Today, we’ll be playing with knives!
Knives is a but of a misnomer, but that’s what they are typically called.
Our Knives Vs Noga
You may have seen a Noga ceramic knife, which last forever but cost a small fortune. I have one at home, and only one, because of the price. The edges stay sharp because they are made of ceramic. Kind of like a skate blade, where the side edge of the blade you could basically shave your nail off of it, but you’re not going to cut yourself anywhere on it.
Unlike the Noga, our ceramic deburring tools come in six different sizes and shapes.
The first one has a flat edge on the front with a pretty tight curve at the top, and then another straight edge. All the flare edges are sharpened.
The second knife has three flat edges, which could be useful if you needed to get in somewhere and scrape off some plastic.
The third has a little bit of a curved profile with two flat edges and a tight bend at the top. It has a C-shaped cutout in the angled flat edge.
The fourth knife is shaped like a standard chisel with one flat edge and an angled flat edge.
The fifth has two 90° cutouts on one edge and three flat edges. The cutout makes it perfect for lining it up right on the corner of your print to get a nice sharp corner.
The last knife has a rounded edge, a sweeping concave bend on one edge and a convex bend on the other edge around to the top.
I printed some brackets using a polycarbonate. I had to peel off the brim and wound up with a sharp edge, as per usual. This can also happen if you are having a little bit of an elephant foot, from perhaps printing with the bed too hot, and it made your print expand out at the bottom. When you peel off the brim or excess material, you are left with a sharp edge.
To clean up the edge you could use a normal hobby knife or an Xacto knife. This runs the risk of cutting yourself and damaging the print. Instead, you should use a ceramic knife.
For a sharp edge like this, I would use the fourth blade from the list above. The way I find this blade works best is by placing it on a 45° angle and drag it towards your body. Apply downward pressure and drag it quickly to shave off the burs and a tiny amount of plastic with each pass.
Keep the pressure consistent but vary the angle with each pass to smooth the edge. If you want, grab a rounded knife and you can put a bit of a profile on the print.
To deburr the inside of a print, select whichever blade fits best inside and conforms to the shape you want. Scrape the blade back and forth to knock off any of the sharp edges.
You don’t have to overdo it, a pass or two will usually get the print into the right shape.
You can use the knives to shave off a bit of the print if it’s just off from the right size to make it fit. For instance, if you’re prototyping something, instead of redesigning and repainting the part, just shave a little off until it fits.
Usually if I’m designing something, I would put a bit of a bevel on the sharp corners to give it a polished look. When something is printing flat in the bed, having the bevel at the bottom increases the likelihood of the print warping, especially if you’re using a warping material like ABS or something.
To add a bevel after printing, simply press the curved part of the blade to the print and repeat the motions above until it has the desired shaped.
To get sharp edges, use the deburring tool with the 90° cutouts. If your print is meant to have any 90°, this blade will be great for touching them up after printing. Simply hold the cutout to the print and, again, drag it towards yourself while applying steady pressure.
The 90° blade may take some practice. At some point you might end up marring the print. The issue may be as small as a slight discoloration on one edge of the print. If this happens, run a lighter over the print and it should clear up the discoloration and make is glossy again.
No matter what you’re deburring you will want to turn it around and go in the opposite direction as well because you may not start right at the edge, but in a little bit. This means the very edge of the print will not be filed down.
I find these are also great to have when doing multiple prints at once.
Sometimes when you do multiple prints at the same time, the nozzle can leave rough bumps when switching between prints. Ideally, you would watch to keep any stringing or drooling between your prints to a minimum so this doesn’t happen, but no one is perfect.
Any of the flat blades would be great for scratching those bumps off without marring the finish too much. Doing this will leave the print discolored. As I mentioned above, quickly pass a lighter over the print and it will return to its glossy state.
Replacing Blades and Hold
Another thing I like about these is how easy it is to change the blades if something happens. The two pieces of clamshell that make up the handle just slide opposite one another and the blades can easily be swapped out. Make sure the blade is slid down into the handle far enough, otherwise it’ll be wobbly and might fall out.
I like to hold it right at the top of the handle or even on the blade itself. This is perfectly safe since the knives won’t cut you, and it gives you better control.
Hopefully you found this article useful!