Self Learners Way to Cut Acrylic for Smart Mirror

About: I'm a Mechanical Engineer turned IT Professional . I came into the Information Technology world because someone challenged me to. But at heart, I'm still a grease monkey with no desire to lose touch with the...

In this instructable, we will go through how a self learner can go about cutting an Acrylic See-through mirror in a safe and satisfying way using basic workshop tools.

This sub-project is part of a larger Smart mirror that I'm currently working on. The steps described here are applicable to an Acrylic See-through mirror sheet such as this one that is 18 inches x 24 inches and 1 mm thick.

The 1 mm thickness of this sheet enables us to cut it without using fancy specialist tools.

Let's roll!

Step 1: Safety First! the DOs and DON'Ts!

Acrylic by nature is extremely brittle and can crack or fragment into sharp pieces that can result in injuries!

Therefore, the DON'Ts!

  1. Do not use aggressive cutting methods such as Jigsaws or scissors - such methods of cutting can cause the mirror to send brittle fragments flying into the air or rapidly crack and destroy the mirror instantly!
  2. Do not use any kind of tape along the cut lines - the acrylic comes well packaged in plastic wrap and applying tape along the cut lines increases the thickness of the sheet making it harder to cut

The DOs

  • Use safety goggles and gloves if necessary
  • Be relaxed and do not rush through the cutting process
  • Make a cardboard template of the dimensions you will need to cut the sheet - reduces the risk of damaging the mirror by eliminating needless handling

Step 2: The Simple Tool Set

You will need the following most of which are readily available in a makers shop or can be bought inexpensively:

A set of cheap padded clamps

A combination square

Scissors to unpack the acrylic and also to cut the plastic wrap after the cutting operation

A straight edge of some kind - the one shown in the picture is a heavy Pittsburgh Try-Square. It's long enough to accommodate the 18 in x 24 in acrylic sheet and is also heavy enough to hold down the sheet during the cutting process

And the most important tool?

A Husky knife or equivalent - the good heavy ones typically from Home Depot . The weight of the knife makes it easier to apply pressure on the acrylic during the cutting process.

VERY IMPORTANT

Do not use metal clamps! You may end up damaging your Try-square or the acrylic sheet!

Start with a fresh blade on the knife - A crappy or blunted edge can end up destroying the expensive acrylic

Remember! You need to cut along a fine line repeatedly - therefore sharper the blade, better the cut!

Step 3: Top Tip: Work on the Shorter Edge First

In order to make the acrylic easier to work with , it's recommended to cut along the shorter edge first for the following reasons:

  1. The longer edge is more work and is relatively less easier to work with
  2. Cutting along the shorter edge shortens the longer edge making it easier to cut
  3. Lastly, a shorter sheet fits better if you have a smaller workbench improving the success rate of the longer cut

The picture shows the sheet after the shorter edge was cut off reducing the longer edge to less than the stock length of 24 inches. This makes the sheet fit just right on my workbench, ready for the next cut.

Step 4: Finally! Making the Cut!

The steps are pretty simple but require patience especially if you're new to this:

  1. Use the cardboard template to make a mark of the cut line - there is no need to draw an entire cut line because the Try-square or straight-edge will help us do that.
  2. Set your Try-square along the mark and lock its position using the clamps
  3. IMPORTANT - Do not apply the clamps directly on the acrylic!
  4. Start the cut of by bracing the blade against the straight edge and holding the knife edge at approximately 30-degrees to the work surface
  5. Make the first cut line with the least amount of pressure and by moving the blade along the straight edge - the idea here is to set the cut line correctly
  6. If you've moved the knife along the straight edge, it becomes that much easier for the knife to find the cut line when you start the next cut
  7. Start at the top again and score along the cut line with increasing pressure - apply slightly higher pressure at the beginning and end of the cut as the edges require a bit more effort than the middle of the sheet
  8. Based on the strength applied, the process would take from anywhere to 15 to 24 repetitions (see note below)
  9. Unclamp the sheet and move the cut line to the edge of the workbench - hold the sheet down gently but firmly on the workbench
  10. With your palm parallel to the work surface, give the overhanging part of the sheet a swift pat - once you make up your mind to bring down your palm, do not hesitate!
  11. As you can see the sheet breaks off along the cut line without any cracks
  12. Use the scissors to cut the plastic sheet and remove the breakaway piece

IMPORTANT

You will hear the acrylic crinkle as you repeat the cuts - stop when you consistently hear the crinkling 2 - 3 times in succession

Note that you must not cut through to the other side of the acrylic - this can flex the bottom edge of the sheet and cause the acrylic to crack!

Thanks for reading my IBLE and I hope you find it useful in your projects.

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    2 Discussions

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    tytower

    2 months ago

    Someone told me to drill it you need to grind the cutting edges off the drill bit so it scrapes away the plastic is this true . do you have any secrets on drilling the sheet?

    1 reply
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    andymenontytower

    Reply 2 months ago

    Drilling acrylic or plexi-glass sheets requires special drill bits. You may want to research "Plas-Drill Bits" that are worth buying. I don't know if spending time to grind a regular drill bit down would guarantee results because the angles you end up on the ground down bit may end up damaging your stock.

    I hope this helps.