Lesson 1. Feed: the sheet runs through the rollers

After this lesson the canvas has two feed rollers, an A4 sheet and a motor. Turn on a switch and the sheet runs between the rollers, just like in a real fax. This is the first half of the mechanics: the sheet moves lengthwise, and later the head will look for the dot along the line.

We build and run all the mechanics of this kit in Fast mode.

1.1. Idea: the feed

In a real fax a rubber roller pulls the sheet. A motor turns it through gears. The sheet is pressed against the roller and moves as far as the roller's rim has turned.

Our roller is the Feed roller part: a bar with rubber wheels near its ends. A sheet that goes under the wheels moves across the roller. At the ends of the roller there are two mount points, end0 and end1: you put a gear or a pulley on them.

There are two rollers, as in real life: the first pulls the sheet in, the second takes it out. With only one roller the sheet is let go as soon as its tail leaves the roller, and the end of the sheet is never read. A belt links the rollers so they turn the same way.

1.2. Idea: a gear "on edge" and a right-angle drive

The feed roller lies in the plane of the sheet, but the motor stands with its shaft pointing up. The gear on the end of the feed roller stands on edge (from above it looks like a rectangle), and the gear on the motor lies flat. Such a pair is a right-angle drive: the gear on edge sits on the rim of the motor gear, along the roller's axis, and turns the rotation by 90°.

Gears 16 and 16: the roller turns as fast as the motor.

1.3. Build

Step 1. The sheet and the rollers

Step 2. A belt between the rollers

A pulley on the end of a roller stands on edge by itself. A belt between two pulleys on edge looks like a straight strip from above.

Step 3. The motor and the right-angle drive

1.4. Check

The sheet passes under the rollers and stops when it leaves the second one: a sheet that has been let go stays where it is.

Paste for lesson 1 (Cmd+I)

Paste into a new project. No chips needed.

# Lesson 1 - feed: the sheet runs through two rollers.# Paste into a new project (Cmd+I). Chips: fax-chips.json. Run in Fast.# RUN on: the sheet runs between the rollers; DIR - the other way.# ---------- switches ----------input(RUN)input(DIR)# ---------- feed: two rollers, a belt between their right ends; the sheet lies above, its lower edge under roller 1 ----------mfeed feed1{len=310}()mfeed feed2{len=310}()mpulley fp1{d=20}()mpulley fp2{d=20}()mpaper paper{w=210, h=297}()mmotor fm(ON=RUN, DIR=DIR)mgear fg1{teeth=16}()mgear fg2{teeth=16}()at(feed1, 70, 40)at(feed2, 70, 120)at(paper, feed1, 60, -285)at(fm, 18, 32)mount(fp1, feed1.end1)mount(fp2, feed2.end1)mount(fg1, fm.shaft)mount(fg2, feed1.end0)belt(fp1, fp2)