3d Printer shenanigans

**turnburglar** · 08-16-18, 10:39

FMCDH- Thats probably because the smaller holes are loosing tolerances to not only the resolution of the slicer and any mechanical innacuracies in printer, but now the thermal shrinkage is affecting the dimensional acccuracy. As you know with ABS it shrinks and warps alot going from a hot nozzle and heated bed to a fully cooled part. In an injection molded part all the cooling happens at once. With FDM printing the cooling happens layer by layer through the part affecting the over all dimensional stability of the part alot. The higher end polymers like PEEK, PPSF, PSU, and PEI dont have the same dimensional stability issues, but now you need a really high end printer capable of handling 400C. Not only does material choice matter so much when it comes to this, but part orientation also plays a roll. Does your particular printer make better circles in the Y or Z axis? With an AR lower you have holes going in every axis which is why it is such a pain to simply print one out. Honestly though until I watched the video I had no idea how bad dimensional stability and tolerances where gonna be on a lower. I thouhght the tiny LPK pieces like detent springs and trigger pins might not fit. I didnt expect the mag well to be THAT bad though.

rero360- I understand doing a little post processing for a 3D printed part, but at some point you will hit diminishing returns and it becomes better to just use a different method to achieve the same results. If your willing to drill precise holes into plastic just get a polymer 80 lower and have fun. The injection molded plastic will be way more useable. If you are trying to be in the camp: "yea but I want to make a lower from NOTHING, I dont even want to go into public to make a ghost gun!!!" then I would say a solid peice of 3x6 in your favorite grain of wood would probably even make a better lower reciever than a typical consumer grade 3D printer can produce. Im a big fan of 3D printing I just dont like to see it over hyped.

**rero360** · 08-16-18, 13:09

turnburglar - I get what you are saying, and totally agree. I started to design a firearm part that I hope to bring to market some day, sent the solidworks file to a friend to has printing capabilities and used that as a proof of concept, had to make some minor changes to get it to the right overall size and shape. Now I just need to regain access to the software so I can run some finite analysis on it and ensure that my design will hold up to the stresses of use and abuse. A mahogany or walnut lower would be pretty awesome looking.

For my part, I figured the three best methods of manufacturing are: 1) forging followed by drilling and taping a hole and some other finishing work (most expensive and labor intensive) 2) using a combination CNC mill and lathe coupled with a bar stock feeder (expensive and labor intensive on initial setup) 3) use the MarkForged Metal X (least expensive but still a lot of money, likely just as labor intensive as option 2, maybe slightly more)

Ultimately though, I don't have the space nor zoning for any of them therefore I would most likely have to farm out the manufacturing once I complete the design. I have considered setting up a kickstarter page to help purchase the equipment and initial raw materials. The more you think about it the more it costs, space rental, machines, tooling, material, insurance, utilities, postage for shipping out finished products, and that's not even taking into consideration coating the finished good (anodizing, bluing, parkerizing, etc)

**turnburglar** · 08-16-18, 13:27

I dont know what the part is, so this may not apply: but in my veeeery limited design and manufacturing experience it makes good business sense to do all the designing and testing on your own, but to sublet out the manufacturing.

Currently every time I jump on my Mac I try and spend the time chipping away at my fusion classes, but I am starting to feel pretty confident in my modeling and should be finishing my final project in the next week or two. When I am done with that I should be starting a new semseter and will be time limited, but I think I should have enough time to make a new BUIS that I have been thinking about for awhile. First I am gonna model it in Fusion 360, and then 3D print the first prototypes. These will be functional prototypes especially if I use nylon or polycarbonate as a BUIS doesnt take too much stress. For final production I would probably end up milling and lathing the design. Of course I wouldnt mill them myself but sub it out.

**rero360** · 08-16-18, 13:35

My part is a section of rail that attaches to the front BUIS and extends in front of and slightly below the rail handguard so that you can mount a DBAL, or a PEQ-15 (I need to bring my part to the armory some time to see if it fits) or other similar devices. Right now my DBAL is on my AR pistol and it makes for a cramped situation, I want to put the pressure tape on top right behind the BUIS but if I move the DBAL closer to the rear, my thumb blocks the IR beam, so I have to wedge the pressure tape in at the 11 o'clock position opposite of the surefire.

