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valchanov

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  1. Like
    valchanov got a reaction from ossifylife1 in Postprocessing 3D prints   
    Every Slicer software have automatic support function. Just click it and it will generate the right amount of support you need.
    For bone models the important question is - are your fellow surgeons planning to cut the model or not. It will be a shame, if they break their instruments into your model...
    For metal implant premodelling prior the operation, you need smooth bones with high resolution details. In my experience, 0,150mm layer thickness, with 4 perimeters (1,7mm shell thickness with 0,4mm nozzle), 15% gyroid or cuboid infill, a bit colder extrusion temperature (200C for PLA) is perfect. Your fellow surgeons can bend the metalic osteosynthesis implants on the model into their optimal shape, can sterilise them and this whole operation will decrease the surgery time with 1 hour. This is a big difference for the outcome of the operation, the recovery time, the complications ect. ect.
    If you want to print fracture fragments, make them in different colors. Then you can make 3D visualization with the corresponding colors. The model will look marvelous and you'll become the surgeon's best buddy. They will love you, they will cheer you and they will give you a lot of money for that.
    If you need specific information, please tell us - printer model, slicer software, material on choice. I can give you more specific information, if you do that.
  2. Thanks
    valchanov reacted to kopachini in Postprocessing 3D prints   
    Some of you could see it on my Instagram account, but for those who didn't, here are some of the tips if you want a really transparent and water tight models:
    use Polymaker PolySmooth transparent or Prusament PVB filament. According to Prusa you should set layer height to 0.3mm, but I print with 0.2 mm layer height with very satisfying results. Wall thickness 0.6 (you could make 0.8mm but as thicker it gets, model is less transparent so I didn't go at 0.8mm, maybe once I will try). After the print scrape away some irregularities and after that you can put it in chamber for vapor smoothing with isopropyl alcohol. If you don't own one (as me) just spray the model (inside and outside) with IPA for smoothing results. Don't be aggressive as too much alcohol on the model softens and dissolves PVB so it is better to spray a little bit than after drying, spray it again.
     
    Bellow is the example of my aorta model and you can see catheter and guidewire really well.

  3. Like
    valchanov got a reaction from Angel Sosa in Internal latticing a requirement for 3D printing?   
    - Is it typically a requirement to have latticed internal volumes to reduce material costs?
    In my experience, the model have to be solid and without internal meshes. The material cost can be controlled with the percentage and the type of the infill.
    - What about dowels/pins so that the model can be assembled? Do people usually want this?
    If you're printing a bone model in two parts, its better to glue them together after the print. If you're printing a model with a important cavity (skull or aorta), pins or sockets for neodymium magnets are a choice, which guarantees good alignment for the parts of the model and increases usability. The magnets are better, unless your client specifically prefer pins.
    - Are there any other considerations that would make these models more valuable to the community - I potentially have a few more anatomies that could be of value. Make them shinier, more stable and design a stand for the model.

  4. Thanks
    valchanov got a reaction from inyazserg in Entry/Minimal Use 3d Printer recommendation?   
    If you want to scan people for fun, you can  use your cell phone for photogrammetry with free software. Then you can put the heads on different bodies and to print them. Something like this:

    For this purpose you can use every 3d printer up to 2000$. I myself prefer my original Prusa MK3, because I'm not an engineer and I prefer something to do all the printing stuff for me. Here is the result:

