The title should have read WEIRD PRINT LIFT ISSUE. Throwing this out to “the team” to see if anybody has any answers. So I designed a cage to fit around the outside of some Z-scale semi trailers I also designed and am selling on eBay. These are designed for the 1950’s-1960’s era. The cage is needed to protect the landing gear and the mudflaps from damage during shipping. The rear dual axles are provided separately for painting purposes. If anybody is curious, I print the trailers directly to the plate in order to get a perfectly flat surface for the top, which also eliminates the need to do any sanding on the top. Everything lifts quite nicely with a razor blade slid carefully under each assembly. Now, as you can see in the pictures below, the three center cages all lifted on one end in an “arcing” manner. The trailers oddly enough stayed perfectly fixed to the plate and did not lift, but the cages did. Below is a picture of the opposite end of the build plate, and it is affixed to the plate as it should be. As a final note, I probably do need some support in between the upper and lower beams of the cage because I did notice there was some drooping going on. So certainly more support vertical rods would help that aspect. You can see the drooping in this pic. And for those curious, here’s a few pictures of the actual completed trailers. Yeah, in Z-scale! They are really nice, but the design time was the time consumer. Funny final note, but by printing the trailers directly to the build plate, I get a very minor degree of elephant’s foot around the top of each trailer. It actually adds a nice ridge that looks very prototypical of a real trailer. Anyway anybody’s input as to what is going on with the cages lifting is certainly appreciated in advance.
Have you inspected the FEP to see if there's anything stuck to it in the pattern of the lift? Kinda looks like that part of the model wasn't setting solid on the build plate. You should also be able to see that in the slicer, slide the layer down to 0 and see what's attached.
It's interesting that the closer to center, the worse the lift. I'd pull the vat off and do a screen test to see if you're getting even LED illumination, particularly in that area. If you rotate the models 90deg (can you fit 2x2 in that orientation?) you can see if they print fine by avoiding that area. You can also try to bump up the initial exposure time but then that elephant's foot is going to be more severe. Trailers look awesome, by the way! -Mike
This is the second print that failed in this manner. However, after the first failure, I drained the vat and wiped it clean, and there were no issues or stuck residue whatsoever. In fact, the FEP looked really good with minimal scratches. But you raise an interesting question. Rather than something being stuck to the FEP, could it be that the FEP is loose in that area?? I think it will heed your advice and put on a new FEP. Oh, and just a note, I am meticulous about zeroing out my build plate on every print.
Mike, You are exactly right about a screen test and that crossed my mind as well. I questioned whether maybe LED was burning out in that area. Smartly, I bought a back up LED panel from ELEGOO a while back. So I got one if I need one. Also, I might try first your suggestion of rotating the models 90°, and yes, I would lose one of the assemblies, but it is what it is. At least it would be a good test. What’s baffling, though is that the tops of the trailers are adhered to the build plate perfectly yet the cage surrounding the trailer has lifted from the build plate. Oh, and to Glenn‘s comments above, yeah maybe I should look at the settings. It’ll take me a couple of days to get back to doing some printing because of work, but I will report back to the team about what I find. Oh, and thanks for the comments on the trailers. They’ve been a real challenge to get perfect. LOL
"lift" doesn't do the phenomenon justice, as the lift is happening in the build plate's direction. That the cage members are tapered is telling, says to me the layer zero there wasn't sitting on the build plate and the member just builds that way due to the attachment to the perpendicular cage member that is sitting on the build plate. I've had stuff like this happen due to attachment issues: https://glenn.pulpitrock.net/blog/posts/2022-09-01_168_decorations_pt2/#fabrication
Hmmmmm interesting thought. Let me dig into that attachment that you sent. You may be onto something. I will report back.
If it's only happening near the middle it could be a lift height or speed issue as that's where the FEP will flex the most. Though I haven't encountered this problem in resin printing. With FDM printing this type of issue usually means the bed isn't leveled properly or there's a draft.
