Comment on [Blog] If fiber infused material is abrasive to soft metals, it may be useful as a sanding medium
cecilkorik@lemmy.ca 1 week ago
Your idea certainly has some interesting potential, but I think the biggest problem you might find is that it might clog up quickly or dull and lose its abrasiveness and thus be even more quickly disposable (and thus cost-inefficient) than sandpaper already is. That might not be a deal-breaker, if it enables some particular method that you can come up with, like what you mentioned with the chess piece, but I doubt it’s going to be useful as, or cheaper than, a direct replacement for sandpaper or sanding blocks on a larger scale. Yes, a continuous stream of fiber-infused filament is certainly great at sanding away at a nozzle, but that is mostly all fresh filament right off the roll, inch after inch and layer after layer of it, the nozzle is the piece that’s there continuously enduring the relentless abuse, but it rarely sees the same bit of plastic touch it more than a handful of times.
If you try to use the same bit of plastic that’s already sanded its way through a nozzle it may have lost some of its abrasiveness already, but even if it hasn’t I would still be concerned that it might lose its abrasiveness quickly under actual use as an abrasive, it might be difficult to clear out removed material, it might have a lot of friction and heat up, potentially even to the point of localized softening of the surface, allowing any fibers to be flattened or pushed back into the plastic and smoothing the surface. Lots of things are great abrasives in theory, but don’t have any practical use. Sandpapers and polishes are specifically selected to be as cheap and durable as they can be for the job they’re trying to do.
However it is certainly an interesting idea, and worth trying. I’m curious to find out how it performs. Let us know how it goes! Worst-case scenario, using a printed design to make obscure, form-fitting shapes for other abrasives to be applied to seems like an under-utilized application for 3d printing.
j4k3@lemmy.world 1 week ago
So the trick to sanding longer with abrasives is wet sanding. In addition, in automotive work, a drop of Palmolive dish soap is added to a bucket of water. This addition makes a huge difference.
Overall, the principal of like polishes like is important. In abstract, polish is just fine abrasion. Like your finger prints are around 5k-7k grit equivalent. Rub something long enough and you will both polish and abrade it the same as this grit. The oils in your skin are the polishing agent.
I have played around with 10k grit wet sanding and then machine polishing with a light compound where places I rested my hand showed minor variations after stripping any oils and fillers with wax and grease remover (solvent).
I can think of several aspects to increase the complexity here. One could add inserts into the outer vibrating shell. These could be any materials.
I think the bigger issue will actually be the distance between the object and the shell. You see, the size of the random orbital action is the product of two concentric circles. In the pro automotive world, these are pneumatically driven. There are several models available with different properties related to this motion and the internal balance of the mechanism. Within this range of actuation, it is critical that abrasion does not follow a path of repetition. I think this likely means the shell must be larger than the radius of the largest of these two circles or maybe a more complicated size larger than the combination of overlapping radii including their central connection point. This should enable the part to move within the range of random sanding action. That range means the sanding is over a larger area.
The best shell is likely one with gaps similar to a DA sander with ports for dust collection.
Very little of any fiber touches the actual nozzle during printing. The actual fiber size used in filament is far far smaller than what most people imagine. It is only the waste dust from the production and processing of carbon fiber. All actual fibers of any useful length are sold in industry for use in composites. There are continuous fiber printers, but that is not at all related to what is used in 3d printing. If you actually look at the data from people testing materials, fiber infused materials are always weaker. They print better because they are breaking up the polymer bonds. Lots of people jump on the buzzword thinking it is technomagic mor betterer but do not pay attention to the details. If the fiber had any length to it, it would clog like crazy because a long bunch of fibers distributed in 1.75mm crammed into 0.4mm is never going to happen. It is just like a dust additive that happens to be available and is compatible. So it should be well distributed throughout. With ABS a wipe of acetone should help too, if left to completely flash off the solvent for a week or more. That needs to be super limited though. Acetone tends to get retained in bad bad ways with ABS. It is a massive no no to use in automotive applications.