    When we're talking about medical 3d printing, we're talking about a whole different topic. The medical models have to be very precise and there is an industrial standards about it. For example, my models have 0,5mm deviation from the original body part at 95% confidence interval. I had a presentation at an morphology symposium about my favorite Lusoria model lately and now I have a lot of orders from the local hospitals, because of the standard, which I can achieve. For medical modeling you have to be an expert in all the morphological specialties (Anatomy, Pathology, Radiology) with some serious clinical background. To reach this level, you need:
    1. Medical education.
    2. A lot of treated patients, most of which have to stay alive after your job. The death patients are literally skeletons in the closet.
    3. Some background in the basic dissection techniques, both the pathological and the anatomical ones.
    4. The surgery training is a plus.
    5. Some gaming experience or experience with CAD software. The computer games are like bodybuilding for the visual cortex.
    6. 1+ years of hard work, everyday modeling, studying, drawing, dissections, consultations with the experts in the field, a lot of tears and some joy.
    THEN you can do medical modeling, something like this.
    I started to model, when I was an anatomy assistant professor, with 12 years of experience as an emergency internal physician. I had the chance to find this website with all it resources, tutorials and the awesome support from the administrators and after 1 year of really hard work, I became a professional, (one of the best in my region, in a matter of fact). But still, my biggest nightmare is that, because of my mistakes during the preoperative modeling, a patient will die. So - are we really talking about medical modeling or you just want to do some fun with your client's CT scans?
  5. Like
    valchanov got a reaction from Allen in rabbit bones   
    There are good animal CT scans on Duke University's repository. There are also a lot of stl models, tif's and all kind of media content you can possibly want. Just don't forget to quote them, this is an intellectual property...
    OR you can make a CT scan of a rabbit and segment it into a 3D model by yourself or you can hire one of us to do it. THEN the intellectual rights will be yours.
    If you want just to download a rabbit skeleton and to 3d print it, go for the Duke University. I am really excited by their Ape and Hominin collection - already 3d printed few of them. The dinosaurs are also really good.
  6. Like
    valchanov got a reaction from Dr. Mike in rabbit bones   
    There are good animal CT scans on Duke University's repository. There are also a lot of stl models, tif's and all kind of media content you can possibly want. Just don't forget to quote them, this is an intellectual property...
    OR you can make a CT scan of a rabbit and segment it into a 3D model by yourself or you can hire one of us to do it. THEN the intellectual rights will be yours.
    If you want just to download a rabbit skeleton and to 3d print it, go for the Duke University. I am really excited by their Ape and Hominin collection - already 3d printed few of them. The dinosaurs are also really good.
  7. Like
    valchanov got a reaction from Dr. Mike in Entry/Minimal Use 3d Printer recommendation?   
    Pretty much the same. But there is a new player in town - the Snapmaker. 3d printer, laser engraver and CNC rooter in one machine. I don't have personal experience with it, but it looks so appealing... Almost too appealing.
  8. Like
    valchanov got a reaction from Dr. Mike in How can I print life-sized human skull with disarticulated mandible?   
    The temporomandibular joint is extremely complicated one, a simple hinge won't simulate the movements in the axes properly. A whole system of hinges and strings is needed. For simple demonstration purposes,  the neodymium magnets works great. 
  9. Like
    valchanov got a reaction from 3dsmartprint in Entry/Minimal Use 3d Printer recommendation?   
    Ender 3's bigger bro, Creality CR-10 is better in any possible way - huge building volume (300-300-400 mm), better controller, better extruder and hotend, double Z axis, safer power supply...  I bought my CR-10S on Black Friday for 320$... I'm not printing on it often - my other printers are much better and more expensive. But for small operation, Ender 3 and CR-10 are quite good. There are 3d printing farms with those printers and they can be very reliable after some hardware upgrades and tunning.
  10. Like
    valchanov got a reaction from Jesús Báez in Formlabs Fuse 1 SLS printer   
    There is a game changer on the SLA front - Josef Prusa made an open source SLA printer - Prusa SL1.  You can buy two of those and one Prusa MK3 with the money for one Form 2. It prints down to 10 microns layer thickness (after some tweaking of the slicer). It is open source, which means that the wave of cheap prusa clones is coming. This will change the whole SLA sector because let's face it - with the money for one Form 2 you can buy a whole 3D printer farm with the best printer of Winter 2018 (Prusa MK3) or you can buy two printers of the same class, with the same parameters, which requires more tinkering and experienced staff.  The bad side about the Prusa printers are the limited Wi Fi options...
  11. Like
    valchanov got a reaction from Jesús Báez in Quality of models   
    It looks shiny, but in my honest opinion, Philips are not famous with their software. They have notorious "fame" among the bulgarian radiological community as the worst software with the most non-user-friendly interface. My colleagues are all into Siemens and Esaote here. Besides, Slicer 3D is free, open source program. From the commercial ones, I really like Osirix and Materialise, but the best one in my opinion is Autodesk Within Medical. The price of 17k euro per year is a bit stiff, though.
  12. Like
    valchanov got a reaction from Terrie S in Entry/Minimal Use 3d Printer recommendation?   
    Ender 3's bigger bro, Creality CR-10 is better in any possible way - huge building volume (300-300-400 mm), better controller, better extruder and hotend, double Z axis, safer power supply...  I bought my CR-10S on Black Friday for 320$... I'm not printing on it often - my other printers are much better and more expensive. But for small operation, Ender 3 and CR-10 are quite good. There are 3d printing farms with those printers and they can be very reliable after some hardware upgrades and tunning.
  13. Like
    valchanov reacted to Dr. Mike in 5 Best Slicer Software for 3D Printers   
    Very cool! I did something similar when I designed a functional aortic valve dynamic flow TAVR tester. The hardest part about printing in elastic is the valve leaflets. They are thin and susceptible to tearing. Also, they can stick together. It was a tricky print!
     
