Monday, January 24, 2011
Filling in with the fillings
I've recently been experimenting with the loading of various fibres into CAPA and PLA. This started out as simple strengthening for the 3mm PLA that I sell, but the addition of 20 micron x 1mm nickel fibres makes it conductive. Dunno how useful this will be yet but it certainly allows RFI shields to be printed.
Then I hit on a brainwave: short polyacrylonitrile fibres. There are normally used to reinforce synthetic rubber. But they have another use: The feedstock for carbon fibre.
My trick is to mix polyacrylonitrile and similar materials in with PLA or CAPA. This is then turned into filament, which in turn is printed into an object on a RepRap - this tends to align the fibres.
The object is then encased in a ceramic and heated to the vapourisation point of the PLA or CAPA. You then have a ceramic mould stuffed with oriented polyacrylonitrile. Introduce an inert atmosphere and raise the temperature and you have a mould full of carbon fibre. This can be surface-activated in the usual ways, or coated with vapour deposition before being vacuum-encased in epoxy to form a complex, 3D carbon fibre composite object.
Yes, I am looking for sponsorship :)
Vik :v)
Then I hit on a brainwave: short polyacrylonitrile fibres. There are normally used to reinforce synthetic rubber. But they have another use: The feedstock for carbon fibre.
My trick is to mix polyacrylonitrile and similar materials in with PLA or CAPA. This is then turned into filament, which in turn is printed into an object on a RepRap - this tends to align the fibres.
The object is then encased in a ceramic and heated to the vapourisation point of the PLA or CAPA. You then have a ceramic mould stuffed with oriented polyacrylonitrile. Introduce an inert atmosphere and raise the temperature and you have a mould full of carbon fibre. This can be surface-activated in the usual ways, or coated with vapour deposition before being vacuum-encased in epoxy to form a complex, 3D carbon fibre composite object.
Yes, I am looking for sponsorship :)
Vik :v)
Labels: capa, carbon, composite, epoxy, fiber, fibre, pla, reprap
Tuesday, April 17, 2007
You can't spread a bit of CAPA on your copper
Yesterday I bought a piece of copper-clad board and tried sticking it under Zaphod. The idea being to deposit a trail of CAPA on the copper and then etch the exposed copper. Unfortunately, it looks like copper makes a nigh on perfect non-stick surface for CAPA extrusions. Even after cleaning with contact cleaner and cranking up the heat, I couldn't get any CAPA at all to stick to the copper.
Looks like time for plan B; the etch resist pen.
Vik :v)
Looks like time for plan B; the etch resist pen.
Vik :v)
Labels: board, capa, circuit, etch, pcb, polymorph, track
Tuesday, March 27, 2007
Untimely Lapse Movie
I've had a go at printing one of Ed's Darwin corner brackets. On about the 5th layer, the output detached itself from the stage and got pushed around a bit. While this wasn't exactly a huge success, it does look very much like we're on the right track so I've been persuaded to post the video. As per the last one, there are approximately 2.5 seconds between each frame.
Right at the end you can see the deposited part start to detach and go springy before it gets pushed around. You can also see the second head appearing in the right of the frame in the latter half of the movie. The camera moves around a little as the USB lead was dragging on things, but I fixed that with some tape about half way through; not a problem as it actually gave a better camera angle!
Adhesion to the stage (or lack thereof) is my big bugbear, and I'm going to try a light coat of varnish as previous tests have shown molten CAPA sticks to it like glue. If that doesn't work, I'm onto foam bases like the rest of 'em.
Vik :v)
Right at the end you can see the deposited part start to detach and go springy before it gets pushed around. You can also see the second head appearing in the right of the frame in the latter half of the movie. The camera moves around a little as the USB lead was dragging on things, but I fixed that with some tape about half way through; not a problem as it actually gave a better camera angle!
Adhesion to the stage (or lack thereof) is my big bugbear, and I'm going to try a light coat of varnish as previous tests have shown molten CAPA sticks to it like glue. If that doesn't work, I'm onto foam bases like the rest of 'em.
