Remove the Elephant's Foot from Resin 3D Prints - Plus NEW FREE Bulge Buster App

okay where do i start i've been working on the content of this video for about two months i've done a ton of experiments printed a lot of test prints and i even wrote an app what's it all about it's about getting rid of the elephant's foot i like to print right on the build plate there are a lot of cases where it's just easier and one of the projects i've been working on is an eight millimeter frame by frame film scanner i designed all of the parts to be self supporting and to print right on the build plate but there was one problem the elephant's foot in 3d resin printing it's that little ridge or bulge that forms around the edge that touches the build plate and because of that bulge some of the parts that were designed to fit together didn't like these gears when i printed them on the build plate the elephant's foot distorted the teeth of the gear and prevented them from fitting together properly then a few months ago i thought of an idea i thought of a way to print parts with a resin 3d printer right on the build plate without getting the elephant's foot oh yeah and i wrote an app that sort of handles all of it for you so stick with me i'm going to explain in more detail what the elephant's foot is what causes it my methods for how to get rid of it and then i'll tell you how you can get my app for free [Music] all right so if you never print right on the build plate if you always print with supports this might not be the video for you because i'm going to dive into the details of this problem and how to solve it i'm going to quickly explain what the elephant's foot is and what causes it and then we can explore some ideas on how to get rid of it but first a quick refresher on how lcd printers work because we need that basis to understand the rest on an lcd sla printer there's an lcd screen that displays an image of the slice we're printing some pixels on the lcd screen are black or solid and they block the uv light from passing through other pixels on the lcd screen are white or open and they allow the uv light to pass through and then if your printer supports anti-aliasing there might be gray pixels which would block some of the light and let some of it through and the idea there is that those pixels are sort of an in-between and would help smooth out that pixelated look although it's debatable whether that really works or not when the print starts the empty build plate is lowered into the vat leaving only a sliver of liquid resin between it and the lcd screen an image of the slice is displayed on the lcd screen and the uv light underneath it is turned on this cures the resin in the gap to match the image on the screen this cured slice of resin sticks to the build plate or at least it's supposed to and then the build plate is raised up so resin can flow underneath it and then it's lowered back down leaving a new gap for resin then the next slice is displayed on the lcd screen exposed by uv light and cured except that each new slice instead of needing to stick to the build plate has to stick to the slice before it if you want a deeper explanation of this check out my video on why resin prints fail so one of the very important parts of that process is the part where i said that the first cured slice of resin has to stick to the build plate that has to happen and remember the part is printed upside down and is hanging from the build plate so gravity is working against you you need good adhesion or the part could fall off the build plate also remember that the part gets heavier and heavier as each new slice is added to it so the bigger the part is the better that adhesion needs to be and the way we get that adhesion is by overexposing the first few layers because overexposing those slices cures the resin more deeply and makes everything stick to the build plate better in the slicer this option is usually referred to as bottom layers it might also be called burn in layers or burn layers but here are two main settings that describe these bottom layers as it pertains to build plate adhesion first is that you can set the number of bottom layers how many layers are you going to overexpose second you can set how long you're going to overexpose these layers for example the resin i'm using today needs a 12 second exposure time so i might specify the bottom layers to have an exposure time of 60 or more seconds i would maybe do 10 bottom layers at 60 seconds that's 5 times my normal exposure time of 12 seconds and this overexposure causes the elephant's foot but why on an lcd printer the longer a pixel is exposed or rather the longer the resin is cured by a pixel being opened up and allowing the uv light to pass through the more it will expand if you underexpose it it won't form properly and it might not stick to anything you would get a print failure if you expose it perfectly it should form properly and be precisely the size it should be the exact size of that pixel but as you continue to expose it beyond the perfect amount of time it will start to get larger and by the time you expose it 60 seconds it's larger enough that it forms that bulge around the edge so this is the part i was trying to print this gear you can see that in the grooves where the teeth meet it's sort of webbed and the problem here is that these two gears don't fit together like they should so this isn't going to work very well as a functional part and this was the problem i set out to solve so my idea was to take the bottom layers the ones that would normally be overexposed and to shrink all the shapes erode them or contract them so that they're smaller so that when we print them overexposed and those shapes expand from that overexposure that the expansion is all contained within what would be the original shape then on that same layer without moving the build plate print the original shape for whatever the normal exposure time would be so that this outer edge of the layer would print just like the other layers without any expansion the elephant's foot would then be hidden inside of the original shape this idea might take some trickery to pull off and there are a couple of