HOUSTON, WE DO NOT HAVE LIFT OFF! In this case, no lift off is a good thing, and the lifted print problem is solved!!! So, The first thing I did was drain the last vat that I used and sure enough, the FEP film was a bit looser as compared to the other vat I have. Needless to say, I also decided to run the “same” print on the vat that had a tight FEP, and the print performed as we’d except. All edges of the cage adhered to the build plate. Now, I also added some more vertical supports to the cages to stave off any droop from the top rails. This seemed to work to a degree, but there still was some minor droop. Also note the end vertical supports are a bit distorted. But keep in mind that those are only 1 mm. I could increase the thickness of the supports, but these shipping cages are simply just that - for shipping purposes only. Again they were designed to protect the mudflaps and the landing gear from damage. Just a few comments on the final design - the overall cage should work very well, and you can see by the photos below, the trailer’s top is nice and smooth and requires no sanding. Also, the trailer is only held to the cage via two supports in the center of the trailer, which are attached to the center beam of the cage on top. I think I mentioned it already but all the end user has to do is snip the two support rods and the trailer breaks free. Lastly, the printed wording on the cage “40 FT DOWN” tells me this is a 40 foot trailer with the landing gear in the down position. With Z-scale, it’s pretty hard to tell up from down as there’s only a millimeter or two difference. I tried to produce independent landing gear, which would give the customer the choice of up or down. But I have other 3D projects to work on as well, so putting energy towards those. THANKS FOR EVERYONE’S INPUT!
Well that's a happy ending and cheap fix. If you're extra lucky, you might be able to just tighten down those screws to re-tension the film. I've had some come loose over the years (I've also had to un-screw film I made too tight ) I make cages for super fragile detail parts, too. They're two part prints - a base with the detail parts, and the cage. The cage keys onto tabs and hold the whole thing into a safe bundle ready to be abused during shipping. I also add labels to the side since it's hard to see what's inside. Mike
WOW!!! Now that’s rather ingenious in the way the cage snaps into place. Smart thinking. I was reluctant to create the cage due to the additional resin used in the process. But at the end of the day, I really had no other choice because other alternative just weren’t working. I simply add it into the cost.
If you make the supports diagonal (think bridge truss), it'd might work better as it gives it more cross sectional area across the support. Also, if you have a fdm printer, I believe it's pretty cost effective to print in plastic for the cage?
Noted regarding making the supports horizontal. Interestingly, I just mailed a trailer with cage protector to Scott (CNE 1899) via USPS. The cage structure seemed to work out, but there was one pitfall, and that was the two point mounting concept in the center of the trailer that I took a chance with. The trailer, unfortunately broke free during shipping and the mudflaps and the landing gear were damaged. Scott surmised that trailer took on a seesaw effect during the travel and eventually the two support rods snapped. I am adding a third support rod at the back of the trailer between the axle mount point. This may serve to balance the trailer during shipping. Otherwise, the cage held up with no issues. Unfortunately the trailer didn’t do so well.
you definitely had a loose fep, not enough lift when it was getting loose and some suction issues with it all being so flat. your drooping cage is as you expect...not near enough support and not big enough support. its interesting to see how others go about their prints. id be doing this project completely differently. 1. no cage. dont see a need. imo its just a waste of material. as you see, the print is fine by itself. 2. remove the details from the bottom of the trailer and print them as keyed parts to install. 3. i never print on the plate itself, dont want any suction issues and dont want to deal with any elephant's feet. 4. id print this at a low angle, turn on AA. it will still be smooth and high detail. some sanding would be needed on the bottom, but for Z, hardly enough to matter if you use small supports with tiny penetration. .02 tip by .01 pen. toss a few small .2 by .2 to secure it in place.
Agreed, FEP was loose, hence this created the issues. On the other note - Yes, I've tried to print the details seperately, but since it's Z-scale, the mudflaps are probaby the width of a human hair and the landing gear as well are very delicate. Add to that, the rear step into the trailer is micro-small. Needs to be that way to look more realistic as opposed to what others are offering. Considering a Z-scale figure is about 6MM tall, I am trying to keep everything proportional to them -- and it ain't easy. The cage though was created for shipping these units with the details integrated, less the axle assemblies. I whole heartedly agree, a waste of material, but the goal is to get them through USPS' rough handling operations without the trailer breaking free. Of course, if printing for my own use on my layout, I skip the cage. OH, and I just added another cross-over support on the top of the cage and a single 2MM support "rod" that hits just in the middle where the axles install. This alone made the entire assembly much more robust. I am in the midst of shipping three caged units to a friend in Texas to see how they fair. Fingers crossed. Interesting sub-note -- I print alot on the plate and in this case I can take advantage of the elephants foot. Printed upside down obviously, a small degree of elephant foot creates a nice lip around the top edge of the trailer, giving it the appearance of a bit of overhang from the roof of the trailer. That overhang lip is common on some trailers, but not all. On some older trailers, it seems to be very evident. Plus, printing directly to the plate, I get a near perfect smooth deck for the top of the trailer. I wedge a regular razor blade under the cage and the trailer, and everything seperates quite nicely. Takes a little finese though.
