine the "g" command and it will lower the build table until it stops. Then gently push the build table flat on the VAT window surface. Tighten the four side screws. It's recommended that the top build-table screw be removed at this point, I'm guessing because by pressing the table against the PDMS like this, it can create a slight surface suction that can cause the table to damage the PDMS if you just command the machine to raise it. I may be wrong here, but I've had good luck removing the build table's top hold screw as directed in that wiki instruction page, and raising the z-axis manually with the right Z switch, lifting the arm away from the build table and leaving the build table apparatus flat on the surface of the vat. Then I lift the build platform out by tilting it at an angle, to gently separate it from the PDMS.

It's important to note that you'll probably need to do this every time you change vats or after a new PDMS coating, since the surface is never going to be exactly the same on any two vats coated like this. So a set-up that might have been flush and flat on one vat may actually be askew from the surface of another vat.

ALSO, I don't remember who it was, but someone here has a method where they gently press down on the build table's arm during the first layer of a build, so that first layer really gets the best chance it can to adhere to the build table. I've done that a bit after having some failures like what you describe. I start the print, then press lightly on the sides of the black u-bracket of the build table for about 20-30 seconds during the first layer's exposure, and then stop when I think it's about to finish. It's tricky because you want to remove any pressure before the layer finishes and the vat moves. Also, I think too much pressure during this could flex the Z-worm gear shaft more than it needs to, so use care if you opt to try it.

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Robert Howle
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First print failed need advice

Post#3 » Sun Nov 03, 2013 3:34 pm

If the foundation disk did not stick, Table was not clean enough, table not parallel to PDMS, was the resin mixed well enough?

If u just want to test for table calibration, just do the model flat in the layout and use no supports, be sure to use "snap to floor". An item this thin should print in a few minutes. Just as a test do the build at 38 microns. Same settings u used for the 31 z, If this does not stick then let us know.
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Robert Howle
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First print failed need advice

Post#4 » Sun Nov 03, 2013 3:37 pm

Like this. Click in image to enlarge. Just FYI.


Image
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ckl81
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First print failed need advice

Post#5 » Sun Nov 03, 2013 9:03 pm

It might be not having enough supports for your model or the support is too small. Are you using small or medium support? I used to not getting print due to small support and the speed of the vat at default. then Robert suggest to lower it. So, i am doing 10 open and 5 close. I am printing at 50xy 25z. my last night print wasnot doing well on one of the ring due to not enough support.

hope it helps

ken

benp
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First print failed need advice

Post#6 » Sun Nov 03, 2013 9:19 pm

Your supports are not located correctly on the model - They are not supporting the model...
You also need more supports and a wider one where the hanging is (pipe).
Try to locate them on the "higher" point of the edge. Take a look at my drawing:

Hope that helps...

Image

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perpetual_dreamer
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Post#7 » Sun Nov 03, 2013 9:21 pm

Aside from the base not sticking to your build table, I can see about 5 spots on your object where supports should be added but there aren't any. You might get away without supports but you'd likely end up with floating bits which could lead to more problems and floating bits.

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perpetual_dreamer
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First print failed need advice

Post#8 » Sun Nov 03, 2013 9:27 pm

highlighted areas extra supports would help
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danmr
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Post#9 » Mon Nov 04, 2013 5:33 am

it seems like the consensus is that I need more supports, but I like Robert's idea of laying it flat for time constrain issues. I will try that later this evening and will report my progress, also it seems that re calibration is needed.

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Robert Howle
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Post#10 » Mon Nov 04, 2013 6:08 am

When u use the "flat" method u will get a fabulous back on the piece. I only do this for flat backed items. I was taking into account your comment about time. This type item is good test for table calibration and initial settings. Best thing is u will know in a matter of minutes if your print is successful. But even more important, If the print is sticking to the build table.

