Kind of like building blocks, I’m taking what I learn and then adding to it. In this case, the original design for this core swager was 100 holes. Because of the warping problem, I divided the part into quarters and printed them separately. I still had some warping, but after printing the first few my ‘mentor’ suggested something that helped a ton! Since I knew the basic concept worked, and while I worked on solving the warping / shrinking problem, I printed enough pieces to make a whole top piece. Next step – combine them.
When I brought up glue, my ‘mentor’ seemed to scoff (if you can infer emotion in an e-mail without emoticons). Not glue, ABS slurry (pieces of ABS melted in acetone). Easy enough and I certainly have enough scrap ABS built up! While I don’t know the strength of the joint yet (it’s still drying), this is a common practice for 3D printers.
The other obvious takeaway here is that 3D printing isn’t limited to objects that are the size of the build plate. Pieces can be printed and bonded as necessary to create a much larger object. Even a car! Check this out.
The pieces that make up this top plate of the core shaker are a hodgepodge of proofs of concept; the amount of warping on the bottom varies as I worked out the kinks. The white one? Yeah, that’s what happens when you’re tired & trying to get a print started before going to bed. I told it to use the wrong extruder (…that was loaded with white ABS instead of black). Oh well – great visual reminder for me to check all of the details twice (or, from an earlier post, ‘measure twice, print once’. Yes, sometimes I’m a slow learner.
After several setbacks, I have a working proof of concept for a core shaker, adapted from a design from a member over on CastBoolits! It’s not perfect, but it works. But, there are still several problems to solve:
I’m still fighting some lifting / warping on the bottom, even though this print is much smaller. However, even though the bottom is a little bowed, it will still work. It’s not as pretty as it could be though.
My hole sizes may be a little large. I’m finding that with ABS, holes (in particular) tend to shrink from the size they’re drawn at. So, after my first prints, I had to enlarge the holes but I didn’t know for sure how large to go. After a few trials, I went with a 7.4mm (.291″) on the drawing. That translated to a 6.6mm (.259″) hole in the plastic. That works for the jackets, but the cores tend to hang up on the edges of the jackets as they’re going in the holes. This may also be solved by making one of the trays a bit higher (so the core is at a steeper angle falling into the hole and less prone to catch on the lip of the jacket). Or, a combination of both.
Combining pieces together. As drawn, I included a small cut / relief on the base edges thinking they’d align well and be a place for the glue to go. But, with the warping, those edges may need to be at the top, and I’ll glue these together sitting face down. These pieces will make a good test for that.
Layer alignment. Right now, nothing is implemented to align the top & bottom layers. I’m thinking of putting little nubs on the bottom layer that would align with small divots on the top layer.
The fence. This part (should) be simple :). This should just amount to a box. But, given the warping / lifting, I anticipate the size of the completed box is going to cause some problems.
So, in case I jumped into the weeds and the concept of this ‘core shaker’ doesn’t make sense, here’s a brief explanation. The cores need to go into the jackets; doing it manually takes time. After stacking the black tray on the white tray & surrounding both with a fence (the index cards for now), empty jackets are poured onto the top of the black tray. Shaking the whole thing around causes the jackets to tip & fall heavy-end first into the chamfered holes. Then, cores are poured on top of the black plate and shaking again causes the cores to drop down the holes and into the jackets. Lift off the top plate and you have them all sitting up, ready to be picked up individually for the core seating die.
This one is a bit of a challenge… After learning more about how to control some of the variables, I’m trying again. All it needs to do is stick to the plate & not warp!
Update: Unfortunately, after approximately 6 hours of printing, I came to the realization that this print was doomed. Although not as severe as before, two of the corners started to lift & warp. Because of the tolerances required of this part, this would impair its function.
Back to the drawing board – the next approach will be to design this part in separate pieces, which I’ll glue together after they’re printed. So, the entire assembly will require 9 pieces – 4 for each section of the two trays and 1 for the case that will hold the two trays.
Again, a simple design to solve a basic problem. I have dies that I use often enough that I want them handy, but I’d rather not dig through a bunch of boxes. I don’t use these on a progressive press, so they don’t sit in a shell plate. So, I made up a die holder:
Handy for either the top of the bench / desk, or in a drawer. Problem solved!
After a week of travel, I came home to a new shipment of plastic, including a roll of lime green ABS. Lime green just so happens to be my wife’s favorite color, so the next thing out of the printer was a pencil cup for her desk. She’ll wake up to see it this morning. I think she’s having some trouble seeing the practical application for this printer, so perhaps this will help :).
Pencil cup; downloaded from Thingiverse & printed in green
This was treated in acetone vapor for the shiny, faux injection molded look.
Another milestone today. Overnight, my ‘catch tray’ finished printing. In the thread over at Castboolits, a member that I’d already printed & boxed up an RCBS decap tray for expressed interest in my design. So, since I’m still cautiously jumping into this, he is my first official beta tester.
For those not familiar with swaging bullets, here’s a video showing cores being swaged to weight. They’re falling out into my new catch tray.
The lead cores you see were originally stick-on wheel weights (almost pure lead). They were melted and cast into rough cores using a purpose-built mold. These cores are what’s inside the jacket of a bullet. The rough cores are swaged to a specific weight (the weight of the cores + the weight of the jacket = the finished weight of the bullet). Consistency in weight is very important – these will become 55 grain FMJ bullets when they’re done.
When the cores are swaged, they are compressed under tremendous pressure, forcing the extra lead out through a hole in the side of the die (and into the small cup at the top of the press in the video). Then, when the handle of the press is lowered, the core is ejected and it drops into the catch tray.
One of the amazing things about this technology is that designs are made available for public use, and they can be downloaded & printed. When I was describing my printing of swaging accessories on the Castboolits forum, a user chimed in about wanting an improved part for his RCBS press. The primer catcher / decap tray that comes with RCBS single stage presses is notorious for allowing primers to escape (and fall on the floor / roll out of sight). I agreed to check into it and see what I could come up with.
Before going off and designing a new part (which for this, would probably take me a considerable amount of time), I checked on thingiverse.com. Low & behold, another Thingiverse member had designed and uploaded exactly this part! He has a left hand and right hand variant, which is a fantastic mod that users will appreciate. How cool is that?!?
I reached out to the designer of the part (lcecil) and we’ve exchanged several e-mails. He’s a reloader & 3D printer with lots of wisdom that I’ll put to use. This morning, I downloaded the part, prepared it for printing (“sliced it”) and assuming another project finishes up in time, this will print while I’m at work today.
Our conversation led into the use of others’ designs and selling them. He licensed this part under the Creative Commons – Attribution License, which can be used and even sold in small quantities by others.
So… actually selling this stuff is something to consider. Clearly, I’ve got my eye on that and I’m working through all of the different implications before I make a final decision. Stay tuned.