If there isn’t already a current sensor on the Peel Motor, I would like to suggest adding one. This will make it possible to detect whether the print job has failed. Before each print, have the peel motor lower the tray and raise it (as it currently does) and measure the current profile. If during the print the amount of area for the active layer does not reflect the additional current the peel motor should be using then abort the print job. This will prevent damage to the PDMS liner on the resin tank.
Excellent idea. A failed print wastes resin and can damage the resin tank.
It would be nice to have the printer pause in these situations instead of continuing.
(This post was moved to it’s own thread)
Everyone says failed prints damage the PDMS, so it must, but when it happens to me I just lift it off and throw it away. My tank is always fine. Under what conditions does the tank get ruined? Does the printer ruin it or the attempt to pull the cured resin off?
Damage usually occurs in the form of the PDMS becoming more cloudy than it was when you started. If the area that failed is small and occurred 50-100 layers from the end, then it’s relatively benign. I usually have no problem removing the cured resin from the PDMS without creating gouge marks. Furthermore I’m now using my own tool when scraping and stirring inside the resin tank. I have a piece of 3" x 5" .063" aluminum that I used my deburring wheel to make very smooth corners and edges. I find that this all but eliminates any chance of the corner of the scraping tool that comes with the machine from having its corner damage the PDMS liner. If the part fails with 250 layers to go, and the laser subsequently hits the same resin 250 times because you are not able to sit there and watch the print for several hours on end, then you can get into more trouble as the resin is very difficult to remove and the PDMS liner area can become noticeably more cloudy.
From various experiments with lots of different resins, some resins make the PDMS get cloudy much faster than others. Those same resins get really hot when curing, so I think the PDMS cloudiness is a heat issue. Usually when the part fails and the print keeps going at that one spot without separation, the area warms up and the fogging occurs.
With some 3rd part resins I’ve had the tank get cloudy from just a single successful print.
Anyway, I agree that some kind of sensor/camera to detect a failed print and stop or pause the print for inspection can be a good feature…on the next version of the printer.
Monger_Designs - which colors give you the most clouding?
The worst clouding I got was from the MadeSolid black resin. After one print, I saw a clear cloudy outline of the part’s support base on the PDMS along with the lines for the rest of the part.
To be fair it was an early batch.
I’ve never had too many problems with the formlabs resins when it comes to clouding.
I can believe MadeSolid resin may get very hot during cure and damage the PDMS during normal printing. But since the heat comes from the curing reaction, failed prints should be gentler on the PDMS than successful ones. There must be something more.
So I think we can work with “heat damages PDMS” as a fact. I have seen it in silicone mold making.
MadeSolid resin is being used at the time of the failures and that is the root cause. Or…
Printing in warm environments plus heat from the curing works together to achieve a temp too high for the PDMS to handle.
Can anyone that has seen tank damage rule those out? I haven’t had tank damage so I am thinking out loud (well kinda :)).
Sorry for the late reply @Justin_Shumaker . Thanks for the info on the clouding. I have not been around before and printed 500 failed layers and didn’t notice any ill effect to my tank. Where you using FormLabs resin too during your failure?
I have clouding in my resin tanks. I think, like Monger, the heat damage the pdms. It’s the laser that passes through the glass and warm the pdms.
I think the curing of resin is not related BUT certainly the formula of the resin. Maybe the formlabs resin better redistributes the heat than other resins ?
If you have a failed print the cured resin stuck in the pdsm will keep the heat in that area.
I noticed that, for some of my prints, they are pretty hot when i remove it from the build platform.
I think you may notice cloudiness depending of manys factor :
- the time of printing
- the size of the print
- the formula of the resin
- the amount of successive prints ( i print like 20 hours per day, so my pdsm don’t have the time to cold down )
Maybe a good think to reduce the cloudiness is to change constantly the area where you print.
I think the thickness of the glass could certainly increase or decrease the amount of heat distributed to the pdsm
I only have experience with:
- Formlabs White
- Formlabs Black
- MakerJuice Grey
- MakerJuice Black
I like Formlabs White the most, because it allows me to make large parts that are strong and functional. With the formlabs white, the clouding is very benign. I agree with the heating theory, I don’t have any experience with Spot resins or MadeSolid resins.
I think you bring up a very interesting point. What we need as a community is a parametric study of how these resins compare on a qualitative basis. A Quantitative study could occur at a later time if it was funded. As a community we need to figure out what those parameters should be and how the test should be conducted.
A fresh resin tank will be required for each test. The test should include:
- Resin remaining in the tank for an extended period of time and any ill effects on the resin tank
- An image of the PDMS layer after a specific number of prints of the same object in the same place
- An image of the PDMS layer (using a different part of the PDMS) of a failed print by specifying a Z offset that makes the failure repeatable.
A camera and lighting arrangement needs to be setup so that each image from each test receives the same camera angle, zoom, aperture, shutter speed with the same lighting.
I’ve always used FormLabs resins (except half FL/B9 mix once before black came out). I’m getting the impression tank damage only happens to tanks that are loaded with different brands of resin. It surprises me that some users buy a top of the line machine, then load it with the cheapest resin they can find.
I don’t know if this is related, but when I used to have a b9, I noticed that the resin tank would get hot from the projector heat. That could be the reason why the b9 users change the pdms so often, failure or not.
If the PDMS is porous, then heating it will allow all sorts of gasses and chemicals to seep into it faster, and maybe that’s what the clouding/fogging is.
It may be possible to get rid of the cloudiness by warming up the area and treating it somehow to get the contaminants out.
Just a theory.
Cloudiness is not only for third part resins, formlabs suggest to change the resin tank after about 2 liters of resin (am i correct ? ). I think we can go up to 3-4 liters, it’s a better approximation. ( but of course that’s really depend of how you use your forml1)
Silicones in general can take a lot of heat and abuse. If there is clouding from heat it is probably the blockers fusing or baking into the PDMS surface.
I started to see a slight haze in my tank but following the advice posted on the forums I not only dragged the scraper to check clarity but also pushed it which seemed to clear the slightly fogged areas. Also followed the advise on lightly dragging to look for any lumps or artifacts and straining the contents if there were.
Not sure how you could detect a failed layer, perhaps a pressure sensor to detect a skip?
Optics would be out since the tank is full of resin. Not much to see.