3D printing a chassis similar to SBI's Superlight?

[mmattockx]

As the title says, has anyone tried 3D printing a chassis setup similar to the SBI Superlight? I've been working on a printed full chassis for the 10/22 for a bit now, but I really like the looks of the SBI Superlight and it seems to me that is a decent concept for a printed chassis where it is using the receiver body for the rigidity of the overall firearm instead of attaching everything to a more flexible printed chassis that allows the handguard to move around, etc.

All thoughts/experiences/ideas welcome.


Thanks,
Mark

 

[old303]

There's going to be enough stress between stock, grip, and receiver that a real one in aluminum from SBI would be the sensible choice. I've had 3D prints crack apart on me before.

 

[Stevo]

As the title says, has anyone tried 3D printing a chassis setup similar to the SBI Superlight? I've been working on a printed full chassis for the 10/22 for a bit now, but I really like the looks of the SBI Superlight and it seems to me that is a decent concept for a printed chassis where it is using the receiver body for the rigidity of the overall firearm instead of attaching everything to a more flexible printed chassis that allows the handguard to move around, etc.

All thoughts/experiences/ideas welcome.


Thanks,
Mark

The SBI Ultralight looks great and is light, but I sold mine.

Consider it anecdotal, but my failure to feed rate, particularly with Tuf mags, was much higher in that chassis, compared to the same receiver in my Tapco, Ruger and RTI stocks/chassis.

I attribute that to the lack of support on the mag sides, allowing more wobble.

Assembly of the rear portion could be a PITA from time to time having to align 3 pieces instead of just the receiver and trigger group.

Personally, if I could print one I'd just do a regular chassis shape like the RTI and "window" it to lighten it.

YMMV.

 

[unstableryan]

If you have the design and the file, I can print it for you in some carbon fibre petg or nylon material that will be lighter and tougher than aluminum.

 

[mmattockx]

There's going to be enough stress between stock, grip, and receiver that a real one in aluminum from SBI would be the sensible choice. I've had 3D prints crack apart on me before.

That's what design is all about, dealing with the forces and loads involved and making the structure survive.

Personally, if I could print one I'd just do a regular chassis shape like the RTI and "window" it to lighten it.

Thanks for the information, that is very helpful. The full chassis I have been working on is similar to the RTI, SBI G3 and others in that same style. Because the cost is pretty minimal I may still tinker with the superlight concept, but knowing it may cause feeding issues takes the shine off that idea.

If you have the design and the file, I can print it for you in some carbon fibre petg or nylon material that will be lighter and tougher than aluminum.

I appreciate the offer, but I do print those myself and the final version will be some type of fibre reinforced nylon I expect. If you have a favourite brand for that I always appreciate hearing the experience of others for these things.


Mark

 

[barthammer]

I think it can be done. I've been experimenting with this myself on a 457 ultra-light hunting rifle stock

The limitation in your case I think is the 10/22 using only one action screw, and relying on 3d printed filament may not work well. An aluminum block epoxied into your stock could be a solution to this to provide more solid clamping. Or you could do something similar to MDT where the receiver is also clamped at the rear.

Bambu PA6-CF or GF would be my filament choice for this kind of print.

 

[mmattockx]

The limitation in your case I think is the 10/22 using only one action screw, and relying on 3d printed filament may not work well. An aluminum block epoxied into your stock could be a solution to this to provide more solid clamping. Or you could do something similar to MDT where the receiver is also clamped at the rear.

The SBI Superlight mounts the rear stock/pistol grip through the pins that hold the trigger assembly in place and clamps the receiver and the stock tight to each other. The handguard is mounted using the action screw in front of the receiver, leaving the sides of the receiver uncovered and the mag well fully open on both sides.

It's very clean and minimal and looks great.

I agree on using a metal clamping area under the action screw. I may install a bushing to support the screw and allow it to clamp tight and stay tight.


Mark

 

[Can-down]

Looks like it might not be too hard to extend the length on each side forward to the magwell area.

Maybe even a partial support on the sides would stabilize the magazine better and help with feeding.

 

[mmattockx]

Looks like it might not be too hard to extend the length on each side forward to the magwell area.

