Mold printing - base not flat

Hi All,

i just received my SM 2.0. I want to print molds for metal casting

I have used this stl files

But when I print the STL twice the two wont perfectly fit together.

is this even possible ? or sould I just grind the bottom surface flat ?

Looks like you have at least two problems there. At the bottom it mates up nicer than at the top, looks like it wasn’t even making it to the outer perimeter. Assuming the flats touching one another at the mating surface were the faces on the bed, this could be because you weren’t sticking well enough to the bed so the first couple perimeters didn’t really stick down. You might have been just a touch too far from the bed for your first calibration layer. I can see some layer separation in there too which shouldn’t happen the first couple layers at all, and some stringing.

Have you calibrated your extruder first? What was your print temp and what was your bed temp, and what material is this? Did you wipe down the bed with isopropyl alcohol first make sure it was clean, no oily residue? Did you use a raft at all that was hard to clean off that might also be holding them apart? (I pretty much never use rafts, either a skirt only, 3-5 loops depending on part size to help make sure the nozzle is fully primed and to use them to judge if I want to make a quick change to my calibration level either up or down 0.05mm by one step) or much more rarely if a part has almost no ‘footprint’ I might use the ‘brim’ option.)

FYI ‘too much’ squish at the first layer would result in a ‘ridge’ at the mating surface vs. a waste or lack.
I’ve printed fairly large threaded cylindrical parts in halves and mated them together, and had them line up almost perfectly. I’ve also had the slight ‘ridge’ at the mating surface from too much squish. But never had what you’re showing here.

Hi @rtrski,

first of all, thx for your reply! Ill answer your questions with some bullets points:

  • Have you calibrated your extruder first? : i have done the normal calibration. I was able to slide the paper but very hard.
  • What was your print temp and what was your bed temp, and what material is this? : Bed temparature: tried 50, 70, 75 and 80, nozzletemp was 205. the material is PLA
  • Did you wipe down the bed with isopropyl alcohol first make sure it was clean, no oily residue? I have cleaned the bed with terpentine and toilet paper.

I had printed the default vase of snapmaker to test my printer. that was very smooth so I used this configuration file in luban to print the pawn.but the outcomewas much worse than the first try with default settings:

but also this print was not able to fit together

Good to know that it is possible, but it is just my lack of knowledge.

I will try to take a look at the file when I get home from work today. see if I can see anything there.

your temp range sounds pretty good although there can be variation in pla. I think with the threaded part I printed in clear I was at 208 and 75 for the bed dropping to 70 as the print continued

as far as the calibration I was talking also about calibrating the extruder flow rate. not just the starting position. I would try just the fast print quality level to begin with, it’s actually pretty clean looking. I do turn down the retraction to 1 mm at a rate of 30 though from the default.


i’ll try a print with the fast print quality and will post back the result

I take it from the way your model is split along a parting line this is for cope and drag molding. If not you can ignore this post.

Since the end goal is to affix the model to a pattern board, you might consider printing the part integral with a carrier, a block that sets flush with the pattern board, and then route a pocket into the board into which to insert the carrier+model. You’re going to have to affix to the board somehow. With some excess flat surface you can also use screws and cover the heads with the same filler you’d make fillets with. (And you can print “counterbored” holes in the carrier.)

Doing it this way might also alleviate registration difficulties between the cope and drag, since the flat side of the pocket acts as a feature that’s easy to measure.

I’ll also point out that the models you print can contain other casting features like runners, gates, sprues and risers, or at least stubs for them.

Hi @eh9,

it is indeed for using the cope and drag molding. I want to have one of the parts with some pins and counter pins for the allignment ofcourse. But want to have a smooth transition between the two parts.

its a good point to highlight that I can attach the stubs to the pieces. al the other parts I have printed already some good stuff from swdweep.


hi i have created it with fast quality looks better but a seem

with high quality 1 was with a little flash the other seems to be molted

@rtrski Did you find anything strange in the file?