    Mike
     



     
  14. Like
    valchanov got a reaction from Angel Sosa in 5 Best Slicer Software for 3D Printers   
    Not a word about Prusa Slicer - maybe THE BEST slicer so far, frequently updated and user-friendly. Maybe Simplify3d has more useful options and extras, but it's not updated regularly, so in my opinion, it's number 2 after Prusa Slicer.
    The best slicer is Netfabb - an Autodesk program, which combines design, simulation and CAM in one and can do amazing stuff with basically everything (I'm talking about alchemy level stuff). The price is too hefty for my operation, though.
    Did you know, that you can use the latest version Fusion360 as a slicer? I was also surprised. It's actually not bad at all, but I prefer Prusa Slicer and Cura for my printers.
  15. Like
    valchanov got a reaction from Dr. Mike in 5 Best Slicer Software for 3D Printers   
    Prusa slicer is not hardware-specific and can be used with most Cartesian FDM printers. For example, there are tons of videos in youtube how to set Ender 3, CR-10, Anet, Tevo and similar low-class printer to work with the full extend of features, which comes with Prusa Slicer. The only issue is the retraction speed - the bondtech gears of MK3 are 3x and the retraction have to be set accordingly. I can't run my Rostock max with it, because it's delta printer and I'm using Cura.
    Btw, our lab with be updated with Form 2, because of this Aortic valve TAVI simulator - I made the 3D model and ordered it to be printed with Elastic resign on Form 2. The model is excellent, everyone is happy, my lab will get a brand new Form 2 for serial printing of those things...
  16. Like
    valchanov got a reaction from skwears in Postprocessing 3D prints   
    Every Slicer software have automatic support function. Just click it and it will generate the right amount of support you need.
    For bone models the important question is - are your fellow surgeons planning to cut the model or not. It will be a shame, if they break their instruments into your model...
    For metal implant premodelling prior the operation, you need smooth bones with high resolution details. In my experience, 0,150mm layer thickness, with 4 perimeters (1,7mm shell thickness with 0,4mm nozzle), 15% gyroid or cuboid infill, a bit colder extrusion temperature (200C for PLA) is perfect. Your fellow surgeons can bend the metalic osteosynthesis implants on the model into their optimal shape, can sterilise them and this whole operation will decrease the surgery time with 1 hour. This is a big difference for the outcome of the operation, the recovery time, the complications ect. ect.
    If you want to print fracture fragments, make them in different colors. Then you can make 3D visualization with the corresponding colors. The model will look marvelous and you'll become the surgeon's best buddy. They will love you, they will cheer you and they will give you a lot of money for that.
    If you need specific information, please tell us - printer model, slicer software, material on choice. I can give you more specific information, if you do that.
  17. Like
    valchanov got a reaction from Dr. Mike in How can 3D printing help with the coronavirus pandemic?   
    I used this version.  PETG/PET, chemically resistant face max.


  18. Thanks
    valchanov got a reaction from Angel Sosa in How can 3D printing help with the coronavirus pandemic?   
    I used this version.  PETG/PET, chemically resistant face max.


