So Im testing out a new printer...

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erykd1

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I'm wondering if my LCD screen is bad. I tried it again using the new resin and there still isn't anything building on my build plate. I used chitubox to slice it and used the new resin profile and still nothing. I know that the UV light is working, I can see it coming on when it's supposed to and turning off as well.
On the front of the printer you can test the LCD in the configuration settings. With no resin in the vat, there are some patterns you can project to see if it's working properly. Also, make sure your Z axis build plate is adjusted properly against the LCD. Any other ideas @zero_zero?
 
FastShipper

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I'll try the LCD test tomorrow when I'm back at the lab. I did adjust the Z axis build plate when I first got it but I'll do it again just to be sure.
 
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personally id rather make teeth and have model that is really reliable. i use a mid cost printer that is open that i know is accurate all the time my printer is 11000 usd it not going to break the bank but loosing clients may due to poor fits, down time distortions that you cant see etc.
 
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how are you finding nextdent coolhand is it what you expected
 
Jenners

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I'm wondering if my LCD screen is bad. I tried it again using the new resin and there still isn't anything building on my build plate. I used chitubox to slice it and used the new resin profile and still nothing. I know that the UV light is working, I can see it coming on when it's supposed to and turning off as well.
I"ve noticed that any prints not adhering to the plate is either the plate isn't level or you need to increase the exposure time for the bottom layers. I had to level mine a few times before getting the hang of it and having successful prints.
 
Jenners

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I mean dies fitting into the models, I've only tested one surgical guide and that fit pretty good on a model made with an anycubic photon.
I'm having the same problem. Everything looks good but the die is a little... bloated. I ordered my usual model from Argen alongside printing my own in Anycubic Dental Resin. My die is too tight for my model, but the Argen die fits in my model perfectly. I'm going to run an exposure test when I get home. Over exposing the resin can create bad fits.

The only reason I'm bothering with tinkering with a cheap printer is my lab isn't busy enough to justify spending a ton of money on a "dental" printer, but I believe that if we demonstrate our ability to print in-house, then Drs will be more comfortable with upping their technology and using our services.
I'm not the lab owner, but I've taken it upon myself to experiment with my hobby printer. I'm hoping that the knowledge of these printers will also give the lab owner more confidence in buying a printer for the lab in the future.
 
HygienicBee

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Some dental printers even have the die fitting issue anyway, we had a demo for the cara print 4.0 for dentures, asked the guys if I could demo some models for a case we were working on, models looked good, die was just a tiny bit too big for the model, so it could even be an issue with parameters for models in whichever design software is being used. Even had to have a tech work with our design team to fine tune parameters for one of the 20K+ printers we ended up purchasing.
 
Jenners

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Some dental printers even have the die fitting issue anyway, we had a demo for the cara print 4.0 for dentures, asked the guys if I could demo some models for a case we were working on, models looked good, die was just a tiny bit too big for the model, so it could even be an issue with parameters for models in whichever design software is being used. Even had to have a tech work with our design team to fine tune parameters for one of the 20K+ printers we ended up purchasing.

It sounds like no matter what printer is bought, there will be some fiddling with settings. Was there any particular reason that the die was too big? Was it the exposure time? I'm liking the look of my print better than the one that I ordered... but that die. It just looks....puffy. I did manage to dig up info on the resin I ordered and recommended exposure is around 4 and I left it default 8. I'm anxious to get home and experiment.

Also, I've seen models print flat on the build plate and also at an angle with supports. Is there a better way? Mine come out great flat, but I'm not sure there would be more detail at an angle.... or just increased print time.
 
zero_zero

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You guys make sure you clean your models really good, use a soft toothbrush,rinse them a second time in clear alcohol. Uncured resin left on will interfere with tightly fitting parts. We are printing solid models with extra dies...less headaches that way, got two dies to crosscheck
 
zero_zero

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On the front of the printer you can test the LCD in the configuration settings. With no resin in the vat, there are some patterns you can project to see if it's working properly. Also, make sure your Z axis build plate is adjusted properly against the LCD. Any other ideas @zero_zero?
1. Calibrate the build plate
2. Make sure the bottom of the buildplate is rough enough for the resin to stick, use a 200 grit sandpaper of rough it up. If find the resins I am using react somewhat with the aluminum (ie. i see black marks on the paper tower when I wiping it clean) that leads to the bottom to smooth up with time. I re-sand prolly every other week.
3. Try some see-through resins first, the cheapo ones, till you get the hang of it...they tend to print faster and with ease. Pigmented resins are more finicky
4. Before you print make sure you mix up the resin in the vat with the plastic spatula, the pigments settle on the bottom and not letting the light through
5. First few layers needs to be overexposed like 60-80 secs, and you need a big enough support surface to stick to the buildplate, nesting is important:
nesting.png
6. Decrease the motor speed to about 160-180 um/sec for more gentle peel offs, see my current setup:
settings.png
7. I got thirsty from so much writing :banghead:
 
Jenners

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So now that I have this printer I'm going to drive you all nuts.

