switched from anycubic green to gray.. what variable is wrong?

[Stephane]

So I ran out of the 250ml green resin that came with the printer, and now switched over to the Anycubic Gray resin.  I figured I'd try printing something old to compare.  The problem is that I can't get quite the same details out of the gray, and I find that hard to believe considering what I've read online.

See the picture below...

[ Guests cannot view attachments ]

This is a wheel from the Grand Cherokee vehicle we've seen in other threads here, printed by Mark and I.  The Anycubic Clear Green was printed at 0.02mm, 8 base layers at 80s each, and normal layers at 7.5 seconds.
The grey was printed using 0.02mm, 8 base at 110s, and normal layers at 12 seconds.

the problem I have is with the holes in the rim, they seem "filled" in a lot more in the gray resin (i.e. the holes are definitely smaller than the green resin).  I figured it might be overexposure, so I tried again the same print, but at 11 seconds per normal layer, and reduces the bottom layers to 95 seconds.  No change, the print looks identical.  I also thought that maybe I had not shaken the resin well enough, so in the second print, I really shook that bottle like crazy, poured into the vat, then waited half an hour for the bubbles to settle in the vat before agitating again with the scraper before starting the print.

So, what do the experts think? Is this overexposure, or maybe under-exposure (seems weird if it was)? 

Could the bottom 8 layers be to blame? I find that the the raft and supports are much harder to remove on the gray prints compared to the green (they seem thicker)!  Also, while the top of the vehicles themselves appear to be printed fairly well, the bottoms seem to bulge somewhat.

Rather stumped here!

[IronPenguin]

Maybe it's "pooling" in the openings?  I'd fool around with the exposure time. Are you printing flat on the bed or supported?
I've been using Phrozen ABS-Like gray and have gotten very nice results and details. Its considerably thinner than AC resin.

[Stephane]

Well, I can't say it isn't pooling, I suppose that's possible.  Even though I've now worked with both the Green and the Gray, I can't say which is thicker.  As for the print orientation, the vehicles were printed flat, and the wheels were printed with the "face" pointed up (axle down).

I tried another print this evening, and now I'm even more confused.  I figured I try an extreme.  I printed the Grand Cherokee with 0.02mm @ 8.5s normal, and 8 x 80s base.

In the following picture, we have two jeeps...
one of them is at 0.02mm @ 8.5s normal, and 8 x 80s base, and
the other is at 0.02mm @ 11.0s normal, and 8 x 116s base

In the second photo, I just had them switch places because the light was falling on them differently.

Can you tell which is which??

[ Guests cannot view attachments ]

I really thought 8.5 vs 11 seconds would make a lot more difference!!

Here's what the wheels look like...

[ Guests cannot view attachments ]

One the plus side, at 8.5 seconds, the supports were breaking off much more like they were with the green resin.


I really wish the resin bottle was more accurate in it's recommendations.. really? 3-15 second recommended exposure?? 

[Mark W]

Interesting.. I may have to play around with reducing exposure. 


The weird part is, when I look at the wheel comparison of gray vs green; of course the holes are smaller in the gray, which one might attribute to some kind of swelling or overexposure.  But then the layer lines int he gray are much more sharp!  Those two features should be mutually exclusive.   

But that aside, I have observed the same issue on small holes specifically for Gray and White.  Embossed details seem to be identical across the board (slight edge to Black being the most detailed all around).  But small holes, less than about .75mm diameter, in Gray and White just need to be drawn a few tenths of a mm larger than desired.  Once you get to around 1mm diameter, they print just fine.  ¯\_(ツ)_/¯

[Stephane]

I look forward to see what your results are with shorter exposures.

I'm at work now, so I can't do any printing, but tonight I'm going to switch models and print the Semi truck.  Except I'm just going to print it using the Anycubic Green settings I previously used, I won't even bother increasing the exposure.  At this point I'm curious to see what the results will be.  If I remember right, that .photon file even has the grand cherokee with the wheels still attached.

I'm not sure whether the softer layer lines are a result of the poor quality cellphone pictures.  When I compared the vehicles side by side under magnifier, I couldn't really find any differences (oh! In the picture above with the four jeep cherokees side by side - from left to right, 8.5s, 11s, 11s, 8.5s ).  In any case, I'll take out my dSLR and micro lens for the next pictures.

[Stephane]

Trying to post but keep getting 403 forbidden...
Edit: might just be the four pictures then it doesn't like.

[Stephane]

And here comes yet another post on this experiment to get Anycubic Gray to look just as good as Anycubic Green!

Okay, so I'm happy to announce that printing Gray at the same exposure settings as the Green resulted in a print failure, ha! Happy because for once it gives me results I actually expect!

I didn't print the semi, but I went back to the road grader I printed a while back.  It has lots of little details and I don't already have three of these printed

This is the original green grader, cleaned up and also a bit scratched up where I filed down some of the areas to get rid of the support "pimples":

[ Guests cannot view attachments ]

This was printed 0.02mm at 7.5s, 8 base layers at 80s.