Maybe even a partial support on the sides would stabilize the magazine better and help with feeding.

The big improvement on the superlight in terms of rigidity is clamping through the trigger assembly pin holes. Just adding that to a conventional printed chassis that covers the sides of the receiver would make a huge difference in the stiffness of the complete assembly. The only downside is take down for cleaning is more fiddly and time consuming. I'm considering test printing one like that to see how it feels and if it justifies the extra nuisance.


Mark

 

[_Shorty]

Filaments with glass fibres or carbon fibres in them actually result in weaker prints. The only thing the fibres can do is help with dimensional accuracy. They don't increase strength. Many of the popular 3D printing YouTubers have shown this time and again. Getting the fibres stuck in your skin or breathing them in, isn't much good for you, either.

 

[mmattockx]

Filaments with glass fibres or carbon fibres in them actually result in weaker prints. The only thing the fibres can do is help with dimensional accuracy.

Yes, I'm aware. They also increase rigidity, increase temperature resistance and greatly reduce warping, which is a significant problem with nylon.


Mark

 

[barthammer]

Polycarbonate is another filament option to consider. Superior UV resistance. Very stiff and strong. A stock in translucent PC would be very cool...

Print orientation will be the most important for strength as I'm sure you're already aware. Layer lines converging in the wrong spot can't be solved by stronger filament!

 

[BP4W]

Polycarbonate is another filament option to consider. Superior UV resistance. Very stiff and strong. A stock in translucent PC would be very cool...

Print orientation will be the most important for strength as I'm sure you're already aware. Layer lines converging in the wrong spot can't be solved by stronger filament!

I personally used Polycarbonate CF for both of my handguard designs. They both held up well.
In fact, one of them was used at the Carleton University event last weekend in -20C weather, being handled by a couple dozen students:

Yes, I'm aware. They also increase rigidity, increase temperature resistance and greatly reduce warping, which is a significant problem with nylon.


Mark

Well said. Ultimate strength is usually not the issue here as long as your layer lines aren't in bending/tension (PLA+ is a popular material in certain communities for a reason!), and I'd gladly trade 5-10% of my UTS for a significant increase in dimensional/thermal stability. Pure polycarbonate is way too brittle.

Moreover, there are zero concerns for CF filaments. I work with actual carbon fibre composites in my past life (from layup to post-processing) and it's not exactly rocket science to wetsand, prime, and paint these parts with a glove and a N95 mask/respirator (something I wear anyways for painting). You don't need a full Tyvek suit or whatever.

Looks like it might not be too hard to extend the length on each side forward to the magwell area.

Maybe even a partial support on the sides would stabilize the magazine better and help with feeding.

Here's the other design of mine that extends backwards to cover the magwell void. That's the only way I could get a 597 magazine + adaptor to function reliably. Otherwise the wobble will cause feeding issues like others mentioned above. The handguard attaches to the original stock screw (similar to SBI's own handguard).

Overall, I'd keep using the SBI Superlite chassis for a reliable stock/grip attachment (as they see the bulk of the bending moment) and I'd only print my own handguard. Mine friction fits over the Grey Birch barrel nut and is then indexed & fastened via the stock screw.

 

[mmattockx]

I personally used Polycarbonate CF for both of my handguard designs.

Brand/type? I haven't tried PC yet, but I'm always open to new and wonderful options.


Mark

 

[BP4W]

Brand/type? I haven't tried PC yet, but I'm always open to new and wonderful options.


Mark

Polymaker makes multiple PC "blends" like PC-ABS for example. For PC-CF I've been using CC3D and it's very nice ($66/kg). But their regular PC ($23/kg) is comically brittle and would shatter like glass even if you dry them. I would stay away from "pure" PC and go for blends (ABS/ASA/PETG) as they are usually less brittle and could be easier to print.

Some people say you should anneal PC to make it less brittle. PC is amorphous and would not get stronger if you anneal it, but it would still serve as a stress relief and reduces the residual stress caused by the gradual cooling of the part when printed. For something like PA I would definitely anneal it, as it's semi-crystalline and there are countless documentation online about how it's beneficial to anneal (semi) crystalline prints.