Working with Acrylic plastic

Working with acrylic plastic is an interesting thing in itself. Acrylic is a type of plastic that has many positive attributes- it’s clear, sturdy, and easy to work with. You can use acrylic in almost any way you like to create any number of objects.

One of the best things about working with acrylic plastic sheets is that if you screw up, you can easily scrape or file away your mistake, peel it off and try again. There is little to no risk of destroying the sheet itself. However, if you’re using hot tools, there are certain safety measures you need to take into consideration-

Acrylic plastic sheets can be worked with using many different types of methods- cutting them with a saw, drilling them with a drill or rotary tool, heating them up to bend them into different shapes, sanding them down along the edges- you can do anything you want with these plastic sheets.

Drawing on the sheet (windows and door labels)

The best way to draw on clear acrylic sheets is by using white-out correction fluid. This material will dry inside your lines and give them some opacity, while still allowing light through. Use this to make custom window labels, or door signs (e.g. “STAFF ONLY”).

Cutting with knife or scriber

The best way to cut sheet is using a hobby knife or scriber. This produces the cleanest edge, and the sheet isn’t damaged when you place it over your model for cutting in. The sheet can be held vertically in a clamp, but this requires additional material as a guide and it’s only possible if you sheet is large enough to fit in the clamp.

If your hobby knife or scriber won’t cut all the way through immediately, then place it in a clamp instead so that only the very tip protrudes. Then use this to push down on part of the sheet above where you want to cut, which will provide additional pressure for the tool to finish the cut. Note that you should not do this with a hobby knife, since it can slip and cause serious damage if pressure is applied improperly.

Using a hobby saw

Cutting sheet with a hobby saw produces a clean edge as well, but it’s harder to control where the plastic will be cut due to the blade moving around freely. To avoid this you can use a metal guide to fix the position, which also provides better support against tear-out. This works best if the sheet is placed vertically in a clamp as before, but additional material is needed as a guide and it will only work if your sheet can fit in the clamp.

Cutting with Saber saw

Putting sheet beneath the blade of a saber saw is not recommended. If you use too much force, or even if you don’t push hard enough, then this method will cause damage to the sheet which can lead to cracks forming at points where they’re not wanted. This can be frustrating and wasteful, but it’s often used by beginners due to the fact that saber saws are so common.

Hand saw

Using a hand saw is slow and it’s hard to get straight cuts, which means that the cut edges are not smooth. This can be worked around by sanding or filing, but it’s much easier if you use one of the other methods described here.

Routers and shapers

You can use routers to cut clean shapes out of acrylic sheets. But first, you need to build templates and guides. This is usually done by using a router to cut a shape (called the fixed piece), and attaching this as an additional template for subsequent shapes that are similar to the first. Scrapers can then be used to shave away unwanted areas until you’re left with your final form.

Cutting out circular holes

A circle cutter is a tool for cutting perfect circles from an acrylic sheet. This can be used to cut windows from a cockpit canopy, or to create round lights on your model. A good example of this is the lighted dome in the nose of a B-17 bomber: there isn’t a real dome there, but a flat piece of clear plastic with circular lights cut from it.

Dremel tool, an easy way to cut acrylic at home

A fairly neat way to cut acrylic sheeting is using a Dremel tool with a cutting disk, preferably for plastics (the grit isn’t as important as for metal). If you don’t have the track of where you are cutting, you can make an index using black marker pen.

Procedure: The first step is to remove the protective film from one side of your piece of plastic sheeting (if not already removed), and test-fit it in place on your model (without glue). Try to center the cut as best as possible, because this will give you a better end result. Now decide where you want to start cutting from, and use the marker pen to create an index on that side. The Dremel tool can be held in either hand, depending on your preference. Then simply rotate the disk clockwise as if it were a screwdriver (at a speed of about 300 RPMs). If you are cutting through more than 1/8 of an inch, try using a thicker disk if possible.

