Unbending warped FUD

Hi All,

I have 3 FUD prints of the same model that have been printed at different times. The first come out with a distinctive bow/twist that was not in the STL file. The second came out prefect, the third also has the bow, but not as pronounced as the first. I have attached a photo, the model on the left is the 3rd print and the one on the right is the 2nd.



I believe it is caused by the orientation of the print run but I know I have no control over that.

What I want to know, is there anyway to take the bend/warp out? The model will bend under a little presser back to the correct place but will not stay there. I was wondering if hot water or a chemical to soften it then letting it dry in clamp might work?

Just for info, the model was cleaned in Goo Gone to remove the wax residue.

Thanks,

James

I'd try hot water - probably best to try moderate temperatures first, not scalding hot. Not convinced that print orientation plays a role in this, maybe it was
handled too early after printing or (parts of) the parcel got too warm during shipping.

Hi mkroeker,

That did the trick!



I used a little water from the kettle after it had cooled a little and hay presto! It almost sprang to where it should be.

Thanks,

James

This has nothing to do with orientation of the print. FUD is printed with a waxy "support material", and then placed in an oven to remove the wax. This kind of warping is due to the item being long and thin, and being cooled quicker on one side than the other.. it's a normal reaction similar to this: http://en.wikipedia.org/wiki/Bimetallic_strip

150F water will warm it back up so that it can be straightened, and it should hold the new shape once it cools. My advice is to add a small amount of weight to hold it straight, and let it cool slowly. This process has worked fine for me in many instances.

Thanks stonysmith,

That explains a lot, I am learning more every day!

James

I asked Customer Service about a model with a similar bend and was told it was a printer calibration error and it qualified for a reprint. As mine was a test print that has a glaring mistake I didn't bother.

Stony's explanation makes sense, though, and I wonder if CS knew what they were talking about.

Nice to know about the hot water trick, but not sure how that would go over with a customer order.

Dave Yale

I have on several occations had FD/FUD that had warped so the model was arching. After cleaning in our local version of Bestine I painted using Vallejo acrylics. The model straightens when painted but arches back once dry.

Last week I received a model in 2 parts both with an unacceptable arch. Both straightened perfectly when painted but then crept back where they came from. When put in water they straighten but then arch back. I tried putting the parts in warm water and let them cool with the water. One of the parts ended up less arched but still not straight.

I've seen the arching on many models and it is for many application a showstopper. Is it really supposed to be like that? I've seen something similar on numeous occations (where it didn't matter quite as much) so it doesn't seem like a one-off production problem.

Carsten Lundsten

Not knowing the geometry of your models, any chance you could fixate them in the "straightened" pose while they cool ?

The model is this one: https://www.shapeways.com/model/2841969/n-scale-36-riveted-bs x-covered-slab-car.html?li=shop-results&materialId=109

It may be possible to fix it but that is not a solution for items offered for sale. They need to be a predictable quality. And, BTW, it seems (from eyemeasure) that the model has now arched fully back where it came from so the warm water wasn't a cure. :-(

Did anyone else notice that the models deform when wet?

/Carsten Lundsten

I've seen a good bit of deformation, but never because of being wet.. only because of heat.
Let me guess.. on your model, it's the top insert that is bending...

It seems to me that you've got a bit of thermocouple action going on.. the frame is not thick enough to prevent the bending.
If your design would allow, you might put something between the crates, so as to strengthen the overall structure. (perhaps some ropes or support timbers?)

Thanks for your reply. Both parts are arching. Both parts are sort of a gondola shape and the open side becomes the hollow side. Atttached is a photo of the model as it sits. I then soaked the model in room temperature water for 10 minutes and 2nd photo is the result...

As far as extra reinforcement goes it may or may not help. In this particular model it would be possible to add but in others not. The sides are not at minimum thickness.

/Carsten Lundsten

Hello,

I had a similar problem with warping on my first (and only so far) print with black Detail. The piece actually arrived straight. I began using the piece immediately and it slowly developed the warp over about a day and half. The warp is quite small, but the piece in question has a long flat section which is vital that it remain perfectly flat for what I'm using it for. After having the piece for two days I then sanded the flat section perfectly flat again. The piece has now been in use for three days and remained flat.

What I've been trying to ask customer service is whether the piece should have stayed unused for a few days. I don't think that it's my imagination that the piece arrived quite a bit softer than it is now. Do these pieces need to cure for longer after receiving them? And would additional UV (the sun for example) help?

Warm water will not work. The water needs to be near to 80C, which is the temperature that FUD starts to soften. What I do is to place distorted pieces in to a plastic tray and then pour boiling water into the tray, but not onto the pieces. The pieces are up to temperature they will revert to the as printed configuration. I let the pieces cool slowly in the water bath.

Sometimes pieces will distort even more as they come up to temperature, but while dramatic this is not some to worry about, I've never had a solid piece which this method did not work on.