And here is my gray failure, same exact print settings!

[ Guests cannot view attachments ]

Really, the biggest failure was the blade and "disk", which were mostly held down with light supports.  The rest of the model looks mostly fine - the ladders also broke from the supports, are a little warped but still managed to print.  Oh, and one of the rear view mirrors actually survived.

[Stephane]

okay, splitting the post might work? 

Here's a closeup of the front...

[ Guests cannot view attachments ]

The headlights look just about identical, and the detail on the wheel axles appear pretty much identical, down to the large "bolts".  The tire treads may be softer, but I'm not convinced whether that may be how light falls on the semi-transparent green material.  I have a hard time judging under magnifier whether the sharp edges are sharper on the green, though they do look softer in the photos.

[Stephane]

There's something wrong with the original post (something about the text) and I can't seem to post it as original.  My apologies for splitting the post into three. 

Anyway, this last picture is where I'm most disappointed in the gray resin, and I wish I had bought a liter of green instead of the gray:

[ Guests cannot view attachments ]

The problem is really apparent around the axles, where the gray ends up being bloated.  This appears to happen on all surfaces that are facing the build-plate, but more so on those closest to that build plate.  I'm not sure if the problem is then the 80 second base exposure.

I feel I'm getting closer to getting an acceptable gray resin print.  Now I need to figure out the exposure needed to have the light supports survive the print.  Here is a question for you all - based on what you see here, how much would you increase the exposure from 7.5 seconds?

[Mark W]

Well I'm definitely enjoying the analysis! 

So far I think results are mostly in line with my own observations.  When I shortened exposure, supports are the first thing to fail.   I'm using Netfabb and supports appears to be a bit thinner than you have, so based on your results, my .02 layer time of ~12 seconds sounds about right to keep the model in tact.

Another thing to keep in mind is 'drainability'.  I've observed the same kind of bloating in tight spaces with lots of supports.  Anything you can do to open up, re-position, or remove supports should help.  But then there's a trade off there too. 

[IronPenguin]

Stephane,
Is the road grader file available? I can print it on mine with the Phrozen ABS -like resin and see if it makes a difference.

[Stephane]

IronPenguin - I downloaded the file from free3d.com, search for "motor grader" - it's a free model.  But only print it if you want it for yourself, not for me   I really am interested only in the exposure settings for the Anycubic Gray resin.  I've had great results in Green and if I can't get what I want in the Gray, my next bottle will simply be back to Green (or maybe a small black bottle to try).  I'm limited to what I can buy inexpensively in Canada.

Mark - I've not tried NetFabb, but so far I've learned to use ChituBox and seems to do ok for me.  I use the default support sizes for Heavy, Medium and Light, and just add the supports by hand.  I do have a lot of supports though, and that draining effect is definitely something to look into!

The room temperature may be affecting the gray resin more than the green.  My printer in the in the garage, and while it is heated, it's not quite to the level of the rest of the home.  When I get in, the thermometer I keep next to the printer is usually around 17.5 to 18.5 C.  I then fill the vat with resin, and turn on a space heater in the middle of the area.  When I start the print, the air temp is usually around 20C, but I'm sure the resin heats up more slowly in it's metal vat.

Anyway, tonight I'll start the same print again, but at 9 seconds per layer, and reduce the base layer to 60 seconds.  Fingers crossed!  I probably won't have results until tomorrow however, I won't be able to start the print early enough.

[peteski]

Trying to post but keep getting 403 forbidden...
Edit: might just be the four pictures then it doesn't like.

The forum seems to choke on certain word/punctuation combinations (which might resemble computer code).  I figured out one of them in a thread we had about the 403 error. See https://www.therailwire.net/forum/index.php?topic=46244.msg610481#msg610481
  The length is not a problem - I have posted very lengthy threads and when I tried to post, it was rejected with an error stating that the post was too long. Not a 404 error.

[IronPenguin]

I've been planning on doing some construction stuff, so it's not a problem trying this. What scale did you do it in?

[Stephane]

peteski: yup, after trying to edit the picture a few times, I figured it might be some string of characters in the last bit of text and just rewrote what I was going to say

IronPenguin: I printed it in n-scale.  I don't remember how exactly, but I lucked out and figured that the designer appears to have used the Deere 872G motor grader for the design.  In re-scaling it, I just started googling Motor Graders and just happened to find that the 872G was very very similar to the model!  Anyway, for n-scale, I set the long dimension to 55.5625mm in Meshmixer. 

Oh! I recall another issue with the model - the disk that holds the blade is not attached to the frame!  I remember that I had hand placed all the supports, sliced the model, and then only found the problem when I viewed the .photon file in the Photon Validator tool.  I had to go back, select the top of the disk, and extrude it up until it overlapped into the frame by a fraction of a mm.  I don't believe I made any other changes to the model.