Unfortunately, plastic-ready cutting disks are not common at your local hardware store… but you can also use a cuttong bits with success. The speed for these is slightly higher, and you may need to re-heat the plastic so that it can be sawn through using normal drill bits.

Circular saws/band saws

If you have access to a band saw or a circular saw, then these tools will also do a good job of cutting acrylic plastic sheets. A band saw is preferable since it will give you a much more accurate cut. If you are using a circular saw, then make sure to use the side of the blade that has no teeth. This will give you an almost perfect 90 degree corner after cutting, but it’s trickier to see your index line on this side because there is less contrast between plastic and metal.

The speed used for cutting plastic is almost the same as for metal, but I find it best to start slowly until you see how fast the blade goes through the plastic… very important! Watch out for splinters on your index line, because they will make it difficult to place your glued piece in the right position.

Circular saws can be used as straight-cut or to make curved cuts. Just start at a corner and follow the line. If you have access to a band saw, this is obviously much easier since it will need only one pass for a 90 degree corner.

A circular saw can also be used for very small radii (e.g. a cockpit rim), but this will take a few minutes longer. You can switch to a metal saw blade for this job, because the plastic one will have trouble going through the thicker material.

Drilling holes for screws and rivets

Acrylic plastic sheets are normally very easy to drill into with normal twist drill bits, as long as the material is thicker than 1/8 of an inch. For thinner pieces, it’s best to use bits intended for wood or metal (they have bigger flutes so they won’t get stuck in the plastic). If you can turn on your drill press at high speed, then this will also help because acrylic plastic is very brittle and snaps easily (this is the same as for fiberglass). If you do manage to break your drill bit, then just heat it over a flame until it becomes soft, and pull outwards. You can easily drill holes in acrylic plastic sheeting by clamping the sheet vertically on its edge, so that it’s held taut. This way you won’t need to use any support material, and the sheet won’t twist under the pressure. Normally you should be able to drill right through in one go with a 1/8 inch bit. If you can’t get your drill into position for some reason, then just drill holes every few inches that are slightly larger than your screw or rivet. You can use this to hold the sheet in its correct position.

Laser cutting

You can save time by having pieces of acrylic cut at a laser cutting service. This is usually more expensive than using other methods depending on the number of pieces you need, but it requires less skill and produces less mess than some others.

Cutting off burrs and sharp edges

If you need to cut the corners off an acrylic sheet because it’s too wide, then you mustn’t do this when the sheet is resting on a flat surface… the edge will always be at the wrong angle. Instead, clamp it vertically on its edge to a table or bench leg for support (see picture at top of page). The edge will always be at the correct 90 degree angle and if your sheet is large enough then you won’t need any additional material as a guide.

Sanding and filing

There’s no need to sand or file your acrylic sheet before gluing it down. But if you want to sand or file something that you’ve cut from a sheet then this is the best way to do it. Sanding will leave scratches on the sheet, but these are easy to buff out with some water and a cloth. Filing can also be used to remove blemishes caused by cutting.

For sanding, you start with a rough grit sand paper like 80 (Depending on the project). After you get the shape cut out, use a back and forth motion to sand to keep from melting away your model. Use a 600 grit paper follow by a 1000 grit paper If needed. For filing use a small flat file or if needed to finish with a very fine metal file.

Bending acrylic plastic sheets

Acrylic plastic is normally rather easy to bend, but it’s important to understand how this works. The sheet can be bent by heating it over a flame, or by placing something hot directly on the surface (e.g. a soldering iron). It should take no more than 20 seconds to soften the material enough for it bend easily without cracking, and you only need to hold it in the desired shape for at most 2 seconds.

If you try to press too hard, or bend it too quickly, then cracks will form on the inside near the bend. These won’t be visible from the outside, but they will make your plastic sheet very brittle and it might shatter if bent again at that point.

