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 Post subject: Re: 3D printing
PostPosted: Tue Jan 18, 2022 3:53 am 
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Well, assembly usually is the challenge - how many times did I loose parts or screwed them up when painting or during assembly :mad_2:

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 Post subject: Re: 3D printing
PostPosted: Tue Jan 18, 2022 11:18 pm 
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Location: Corvallis, Oregon, USA
I have been experimenting with printing at different vertical resolutions of 0.05 mm and 0.01 mm. The metal scale in the pictures has 1 mm divisions.

Here are the bow capstans for the 1:96 USS Oklahoma City CLG-5 model:

Attachment:
Capstans 05 mm and 01 mm 2 small.jpg
Capstans 05 mm and 01 mm 2 small.jpg [ 110.74 KiB | Viewed 261 times ]


The one on the left was printed with a 0.05 mm vertical step. The digital "jaggies" are obvious. The one on the right was printed at 0.01 mm vertical step. No jaggies! The top surface is quite smooth, but with high magnification (10x) you can see a faint trace of digitization.

Here are the wildcats:

Attachment:
Wildcats 05 mm and 01 mm 2 small.jpg
Wildcats 05 mm and 01 mm 2 small.jpg [ 107.14 KiB | Viewed 261 times ]


Again, 0.05 mm on the left and 0.01 mm on the right. The jaggies are obvious on the 0.05 mm print.

The chain pipe:

Attachment:
Chain pipe 05 mm and 01 mm 2 small.jpg
Chain pipe 05 mm and 01 mm 2 small.jpg [ 127.38 KiB | Viewed 261 times ]


Here the digitization effect is pretty bad on the 0.05 mm print (left). But even the 0.01 mm print shows a bit of roughness on the sloping part on the right. Also, I enlarged the dog handles that hold the buckler down. Those on the left are accurate scale but were only 0.0085 inch (0.2 mm) thick. Just handling the parts caused a few to break off. On the right they are 0.0145 inch thick (0.37 mm) and much more durable.

The chain pipe gave me quite a bit of trouble. Microsoft's 3D Builder kept placing an internal surface over the opening through the buckler where the anchor chain ran. After five versions I finally discovered the culprit and got a part that printed with an open path for the chain.

Not everything came out smoother at the higher resolution. Here is an open chock on the fantail that had a support for the flag staff. At sea the flag flew from the forward radar tower and we folded the flag staff down and clamped it in place on the chock.

Attachment:
Closed chock with support 05 mm and 01 mm small.jpg
Closed chock with support 05 mm and 01 mm small.jpg [ 113.87 KiB | Viewed 261 times ]


The 0.05 mm steps are more apparent on the chock surface on the left, but you can also see some smaller steps on the 0.01 mm step part on the right. But there is little difference on the edges of the vertical support parts. To put this in perspective, the vertical supports are 0.0055 inches (0.14 mm) thick, the cylindrical tube is about 0.012" (0.3 mm) thick, and the diameter of the opening in the tube is about 0.032 inches (0.8 mm). I was amazed to be able to print anything this small! You can't see them in the photo, but there are two bolts on the flanges either side of the tube, but they are just tiny nubs (didn't print six sided).

Lastly, here is a fire hydrant printed at 0.05 mm:

Attachment:
Horizontal fire hydrant and strainer.jpg
Horizontal fire hydrant and strainer.jpg [ 134.55 KiB | Viewed 261 times ]


The jaggies are very obvious - I have reprinted these at 0.01 mm vertical steps and they are a lot smoother. But even the coarse resolution part has a complete hand wheel. It is only about 0.078 inch (2 mm) diameter and the diameter of the circular part is only about 0.013 inch (0.3 mm)! I beefed up the shaft of the wheel a bit and made the circular part of the handle circular in cross section for the 0.01 mm step part. This allowed me to eliminate the wheel support you see on the right. A bunch of them printed OK without any supports for the wheels, and at 0.01 mm step size the wheel printed in 30 layers with no jaggies!

Printing at 0.01 mm vertical step size is very slow - about 6 hours for these parts (and a bunch other taller parts) to print, but the quality of the parts is much superior.