**FromMyColdDeadHand** · 08-16-18, 16:49

My printer is far better in the x-y than the z, if nothing else than overhangs are tough, especially when you are balancing fan settings for layer adhesion versus overhang dropping.

I think the main issue is that the AR lower is it wasn't designed to be printed. You really need to redesign the parts to avoid the weakness of the production method. On the parts and holes, going to a self contained trigger group like a Timmeny or CNC would reduce the requirement for exact geometry of the pin holes.

**Doc Safari** · 08-16-18, 16:51

Originally Posted by FromMyColdDeadHand

My printer is far better in the x-y than the z, if nothing else than overhangs are tough, especially when you are balancing fan settings for layer adhesion versus overhang dropping.

I think the main issue is that the AR lower is it wasn't designed to be printed. You really need to redesign the parts to avoid the weakness of the production method. On the parts and holes, going to a self contained trigger group like a Timmeny or CNC would reduce the requirement for exact geometry of the pin holes.

3D printing is still in its infancy. As improvements are made it will be fine. Today's 3D printing is like the Atari video games of yesteryear. The only thing I can't see the technology overcoming is in metal hardening or anodizing. That may still have to be done the old-fashioned way.

**FromMyColdDeadHand** · 08-16-18, 17:09

Originally Posted by Doc Safari

3D printing is still in its infancy. As improvements are made it will be fine. Today's 3D printing is like the Atari video games of yesteryear. The only thing I can't see the technology overcoming is in metal hardening or anodizing. That may still have to be done the old-fashioned way.

I'd take it a step further. Just trying to replicate past materials, production methods and designs doesn't take advantage of the inherent advantages of 3D(Additive) printing. Multi-materials arrayed in complex forms in designs that can be one-of-a-kind made anywhere are the changes that will have to be exploited to get the best advantages. I think ceramics are going to make a comeback, especially composites and in geopolymer versions that are low/no temp processed. You make something out of silica, powered by solar energy and you are outside the carbon cycle.

3D printer tech has really stalled, at least on the DIY front. Multimaterial was the latest a few years ago and nothing has really come since. The laser sintered plastics are cool, but you are talking $5k plus.

Lulzbot did just start talking about a new model of printer (same Filament tech) designed from the get-go for smaller printing more accurately. It would be interesting to see that small nozzle and whatever tweaks for accuracy they did on the gantry system paired with a 0.6 hoser nozzle for non-critical dimension areas.

**Doc Safari** · 08-16-18, 17:11

Originally Posted by FromMyColdDeadHand

I'd take it a step further. Just trying to replicate past materials, production methods and designs doesn't take advantage of the inherent advantages of 3D(Additive) printing. Multi-materials arrayed in complex forms in designs that can be one-of-a-kind made anywhere are the changes that will have to be exploited to get the best advantages. I think ceramics are going to make a comeback, especially composites and in geopolymer versions that are low/no temp processed. You make something out of silica, powered by solar energy and you are outside the carbon cycle.

3D printer tech has really stalled, at least on the DIY front. Multimaterial was the latest a few years ago and nothing has really come since. The laser sintered plastics are cool, but you are talking $5k plus.

Lulzbot did just start talking about a new model of printer (same Filament tech) designed from the get-go for smaller printing more accurately. It would be interesting to see that small nozzle and whatever tweaks for accuracy they did on the gantry system paired with a 0.6 hoser nozzle for non-critical dimension areas.

Twisted people with money will perfect it. Always have.

Imagine a lower receiver redesigned with some type of high tech ceramic or laminated material that's almost indestructible. That's what's coming.

**jpmuscle** · 08-16-18, 20:51

Originally Posted by Doc Safari

Twisted people with money will perfect it. Always have.

Imagine a lower receiver redesigned with some type of high tech ceramic or laminated material that's almost indestructible. That's what's coming.

Why is circumventing stupid laws twisted?

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