3D Printing: Rapid Prototyping

One thing leads to another... and suddenly....

As I may have mentioned before I often get asked.... so what is a 3d printer actually good for? Well if you look at this picture and follow along with me I may be able to walk you through one thing they are just fantastic for. Rapid Prototyping. 

Over on the left you will see a pale green bulbous plastic thingamabob with a hole in it. This is half of a doggie poop bag dispenser sort of shaped like a bone that is missing its other half. What happened to it? Don't know. Fell off during a walk we think. Anyway... doggie poop back dispenser with only one half isn't much use now is it. If I were a normal person I would have gotten on Amazon or headed to Petsmart and just gotten a new one. But....... 3D PRINTER. #I_CAN_DO_IT #MakeItYourOwn etc... etc.... etc....  

Right, much scrambling in fusion 360 later produces the missing half. You won't find it on here because.... shocker... it fell off too. Ok... Fusion has a nice feature that auto does threads... so I just make a whole new doggie poop bag holder. Move to the right from patient zero we can follow the home brewed epidemic as it spreads. The White, Blue and White, green and blue and first all blue.... errr.... creations. Are indeed functional 3d printed doggie poop bag dispensing thingamabobs... and they work just fine and dandy.... 4 iterations into it. First one was the half that didn't work. Then I made the other half... the one that actually dispenses. Oval hole, roughly size of the example. Check, handle.... hmmmm this will work. Nope.... to skinny to fit a Carabiner... kinda flimsy to. This will work... Nope... big enough but Carabiner doesn't move well in it... making it bigger gets awkward so make it round. This will work... success. Well work on the supports a little. Different material? Ok... this works. There are several of these steps not pictured. Gift to Mom, first fully functional one is sitting in my window at work etc... but you get the idea. Towards the middle of the table the original plan has been executed and a fully working prototype has been made and refined. Let us not really think about the cost comparison when it comes to filament vs the 5$ish cost likely to replace it... if that. This was fun. 

However... that is only half the story. We are only at the middle of the table when things get really fun. My Wife was in the midst of making one of her diaper changing stations with nice fleece, storage and it all folds up nicely. So... she asked if I would make one of these for diaper bag duty in her latest baby shower offering. Sure. 

Hmmmmmmm...... Baby's. How about I add a baby powder holder on the bottom of the bag holder? Two in one. Does it make sense? Who cares? Because...... yep.... you guessed it.... 3D PRINTER!!!! Now my simple two sided tube with a hole in it and a ring on it gets a bit more complicated. The simple end now needs to connect to the new piece so it gets re-designed. Then I need a reservoir to hold some powder. And the powder needs a way to get dispensed so I need  a cap. That has open and closed states. Preferably without requiring lots of hands in the midst of the joyous rigamarole that is changing a poopy diaper with a squirmy little 'un. No need to over think it, Johnson's has had this licked for ages. Twisty cap that aligns closed one way, open the other. Easy peasy. Or not. 

The connector is easy enough, just have to get the dimensions right and do the threading tool right... the second time. Why get it right the first time? To easy that way, no fun. Ok, reservoir. Now I learn the revolve tool to make a rounded contour on the lower bit for the cap to go over. How big to make the holes? How many holes? Here is where the rapid part of rapid prototyping comes in. Of course... I can't test the holes because I can't get the tolerances right for a cap made out of PLA or PETG to snap over the end of the reservoir without snapping bits off. Ack. In the midst of trying to do this I have enough success to realize that eyeballing it to figure out if the holes are aligned isn't going to cut it so the bottom reservoir and cap grow some bumps. The bump on the cap stays between the bumps on the reservoir (if you don't get to spin happy at least). At one end opened, at the other closed. Also figured out I need larger holes, and a better alignment for closed/open. Square pattern(easy) gives way to round (easy now that I know how to do it). But... won't do any good if you can't get the cap on the gosh darned thing without breaking it in the process. 

There is this stuff called TPU. Flexible filament. Those who know 3d printing are now cringing. It is darned useful stuff. But.... its primary attribute of flexibility is present when trying to get it to feed through your printer as well. Yeah.... let us just say it is a wet noodle when you want something a bit more stiff. I have avoided it. But now I have an actual problem that it can solve. I learned something. I was right about staying away from it. It can and does lead to some painful jams. I had one that was so goofed up in the midst of this the filament was both pulling in and pushing out at the same time on one side of the gear. Tell me how the hell that happens? Cause I still can't figure it out. Thankfully I got it all out of there somehow and finished the job. And this stuff is addictive. In the midst of this I designed an 'extruded' shock absorber to go on 20x20 extrusion to keep my baby CNC router from walking around on the work bench when it was doing its poor imitation of CNC wood cutting. But that is a story for another time. 

Much easier idea... some squares, concentric circles and a single extrude, made a second that was a bit squishier for options... even printed on the first attempt. 

Now we are getting to the far right of the table and we see some taller 3d printed thingamabobs that dispense both poop bags and baby powder with a functioning sealed cap.... ish. Johnson's baby powder containers are not exactly perfect seals either. Mine is not as quite as good... but it is 100% better at dispensing poop bags so take that Johnson and Johnson's! 

Now we are all the way to the right and you see some silverish with blue bottomed "production" units of the "Diaper Bag Buddy". Now we are done. 

All the bits and bobs. Flexible Cap to the far left. Powder Reservoir next, Connector, and finally, the Poop Bag dispenser

All assembled and ready to go

Open

Closed

Right????

Ummmm..... "How about one that dispenses dog treats instead of the baby powder?" Yes dear... coming right up, because......  3D PRINTER!

The silly nature of this particular venture aside, you have to sit back in amazement if you have any real appreciation of what exactly it takes to iterate a real design. Prior to having something like FDM printers (now more likely SLA, or SLM) available could make the above represent quite a chunk of change to walk through some variations and ideas to get to a finished product. Until the patents ran out and the RepRap crowed launched the whole home cooked 3d printer world even what I did here could have cost thousands, tens of thousands if you counted the cost of the machine itself.  That I can do this in my home now for a few hundred bucks is simply astounding.

If you want to make your own, you can download the files at MyMiniFactory.