First time with lost wax casting - brain-shaped brass ring box

#1

Quick background - I’m proposing to my girlfriend. When we were both undergrads, she was a participant in an MRI study in the lab I worked in. As an anniversary gift, I 3D printed her brain. Unfortunately, it was pretty small (maybe an inch and a half or so long), low resolution (I built the model almost slice-by-slice by hand) cheaply painted (I dunked it in pink acrylic), and printed on what was retrospectively not an ideal material (something from an old Objet printer that has not been the most dimensionally stable over the past six years).

So now, we’re getting engaged. I’m trying to make a statement piece that doubles as a ring box - it’s a gift inside another gift. Extremely high resolution model, check. Split in two halves, check. Ample space for a ring in a small pouch, and for the magnets I’ll use to keep the whole thing together, check. Test prints in ABS and again in resin to check for sizing and detail, check. Wall thickness analysis passed, check.

I’d like to do this in brass (least expensive) with a red gold plating (her favorite). It’s going to be expensive. I have budgeted for it, and am excited for it, but I really don’t want to throw this kind of money away twice if something goes wrong. I’ve been 3D printing for years - I literally teach a college-level class on it - but I’m still a total novice at this lost wax casting process. I’ve done my best to pay extremely close attention to all the lost wax casting design guide criteria, but you don’t know what you don’t know, you know?

Anyway, I guess what I’m asking is if someone who knows what they’re doing with casting would be so kind as to give me a sanity check on these models before I go ahead and pay for them. Don’t want to dump this amount of money down the drain without a second set of more experienced eyes. I’d really appreciate it. Dropbox links are to two separate stl files, one for each half of the brain. They’ve been created and processed in identical ways, so if something is wrong with one it’s 99% also wrong with the other. Big internet hugs and good vibes for your help.

https://www.dropbox.com/s/3qw827z5uhqwqmm/lh_sphere_2.stl?dl=0

https://www.dropbox.com/s/lyosn0x5q9xfzw1/rh_sphere_2.stl?dl=0

#2

Hi, thanks for the background update. I’ve already looked at the files and see some places where the wall strength is too thin. In our precious metals we require a minimum wall thickness of 0.6 mm.

You can also make an analysis by yourself. If you go to your uploaded models in your personal zone at your i.materialise account, you can check at any time what we see when we check your models by using the module “analyze”.

You just swipe over the model and then you get the choice between the option “open” or “analyze”. By choosing “analyze” the program will start checking your model and at the end (it may take a while) you will get the analysis of your model in your in-box.

For more information how to do this, please check https://imaterialise.helpjuice.com/using-imaterialise/wall-thickness-analysis?from_search=31336007

Considering the value of the pieces, I understand your concern and to be very sure that there is sufficient distance between the different brain pieces, I also forwarded both files to our production and asked if they would already check this. I’ll keep you informed the moment I have their feedback. Kind regards Lizy

#3

Hi, I just got the update from our production manager. He confirmed me that the parts can be printed but need to be solid. As I was already afraid of, the gap is very small and it’s not possible to integrate some escape holes. Unfortunately, the price for a solid part in precious metal is always higher than a hollow part. So, you will need to recalculate the price by uploading your new model to our website. Kind regards Lizy

#4

Thanks so much, Lizy! I’ll tweak those two little spots where the models didn’t pass the analysis.

Absolutely understood re: solid parts. The two models are both solid. I was playing around with hollowing them out a few weeks ago, but after reading more about the casting process, I decided to stick to solid models despite the price.

I really appreciate you reaching out to the production manager, you’ve put my mind at ease. Have a great day!

#5

Hi, glad I could help and good luck with this wonderful and inspiring project. I’m sure your fiancé will appreciate the thought behind the model. Kind regards Lizy

#6

Hi, Lizy. My order was delayed by three weeks from the estimate. Yurii let me know that it should ship this week, but unfortunately my deadline is this weekend - I’m proposing on Sunday. Is there anything I can do to make sure it arrives on time? Pay to upgrade the shipping, perhaps? Thank you.

#7

Hi John, I’m flattered that you’re contacting me for this issue, but I’m afraid if Yurii can’t do anything, I can’t help you either. I don’t know what information he has already received because production only communicates with him, but I am very sure that he did his very best to deliver your order as quickly as possible. I’ll bring it again to his attention again and ask that he give you the latest state of affairs. Kind regards Lizy