You can always just model a flat 1.5 mm thick rectangle. U can pause after half the layers or before that pt. If all is well just resume print and if u don't want to just abort. U will sill know about sticking and settings for the particular resin or mix u are using. If it's just simple geometry u won't know anything about details in a given model, but u will know about calibration.
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danmr
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First print failed need advice

Post#11 » Mon Nov 04, 2013 3:10 pm

Well ... Second print failed the same way the first did.
-I re-calibrated the Build table made sure resin was well mixed.
-I leveled the printer in 3 corners.
-I notice the bubbling still was forming close to the building area does this means table is not flush?
-I put the angel flat and checked after the first 30 or so layers as nothing was sticking to the table I aborted the print.
-after pouring resin on strainer I found again the complete first layer silhouette of the angel, which tells me that resin mix is ok it's just not sticking to building table.
Finally my guess Is that either VAT, PDMS or both are not leveled right build table seems ok. I have a second VAT that I purchased but need to apply the PDMS, so for now I will try to do so and then try to print again

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perpetual_dreamer
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Post#12 » Mon Nov 04, 2013 3:26 pm

the printer being level shouldn't cause too big of a problem... I personally feel the best way to make sure the VAT/resin is level is to eye ball it after the VAT/resin is in place.. look from the left and right corners of the VAT.. Is the resin level almost parallel to your VAT floor? adjust as needed.

I'm going to guess that your build table isn't touching flat on the PDMS surface.. It takes a little skill to tighten the four screws of the build table while pressing the buildtable down on the PDMS with four fingers of one hand, making sure you press evenly while you tighten screws with the other hand.

Also, do you know what settings you used in your 'Printer Cycle Settings - Dynamic Z-axis 'Find Zero' Settings'? It seems like the default now is set to 0 but it used to be these values and I'm not too sure why its 0 now when it used to be these values before. I use these values and so do many others.

Hard Down (mm) 0.953
Up to Flush (mm) 0.762

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Robert Howle
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First print failed need advice

Post#13 » Mon Nov 04, 2013 3:38 pm

When tightening the screws i slide a couple of fingers to the center of the build table, that way i am not tilting the table. Are u cleaning the surface really well with soap and water (I try to never touch it with my fingers as it leaves oils).

Perplexed.
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perpetual_dreamer
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First print failed need advice

Post#14 » Mon Nov 04, 2013 3:45 pm

wipe the buildtable surface with paper towel and alcohol

pbs
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First print failed need advice

Post#15 » Mon Nov 04, 2013 4:50 pm

I've found that it's really important for the first couple layers to have a long exposure time. I use a resin that's tinted darker than Cherry so adjust yours accordingly. I use 40 seconds for my first two layers. The trade-off for going too long on exposure time seems to be damaging the PDMS so don't get too crazy with super long times. Exposure needs to be adequate for the slice thickness and resin type/tint; it takes some experimenting.

What has your initial exposure time been set to?

danmr
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Post#16 » Tue Nov 05, 2013 3:05 am

-I did notice is tricky to tighten the build table, but I did all what has been said so far except what billions suggested, to hold down the build table at the first layer.
that's why I think I have either a bad vat or PDMS.

ckl81
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First print failed need advice

Post#17 » Tue Nov 05, 2013 3:53 am

can you post your exposure setting?

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mikej
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First print failed need advice

Post#18 » Tue Nov 05, 2013 3:57 am

I always put some downward pressure on the build table during the first (long) exposure to help squeeze out any excess resin. If that first layer of resin is too thick it won't cure deep enough to stick to the table.
Measure Twice, Cut Once.

danmr
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First print failed need advice

Post#19 » Tue Nov 05, 2013 5:28 am

I'm using Justin's settings, as described on his posting "veredict after two months",
and Mike, I will try that before changing vats.

danmr
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First print failed need advice

Post#20 » Tue Nov 05, 2013 11:22 am

Mike, when comparing the "stock VAT" vs The Spare VAT I purchased from you, I noticed the " middle pegs" protruded just a bit more on the "STOCK VAT" and the spare vat is flush, so when a put a ruler on the bottom of the "Stock VAT" it creates a gap at the end of it of aprox 1mm, I think this could be the culprit of my problems calibrating the build table, To fix it I could file down the excess material but wnat to know your input first as I don't want to void any warranty I could have on the Stock VAT.

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