Big Tape

I got these big rolls of packing tape on a 3” core from an auction. I think they’re meant to be used in some kind of taping machine. To use them I built a dispenser modeled after the iconic hand-held 3M Scotch tape dispensers typically used for small tape. I built one of wood years ago, but I’ve always wanted to make it in clear plastic.

vector files from ponoko P2 clear acrylic (.220”) $18.50 + $12.50 cutting+ $19 shipping = $41.66

PDF of flat side of tape holder

3” OD x 2.75” ID x 11 ⅞” clear acrylic tube from estreetplastics $6.99 + shipping ¼”

clear acrylic sheet (6” x 24”)

scrap wood for bending forms

SCIGRIP 16 Acrylic Solvent Cement $5.34 on Amazon

cutter blade from a 2” packing tape dispenser

#8-32 tap to cut threads to hold the blade on

2 #8-32 bolts to hold the blade on

2 tiny bolts or screws to act as stops to hold the roll on the spindle

big roll of tape (10” diameter, 2” wide on a 3” core) I don’t know where to get this…

tools: table saw w fine tooth blade, band saw, drill, disk sander, router table with flush trim bit, clamps, drill bits

It’s recommended when cutting plastic to use a fine tooth saw blade which prevents chipping.
Cut a piece of the 3” tube to 2 ⅜” long on the table saw. I did this by rotating the tube against the rip fence. This piece will be the spindle that holds the tape roll. Sand the ends flat. Drill 2 tiny holes about 3/16” from one end that will accept tiny bolts to act as roll stops. These keep the roll on the spindle. Cut 2 strips of acrylic ¼” x 2 ¼” x 22” on the table saw. These will be formed in two separate molds and glued together to become the curved side of the dispenser.

This is the most tedious part. Print out the PDF of the flat side of the dispenser. I did this at 100% on three sheets, and matched them up on a light table. The green line represents the curved side that the strips will become. To form the strips I made a mold of the shapes on each side of the green line. The curved side was formed as two pieces in two separate 2-part molds, then glued together before attaching to the flat side.

To make the molds I glued the paper pattern to a scrap of ½” plywood. Then I divided it into the front and back sections. Then I rough cut the mold pieces on the bandsaw by cutting right down the middle of the green lines. Then I took the laser cut outside piece and divided it into front and back sections. These sections were then drilled and screwed to the rough cut plywood pieces. On the router table, adjust the flush cut bit so the bearing rides on the laser cut plastic, and the cutter hits the wood. This makes a perfect smooth matching shape. Now trace the shape onto another scrap of plywood or MDF, and rough cut it out on the bandsaw. Then screw it to the perfect smooth piece and router it to match. Repeat this process until you have a stack that is 2 ¼” thick.

The inner parts of the molds cannot use the laser cut plastic as a pattern as it is the wrong size. To make the inner parts you need to sand away the green line on the rough cuts left from the outside part. I used my disk sander with 36 grit paper on it to do this. Do it carefully as this is the pattern for the inside parts. Once you’re happy with the shape, drill and screw it to one of the rough cuts and router it just as before. Build it up to 2 ¼” thick as before.

Now the big round outside mold needs a hinge. I attached the hinge with screws before cutting it in half. This helps with alignment when putting it back together. I drilled some big holes to allow for clamping the mold halves together.

This part is fun but a little tricky. The ideal forming temp for acrylic is 315 F. I preheated the oven to 365 F. and turned it off. Then I put 1 strip of acrylic in the oven on some aluminum foil which rested on a board that had been preheated in the oven. I did it this way because an early test bend I tried overcooked on the ends due to the gas being on and more heat coming from the edges of the oven. Everyone’s oven is different, so a bit of trial and error should be expected. I left the strip in the oven for 10 minutes, then tried to form it. It wasn’t soft enough, so I heated the oven up again to 365 F. and popped it in for another 10 minutes. I wasn’t worried about overheating it because the oven was OFF, and cooling down while the plastic was heating up.
This was just right. I shoved it into the mold and squeezed the halves together and clamped them shut. Then let it cool for a half hour or so.

Before I glued the 2 halves together I had to adjust the size of one so that together they would fit the laser cut flat piece. I cut a little off on the table saw.

Lay masking tape across the bottom of the two haves to keep them aligned. Mask both sides of the seam to catch the glue that will squeeze out. Then apply the glue, wipe off the excess and place a weight on the seam to keep it positioned correctly. Let dry 4 hours. Remove masking.

Carefully sand the edge that will be glued to the laser cut flat piece. It should be flat and square for a good fit. Place the flat piece on top of the curved piece, and tape in place in a few places. Then with an Exacto knife cut the inside masking on the flat piece all along the edge of the curved piece. Then take the two pieces apart and remove the narrow bit of paper around the edge of the flat piece.

Mask both edges of the curved piece. Apply glue to the edge of the curved piece and put the flat piece on aligning everything neatly. Then place some weights on top to hold the joint tight. Let set 15 minutes, then remove masking.

Next mask and glue on the spindle, weight, and let set 15 minutes. Remove masking and let set 24hrs.

Hold the cutter up to the front so that the teeth are at about the same height as the highest part of the nose, and mark through the holes with a Sharpie. Drill 9/64” holes, and tap to #8-32. Bolt on the blade.

Cheers, enjoy!