  19. Like
    valchanov got a reaction from Angel Sosa in Entry/Minimal Use 3d Printer recommendation?   
    Hello

    For a limited budged - Ender 3. Several of my colleagues and some students purchased such machines. An amazing printing right from the box. 
    For minimum troubles and great beginner experience - Prusa MK3S. It's declared "the best 3d printer of 2019" for a reason. Fantastic learning curve and results. The new Prusa Mini also looks quite formidable. Those are machines with automatic features, which are quite useful.
    For professional settings - Ultimaker. It doesn't matter what kind of task you're trowing at it, it works and works and works. The minimum professional level machine.
    DLP for limited budget - Anycubic Photon or Elegoo Mars. They cheap, dirty and reliable. They requires an exposure to chemicals, but the printing is fantastic.
    STL - Form 3. The best in it's class. Because of it release, you can also purchase brand new Form 2 for 2k$, which was the best in it's class last year...
    There are also the 3D systems, Stratasys and similar corporations, but it's a whole different world there - the machines are fantastic. costs thousands of thousands and provides a quality, which is impossible for the low class, for which you're asking.

     
  20. Like
    valchanov got a reaction from Allen in Entry/Minimal Use 3d Printer recommendation?   
    Hello

    For a limited budged - Ender 3. Several of my colleagues and some students purchased such machines. An amazing printing right from the box. 
    For minimum troubles and great beginner experience - Prusa MK3S. It's declared "the best 3d printer of 2019" for a reason. Fantastic learning curve and results. The new Prusa Mini also looks quite formidable. Those are machines with automatic features, which are quite useful.
    For professional settings - Ultimaker. It doesn't matter what kind of task you're trowing at it, it works and works and works. The minimum professional level machine.
    DLP for limited budget - Anycubic Photon or Elegoo Mars. They cheap, dirty and reliable. They requires an exposure to chemicals, but the printing is fantastic.
    STL - Form 3. The best in it's class. Because of it release, you can also purchase brand new Form 2 for 2k$, which was the best in it's class last year...
    There are also the 3D systems, Stratasys and similar corporations, but it's a whole different world there - the machines are fantastic. costs thousands of thousands and provides a quality, which is impossible for the low class, for which you're asking.

     
  21. Like
    valchanov got a reaction from Dr. Mike in Comparing FDM multi material options: Prusa MMU2 and Palette 2+   
    It works with any Carthesian purging tower generating printer, which includes MMU2, Pallete2 and the 2-in-one hotends. There are config files for most slicers, Prusa Slicer and Cura included. I didn't tested it myself yet, but it looks quite promising.
  22. Like
    valchanov got a reaction from Dr. Mike in Size of the 3D print vs Actual size   
    The shrinking is a major and complicated issue for all the 3D printing methods in general. I didn't cared about it, until I had to made really accurate, industrial-grade model, in which every micron matters. I'm not a material science engineer, but I have to address this issue even further, because my research group is planning to go in the direction of the temporary and permanent implants, in which even the slightest deviation can cause slow recovery, pain, inflammatory reaction or rejection. This is especially true for the 3d printed dentures and maxillofacial implants, in which even 50 micron deviation can cause significant problems for the patient. It's so good for me, that I'm not working for the dental medicine faculty, because for the bone implants deviation of 200 microns is perfectly acceptable. For the diagnostic models (presurgical, demonstration, teaching etc.) the acceptable deviation is even bigger - up to 500 microns.
    Every 3d printing method have some base shrinkage and warping, which is combined with the base deviation of the STL model itself and with the base shrinkage of the material. To make the issue even harder, the manufacturers didn't post the basic deviation of their materials, because this can ruin their trade secret. Every material in the market is not just a single polymer, but a composite of several polymers, with a lot of additives, which makes the issue even more complicated.

    There are several general rules:
    1. Material Jetting > SLS > STL/DLP/FDM. From the termoplastic modalities, the material jetting is most accurate method, while STL/DLP/FDM are relatively equal in their accuracy. STL and DLP have better porstprocessing option than FDM, though. Overall, for the lower industrial segment, FDM is better in the printing of large objects (more than 10 cm), while STL and DLP are better in the smaller part printing.
    2. Stiffer materials (high Young's modulus) are more accurate than the elastic materials. PLA (high stiffness) is more accurate than PETG or Nylon. This also depends on the 3d printing method.
    3. Material with lower extrusion temperature are more accurate than materials with high extrusion temperature. PLA shrinks with 2-5% (depending on the manufacturer), while ABS ~8%. You can control this process even further by tuning the cooling fan. 
    4. Larger objects shrinks more than the smaller ones. It's better to cut your model into several attachable parts, printed individually, than to print it as a whole.
    5. Enclosed system is more accurate than unenclosed one. The constant temperature in the enclosure will make the shrinkage more uniform in all the segments of the object, resulting on overall more accurate final product.

