V2.8 AR-15 Super Lower and other designs in the works.

I’d like to let you know that V2.8 is out, though it’s not that exciting of a release. The primary improvement is that the support rib has been redesigned to allow the use of Bear Creak Armory slick side uppers. V2.7 had a small amount of interference between these oversized uppers and the rib, this problem has been eliminated. There are a few other minor improvements, but the new rib is the main one. You can download the files here.

There have been many requests for a AR-9 lower. I have began to design one that will work with Glock mags. I have been displeased with the current work I have done with the design, so I will be starting over and can not give a fixed release date. Though it is coming.

I would like to have a fully functional AR-9 lower that includes a proper last round bolt hold open and will work with any Glock compatible upper. One of the primary challenges is sourcing 9MM specific parts. E.G. the mag catch, extractor and last round bolt hold open. Since most manufacturers make these parts for there own firearms they are hard to find alone. I believe the best solution to this is to 3D print all of the none AR-15 parts. The extractor will have the most stress and is normally made of steel, but plastic extractors have been used with great results before, the Endomag being a good example of this.

If the design works out I will most likely provide a AR-9 Reinforcement Kit that includes all of the small printed parts preprinted from the correct plastic.

Another item that needs to be designed is a new stock. There are several improvements to be made to the current stock design. I would like to add a TPU butt pad and also have several stock designs available of different lengths that will allow the end user to pick the size best for them. The current recommended print settings for stocks is three walls and fifteen percent honeycomb infill. This results in a nice light stock of good strength. There is but one weak point, the clamping mechanism. If the clamping screw is over tightened the plastic that supports it can break. It’s a fine balance. If the wall count and infill are increased this problem is resolved, but the then the stock is overly heavy. The only solution to this is to have a variable infill density. Unfortunately most slicers don’t support this. So I will have to design custom infill into the stock. Which I think is what I will do. Of course the custom infill will only work with the extrusion width it is designed for, so a 0.4 MM nozzle will be needed to print the stock.

I will be doing a dedicated post on filament, but as of now I have found that the PC/PBT blend from Push Plastic works quite well for lowers. It is tricky to print with, but still much better then any Nylon and other Polycarbonates. A gentleman has sent some print settings that he has developed and he states that they greatly reduce warping with PC. I will try them and see how well it works.

I have also obtained a roll of the PC/PBT with ten percent carbon fiber. These fibers may reduce warping enough that it is easy to use.

Along another line I have obtained five different PLA+ filaments that I will be testing. Several of them claim increased thermal resistants. I will compare them and see which has the best merits and whether any of them have the temperature resistants needed to hold up to the high temps that a lower may encounter in a vehicle.

Anyway, I though a quick update would be good. Be sure to stay tuned!

20 thoughts on “V2.8 AR-15 Super Lower and other designs in the works.”

  1. freestylefellowship

    if you are interested in making the ar9 work “with any glock style upper” test on an fm9. the side fin brace of the current designs is too narrow for them (and they are good running, cheap 9mm uppers).

  2. David Stewart

    An AR9 that uses a Smith&Wesson M&P mag would be nice. The magazines are extremely robust and surplus pistols are available for low cost. I got a Gen1 with 3 magazines and night sights for $269. They are all over the shows here in Ohio. Thanks for what you do. David Stewart

  3. Thank you for all the hours you put in on these designs! You are a very intelligent person! Keep up the good work.

  4. john redcorn

    in version 2.8 there seems to be a missing stl? there are some new grooves and it looks like something may go there.

    1. 3dfuel pro PLA is 3d870, which was already tested as “push plastic 3d870”.

      Now…3dfuel’s glass filled PLA would be interesting…

  5. Any chance you could include a fusion 360 compatible CAD file in the downloads? I can’t import the SLDPRT files with the “hobbyist” version of 360.

  6. Robert Campbell

    Instead of making a ar9 lower how about making a mag well adapter for glock mags to work in the Ar15 lower, or make both lol

    1. The problem I ran into with a mag well insert was that there is very little room on the sides of the mag well. It can problebly be done, but I think a dedicated lower will be better.

  7. I love the AR15 Super Lowers. 2.5 and 2.6 installed and function wonderfully. I regret though that I didn’t just buy your 308 combo kit because the PSA10 parts kit don’t see to be in spec for this design. The rear takedown pin head is to broad to fit flush against the lower and the bolt catch seems to want to sit too deep into the recess. Correct me if I’m wrong but there isn’t way to get the a roll pin for the bolt catch out once installed.

    1. The bolt catch pin on LR-308 lowers is normally threaded, so you should be able to screw it back out. PSA may be different. Though all of the LR-308’s I’ve seen have the blind threaded pin.
      A lot of these problems could be avoided if the LR-308 lowers where standardized like the AR-15, but unfortunately there is a lot of variation.

  8. Barry Jindra

    Have you tried GST3D PLA+ I have been using and seems to work I did leave one in my truck on a hot day and seemed not to bother it. I am in Oklahoma.

  9. Cory Maxwell-Stewart

    Printed 4 of these at varying temperatures. So far I’ve experienced cracking under the safety selector switch .

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