Phil

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 Post subject: Re: 3D printing
PostPosted: Wed Jan 19, 2022 2:08 am 
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I'm liking what I'm seeing! :thumbs_up_1:

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 Post subject: Re: 3D printing
PostPosted: Wed Jan 19, 2022 2:51 am 
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The printing seems to take indeed quite some time, but the results with higher spatial resolution are definitively worth it :thumbs_up_1:

What is your feeling about messing around with the different resins ? Not having a dedicated workshop (I have set aside 1/4 of the study/library in which I pursue my day-job), handling liquid chemicals is a bit of a challenge.

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 Post subject: Re: 3D printing
PostPosted: Wed Jan 19, 2022 10:02 pm 
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wefalck,

I haven't tried experimenting with other resins. I have just used the standard gray Anycubic "Basic" resin that I received with the printer. It is pretty nasty stuff, but not that much of a problem with handling. Just wear rubber gloves and wash your hands with soap and water. The biggest problem is the smell - it stinks. The instructions say to use it in a well ventilated space.

The instructions say to use ethanol to wash the parts, but many people use isopropyl alcohol (rubbing alcohol). I found cheap ($16 per gallon) denatured ethanol (denatured with 5% methanol) at a local store. It is used as a paint stripper for furniture refinishing. It is actually cheaper than an equal amount of rubbing alcohol because you can buy it by the gallon. But the alcohol is more volatile and stinks worse than the resin. It smells like a lot of spilled vodka.

The smell is bad but not overwhelming. But you wouldn't want it in your study. Ask me how I know!

There are "vegetable" resins that are water soluble, and a whole host of other resins with different characteristics. Some more flexible, some more brittle. Some are supposed to be better for fine detail. I haven't tried any of those yet. In fact, that was going to be my next question here.

The printer and associated stuff, including a small uninterruptible power supply, do not take up much room. I put it on the 33 inch x 16 inch (83.8 cm x 40.6 cm) top of a laundry cabinet in my laundry room. I can turn on the clothes dryer on a cool down (not heated) cycle (with no clothes inside) and the machine will suck air out of the laundry room and expel it to outside the house. It isn't nearly as good as a fume hood, but better than nothing.

The printer is very quiet, with just a low whir and hum as the stepper motor raises and lowers the platform.

Phil

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 Post subject: Re: 3D printing
PostPosted: Thu Jan 20, 2022 2:04 am 
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I use this one: Elegoo standard.

No smell and a very good reproduction of the parts compared to the Anycubic.

https://www.amazon.fr/ELEGOO-R%C3%A9sin ... p_2_i&th=1

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•SS Delphine 3D: https://vu.fr/NeuO
•SS Nomadic 3D: https://vu.fr/tAyL
•VLCC Olympic Bravery 3D: https://vu.fr/OZMY
•USS Nokomis 3D: https://vu.fr/kntC
•USS Pamanset 3D: https://vu.fr/jXGQ


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 Post subject: Re: 3D printing
PostPosted: Thu Jan 20, 2022 3:28 am 
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Thanks, DrPR. I am sort of a chemist, so I am rather tolerant towards organic solvent smells, but my wife may have another opinion on that :big_grin: . She got quite used to the smell of the 'cleaning alcohol' sold over here in France quite cheaply due to the Covid-related sanitary measures, but its not one of my favourite smells. I am quite familiar with the smells of acrylic monomers and resins, as Plexiglas has been around our house always since my father worked as biochemist for a subsidiary of the manufacturers.

My concern would be more with the actual handling of the liquid monomer, preventing spills, cleaning of the machine etc. One needs a bit of bench space for that, that can be cleaned up easily.

We will be moving in a couple of years or so and I am planning to have a (small) dedicated workshop, so I will have to think about a work-surface for such printer.

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 Post subject: Re: 3D printing
PostPosted: Thu Jan 20, 2022 1:03 pm 
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I have exclusively used the water washable resins as I do my printing in a small office right off the library, where the design computer also resides. They have very little odor. I do use alcohol for an initial rinse which I think works better. Of course it may be that the standard resins have some better properties that I have not as yet explored. I can appreciate that a small apartment with a resident spousal unit could be problematical as would be some of the other effluvia of the hobby.