Vik :v)
Labels: bracket, capa, darwin, detached, fails, reprap, stage, zaphod
Sunday, March 25, 2007
Time-lapse video of test hexagon.
A few people have asked me if I would make a short time-lapse movie of something being RepRapped. So, thank you for the inspiration. I finally got round to it on the second attempt, after earlier borrowing a higher quality camera that unfortunately lacked macro focus:
The object is a standard 20mm (approx) test hexagon, 5mm (quite accurate) thick, extruded from CAPA. There are approximately 2.5 seconds per frame. I used a Linux script of my own devising and a Logitech 320x240 webcam clamped to the base board, which I will document and GPL if anyone is interested. Donations of higher quality equipment greatfully accepted!
Here's what that lot looks like:
Vik :v)
The object is a standard 20mm (approx) test hexagon, 5mm (quite accurate) thick, extruded from CAPA. There are approximately 2.5 seconds per frame. I used a Linux script of my own devising and a Logitech 320x240 webcam clamped to the base board, which I will document and GPL if anyone is interested. Donations of higher quality equipment greatfully accepted!
Here's what that lot looks like:
Vik :v)
Labels: capa, extrusion, fast, hexagon, polymorph, reprap, sped up, test, time lapse, video, zaphod
Tuesday, March 06, 2007
The Extruded Extruder Extrudes!
I tidied up the bearings and rammed a pin through the top of the screw thread to join it to the coupler. It now extrudes! Yay! Can't say for how long because it's strong enough to split the nozzle, or at least blow out the weak parts on it. Closer inspection shows where I cut things just a little too fine drilling the nozzle out, and a bit of soldering is required to patch it.
The extruded extruder is the one with the red light on. The black thing on the board is just to allow a bit of contrast so you can see the extruded stuff. I've used an ABS clamp off the Stratasys to hold the PTFE part of the nozzle, but I aim to replace that when the software is running happily again.
Zaphod now has two heads.
Vik :v)
The extruded extruder is the one with the red light on. The black thing on the board is just to allow a bit of contrast so you can see the extruded stuff. I've used an ABS clamp off the Stratasys to hold the PTFE part of the nozzle, but I aim to replace that when the software is running happily again.
Zaphod now has two heads.
Vik :v)
Labels: capa, extruded, extruder, reprap, zaphod
Sunday, March 04, 2007
CAPA vs. ABS bodies extruders
I've hit a temporary snag with the PC software, so I'm going for the firmware while fixes happen by magic. Well, sweat & swears - er - tears from Simon and Adrian, I suspect, but let me carry on in ignorant bliss...
I've noticed that my half-washer bearings slip a bit (crappy job of smoothing the lands on the screw, I suspect), so I've packed a little bit of CAPA on top of them. This prevents exposed sharp edges engaging with the filament from dragging things around. In short, it stops your half-washers from popping out. I hope. Here's an old ABS one compared to the freshly-minted CAPA part. The CAPA part is the one on the left. The slightly fuzzy appearance of the bearing is due to Vaseline.
I've taken advantage of the squishy properties of CAPA a bit, I know, but it seems to work. Now we just hope the bearings don't heat up enough to melt the CAPA when you run them fast.
Keep on reading for our shameless fund-raising plug...
Vik :v)
I've noticed that my half-washer bearings slip a bit (crappy job of smoothing the lands on the screw, I suspect), so I've packed a little bit of CAPA on top of them. This prevents exposed sharp edges engaging with the filament from dragging things around. In short, it stops your half-washers from popping out. I hope. Here's an old ABS one compared to the freshly-minted CAPA part. The CAPA part is the one on the left. The slightly fuzzy appearance of the bearing is due to Vaseline.
I've taken advantage of the squishy properties of CAPA a bit, I know, but it seems to work. Now we just hope the bearings don't heat up enough to melt the CAPA when you run them fast.
Keep on reading for our shameless fund-raising plug...
Vik :v)
Labels: bearing, capa, darwin, extruder, polymorph, reprap, washer
