Quick 3D printing tip...

[JeffB]

Hey all...

I've been printing S scale 6 over 6 pattern double hung windows of late...  The mullions on these windows are 0.4mm wide x 0.55mm deep (about 0.016" x 0.022").

Fresh off the printer, the mullions are warped, bowed in or out.  If you don't want them to stay that way, let the prints "dry out" for about 24 hours before UV curing.

I want to say that there's some moisture content (of some kind) in fresh prints that has to evaporate off.  Once this does so, the mullions tighten up and the warp disappears, resulting in more or less flat/straight sashes and mullions.  Then you can UV cure them.

I aid this buy putting the prints on a grate over my natural gas fired furnace, which is in my work shop where I do the printing.  The heat given off is not intense enough to warp the 3D prints, which can happen.  But it's warm enough to thoroughly dry out the prints overnight so they're ready for UV curing in the morning.

Did this same trick with boxcar roof prints I've been doing for Maine 2' rolling stock in Sn2...  But I let them "season" for about a week (minimum) prior to UV curing to make sure they're fully "shrunk" prior to UV curing. 

I've found that the 3D prints I've been making shrink some over time.  Obviously much more noticeable with longer prints.  I see this in the boxcar roof prints, they shrink up about 0.020"/0.5mm on a roughly 6" long print.

Anyway...  Not sure if anyone knew this or not, so I figured I'd share the tip.  It's based off info I got in a conversation with Ray Persing, an HOn30 modeler that prints and sells HOn30 rolling stock kits, specifically passenger cars, which tend to be rather long.

Jeff

[John]

Great tip .. I had this happen to me in the past .. usually if I left them in the IPA too long .. but never thought of putting them over some heat to help dry .. thanks

[JeffB]

Great tip .. I had this happen to me in the past .. usually if I left them in the IPA too long .. but never thought of putting them over some heat to help dry .. thanks

Yup...  Another thing that helps minimize warping is to pull the prints off the printer soon after the print run is done, clean them in IPA (I do a prewash/wash), then blow dry.  Don't let the print sit "wet" for long.  Another tip from Ray.

Jeff

[peteski]

Sounds like a perfect application for a food dehydrator.  Many automotive modelers (me included) use one of those to speed up drying time of paints we use on the car bodies, and on other parts, or for accelerating setting of urethane resin or even epoxy glue, and for lots of other tasks where a dry warm environment is desired. I use mine quite often in my hobbies, especially in the winter when my workshop is rather cool.

Micro-Mark even started selling a drying chamber specifically made for this task, but for fraction of the cost of that unit, food dehydrator provides the same functionality.

Mine is a very simple unit. No temperature control other than adjustable air slots in the top and bottom of the enclosure.  Source of heat is a 40W heating element in the bottom. Since it was designed for drying food items (like fruit or meat) I modified it by removing the multiple trays, which created a larger chamber so I can dry things like 1:24 scale model car body. I installed a food thermometer in it to monitor the temperature.  I keep the temperature around 100-110 F.

I bought mine about 30 years ago for really short money. Nowadays there are many food dehydrators out there in a wide price range.  Many have temperature control, so if you're interested, there are plenty to choose from.

[Chris333]

I always blow my parts dry with compressed air before curing. I have no idea if that gets them completely dry at their core.

So what about those curing stations that work while the parts are still in the cleaning fluid? I never used one or thought they would be any better.

[JoeD]

good tip.  we set our prints out for most of a day before post cure.  I've found that if you cure the underside first you have less chance of warping...   Also, if you are having problems with warp like I did, I switched to Siraia Tech ABS resin and man the difference is remarkable. 

Joe

[JeffB]

good tip.  we set our prints out for most of a day before post cure.  I've found that if you cure the underside first you have less chance of warping...   Also, if you are having problems with warp like I did, I switched to Siraya Tech ABS resin and man the difference is remarkable. 

Joe

Yeah...  I use Siraya Tech Fast ABS-like Gray resin.  I cure the bottom of the raft on "sprued up" parts first, to minimize warping of the raft.  It gets discarded anyway, but it makes it easier to paint and remove the parts if the raft isn't a banana.

Jeff