The Phrozen Rapid Black I favor for fine detail is more likely to have micro steps than the Model Gray which produces a smoother surface. I believe that the difference here is the MG is much more viscous.

Cheers: Tom


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 Post subject: Re: 3D printing
PostPosted: Thu Jan 20, 2022 1:05 pm 
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To clean the parts perfectly I use this machine from Anycubic, no more smell, it's better for the health, and the difference with the manual cleaning is important, the parts come out matte, without the excess of resin that I had despite the intensive cleaning with the brush.

We often underestimate the cleaning in the process, yet it is him who bring out the finest details. I was able to verify this for myself and I wouldn't go back.

It is now available at 119 euros.

It seems to me indispensable if you want quality parts and avoid breathing alcohol fumes.



The new model V2:


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•SS Delphine 3D: https://vu.fr/NeuO
•SS Nomadic 3D: https://vu.fr/tAyL
•VLCC Olympic Bravery 3D: https://vu.fr/OZMY
•USS Nokomis 3D: https://vu.fr/kntC
•USS Pamanset 3D: https://vu.fr/jXGQ


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 Post subject: Re: 3D printing
PostPosted: Fri Jan 21, 2022 1:52 am 
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I need some help here. The process I ahve been following is:

1. I have been creating parts for printing in my CAD program, scaling to 1:96 and converting dimensions to millimeters.

2. Then I save the file in STL format.

3. Next I run it through Microsoft 3D Builder to correct any errors (there are always errors).

4. Then I load the files into Chitubox to add supports and do the slicing.

Larger parts come in OK but smaller parts come in huge, larger than the print area. It appears they are loaded in centimeters instead of millimeters. I can find no way to tell Chitubox to use millimeters, and it seems to be pretty haphazard how the parts will be loaded.

I have found that if I scale the oversize parts 1/10 they seem to come out the correct size in millimeters. However, Chitubox has no way to measure the dimensions of parts, so there is no way to tell if the parts are the right size until after printing. So far they have been pretty accurate - to within a percent or two.

But here is a problem I have encountered:

Attachment:
Part size mismatch.jpg
Part size mismatch.jpg [ 105.88 KiB | Viewed 191 times ]


The cylindrical object is a bucket vent common on WWII US Navy ships. The grid like object is an attempt to print a very fine mesh screen to fit onto the bucket vent. It is supposed to fit into the opening outlined in red.

Both objects were designed in millimeters in the same CAD file, and the grid fit exactly into the opening. Both imported into Chitubox hugely over sized. Both were scaled 1/10. But as you can see, the grid is more than twice the size of the opening. So the two parts, which were designed in the same file, with the same measurement units, are imported into Chitubox with apparently random dimensions.

This one has me stumped! When I asked Chitubox support how to get things to import into the program at a specified dimensions they responded "Huh?" It is like they never considered actually printing at some real dimensions.

NOTE: The retards who created the STL file format failed to include any dimensional information in the files. So there is no way to actually specify object dimensions in STL files. Is that stupid or what??

I can find no way in Chitubox to specify the measurement units to be used when importing files. Again, stupid!

Does anybody have any suggestions?

Does anyone use a slicer that allows you to specify the units to use for importing objects?

Phil

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 Post subject: Re: 3D printing
PostPosted: Fri Jan 21, 2022 3:02 am 
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For me, it never happened, once saved in STL or OBJ file the parts have exactly the size I created it at when I import them in Chitubox.

I think the problem comes from one of the other two programs you use, probably a measurement conversion bug at some point.

The test to do is to create a small simple test piece in mm and follow the usual process to see if it works correctly.

