Author Topic: Cutting acrylic plastic for case? Would a dremel or drill+milling table work?  (Read 6157 times)

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Offline LapTop006

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Proxonn is insanely expensive and some of their tools bear a superficial resemblance I think, perhaps to Liyang, a Chinese brand. They make little saws like that.

They appear to be a huge company - at least from the variety of stuff they make they seem to be so.

Last time I looked deeply into their stuff the bigger things (the saw mentioned earlier, their drill press, a few others) were reasonably priced, even in Australia, although their smaller hand tools were expensive compared to alternatives.

The ones I've used have also been solidly made, and in a shared workshop have stood up better than many other tools.
 
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Offline cdevTopic starter

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I got the little knife and Ive been fooling around with it and it works pretty well! I should have some basic acrylic device cases soon!
"What the large print giveth, the small print taketh away."
 

Offline overlordManny

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Also don't forget that the cut edges can be sanded and flame polished if you want it perfectly clear. It puts off some nasty fumes, but it sure looks great. Use a respirator or be in a well ventilated area.
https://www.youtube.com/watch?list=PLfjdwZlON-2W2cdJAbv0zv_juwcX94K7t&time_continue=66&v=Mmd56UMHDK0
 
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Offline james_s

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For straight lines I usually score it with a utility knife and straight edge. For curves I find someone with a bandsaw or scroll saw. A handheld jigsaw with a fine tooth blade works too as long as it's variable speed so you don't melt the plastic.
 
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Offline basinstreetdesign

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I don't saw or mill it at all. They sell plastic scoring knives for a few bucks. Any craft or big box store should have one. I think mine is Olfa, a good Japanese company. Just take a straight edge and make severeral deep scores and it will snap off clean as a whistle; at least as clean or cleaner than a saw blade. No melting, no plastic dust, no waste. If the edge is going to show, you can sand and polish it but you have to do that no matter how you cut it. When you snap it, do it over a square edge, right under the score line. I cut acrylic for framed pictures with no problem

Sent from my SM-G900V using Tapatalk

Yeah, I have done it this way and it works just fine as long as the score is at least a mm or two deep and the material is held in a vise at the score line and then hit/bent with good fast force along the line.

As for drilling it, a pillar drill works fine with ordinary bits.  It needs to be at the fastest speed the drill can deliver, though, and take it slowly.

It can be bent with a home-made jig made with small hinges and two pieces of plywood and a scavanged heater from a toaster-oven on a variac.  You have to play with the power and time a bit but will bend straight away on the hinge line after a short warm-up time.  Too hot and you get bubbles along the bend.  Too cold and it wont bend at all.
« Last Edit: February 15, 2019, 07:16:31 am by basinstreetdesign »
STAND BACK!  I'm going to try SCIENCE!
 
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Offline timelessbeing

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Offline KL27x

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^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.


« Last Edit: February 16, 2019, 01:15:24 am by KL27x »
 

Offline Richard Crowley

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^He basically made his own cutter. Cutting a notch into the back of the blade make a little single saw tooth.
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.
 

Offline KL27x

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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.
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.
« Last Edit: February 16, 2019, 02:43:35 am by KL27x »
 
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Offline metrologist

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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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Offline billbyrd1945

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I used to make acrylic boxes for hospitals. It took me a couple of years to learn how to get what you're after. I used 1/4" stuff. I used a $200 made-for-acrylic blade on my table saw for rough cuts. But you can use a straight edge and an acrylic scoring tool (Home Depot), and then snap it in two over the edge of a flat surface. Then, I used a router table with a 1/4" carbide spiral up-cut bit to get smooth edges suitable for solvent welding or merely for appearance. Set your fence so that the piece will just fit between it and the bit and do a dry run pushing into the rotation of the bit. Then move the fence ever so slightly toward the bit to get a clean, smooth cut.  I would then break the sharp edges with the scoring tool or a file or a bit of sandpaper, whatever. I usually went for the highest speed on the router, but got pretty good results on just about any speed. Bits are not expensive. I usually go them at MCLS.
 
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