Shrinkage?

[Showme]

  I am in the process of designing a non-dynamic brake filler for Intermountain SD40-2's. I have an original to measure from for dimensions, but I am wondering if I should slightly oversize due to the part shrinking while drying. Or, is this even an issue for N scale? My printer is an Anycubic Mono 4K and I have printed hundreds of items but never really paid attention to final sizes. This piece will be meant to fit with tight tolerances in a closed space.

Bob

[John]

Resins will swell as it cures, including during the printing process .. You can print a cube of known size 20x20x20 - but not directly on the print plate - use supports)  then adjust the settings on your printer after you finished curing it .. don't forget the post print cure will also swell slightly .. You would probably need to do that for each bottle of resin ..

[Chris333]

Just scale it down like 1% and see if it fits.

[learmoia]

[basementcalling]

And the Railwire never fails to disappoint. I knew that clip would be here before I clicked to open the thread.

 

[peteski]

And the Railwire never fails to disappoint. I knew that clip would be here before I clicked to open the thread.

So did I. I was wondering just how long it would take for it to appear. 

[basementcalling]

So did I. I was wondering just how long it would take for it to appear. 

Didn't Peteski's law say a RW thread will have the first off topic post within the first 4 replies? Not sure if that is truly an off topic post or not though.

[Showme]

  Honestly, when I named my post, that episode never crossed my mind. Thanks for the bonafide replies though. I will try both of those methods.

Bob

[Lemosteam]

Snicker, he said "bona fide"....

Phrasing!

[peteski]

Didn't Peteski's law say a RW thread will have the first off topic post within the first 4 replies? Not sure if that is truly an off topic post or not though.

I know you're joking, but it is not that simple.   

[GGNInNScale]

Here is the data:
"Photosensitive resin 3D prints do shrink as you print and cure your models. Typically, a linear shrinkage of approximately 3% can be expected. Shrinkage occurs due to a chemical loss of volume due to the polymerization reaction, accompanied by thermal contraction during cure cool down."
"...Shrinkage of resin 3D prints is unavoidable due to changes in temperature and molecular structure of the resin as it solidifies. Excessive resin shrinkage causes your prints to deform, also referred to as warping."  Source:  Printing It 3D

Also, the amount of shrinkage will depend on the base chemistry of the resin, the amount of carrier fluid, and temperature (small effect as thermal expansion is about 1 part in 10^5 per degree)

[Showme]

   Well, it worked. I designed a little bit oversized and the fit is perfect after slightly touching the sanding disc on the end with the supports. That also takes the little nubs off after the supports are removed. My first prints were at a 30 degree angle but the print lines were terrible. Much better standing on end. I need to go back and redo the little lifting ring nubs thicker because it you breathe on these very hard, they're gone. Excellent fit on the Intermountain shell. I sanded the band off the rear of the BLI dummy filler because it is part of the shell casting after you remove the dynamic brake blister. It is not glued on yet in the pic so there is a slight gap showing at the back end. I have resized the filler to fit the Kato SD40 and will try this weekend on one of those. Future Mopac blue.