Print in Place Mechanical Calculator (Addiator) With Combined Addition and Subtraction

I wanted to model a mechanical calculator as I have always found their mechanisms intriguing. I also wanted to make the model print in place, decreasing the assembly required and allowing more people to enjoy a mechanical calculator. I decided on the Addiator as the simple mechanism was more suitable for printing in place.

I used Fusion 360 for this project.

I'm currently enrolled at Thomas S Wootton High School.

• 3D printer
• Fusion 360

The Addiator consists of multiple sliders arranged vertically within a case. Cutouts are made to show the digits and allow the manipulation of the slides. A stylus is used to move the sliders.

I first began by planning the cutouts. I choose to include four digits as it would allow most calculations without taking up too much space or requiring a highly precise printer.

While typical Addiators have the cane shaped slots for addition and subtraction separately, while I combined the slots, increasing functionality without sacrificing the compactness.

I planned to make the addiator 80mm by 127.1mm through mostly arbitrary estimates. You can choose almost any size as long as your printer is capable of the scale. Smaller prints will lose more detail and are more likely to bind the slide to the case, but larger prints take more time and filament.

First you need to determine dimensions for the slide, or pick randomly.

If you planned the size of the case, you can calculate the slide length by taking the planned length of the internal space of the case and multiplying by 2/3.

Each slot should be the length of the slide divided by 44, as there are 22 spaces and 22 protrusions.

You can begin by creating a taller rectangular prism that will be used to reach the baseplate.

Above the rectangle, you should create a wider rectangle for the slide.

The protrusions can then be added to the side of the slide and duplicated twenty two times using a pattern, then mirrored to the other side

The numbering throughout the design is staggered to make the text larger and easier to print. The "^" and "V" characters are used to denote a carryover, and are placed before and after the digits. Each number 9 to 0 is aligned to one of the ten spaces after the "^".

You may have noticed there are remaining empty spaces. These are used to reach the slots in the case that the user will use to move the slides.

Using the pattern tool, the completed slides can be duplicated four times.

The slides are finished at this point. You can add a slight chamfer to the edges to help print the overhangs, however they are not necessary.

The case can be created by either using the planned dimensions or drawing a box over the area of the four slides, then hollowed out through the shell tool.

Remove the portions that touch the extension of the slide that touches the baseplate and extend the hole to near the end of the case.

There should be sufficient space between each slide to fit a separator, and between any of the slides and case.

The top plate is created on an offset plane from the xy plane with the height of the other part of the case. Then you can sketch and extrude the matching top plate of the case.

You can align the holes of the top plate by using section analysis in the utilities tab of Fusion 360. Select the top plate, and create a section the thickness of the top plate. You may need to make this value negative. This will allow you to see through the top plate.

Digits:

Form holes for the digits by cutting a rectangle the width of the top plate over the "V" and wide enough to accommodate other digits on the same slide, then duplicating over the other slides. Watch out especially if you used staggered numbers.

The example has the hole at "0" by adding extra space above the slider. This is only for aesthetics.

Vertical of "cane":

The cutouts for user input can be created by first cutting open a section of eleven slots from the left edge of the leftmost slide. Duplicate this with a pattern to easily cover all other slides.

"Hook" of cane:

The hook of the "cane" should be added only on and after the second vertical cutout from above. They should be on both the top and bottom of the cutouts. This enables addition and subtraction from a single cutout.

The hole should start at the top of the hole we just created earlier and extending it to cut and include two slots from the right edge of the slide to the left.

You must also remove a portion of the separator at least the height of a space on the slider and from the top of the cane.

Refer to images if needed.

The numbers for addition should start at the second space and count down from 9. You don't need a zero, as you won't add zero.

The numbers for subtraction is unnecessary as they are simply the numbers listed for addition subtracted from 10, but can be added.

The case is now finished.

You can create a stylus to use the addinator with by starting with a rectangular tip smaller the the spaces of the slides. The should be significant play between the tip and the spaces.

Next, you can create any handle on top of the tip.

This is not needed if you have another tool that can reach between the spaces of the slides.

Congratulations! You've just modeled an Addiator.

You can now 3d print the model, or further customize it to your own liking.

The Addinator adds by inserting the stylus at the digit you wish to add and pulling down until zero, or going back up and through the cane if you reach a carryover.

Subtraction works the opposite way, where you find the number you wish to subtract and bring the stylus up until zero or the carry over. You bring the stylus down instead of up at a carryover.

The calculations can be reset by bringing the bars back up from the backside of the calculator, using the slide extensions.