I've been daydreaming about getting a 3D printer and making nosecones and av-bay parts. Today I ordered a Bambu P1P with the automatic material system. I have a build strategy I wanted to run by you guys:
I'm planning to make a 38mm, high speed (let's say Mach 3) nosecone for a 2-stage project. I think the final cone will need to be made out of composites, and I'm prepared to do that. I have made fiberglass molds before, and for me they are a PITA last resort, so I have been planning thinking about printing a disposable interior made out of PVA, laying up carbon fiber and fiberglass over that, and also printing an outer surface sanding tool to enforce a perfect outer shape.
I bought a 2' section of 1/2" steel hex bar from McMaster that can go down the centerline during construction to keep all the PVA sections aligned with each other. It will also chuck straight into a drill so I can spin the assembly like a lathe. I'll print the nosecone sections with a hex hole down the center for the bar, and then glue them together. Then I'll lay up the nosecone shell, with mostly uni-directional carbon fiber but with fiberglass where the tracker needs to see out. Vacuum bag, room temperature (plus a bit) cure of high-temperature epoxy.
The outside will start out pretty rough after vacuum bagging, which is where a printed outer mold line (OML) sanding jig will come into play. The jig I'm envisioning will have 2 arms that have the OML diameter and shape between them, plus a small allowance for the sand paper thickness. Considering the build volume of the Bambu P1P, this will likely need to be made in several pieces and glued together, also. Once I get done shaping the outside, it's time to remove the interior, and here is where using PVA will hopefully let me just dissolve it away. After that I'm left with a thin composite shell that I plan to post cure in an oven.
Questions:
1. I'm also thinking about printing in a structural feature or two that will go on the inside of the shell to help hold an av-bay in place. I'm wondering if I could print it in nylon-CF or PET-CF as a materials change while I'm printing the rest of the material out of PVA. The printing temperatures may not be compatible. I don't need incredible strength, but I would like to be able to post-cure the nosecone shell to about 200C with this printed feature in place. I suppose I could just print it separately and glue it in afterward, but I like the idea of avoiding misalignments by building it in from the beginning.
2. Should I print the whole disposable center out of PVA, or maybe print most of it with a better material and then just have the outer shell be PVA, maybe with some axial channels in between so the water can get access to dissolve the PVA? Is the PVA strong and stable enough to use as the disposable core by itself?
I'm planning to make a 38mm, high speed (let's say Mach 3) nosecone for a 2-stage project. I think the final cone will need to be made out of composites, and I'm prepared to do that. I have made fiberglass molds before, and for me they are a PITA last resort, so I have been planning thinking about printing a disposable interior made out of PVA, laying up carbon fiber and fiberglass over that, and also printing an outer surface sanding tool to enforce a perfect outer shape.
I bought a 2' section of 1/2" steel hex bar from McMaster that can go down the centerline during construction to keep all the PVA sections aligned with each other. It will also chuck straight into a drill so I can spin the assembly like a lathe. I'll print the nosecone sections with a hex hole down the center for the bar, and then glue them together. Then I'll lay up the nosecone shell, with mostly uni-directional carbon fiber but with fiberglass where the tracker needs to see out. Vacuum bag, room temperature (plus a bit) cure of high-temperature epoxy.
The outside will start out pretty rough after vacuum bagging, which is where a printed outer mold line (OML) sanding jig will come into play. The jig I'm envisioning will have 2 arms that have the OML diameter and shape between them, plus a small allowance for the sand paper thickness. Considering the build volume of the Bambu P1P, this will likely need to be made in several pieces and glued together, also. Once I get done shaping the outside, it's time to remove the interior, and here is where using PVA will hopefully let me just dissolve it away. After that I'm left with a thin composite shell that I plan to post cure in an oven.
Questions:
1. I'm also thinking about printing in a structural feature or two that will go on the inside of the shell to help hold an av-bay in place. I'm wondering if I could print it in nylon-CF or PET-CF as a materials change while I'm printing the rest of the material out of PVA. The printing temperatures may not be compatible. I don't need incredible strength, but I would like to be able to post-cure the nosecone shell to about 200C with this printed feature in place. I suppose I could just print it separately and glue it in afterward, but I like the idea of avoiding misalignments by building it in from the beginning.
2. Should I print the whole disposable center out of PVA, or maybe print most of it with a better material and then just have the outer shell be PVA, maybe with some axial channels in between so the water can get access to dissolve the PVA? Is the PVA strong and stable enough to use as the disposable core by itself?
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