Hello,
I discovered this project and I want to know if I can use the machine to do a particular piece that now I can get turned by professionals. At the moment the piece is made out of plexyglass bars and glued in a polycarbonate tube.

The piece is a sort of cap rounded at the top at least hemi-spherical with a cylinder at the bottom. The cylinder fits into the tube and is glued to avoid that it can fly away. The tube is used as blade in sword replicas that I use to actually fight, so the cap must be resistant to hits and stress. I need a transparent material, no worries if there is to work on it to make it shine, I have to anyway also now with a particular liquid for mechanics.

Questions are:

1- Can I use the polycarbonate to do the piece?

2- If I can't, what can I use as alternative material?

3- How much the piece can be sturdy?

I have access to a RepRap machine to do some test, but any advice, before I try on my own, is very welcome! In case that it will work I am planning to build a RepRap by myself.

Thank you
Lord M

PVC and plexiglass generally fit well together, and there exist welding rods for it. (You can even weld PVC and Plexiglass together)
You can probably print with PVC but there would be a major effort in tweaking the extruder, it requires high temperature to melt and is very viscous.

There is "transparent pvc" but it could just be a special kind of plexi glass.

Hi,
thank you for your answer, but I know the difference of the materials itself, PVC does not work it is too fragile, first strong contact it will go to pieces. Tested. Plexiglass is what I currently use turned from stardard bars.
For your use the transparent PVC is not Plexyglass they are very different.

Question is if the printed cap can have the same density of the standard extruded bar or if the RepRap can manage a polycarbonite melt as alternative to PVC or Plexyglass with the same density of the blade.

Having a RepRap printer to do the job would be quicker and simple. To have a metalworking lathe to do the job on the plastic would be at least the double expensive end I have to turn manually the single piece, because the programmable lathes are very big and much more expensive than the manual ones.

So RepRap would be cheaper and automated work instead of painful manual job on the much more expensive lathe.
If anyone does not know, I will run some tests on September, after summer holidays, and I will make you know. So if anyone needs some similar piece in the future he/she will have a feedback.

Hello,

What are the dimensions of this part? Do you have any pictures?

Regards,

Brian



Lord M Wrote:
-------------------------------------------------------
> Hello,
> I discovered this project and I want to know if I
> can use the machine to do a particular piece that
> now I can get turned by professionals. At the
> moment the piece is made out of plexyglass bars
> and glued in a polycarbonate tube.
>
> The piece is a sort of cap rounded at the top at
> least hemi-spherical with a cylinder at the
> bottom. The cylinder fits into the tube and is
> glued to avoid that it can fly away. The tube is
> used as blade in sword replicas that I use to
> actually fight, so the cap must be resistant to
> hits and stress. I need a transparent material, no
> worries if there is to work on it to make it
> shine, I have to anyway also now with a particular
> liquid for mechanics.
>
> Questions are:
>
> 1- Can I use the polycarbonate to do the piece?
>
> 2- If I can't, what can I use as alternative
> material?
>
> 3- How much the piece can be sturdy?
>
> I have access to a RepRap machine to do some test,
> but any advice, before I try on my own, is very
> welcome! In case that it will work I am planning
> to build a RepRap by myself.
>
> Thank you
> Lord M

Polycarbonate has a melt temperature around 265 degrees C and a glass transistion temperature around 150 C, so it could be done. I know you can order polycarbonate rods small enough to fit into the extruders. The main issue I'd see with doing it would be the fumes, polycarbonate gives off some nasty toxic fumes when melted.

I'm also not sure that it would extrude out clear.

However, you could reprap a negative mold for the part uisng PLA and then use polycarbonate resin to cast the part.

Hi,

@criswilson10: thanks for the infos, very interesting. So I have to do it in open air or under some sort of air-changer system to get rid of the fumes.

@reifsnyderb: the piece is an hemisphere (or rounded form) of 25mm of diameter, with a cylinder under the hemysphere about 10mm long and of 21mm of diameter, the piece is empty inside, so the cylinder has 1-2mm of inner offset. I will provide pictures of the turned prototipe I have at home.

Thanks so much
Lord M

If it were about just having enough parts like this and cheap, you might want to take a look on rotomolding since it is hollow.
This is a fairly uncommonly known technique but has been replicated very successfully at home by quite a few people.

I think I understand what you are making now. A hollow mushroom shape?
Look for an "end rounder" in a woodworking catalog.
It's a jig you add to a grinding wheel or sanding wheel to make rounded dowel ends.
I've seen them for broom handles (25mm) and shovel handles (35mm).

Again, be aware of the dangers of polycarbonate fumes, it's not a bio-friendly plastic!

Quote
Lord M
. I need a transparent material, no worries if there is to work on it to make it shine, I have to anyway also now with a particular liquid for mechanics

Note that FDM printers build parts by laying down filaments of plastic so it won't give you transparent parts that you can see clearly through. I've ordered parts printed with polycarbonate from Stratasys but they were also white colored.

Actually, if you use zero degrees rotation layer to layer, you get something close to transparent because it traps less air. I made a chess piece a while back where I rotated the layers 1 degree each time. The part became polarized, and seemed to exibit an internal spiral in bright light.

brnrd Wrote:
-------------------------------------------------------
> > . I need a transparent material, no worries if
> there is to work on it to make it shine, I have to
> anyway also now with a particular liquid for
> mechanics
>
>
> Note that FDM printers build parts by laying down
> filaments of plastic so it won't give you
> transparent parts that you can see clearly
> through. I've ordered parts printed with
> polycarbonate from Stratasys but they were also
> white colored.