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•SS Delphine 3D: https://vu.fr/NeuO
•SS Nomadic 3D: https://vu.fr/tAyL
•VLCC Olympic Bravery 3D: https://vu.fr/OZMY
•USS Nokomis 3D: https://vu.fr/kntC
•USS Pamanset 3D: https://vu.fr/jXGQ


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 Post subject: Re: 3D printing
PostPosted: Fri Jan 21, 2022 9:08 am 
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Phil,

First off, I'm certainly no expert in the 3D design/printing arena BUT I do have a suggestion or two regarding your design/printing process - this may get a bit lengthy but who cares, time is all we have, right?? :doh_1:

1) Your 3D design program DesignCAD 3D Max probably can be reset to draw in metric and it might be advisable to do so. I know we're all used to drawing in ft/inches but the 3D printing programs aren't. So, that's problem #1 - when I started out with DSM in 2019, I set the program to ft/inches and then found that Chitubox doesn't work in that format. So, I went back and reset DSM and began learning to draw in metric. Now, that steel metric rule is my "6th finger" - don't leave home without it!!!! :thumbs_up_1: While all my paper plans/blueprints are in ft/inches, they are to scale so it doesn't matter if you make your parts in mm - in fact, I'm doing that all the time now. The only ft/inch parts will be the hull as I'm still using MicroStation 2D to draw up my hull sections for cutting out of plywood, etc. I have 3 hand calculators (all identical Measure Master Pro models) that will do std to metric conversions and that is my "7th finger". So, I've reset DSM to draw in mm and that's how the design file is done and when I create the .stl printing file, it is already in metric and ready for the slicer. I'm fairly sure that your 3D design program can be set to metric from the Settings menu. I can't answer the obvious question as to whether or not if you reset it to metric that your current CAD files will be scaled correctly. I do think there is a scale factor involved but you'll have to determine that.

2) I have no idea what Microsoft 3D Builder is or even WHY it would be necessary!!! Neither Tom nor I use it with DSM and we both use Chitubox as slicers, so what is that all about? My initial feeling is that this is an unnecessary step in your process. Once the .stl file is created, it should be able to be read by any slicer as far as I my limited knowledge understands this. If I'm incorrect, please let me know!!!

3) Chitubox - true, it does not have any sort of dimensioning tools or readouts - however, it DOES have a little warning message if once your parts are sliced and it finds any disconnected or stray items (it calls them "islands" or "lonely islands") it will let you know down in the lower right corner of the screen. I do know that if your design file has NO "surfaces", then you won't incur this warning message. Quite a few times I do get the message "model scale is too small to fit" or something along those lines. I ignore it because I usually use a 0.5% scaling up factor due to shrinkage and so far, haven't had any parts come out other than what I've expected in size. On the other side of the coin, it will also tell you when your part is too big to fit on the drawing surface. I'm currently working around a situation where that occurred so I'm re-orienting my part to avoid this.

I think if I were you, I would go back to those parts that are oversized and recheck the design file and make sure they are drawn in mm, not cm. One other solution would possibly be then to scale down the part and then recreate the .stl and then reslice in Chitu. I too have drawn up bucket vents in DSM - at 1/144 scale the grating will not print, so I didn't worry about it. However, on my T-3 tanker parts, I was able to get a fairly successful diagonal grating to print as long as I made a solid surface BEHIND the grating. This did print very nicely, so I would think that at 1/96 scale, this should work well for you, as well.

Hope this helps....!

Hank

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USN Sloop/Ship PEACOCK (1813) 1:48
ROYAL CAROLINE (1748) 1:47
AVS (1768) 1:48


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 Post subject: Re: 3D printing
PostPosted: Fri Jan 21, 2022 11:00 am 
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Phil:

Chitubox has a scaling function. It will give the long dimensions in the three axis, in MM. if you have the correct dimensions in mm for the print part you can type these in. One can either lock the change of scale or size the axis independently. Reading these dimensions is always a good check on a part being correct size. As I sometimes print in various scales I can either scale the item in my design program of just adjust in Chitubox.

Haven't had this issue, but not using any intermediate program and always designing in MM.

Good Luck! Tom


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 Post subject: Re: 3D printing
PostPosted: Fri Jan 21, 2022 1:04 pm 
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Stl files contain a line that records the units it was created in but that is just a note. The software you use to create in has an option when saving to set your units.
Same thing happens when software imports it in. If your parts are 25 times bigger then it is inches to metric scaling issue and it was set up to read wrong. If it is 10 times bigger then it is a mm/cm issue.

I see this everyday with my work and our clients calling in for support with their CAD models.