    The best practice is to start measuring your models.
    1. When you're done with the model, reimport the stl again in the medical data program, used for segmentation, convert it into a label map and compare the geometry with the voxels of the source dataset. If you're using control points on the antropometric points (separate segmentation on the classical points of orientation in the human body, several voxels in size), every deviation will be visible and editable. If you're not, you'll have to compare it visually.
    2. Use a professional CAD program (Fusion360, Solidworks) to measure the parts of the STL model. The digital simulations of those programs makes the quality control even better.
    3. Use dicom viewer to measure the same distances in the DICOM dataset.
    4. Use a caliper to measure the same distances on the 3d printed object.
    5. 6-8 measurements per distance will be more than enough. 4-6 distances will be enough for a model.
    6. Calculate average deviation at 90% confidence interval.
    7. The resulting score will give you the accuracy of your model.
    8. If you're not specifically targeting high accuracy or you're not a detail freak as myself, point 1 will be enough.

    You can check this guide, in which the issue is well explained. You can also check Form Lab's guide for dimensional accuracy, since you're regularly using Form2. For now, I can achieve without a problem 0,5 mm accuracy from CT scan to the 3D printed object (in some cases 0,2 mm), but I'm constantly fighting for every micron and I won't quit, until I achieve 0,2 mm on all of my models. I guess on some point I'll have to add a material science engineer to my research group. I'm also considering machine learning algorithm for quality control, but this is way over my head right now.

    To check how accurate are your models, you can use 3d printed tests. You can try the tolerance test and the all-in-one test. They work only for FDM, though.
  23. Like
    valchanov got a reaction from Dr. Mike in Comparing FDM multi material options: Prusa MMU2 and Palette 2+   
    I ordered this mechanism few days ago, the reviews for it are awesome. It's a retractable purging mechanism for printers with  Prusa multimaterial and Pallete. Instead of generating a wipe tower, the filament change is performed on the mechanism. This increases the speed of the filament change and the entire build plate is free for 3d printing.
  24. Like
    valchanov got a reaction from Dr. Mike in Postprocessing 3D prints   
    A little update about the Clear PLA filaments for FDM printers. It's also considered Natural PLA, because it doesn't contains additives and colorants, which makes it a bit complicated for printing. It looks a bit transparent, but it doesn't have the optical properties of the glass - for fully transparent prints the STL and DLP are the right choice. The clear PLA is very susceptible to moisture and should be sealed in vacuum back, with silica gel.
    For the Clear PLA, higher temperatures are better for best results. The hotend temperature should be 220-230 degrees. Otherwise the adhesion between the layers won't be strong enough and the model will become brittle. I learned all of this the hard way...
    The clear PLA is an excellent material for vascular models. A hollow vascular model should be printed with 4 perimeters, 100% concentric infill and support from the build plate only. On the pictures below you can check why I prefer those parameters. Happy printing!
     



  25. Like
    valchanov got a reaction from Terrie S in Postprocessing 3D prints   
    I was thinking the same, until I found the Silk PLA. It's a composite - 85% PLA, 15% Polyester and it's dirt cheap. The advantages are:
    1. In contrast to the natural PLA, the Silk one doesn't warp or deform during the cooling (or at least the deformation is minimal).
    2. It prints really well. You can make the impossible possible with this material.
    3. It looks amazing. The layer lines are almost invisible, the silk finishing is appealing, the colors are vivid.
    4. The supports falls easily. You just have to pull them and they are done. Tried this on a heart, brain and aorta models. You don't even need increased retraction for this.
    5. The stringing is minimal. No more "hairs".
    6. It's cheap.
    7. Because of those characteristics, this is material of choice for models with accurate morphological measurements. I'm using mostly this material, when I want to have an accurate model.
    So, check the local store for this material and try it yourself. You can thank me latter.

    P.S. For best results, print it at 200C.
     
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