ways to approach it first is the double exposure or multiple exposure method have you seen one of these test prints where it prints several strips on the same build plate each at a different exposure time they might call this a resin exposure test or a rangefinder but each strip on the plate is printed at a different exposure time and the way it accomplishes this is by doing multiple exposures on a single layer without moving the build plate let's say you want to print four test strips one at 10 seconds one at 11 one at 12 and one at 13. without moving the build plate you could display all four strips for 10 seconds then three of them for another second then two for another and then the last one for one more second when done this strip would have been exposed for 10 seconds total this one for 11 seconds total this one for 12 and this one for 13. i call this an additive exposure method because the total exposure time for each of these strips is the sum of each of the exposure bursts another way to accomplish the same thing is to do it in a non-additive exposure method in that case you'd expose only the first strip for 10 seconds then only the second one for 11 then only the next for 12 and only the last for 13. this method takes longer to print but it's more accurate these two methods would theoretically produce the same results however in practice i'm not so sure they do because i'm not sure resin works that exact way do four bursts of three seconds each produce the same result as one single burst of 12 seconds i'm not sure that it does but all i can say at this point is that more experimentation is needed and it's possible that different resins would even react differently to that sort of test still the point of those rangefinder test prints is that when it's done you can examine each of the strips to see which one looks the best and therefore hopefully determine the best exposure time for your resin so my initial big idea on how to remove the elephant's foot was to use this type of double exposure take the bottom layers and first print them at the normal exposure time let's say that it's 12 seconds and then contract or erode the layer in a bit and without moving the build plate re-expose that portion for the remainder of the time to reach the burn-in time so to total 60 seconds that would be 48 more seconds double exposure prints do work on my printer the frozen transform so i sort of assumed they'd work on all printers but i found out the hard way they don't to say the least it's complicated i did a ton of testing trying this double exposure method to bust the bulge and had limited success so i explored some other methods what if you could figure out the exact number of pixels that your resin is expanding when printing at the longer bottom layer exposure time if you knew the exact amount you could contract the bottom layers of your part by the exact same amount basically cancel out the expansion on the bottom layers by pre-shrinking them by the exact same amount the problem is that it's difficult to know exactly how much expansion will take place for any given amount of overexposure time it's not a linear thing however for now let's assume that you can derive this information for any given resin at any given overexposure setting because if we did know for example that 60 seconds produced a 2 pixel expansion then you could use that to basically remove the elephant's foot by printing those layers 2 pixels smaller here's the first complication with an exact reduction method when a pixel is printed at the right exposure setting it should be fairly square when you print a bed of nails test or something similar to test exposure you look at the pegs to see that they're the right size but also that they're square and not rounded but when you print a pixel at a five times over exposure setting it will be more rounded because that expansion happens as the uv light bleeds out and cures nearby resin particles and light bleed doesn't follow the square corners the other problem is that small openings are still likely to occlude if you have a small concave opening the light bleed comes from all around it and when you mix that light bleed from multiple sides it's enough to cure the opening and occlude it completely on the other hand if you have a small convex shape you don't get light bleed from all around it only from one side so a flat or convex edge will have a smaller elephant's foot bulge than an edge that curves in or is concave the conclusion here is that a reduction only method isn't too bad of a way to go it can work okay but a better way would be to reduce more than you need to so that you don't risk occluding small details and then fill in the rest of the shape another way either with the double exposure method or with this next method remember i said that a pixel on the lcd panel could be black and block the uv light could be white which is really open or clear and pass the uv light through or it could be somewhere in between a shade of gray which will pass some uv light through so with pixel dimming you print some portions of the slice full white which delivers the full level of the uv light and then you print other portions of the slice at a gray scale which will deliver a lower level of uv light and therefore cure those sections differently it is sort of another way of doing a double exposure but unlike double exposures it's easier to do and is more compatible with a lot more printers however again it is not linear it's very difficult to guess or calculate how much less exposed the resin will be at half the brightness to solve all of these problems we just have to do some experiments and the app can create those test prints okay so i'm going to show you the app and go over a couple of the things that it does but first i have to take care of some business if you haven't subscribed yet do that now and hit the bell icon a lot of the projects i have planned are going to take weeks to do maybe months like my eight millimeter film scanner project it's a little ambitious and i think i'm still a month away from finishing that project and that means that i can't release videos every week or even on a regular basis i want to