Front fender printer line

[hedotwo]

Just out of curiosity, it sure seems like most all 3d prints (at least the ones I've built and have in my stash) have a deep-ish diagonal line on the front fenders and then another in front of the rear fender wheel wells.  Not impossible to deal with but just wondering why they're there.  I know nothing much about the printing process.  Thanks!

[Fat Brian]

Due to the size of the build plate some car bodies have to be oriented at an angle to fit the available length of the plate. There can also been some reasons why a shape will print better at an angle than flat. Printing the trunk lid and roof with the body oriented flat would be very difficult, it would hold resin as the body went up and down and probably tear before it built up enough thickness to support the weight. The parts print upside down essentially.

[bobss396]

8 hours ago, Fat Brian said:

Due to the size of the build plate some car bodies have to be oriented at an angle to fit the available length of the plate. There can also been some reasons why a shape will print better at an angle than flat. Printing the trunk lid and roof with the body oriented flat would be very difficult, it would hold resin as the body went up and down and probably tear before it built up enough thickness to support the weight. The parts print upside down essentially.

All of the above. There is a simple formula that determines the offset print angle. Which is not always perfect since car bodies have all sorts of angles to them.

The phenomena with the bodies with lines in them is called "print shift". I have seen the same STL file used by different vendors, some have the print shift, some don't. I'm not sure what causes it yet 

EDIT: I did a search on "print shift" and the correct term is layer shift.

This is where experience and troubleshooting skills come into play. 

I saw one very good video that explained the physical obstructions that occur during a print. This has nothing to do with the file.

Things to look for are hitches in the axis motions. A harness or tube that may catch on something during the print. Even a small tangle of the filament as it comes off the spool will do it.

Edited Friday at 12:13 PM by bobss396

[stitchdup]

its an easy fix. the printer isn't using stiff enough supports or enough of them. i'll hazzard a guess the bodies will have a slight droop forward of the lines as well. if you give the bodies slight left or right tilt along with the front to back, along with extra supports you can avoid most of it. for example, i give the body a 30-45 degree front to back angle along with 4 or 5 degrees left or right. since doing this my prints have been loads better

[bobss396]

2 hours ago, stitchdup said:

its an easy fix. the printer isn't using stiff enough supports or enough of them. i'll hazzard a guess the bodies will have a slight droop forward of the lines as well. if you give the bodies slight left or right tilt along with the front to back, along with extra supports you can avoid most of it. for example, i give the body a 30-45 degree front to back angle along with 4 or 5 degrees left or right. since doing this my prints have been loads better

This makes total sense. I'm not going to call out any makers of things I have had issues with in the past.

I'm on good enough terms with 1 and I can talk to him. Quite possible he does not know about how to fix it.

Just about any kit he does has a layer shift issue. One body in particular might be available from someone else. This person leaves the scaffolding in place and the buyer removes it. I'd say it is very well supported. The one guy who strips all that out, I can't say what he does or doesn't do.

Are the files plug-and-play? I know who the originator of the file is and he knows his stuff. I know there are programs available to post-process files before printing.

[bobss396]

I did a little more digging into causes of layer shift. Some are mechanical related to motion hiccups like an unstable work platform, bed and belt problems. I think a novice printed would likely miss these. Plus others I mentioned. 

I was reading up on things like slic3r and netfabb that will fix support problems, etc. It seems that these are advanced auxiliary programs that new users may not yet know about.

[stitchdup]

59 minutes ago, bobss396 said:

I did a little more digging into causes of layer shift. Some are mechanical related to motion hiccups like an unstable work platform, bed and belt problems. I think a novice printed would likely miss these. Plus others I mentioned. 

I was reading up on things like slic3r and netfabb that will fix support problems, etc. It seems that these are advanced auxiliary programs that new users may not yet know about.

those are a different type of printer that uses reels of plastic and a heated moving nozzle sorta like a milling machine in reverse. the resin printers are just a tank for the resin, a plate that raises and lowers that the print holds on to and a light under the tank that cures specific areas of the tank bottom onto the plate. the only moving part is the plate which needs levelled regularly and the temprature needs to be warm enough.