Model cut in halve + warping = help!

[Titus 170]

Dear Community,

It's been study time lately with less time to print, but I've got a ball coming up and I need some props. So I've been trying to print this awesome model in glowfill:

http://www.myminifactory.com/object/duke-mk-44-hand-cannon-from-destiny-2140

Barnecules did a video on it, check it out:

Anyway, I've printed the two handle parts on my UMO and when I tried fitting them together to see how it looks, I noticed both parts, having a large surface area, were a bit warped :( So it's not a 'tight' enough fit to actually glue.

I was wondering whether you guys had any experience with models cut in halve and glued together & warping issues.

P.S. on an unrelated side note, how can you seperate parts that are merged into 1 STL file?

Thanks!!

 

[solid-print-3d 30]

 

Or do you mean separate parts of an assembly? Cura has a split parts function.

I have to fit parts together often that require absolutely flat surfaces. Best thing to do is make sure they are stuck like crazy to the bed when printing.

maybe someone else has some insight to working with warped pieces.

Heat gun maybe?

Find the perfect temperature in the oven so that you can clamp the two pieces together, taking out the warp?

Belt sander?

 

[DidierKlein 729]

Thanks for the video SolidPrint i wasn't aware netfabb could cut STL files

I usually use MeshMixer to cut (there's a plane cut option).

For warping i guess you have to use a lot of brim to prevent this, i'm not sur it's possible to unwarp a print.

For PLA it's possible to change the object if you put it in hot water a couple of seconds (70°c - 80°c). You can then bend it a bit and when it cools it should stay in position. I'd say it depends on the object and of the amount of warpage

 

[valcrow 144]

You can try cutting some relief shapes onto the bottom to reduce the warping. Particularly at the corners.

This is where the UMO+ and UM2 shines, the heated bed makes joining halves a real treat. With a glass bottom, it's almost perfectly seamless.

 

[Titus 170]

OMG, Solid Print 3D, thanks for the notice of split parts function! I've wondered many times what it does, and now I forgot about it. It works perfect

I'll try the hot bath and the strain relief cuts. Let me post some pictures this week. For the rest of the parts, you said a large brim, as in, a wide brim around the object?

The problem is this large part: http://www.myminifactory.com/uploads/object-images/6debd2cad0fa7550b90b8fdac79614bb3d4543fa.jpg

I had to scale everything down 0.9 to get the large part to fit diagonally in my machine, and disable skirt. So I fear there is not really a way to get a brim around that. Or perhaps I should cut that part up in 2 parts again?

 

[yellowshark 153]

I can see you problem; I do not think I would be very confident in printing a piece across the entire bed without using a brim - in fact I wouldn't A couple of points on warping. This will depend on the specific printer but if you test the bed in the middle and it says, say, 60 deg it is quite probable that outer areas of the bed are cooler. So it maybe that you would want to wait awhile until the entire bed (or at least the area you are using) has reached 60 before starting the print.

I have never tried nor seen a raft. But I wonder if you tried a raft this would help with your warping. The downside I guess would be a need to do some sanding afterwards to remove any remnants of the raft from the surface.

 

[DidierKlein 729]

The raft would probably make it impossible to glue the two cut pieces together after (i never used raft but i read the surface was quite damaged with it).

Maybe the way to go is to cut it in half again to make it possible to add a large brim?

 

[Titus 170]

To prevent warping, I was thinking, would this work? It's 45 degrees...

 

[DidierKlein 729]

Not sure if you'd get a good result for two main reasons:

1. The area touching the build plate is very small, and at the slightest shock it will probably get detached.

2. The parts printed at 45° will probably tend to curl up and leave and ugly "bottom".

No who knows, sometimes i try things and i think it will fail but i've got to try it, and it turns out great, but sometimes it's a mess like i thought :mrgreen:

 

[zoev89 73]

I tried to do some post processing on PLA with a heath gun but was not very successful. If the part is thin then it easily deforms and typically you will not get it back without squashing the layers. So if you have a gap fill it up and sand it. If you can paint the object then those imperfections can be eliminated. I would try to use a fair amount of brim lines to make sure it keeps to the build plate. Raft as you said would make it ugly.

 

[Titus 170]

Just a quick question, I really need to start this print. What would happen if you uncheck print solid bottom.

It would start with the infill precentage. Would that warp less/ And would it still be glueable?

 

[DidierKlein 729]

It would still be gluable i think (depending on the infill %) but i'm not sure it will change anything in Warping as it's mostly impacted by the upper layers shrinking and applying force on the bottom of the object (correct me if i'm wrong)

 

[Titus 170]

Interesting, I always thought it was the cooling of the bottom layer that shrinks and pops off.

Managed to get 3 layers brim arround it, although they kinda let go of the build plate. Printing now, fingers crossed.

 

[Titus 170]

It actually printed without that much warping

There's one part that kinda got to much local heat I believe, it snapped out :(

 

[Titus 170]

Really old topic, but never showed the result

Boiling water+flat table+4 hours time => Flat enough surface to glue!

Submerge in boiling water until somewhat soft, then press on the flat table.

Results:

And when the lights go out:

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Edited March 2, 2016 by Guest