but i just can't right now so subscribing will make sure that you don't miss anything okay back to it i need to cover one more concept real quick and then i'll get into the app the elephant's foot is a function of two settings first is the overexposure of the bottom layers or more specifically the overexposure duration the exposure time and the longer the exposure the larger the elephant's foot and the lower the overexposure the smaller the elephant's foot second is the number of bottom layers that are going to be overexposed obviously the more bottom layers you have the thicker the bulge will be in the z-axis but also the better the adhesion will be so you could reduce the elephant's foot by reducing the bottom layer exposure time or by reducing the number of bottom layers but i don't like this idea the way i see it a thicker elephant's foot means a better adhesion to the build plate so you have to consider that especially if you're printing something larger that is therefore also heavier because reducing either the time or the number of layers too much will reduce adhesion and could lead to a print failure so in my opinion it's better to use one of my methods because they don't require you to reduce the bottom layer exposure time or to reduce the number of bottom layers in fact if there were no impact on the physical appearance of your printed part it might make sense to increase one or both of the values use a longer bottom layer exposure time or have more bottom layers if good adhesion didn't impact the part visually or physically then you'd choose good adhesion let's dive into the app and i'll explain the tests that you can do with it and then how to dial in each of the three methods as we try to remove the elephant's foot the app is called bulge buster it works on a mac or pc and it's free but you should also know that it is in beta it is experimental and you should know that it doesn't work on all printers yet it was a lot more effort than i expected to get the app even to this place so it is sort of what it is at this point as i find time i will update it and add support for more printers also remember that so far the double exposure method only works on the frozen transform so if you don't have that printer you'll want to stick with either doing the reduction only method or with the pixel dimming method you start off by slicing a file in chetubox or whatever your favorite slicer is to keep this video simple i'm only going to print these gears there are a lot of different test scenarios that we could test in the app but to keep this video more on topic i'm going to focus on just explaining the concepts and showing how to use the app and the gear is actually a little bit of a stress test because it has both the outside convex shapes here on the outside tips of the teeth and it also has the inside concave shapes here in the creases between the teeth and the trick is to not only remove the elephant's foot bulge but also to prevent those concave areas from occluding while at the same time maintaining as much of the original shape as possible on these bottom layers okay also my printer is the frozen transform and there are some idiosyncrasies about that printer that i don't want to dive too far into in this video because it is a huge rabbit hole but you put in your layer height lift heights exposure and bottom layer exposure in here just like normal if you see this option called transition layer count for best results make sure that this is set to zero that option ramps down the exposure setting from whatever the bottom layer is to down to whatever the normal layer exposure is and this can work to ramp down the elephant's foot as well but since we're doing our own thing to remove the elephant's foot just leave this at zero but if you do have a transition in there bulge buster will remove it now with my printer the frozen transform we don't typically have to put in our lift height or exposure times in chi-2 box because on the transform we will use a resin profile that has all that information in it that's one of the idiosyncrasies i was talking about however i'm going to put all that info in here anyway and i suggest that if you're going to bulge bust that you do that also just to keep things straight so my resin works best at 12 seconds and then i'm going to do 10 bottom layers at 60 seconds so i'll slice that and then save it with the frozen transform ch2 box will save it out as a zip file and that's fine but when we save it out of bulgebuster it will be a dot phz file okay first you open bulge buster i'm on a mac and in dark mode and this is where the app looks best here's what it looks like running on windows here it says to drag a file on so i'll drag the zip file we just saved onto here and to be clear you can't drag stl or other 3d files on here bulgebuster is not a slicer it is a utility app that modifies an already sliced file and it also creates various test print files but you can only drag on a file that has already been sliced for now it accepts ctb files dot cbd dlp files dot photon dot ph z and dot zip i will be expanding the file format support over time but this is what i was able to accomplish so far in bulgebuster there's no place to enter in any setup information about your printer you don't need to tell it your printer's pixel or physical size it will get all that information from the file you drag in so even if you're using the app to create a test file you still start by dragging in a sliced printer file down here in the corner is the pixel size it also gets the layer height from there and all of this information in here so these are the values we typed into ch2 box over here are the bulge buster settings we can pick a method to do the busting and this is one of the three methods i just described and then there are a couple of other settings i'll tell you what those mean in a minute and then we have a button to make a busted file and there is a check box here for saving a zip file as a phz so with the frozen transform as i said cheat box saves it as a zip but then that means that you have to pair it with a resin profile and that resin profile is where it gets the exposure time the lift height