Electronics > Beginners
Cutting acrylic plastic for case? Would a dremel or drill+milling table work?
timelessbeing:
KL27x:
^He basically made his own cutter. Cutting a notch into the back of the blade make a little single saw tooth. I was wondering how he got that result (and that sound) with a blade. Had to rewind it to see what he was doing.
I used to have one of those carbide tipped knives for scoring and snapping carpet backer board. Bought it on the rec of some forum members for FR-4 and the like. I eventually lost it, and I just made my own out of an old jig saw blade stuck into a wood handle (like a tiny scythe, stuck in from the side at an angle). It dulls, but I am pretty good at sharpening things. It's essentially the same as a tip of a knife blade, except you use it backwards with the flat "spine of the knife" going into the cut and the sharp edge trailing behind. You just have to get the right angle. A bit of positive rake so it doesn't dig in and jam. Gonna post a pic, because it started out super crude and I eventually figured out what to remove from the handle to make it more efficient in size and shape and ergos.
Soda bottle cap for size reference
[Imgur](
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The single bevel makes it "right handed," to score right against a straight edge.
In addition to scoring, I find it makes a great marking knife for metals and wood. For wood, you just gotta go light on the first pass or two. After you get through the surface fibers, you can make your mark/score as deep as you want, unlike with a regular marking knife.
I found this so handy, I eventually made an ambidextrous version, years later.
[Imgur](https://i.imgur.com/aIuyZrd.jpg?1)
Heh, the original is a little burnt and has some melted parts on the blade, because I used it as a hold down while welding.
Richard Crowley:
--- Quote from: KL27x on February 16, 2019, 01:10:40 am ---^He basically made his own cutter. Cutting a notch into the back of the blade make a little single saw tooth.
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No, the blade comes with that notch. But only the first of the snap-off blade segments have this notch.
That is why he advises to never snap off the first segment if you want to use it for scoring acrylic.
The reason it works is because it cuts a square-shape notch in the plastic. While the "regular" sharp end only "plows" a small V-groove. In this way, it is similar to the purpose-made acrylic scoring tools.
KL27x:
That's pretty neat. If you get the angle right, the front of the cutout will act like the mouth/sole of a plane, so you can potentially use a more aggressive rake angle. Even if you snap the tip off, you can make a new one with a dremel and a cutoff disc in a hot minute.
After learning how to sharpen things, I have pretty much stopped using disposable box cutters and exacto knives, myself.
--- Quote ---The reason it works is because it cuts a square-shape notch in the plastic. While the "regular" sharp end only "plows" a small V-groove.
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Yeah, I see that. Mine cuts a pointed V groove, but it works because it's like a sawtooth. It removes a curl to clear its own kerf, deeper on each pass. The flat face is the widest part, so it cuts from the edges of its silhouette and has proper clearance, like a saw tooth. I copied how the carpet scoring knife tip works. The "regular sharp end" of any knife would also work if you turned it backwards (assuming is has a flat spine with crisp edges all the way to the very point), but the angle from the handle would be ergonomically wrong, and that would be a good way to screw up your line, scratch up your plexiglass, and stab yourself.
metrologist:
I've used the score and snap technique on many things. I also use a small band saw and a milling machine on acrylic. It's OK, just a little brittle.
A tip, if you are using a mill and cutting to an edge, you can chamfer the edge before cutting to avoid chipping.
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