Bending acrylic plastic sheets – an example

The best way to bend sheet is to do this at the position where it’s needed on your model. For example, if you want to cut out a cockpit rim from 1/8 inch acrylic plastic, then place your sheet over the corresponding area on the model and mark it with a pencil. You can just cut out the shape with a hobby knife, but this will produce an edge that is not smooth. Instead, place the sheet on edge over the cockpit rim part of your model, and heat it up at several points close together until it’s soft enough to bend easily without cracking. Leave in this position for 20 seconds or so, and it should stay in place without you needing to glue it down. Then take a hobby knife and cut through the plastic along the inside edge of your cockpit rim, thus leaving a smooth edge that will fit neatly into place.

Flame polishing

Acrylic plastic can also be flame polished, with the help of a common torch. Hold the piece in question (no larger than half an inch thick) at about 40 degrees angle to the flame, and draw it back and forth over the rim of the torch. The idea is to get enough heat on one side so that you can see the shiny result through the semi-opaque another side.

The process can be speeded up by heating a large piece over a flame, and then holding it at the edges with pliers as you drag it back and forth across the torch. If the plastic is not warm enough to melt, then place it near a heater or an open window to heat up.

I find that the piece cools pretty fast, and then you need to reheat it for another go.

Remember, too much heat is as bad as not enough… so be careful.

If you want to get those nice tube-like swirls on the edges, don’t drag the plastic over the flame as normal. Instead, simply rotate the piece so that the entire side being worked on is exposed to flame for about 5 seconds or so. It helps if you have someone else working the torch while another person rotates the pieces.

The above process will give you an idea of how much heat is required in order to get a certain result. With a bit of practice you will be able to tell how much heat is required and in which direction you need to drag the piece so that it doesn’t overheat. Very nice results are possible, but only if the plastic sheeting is not too thick…

After flame polishing, acrylic plastic sheets will have a slightly wavy texture on one side. This can be removed by sanding it again with some fine sandpaper and re-polish the edge. Moreover, the more you sand the plastic, the more translucent it becomes.

Acrylic solvent for bonding

Solvents are chemicals that will dissolve acrylic plastic. The most common one is cyanoacrylate, which you can buy as various brands that include the word ‘super’ in their name (such as Superglue). Acrylic solvent is not dangerous if used correctly, but it’s important to keep some safety precautions in mind.

Never use acetone, paint thinner or any other solvent in place of the special solvent designed for dissolving acrylic plastic. The others will attack your eyes and lungs when inhaled, or they can irritate your skin. Read the product labels so you know what each chemical is used for.

When using solvents to dissolve sheet, always use a mask to filter out the fumes which are released during this process. Acrylic solvent is not dangerous in small quantities, but using any chemical for extended periods of time without protection will cause damage to your eyes and lungs if inhaled over time.

This substance can also be harmful if it comes into contact with skin, so you should wear gloves when handling it.

When you’re done, make sure to wash your hands immediately, because any remaining solvent will irritate your skin. You should also work in a well-ventilated area or place the parts in an open container with ventilation holes, otherwise the fumes will build up in enclosed areas and will be dangerous to inhale.

Re-using acrylic plastic sheets

It’s possible to re-use clear sheet many times, but you have to be careful about how you do it. The sheet might be damaged during the modeling process, for example by cutting or melting it. This is not a problem as long as the damage isn’t too big (small holes or elongated cracks), since these will not cause any problems when re-using the plastic. But if your sheet is badly discolored on one side, then it’s better to just throw this away and use a new sheet. If you want to re-use plastic then hold the sheet with tongs over an open flame for some seconds. This will remove the dirt but not the coloration, so your sheet should be as transparent as ever after doing this.

Conclusion

Using acrylic plastic sheets is an easy way to get the material you need for any number of projects. Just keep in mind that there are some limitations when it comes to cutting, and if you use the right techniques then they can be overcome. As long as you know what you’re doing, then it’s possible to get satisfying results every time.

Hope this article will help you to get more knowledge about Acrylic Plastic sheet and how to work with it. Please feel free to ask any questions or share your ideas in the comment section below. And, please don’t forget to check my other article on how to build a fish tank with acrylic.

Thank you!