I did the exposure test and column 5 or 6 seems the best. The instructions say to multiply by 2 on slow curing resins to get the exposure time, but 10-12 seconds seem a little much. I'm not sure this resin is considered slow curing. This is with the Anycubic Dental resin. I admit I don't fully grasp the exposure test.

I downloaded the blocks linked in this thread, set the exposure to 5 ( as I saw on some site that 4-6 is average). The dimensions on all blocks, both x and y axis were .2-.3 too large. Consistently so.... I suppose that's something.....

I loaded up Anycubic grey so I don't waste all of my model resin and ran the exposure test on that. I didn't bother with the blocks yet as I'm not sure what to do with this information anway.

I'm using Chitubox as a slicer. 50s bottom exposure, 65 for lift speed. .05 layer height. 5 seconds exposure for the other layers.
 
zero_zero

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The dimensions on all blocks, both x and y axis were .2-.3 too large. Consistently so.... I suppose that's something.....
Just calculate how much shrinkage you need and you're good...Idea
 
CoolHandLuke

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Slow curing or long exposure is necessary only for resin that must remain flexible after it is cured. For solid resin it shouldnt be necessary.
 
Jenners

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I feel goddawful dumb, but I'm not gathering how to calculate shrinkage. The resin itself *should be* somewhat accurate, being a dental resin. There's exposure... but that didn't help a whole lot. I'd hate to resize in the slicer for every model instead of just taking it from the intraoral scan. With the FDM, there are all sorts of tweaks to do in the slicer settings to get a more accurate size, but in the resin slicers (Chitubox in this case) there aren't many boxes to mess with.
 
CoolHandLuke

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Well, easiest method is to make known geometry. Print a cube or a pyramid. Measure with precision instrument. If the cube is smaller than it should be according to the stl file, blow up the stl file accorsing to the ratio of the size difference; if your cube should be 10mm wide but is actuallly 9.2 then the amount it shrank was 0.8mm expressed as a % of the total dimension, that is 8%. So your shrinkage is 8%, meaning you should blow up your parts by 108% to get a part that is closer to complete accuracy.

In almost all 3d print and cnc software there is shrinkage accounting baked in to the material setting. Eg in the 3dsprint software each material has build shrinkage accounting. As it will be with virtually all 3d printers.

The issue is that with many laser or light printers, the accuracy of the head begins at the center of the build plate and gets worse the further from the center you go. A die or crown printed near the center will have different fit and finish than identixal objects printed near the edge. This is common in all resin printers even dlp.

Asiga hides this by creating a proprietary calibration object that is as big as the whole plate.
 
zero_zero

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I feel goddawful dumb, but I'm not gathering how to calculate shrinkage. The resin itself *should be* somewhat accurate, being a dental resin.
Resins have variable shrinkage, that varies from batch to batch. If is not mixed thoroughly before you open the bottle, you'll have different shrinkage between your first print and subsequent ones.

Print a 10mm cube, print it at 100%. Measure. Let's say it measures 10.23mm. Now divide 10 by 10.23, you get 0.9775. Multiply it by 100, that gives you the 99.75% shrinkage you need to put in your software .
20200110_094727.jpg

Print a bunch of cubes across you buildplate, to map the accuracy of your printer. Nest your important parts accordingly.
 
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Jenners

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Thanks for the explanation. I couldn't find any place in the software to adjust for inaccuracies of the resin.... but I'll take another look tonight. Hopefully I'm just missing something... or need to use a different slicer. I'll play with the other resins I have and figure it out.

Edit to add that, while I did give the resin a good swirl, it seemed a little thin comparatively to Anycubic Grey and Clear. I'll have to give it a really good mix and try again.
 
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CoolHandLuke

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Check with your resin dealer too, it should be like liquid honey or molasses, not like water. You may have accidentally impurified resin somehow.
 
Jenners

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Check with your resin dealer too, it should be like liquid honey or molasses, not like water. You may have accidentally impurified resin somehow.
Thanks I will. It was straight from Anycubic and took a while to get here.
 

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