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Id suggest choosing between a "tough" resin and maybe considering cutting it with some flexible resin depending on how much shock resistance you need. siraya tech blu and siraya tech tenacious is a pretty popular combination for this You can use graphite or grease for lubrication, in some things like brass bushings you'll see graphite mixed into it to give it self lubricating properties but I think if you tried to do that with resin you might compromise the strength

glad to hear it I have a mono 4k otw with eco resin. Completely new to this

P.s Great video 😀

Yeah, supports inside are perfectly normal. In most cases, you really even want supports inside because you will be getting geometries such as islands that can happen inside the hollow of a print.

@@3DExtra I was going to print a Hollow Totoro

If I drain the inside of the figure with alcohol to drain the resin, are the supports going to come off and stay there?

@@ivankas52 Supports are going to stay there, but you don't need to remove them. You can just leave them there and everything will be fine.

@@3DExtra Thank you so much ☺️☺️

I can't really argue about that with you Andrius. You, the conclusion on the video is a little bit out dated and it deserves a follow up to be honest. I would still hold a little bit to to not being incredibly important on an RGB machine, since the time it takes to properly start curing could act as a sort of "delay" but on a monochrome machine, you most definitely need a bit more or a pause. I'll keep a more broad application of it in mind when I update this video :).

@@3DExtra Just do a test print with and without it. When it doesn't start away the surfaces are more even. Scientific method, mr. engineer

I do not have personal experience with any of the engineering resins myself, but my advice would be to see if you can get hold of some sample size bottles and test out what works best for you. I believe Sirayatec Blu is the most affordable, but it’s relatively hard to print and not as great at resolving detail as some others. If you’re EU side I would additionally suggest to check out Ameralabs TGM-7 (wasn’t around at the time of making the video I think). While aimed at miniatures, it’s quite a resistant resin and might fit your application. Thank you very much for your sub, it’s greatly appreciated! Just need to find some time to make some more content for the channel.

That's relatively common. Chitu will only ever give you an estimate time. It makes a base assumption of the time based on the speed and layer heights that you input, but your printer movements also have other things involved in them. There's acceleration, jerk, firmware max speeds and firmware speed overrides that come into effect and since chitu doesn't know those values, it won't ever really know the correct time it's going to take. Best bet would be to try rough the difference between the displayed time and actual time and use that as an further rough estimate for the time it will really take.

I can't confirm this 100% since I'm using only Elegoo machines, but I was mostly reporting on how it's handled by chitu and what's in the manual. I've heard from a couple people that anycubic might handle it differently, but since the photon and photon S use the same board as the elegoo machines (Chitu L K1 or something along those lines) I would think maybe those older machines do it the same way. The mono might be different though since it seems to use a custom controller PCB, albeit with the same brain components as the other Chitu products, so it's possible that Anycubic did something different in the firmware or in the machine_parameters.gcode file. This would seem quite weird for them to add more work for themselves and create a sort of further fragmentation to an already badly executed setting.

I can confirm the same behavior on my Anycubic Mono. The LOD is added to the beginning of the cycle before the UV light turns on. No math necessary. I took off the vat and ran a print, keeping time with a stopwatch, while watching the screen through the enclosure. I was slicing with Lychee. The front LCD will project the image during the LOD and during the curing time. I have not testing this behavior with any other slicer.

@@jordangladden Hello. I am using a photon mono with lychee slicer too. Based on your comment, do not I have to do the calculations of this video? I mean, I have my LOD in 1 second, then after the vat is down, it will wait one second and then will turn on the light? please help

I can see where you're coming from and yes, you're right that anything below 9.5s (in my example) will have an actual "light off time" of 9.5s, but that's the logical light off time as the axis moves to perform the peel action off the FEP, and not an actual further "delay", since the setting is light-off delay, and not light off time. To me, and I think to others, the light off delay, implies extra time that the UV source is off for before printing the next layer. I should have indeed said "anything below 9.5s will give you no EXTRA delay at all" but I assumed it would have been clear. The video was overall an attempt to show to people who put 1, 2, or 3s that that specific variable, doesn't actually enable the light off delay setting in their case and their off time is just the sum of the time it takes to move the axis up and down for peel.

And a follow up: would it make a difference (in terms to suction forces and sticking to the build plate) if I place the non-tilted model on supports?