Cheers,
Todd


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 Post subject: Re: 3D printing
PostPosted: Fri Jan 21, 2022 4:43 pm 
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Thanks everyone for the information and suggestions.

1. I use the (DesignCAD 3D MAX) CAD program, and have been using it since 1988. I am very familiar with it and was an alpha and beta tester for decades. You can design in any Imperial and Metric units and switch between different units, with appropriate scaling. You can also scale designs from one size to another. We have used it at work for decades to design everything from huge oceanographic instruments to tiny molds for resin casting, and innumerable mechanical packaging jobs.

For example, my USS Oklahoma City CLG-5 design was created in inches at 1:1 scale. The hull is 7320 inches long (610 feet). But for 2D plotting I change the scale to 1:96 to get full sized 1:96 prints.

But for 3D printing I first change the scale to 1:96 and then change measurement units to millimeters, with appropriate scaling. This changed 96 inches at 1:1 scale to 1 inch at 1:96 scale, and then changes 1 inch to 25.4 millimeters. I save this file as my working 3D print file. From this I generate STL or OBJ files. As I have posted earlier these STL files usually print the 1:96 scale parts with about 100% +/- 0.2% accuracy.

However, I am still using the 2018 version of DesignCAD and it almost always generates STL files that have errors. I have four different programs that report these errors (AccuTrans 3D, 3D Builder, Photon Builder and Chitubox). Microsoft's 3D Builder is the only program I have found that will correct these problems and generate a STL file that works with all the other programs.

What is weird is that the files all appear the correct size in AccuTrans and Builder. Some of the larger objects come in to Chitubox at the correct size. But the smaller objects always come in huge, larger than the print area. But up to now they have all been exactly 10x too large, so I have used the Scale function, changing scale from 100.0 to 10. This brings them back to the correct size.

Except for this tiny grating!

2. Here are photos to show the strange scaling problem I am seeing.

Attachment:
Vent and grills.jpg
Vent and grills.jpg [ 124.26 KiB | Viewed 149 times ]


This is the bucket vent with the 10 grill sections - all created in the same file, 1:96 with millimeter units. It was saved as an STL, blessed by 3D Builder, and imported into Chitubox. Everything came in at the correct size in millimeters. The grid has 1 cm spacing, and the vent is about 14 mm wide. The grids import at the correct size (X = 3.7432 mm, Y = 0.4019 mm , Z = 2.1828 mm). So as long as the total object dimensions are larger than some magic number the parts import at the correct size with no scaling.

Unfortunately, there is no way to edit files in Chitubox to cut out parts that are not wanted - in this case the vent. The vent will print correctly at 0.05 mm vertical stepping, and that will be 5x times as fast as the 0.01 mm stepping that will be necessary to print the grills (if they print at all). I want to print the vents at 0.05 mm stepping and the grills at 0.01 mm stepping. This requires separate files for the vent and the grills.

This leads to the problem illustrated here:

Attachment:
Three sizes.jpg
Three sizes.jpg [ 119.73 KiB | Viewed 149 times ]


After loading the vent and grills file shown above, I loaded two separate files of the grill. One was scaled in millimeters and the other in centimeters before creating the STL files. The grill was just cut out of the bucket vent file, pasted into a new blank file that was already using millimeters as the units. The size measures correctly in both the original and the new grill only file.

Then the middle STL file was generated for the grill with mm units. It came into Chitubox hugely oversized (X = 95.04 mm, Y = 10.19 mm, Z = 55.41 mm). This is actually 25.39 times the real dimensions. Scaling to 1/10, as I have to do with some otherr small objects, I get the size shown in the middle (units - mm) that is2.5 times oversized.

To test the idea that saving the files with centimeters as the units might solve the problem, I redefined the measurement units in the CAD file to centimeters, with appropriate scaling, created another STL file and imported it into Chitubox. It was even larger than the mm scaled file, and when scaled 1/10 came out as you see it on the right (units = cm).

****

My problem probably has something to do with the original DesignCAD STL files. 3D Builder shows the size of the mm grill to be about what I get when I import it into Chitubox and scale it 1/10.