and all the speed information even the layer height comes from there it ignores the information in your g-code and builds new g-code you may have heard that the transform has a built-in slicer it does not what it does have is a built-in g-code generator given the zip file and a resin profile it will generate its own g-code basically then ignoring the g-code written by the slicer and it does this if you have the file named zip at the end rename that same file to dot ph z and then it will obey the g code that's in the file with the bulge buster app we don't want the printer recreating the gcode we wanted to use the g-code that the app writes this will enable it to do things like the double exposure trick so check mark this if you have a frozen transform if not you can uncheck it the contract radius is the number of pixels to contract or erode the shapes so let me show you how that works visually here's the bottom slice from my test print with the gears and i have a really small gear in here as well to show the limitations of the app here's the original shape now here it is one pixel contracted and i'm showing the original shape behind it in red so here's 2 pixels 3 pixels 4 5 6 7 8 9 and 10 pixels as we keep going up the shapes will eventually road until there's nothing left you don't want to set it so high that it would erode any of your parts completely away but before we set it we're going to run some tests to dial in what value we should use here eventually i'll add a graphical view to the app so you can see how much the bottom layer is being eroded but in a minute i'll show you how to check it in the current version to make sure you're not eroding anything away completely so that's the contract radius and how it works the bust layer setting is how many slices or layers you're going to bust or rather how many layers you're going to contract this is similar to a bottom layer setting and in my opinion it's better to go a little higher on this again a higher number might be better on larger or heavier prints because this will help with overall bed adhesion before we bust a file we should dial in our print settings and we do that with some tests that are built into the app i'm only going to touch on this first test really briefly there is a resin exposure test on here that prints several test strips across the build plate each at a different exposure setting this test uses the double or multiple exposure method and right now i've only been able to get that to work on the frozen transform so if you don't have a frozen transform use whatever method you would normally use to dial in your exposure setting okay so you have an exposure setting for your resin for the resin i'm using this is 12 seconds and then i'm going to multiply that by 5 to get my bottom layer exposure time so that's 60 seconds so for my tests i'm going to be using 12 and 60. next we want to do a reduction only test this would help us dial in the best setting to use to do a reduction only bulge bust again we first need to have a print file loaded into the app then go up to the menu and pick bottom layer reduction test this test is going to print a row of test chips from the drop down pick reduce only we set the layer height i'm leaving that at 0.05 or 50 microns you can see on the preview at the side it shows 50 microns 12 seconds 60 seconds and then a minus zero each chip is going to have printed on it to print settings for whatever that chip is so later when you remove them you don't have to keep track of which one is which the base height is three millimeters and the top height is three millimeters you can make them thinner but i suggest having them be the same thickness so the division between the two types of layers is easy to find it will tell you here how many layers that thickness is going to be at whatever layer height you have the base section is shown here and then the top section is shown up here all 60 of these layers will be printed at the bottom exposure or here it is listed as the base exposure it's the same thing but all 60 of these layers will be overexposed at 60 seconds and therefore the entire bottom three millimeters should expand like the elephant's foot however each chip will be contracted or reduced by some amount we can tell it how many test chips to print i have it set to 11 right now then next to contract range you put in the low end and it will tell you the range here it goes in one pixel increments and i do like to set this to zero so i can see what no reduction does this way i can see how much the elephant's foot would normally be you can move this slider back and forth to see a preview of other chips this first one is 0 pixels it takes a second to update the preview each time you move it but then after you get it to render each of these chips you can slide through it and see each of the results now you can see on the high end where it's 10 pixels that you completely lose the circle and this area here on the bottom right but it's still okay to print that and see how that chip comes out so here's the point of this test the overexposure of the bottom half is expanding the shape and contracting it shrinks the shape what we're attempting to do here is to find out how much contraction will exactly undo the expansion then you could just reduce the bottom layers of your print by that amount to remove the elephant's foot spoiler alert it's going to be like two pixels maybe three and unfortunately we can't go in half pixels on this so you have to pick which one just looks the best for you here are the results of this print test for me here is the no reduction chip you can see the ridge here on the other end of the spectrum here is the tin reduction chip so clearly it's eroded away here and this is the two pixel contraction it's pretty good but it's not perfect and the hole is completely gone on the back this is because as i described before the light leak is happening from all around this so those convex areas will still occlude the next test is a pixel dimming range test this one will reduce or contract the base layers by 10 pixels each that's hard coded but instead of simply removing the outer edge like on the reduction only test it