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What Sticks to Ninjaflex?

Posted: Wed Jan 04, 2017 6:24 pm
by Phil
I need to build a part that has a rigid base and a soft, flexible body, (shotgun butt-pad). I intend to print one on top of the other with a dual extruder.
I asked MakerGeeks what sticks to their Makerflex, and they said any type of PLA. The Makerflex is not as flexible as I may want, so, what sticks to Ninjaflex?

Re: What Sticks to Ninjaflex?

Posted: Wed Jan 04, 2017 7:01 pm
by sthone
I've seen a few prints out there where people have done Ninjaflex and ABS together with duel extruders and they have said it sticks well together. If that's the case I'm sure you can just pause the print and switch filaments with a single.

I'm not sure what your pad design looks like but even with Ninjaflex I would think you would have to design the pad with a honeycomb area to it if your looking to absorb some of the recoil as I don't think just using Ninjaflex alone would be enough. (of course it all depends on infill/design I guess.)

Re: What Sticks to Ninjaflex?

Posted: Wed Jan 04, 2017 10:20 pm
by Phil
I had already decided to try using a 50% infill for that purpose. I will let you know how it works.

Re: What Sticks to Ninjaflex?

Posted: Thu Jan 05, 2017 5:01 am
by insta
Phil wrote:I had already decided to try using a 50% infill for that purpose. I will let you know how it works.
There are a lot of MakerGeeks (?) filaments that are down in the 40A durometer range. Those would be spectacular for this. They're a mixture of PVA + foam, and the PVA is dissolved out after printing.

Re: What Sticks to Ninjaflex?

Posted: Thu Jan 05, 2017 6:58 pm
by atomic_peach
Might it be better to have the two pieces printed separately but with a flange of sorts the flexible piece can wrap around and attach by? This would also allow iterative cushion designs in case your first print isn't to your liking.

Re: What Sticks to Ninjaflex?

Posted: Mon Jan 09, 2017 9:42 pm
by Phil
insta wrote:
Phil wrote:I had already decided to try using a 50% infill for that purpose. I will let you know how it works.
There are a lot of MakerGeeks (?) filaments that are down in the 40A durometer range. Those would be spectacular for this. They're a mixture of PVA + foam, and the PVA is dissolved out after printing.
I see what you mean, but they seem to be permanently out of stock.

Re: What Sticks to Ninjaflex?

Posted: Thu Jan 12, 2017 2:20 pm
by willnewton
You can start with PLA and switch to a flex filament mid print, but I have had mixed results. Also some mixed results with regular superglue. I have not tried flexible superglue or the crazy acrylic welding glue stuff. It will want to separate at the transition.

I would recommend Semiflex instead of Ninjaflex for a pad. At high infill it is pretty hard stuff, much more so than Ninjaflex and will hold hardware and accurate dimensions. At low infill it is still stiff, but will give nicely.

You could start with four walls and 50% infill, then transition down to 3 walls at 20% or something like that.

Since you are dual extruding, print the bottom 1/4" in high infill Semiflex, then Semiflex exterior walls and through holes, and print your infill with Ninjaflex. How about a Semiflex base and cap with a Ninjaflex middle, like an Oreo?

I like Semiflex quite a lot and use it more often than Ninjaflex. The print quality is very high and it is very tough stuff.

Ninjaflex is like a rubber band. Semiflex is like leather, flexible with limited stretch.

Re: What Sticks to Ninjaflex?

Posted: Thu Jan 12, 2017 3:16 pm
by Phil
I tried to upload this video, but it must be too large. https://youtu.be/exFbOX4EDJM
Shows the huge difference between flexible filaments. How does Semiflex compare?

Re: What Sticks to Ninjaflex?

Posted: Thu Jan 12, 2017 4:40 pm
by willnewton
The purple one is very close. See how it has initial stiffness, then folds vs. the flexy stuff that deforms immediately?

It will take a bit of futzing around with walls and fills to get what you want. At times, I have found myself making things that are too stiff from Semiflex.

I am no long gun expert, but have shot enough to know that you want a solid feel at the shoulder. It doesn't have to soak up everything, just take the edge off. I think you can find that happy place with something like Semiflex and a honeycomb fill.

Sometimes you have to work to get Ninjaflex to be as stiff as you want and sometimes you have to work to Semiflex as flexible as you want. ;)