I guess I will have to use the Chitubox Scale function to check everything I try to print to be sure that it has imported at the correct size. I tried this in Photon Workshop (a version of Chitubox) and It won't allow me to input dimensions less than 1 mm! When I try to set the X dimension at 3.7432 mm it just uses 3 mm! However, this does seem to work in Chitubox.

Measuring the dimensions of an irregular object could be tricky. Fortunately I can ask DesignCAD what the maximum XYZ dimensions of an object are.

I certainly cannot use a simple import and scaling procedure for everything. PITA!

Of course the whole point in this exercise is to determine if such a tiny (~3x2 mm) object can be printed and if the extremely small openings in the grill will actually be open. The thickness of the grid bars is 0.05 mm, so if I print at 0.01 mm each horizontal bar will get five print layers. I have printed a few vertical objects that are only 0.05 mm thick, so it might be possible.

To be continued ...

Phil

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 Post subject: Re: 3D printing
PostPosted: Fri Jan 21, 2022 9:44 pm 
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Phil:

One vague possibility is there is a popup mentioning you object is too small and will automatically re scale it to something. It is possible that a setting box is checked somewhere.

Ah yes, 3D max, many of the modelers of Flight Sim aircraft used this program to make the 3D model, painters would do the
"skin" and I would do the flight dynamics. Check the scaling in the re size window and see if it is adopting a value other than 100%

Good luck! Tom


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 Post subject: Re: 3D printing
PostPosted: Sat Jan 22, 2022 12:21 am 
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I imported the grossly oversized part into Chitubox and used the Scale function to set the proper X dimension. The "Lock Ratio" box was selected so Y and Z followed suit.

Then I added supports, sliced and printed it with 0.01 mm steps.

Attachment:
48 inch bucket vent grill 2 small.jpg
48 inch bucket vent grill 2 small.jpg [ 117.54 KiB | Viewed 136 times ]


It did print! Both horizontal and vertical bars are supposed to be 0.05 mm diameter. The vertical parts are close, but I don't have a micrometer scale for my microscope. The horizontal bars are several times too thick. My guess would be because at this size the resin is translucent and the 4.5 second exposure time cured a bit more than just the layer at the bottom. But that is a guess.

Here is another photo from an elevated angle. The over sized horizontals is very apparent here.

Attachment:
48 inch bucket vent grill small.jpg
48 inch bucket vent grill small.jpg [ 131.66 KiB | Viewed 136 times ]


The marks at the bottom of the picture are millimeters, and the part is 3.7 mm x 2.2 mm. The grid is there, but is nothing spectacular. This part was washed in ethanol, but it hasn't been cured yet.

I knew these would be fragile so I printed 15 (I need 10 for the vent). I expected problems getting them off the supports, and several broke off when I accidentally touched them with tweezers. Cleaning up the support material at the bottom corners will be a problem, and because they are oversized a bit they may not fit into the openings in the vent.

To be continued ...

***

Now here is another strange thing. I just reloaded this file into Chitubox and it came in at the correct size!

Phil

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 Post subject: Re: 3D printing
PostPosted: Sat Jan 22, 2022 12:28 am 
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Phil…

Perhaps try the screen at 45 deg”


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 Post subject: Re: 3D printing
PostPosted: Sat Jan 22, 2022 12:46 am 
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Joined: Sun Mar 07, 2010 12:01 am
Posts: 1485
Location: Corvallis, Oregon, USA
Good idea. AT 0.01 mm steps it will add another hour to the job (it took 2.5 hours for the part in the photos).

I thought about printing it horizontal, but I suspect there would be no way to release it from the supports without destroying it.

Maybe I will do another run with parts at several angles and see what happens. After all, it is just time.

****

The part that printed 2.5 times oversized came out really good. So maybe I should start over and build a 1:35 scale cruiser. It would be 17.5 feet long! And I could add a lot more detail! Unfortunately, I don't have a work space large enough for that.

Phil

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 Post subject: Re: 3D printing
PostPosted: Sat Jan 22, 2022 10:50 am 
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Joined: Sat Jan 17, 2009 2:12 pm
Posts: 3376
Phil, what microscope are you using as I have a 1000x usb microscope?


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