dims the pixels there and it prints a range of dimming amounts from no dimming or zero percent dimmed to eighty percent dimmed my daughter and i debated about whether no dimming should be zero percent or one hundred percent so like is ten percent almost white or is it almost black i had it the other way but she convinced me that zero percent dimmed is not dimmed at all what do you think let me know in the comments okay again you can slide the bar back and forth to see each of the chips so as discussed before dimming reduces the exposure it's sort of like wearing sunscreen but how much dimming at the higher bottom layer exposure time equals full brightness at the normal exposure time so this is what this test tells you here are my chips from that test you can see that no dimming has the elephants but bulge then as you dim more and more it gets closer to that normal level and then as you keep dimming it starts to be like you didn't expose those pixels at all for this resin and these exposures i think between 50 and 60 looks best again you want to look in these grooves ideally you want the bottom layer to be as square as possible in the cutouts and you can see that at some point the circle shows up on the back side so that's also a good judge of what setting is right two tests in one prints the reduce only test and the pixel dimming range test at the same time on two different rows so you can save print time by doing that the reduce with pixel dimming is sort of the opposite of the dimming range test where the dimming range test prints a single reduction amount with different dimming amounts with this one you can pick the dimming amount say 50 and then it will print different reduction amounts so that might be the last test to do if necessary to dial in the best combo but in my experience it's better to do 10 pixel reduction if you're doing a pixel dimming to counteract the problem with the holes and the contact shapes okay now that we've done those tests we know that for my resin a good reduction only setting would be 2 pixels and that about 50 dimming at 60 seconds is around the same exposure as 12 seconds at full brightness so now we can bulge bust a file if you're on the frozen transform you can do the double exposure method but honestly i think the dimming method works even better so let's start with the reduction only method i'll put two seconds in for the contract radius 10 is good for the bust layers count and click make busted file i'm going to name this so i know how it was made and then we'll print that one in a second to do the pixel dimming method i'll do 10 for the contract radius and still 10 for the bust layers and 50 for dimming and click make busted file again i'm naming it so that i know what method was used and then we'll print that i also want to point out that you can drag an already busted file into bulgebuster to check the results drag this in and then go to documents bulgebuster and then the work folder if you're importing a zip based file like on the frozen transform this folder will automatically populate with the contents of the zip see all the png files in here and then at the bottom there is the g-code file if you have a printer that doesn't take zip files like the saturn or even the sonic mini drag that file in and then you can see this option shows up called unpack images click that and it will save all the layers as png files and then you can go in here and view them so see our 10 pixel contract is a little too much this part will probably not adhere to the build plate so when i print this part i'll probably do only about 5 or 6 pixels for the contract radius okay here are the results these are the original gears printed with the elephant's foot and this is what made me decide to do the whole project but you can see that they don't fit together very well the bulge is large and especially in the creases between the teeth again that's because the overexposure effects concave areas more than convex areas okay here's the double exposure version here's a reduction only version okay and here is the pixel dipping method [Music] really the only problem is a little bit of erosion on the bottom layer more experimentation is needed to perfect that but for my use this works pretty well okay here's how to get the app for free go to nerdtronic3d.com click on bulge buster you can download an installer for mac or windows if you're on linux let me know i do have a linux version as well but i don't have any way to test it and remember to take it slow this app is experimental it's beta but i wanted to get it out to everyone to play with i do need to thank some people for helping me figure all of this out first i want to thank the guys over at photonsters they have a project i believe is called uv tools that also allows you to edit print ready files check out their facebook page at facebook.com photonsters cliff biffle documented a lot of the file formats and those docs were invaluable to helping me get this app written jason with mullen helped me figure out the ctb v3 file format which opened up support for the mars pro 2 and the saturn john driggers helped with the beta testing and put up with me sending him countless test files and finally my friend rich helped with some of the app development and helped to build the executables and the installers so thanks to all you guys well that's it for now i hope to be getting videos out a little more often after this one i do have the eight millimeter film scanner project coming soon and then i have a project i want to do with an led panel but that's it for now bye

Channel: Nerdtronic

Views: 109,782

Keywords: phrozen transform, chitubox, 3d printing, calibration, resin, resin 3d printing, phrozen 3d printer, phrozen 4k, formlabs, uncle jessie, prints too large, prints too small, elgoo, elgoo mars, phrozen, uncured resin, resin printer, calibration block, resin mess, fumes, resin safety, nerdtronic, resin management, resin handling, printer fumes, ventilation, printer ventilation, resin fumes, creality, overhangs, supports, elephant's foot, bulge buster, print failure, free software

Id: piz9VY-1Cfk

Length: 30min 50sec (1850 seconds)

Published: Fri Nov 13 2020