@@readywhen I'll try answer these as best I can: -If you would hollow the model, keep it flat on the plate and put a hole on the surface that's touching with the plate, you wouldn't be achieving anything with regards to venting the model during the print. You'd still have the issue that the model acts like a suction cup and you'd be getting a different pressures inside and outside of the hollow potentially causing a print failure or surface defects. There's a great post on reddit that showed how important venting is: cutt.ly/tjuwKwr. So if you'd want to print it flat on the plate, you'd want to then put the venting hole on the side at the lowest point of the hollow section to avoid issues. -The tilting is more of an orientation optimization thins. You are absolutely right that the minimum cross section will be at the bottom and top of the print, and the middle is going to be a little larger, but I was trying to say that the cross sectional advantage was better relative to a non-hollowed model. -For your follow up, I'm going to be doing a video explaining orientation and why we angle things very soon so I'll ping you when that's out, but the TL;DR is: we want to try avoid having the "first surface that prints at the tip of supports" to be large flat areas. That includes bases, and long flat edges. The reason for this is that once that part starts printing on the support tips, you're looking at a 0.05mm (or less) thin single layer. Just with the peel, it might rip in places if it's under supported and if it survives the peel, it then has to survive traveling 10mm through the resin (5mm up and 5mm down) at whatever your lift and retract speeds are. That's why you see a lot of models that are printed with a flat parallel to the LCD on supports with a horrible surface finish on that face. Hopefully that's helped!

@@3DExtra Thanks for your elaborate reply! The reason I care so much about this topic, is that for the objects I want to print, printing parallel to the build plate would allow the model to go almost suportless, whereas a slight tilt would introduce many islands. Everything you explain makes sense. But there seem to be inconsistencies in all the opinions I find on the internet. Consider this youtube comment I came across and I'd appreciate it a lot if you could share your thoughts on it: "There is effectively no suction being created inside the hollow because no resin nor air has been removed from the hollow after it was sealed. In fact, the air inside is VERY, VERY slightly compressed by the hollow model dipping into the resin. (You can see this in action by taking a drinking glass, turning it upside down, then lowering it into a bath tub or swimming pool. The deeper you go, the more the water will compress the air in the glass and you'll see the water level rise up inside the glass similar to what happens in a diving bell.) For a resin model the hollow cavity has a ~0.05-0.01 gap between the FEP and the model until the light source turns on, so up to that point, the cavity isn't sealed and pressure can equalize. For LCD printers, the resin perimeter will harden, but it will just hold the resin inside and outside now - it doesn't remove any material, so still no suction. When the model starts to lift, there is still no air or resin being removed from the cavity, so that side of the FEP is stable. At the same time as the model lifts, the underside of the FEP is open to the air, so there is no force pulling down on the inside of the hollow. All the force is on the outside perimeter of the model as the FEP is pulled between the edge of the model and the edge of the vat. Once the FEP peels away from the outer perimeter far enough to reach the inside of the hollow, then there is now a hole between the inside and the outside, so air and resin can flow an no vacuum can form to create suction. The only way for significant vacuum to form would be if the entire model stretched more than the depth of the resin in the hollow. At that point, the volume of the interior would have grown by more than the volume of the resin trapped air, and a vacuum would start to form. A flex resin could do this, but standard miniature resins are too rigid.

Looking forward to your upcoming video!

​@@readywhen The term "suction" gets used for a bunch of things interchangeably and the community is not really willing to decide on one specific thing. Suction should only specifically refer to the added force created while peeling an un-vented hollow object from the FEP. There is no suction during regular peeling, that's just a peel and there's no suction between the LCD and FEP since that's a completely open system. -The comment from the very start has no substance to it since there's no air trapped inside the hollow of the model unless your lift height takes the print above the resin line and in most cases that I've seen, the vats are full enough and the lift height is small enough for that not to happen. So while the diving bell analogy works to demonstrate that air is a compressible fluid it is completely invalid for explaining suction forces on hollow resin prints. The right test for this demonstration is: fill your sink up, take a glass, put it under the water and fill it up completely. Turn it bottom side up and try to remove it out of the water. Once the mouth of the glass comes close to the water line, you're going to start feeling some resistance on being able to pull it out of the water and that resistance is equivalent to the suction force on an un-vented model. It's most often not going to cause a catastrophic failure but it might result in a pretty big layer shift and if the model is big enough and the supports aren't quite right, it can result in the model tearing away and staying on the FEP. This graphic (not super accurate but brings the point across) might help with visualising it imgur.com/1M4W5iu. -While there is a small gap there to theoretically be able to "normalise pressure" you're not going to be able to do that once the print builds up past the resin line in the vat, since there's no way for resin to drain out of it and as you keep building up the print, you're left with . As far as things go, that gap might be too small to be able to let things normalise and since the print is always at the lowest point in the vat, there's no way to let air move into it without a vent hole at the highest point of the model. Plus resin is viscous and 0.05 is a super small gap.