Braille Printer Drawings A project from 1980 Part of the Braille Printer Web Pages by Douglas W. Jones and Andrew Appel THE UNIVERSITY OF IOWA Department of Computer Science and Princeton University Department of Computer Science This dates from when we worked at the University of Illinois School of Basic Medical Sciences in Urbana

Dimensions are expressed as:

0.0	are ±0.05
0.00	are ±0.005
0.000	are ±0.0005

All dimensions are in inches.

Most of the parts are aluminum, even those specified as brass, except:

• The circuit board (3.1.7.2)
• The platten (3.2.4.2)
• The paper hold-down pivot strut (3.2.4.3.2)
• The paper hold-down pivot pin (3.2.4.3.3)
• The hinges (3.4.8)

Numbers (such as 3.1.7.1) given with each figure caption reference the parts list making up section 3 of the text.

Base Plate Layout (3.1)

Baseplate (3.1.1)
Thickness 1/4 inch

Rear Cabinet Layout (3.1.2.1)

Rear Cabinet Panel (3.1.2.1)
Thickness: 1/8 inch

Rear Panel Bracket (3.1.2.7)
(2 required)

Heat Sink Support (3.1.3.2)
(2 required)
Material: 1/16 Aluminum
Cut, drilled, then bent into shape

Transformer Mount (3.1.4.1)

Capacitor Clamp (3.1.6)
Thickness: 1/16

Circuit Card Assembly (3.1.7) Transistor must be in thermal but not electrical contact with mounting bar.

Circuit Card Mounting Bar (3.1.7.1)

Circuit Card (3.1.7.2)
Material: Perforated fiberglass board

Microswitch Mount (3.1.12.1)
(thickness 0.500)

Carriage Installation (3.1.12.1)

	To install the carriage cable:
	1) Cut a 6-foot length of cable.
	2) Feed it through the hole in the winding drum and tighten the clamp screw in the winding drum leaving an approximately equal length of cable on either side.
	3) Wind each end around the drum 3 times one end on each side of the clamped cable.
	4) Feed the cable around the pulleys on each end plate,   a) through the small hole in each carriage end plate,   b) down around the short brass rod in the slot in the end plate,   c) down through the carriage clamp bolt,   d) down through the holes in the ends of the carriage bottom plate,   e) and down through the large holes in the base plate.
	5) Tighten one clamp bolt (either one).
	6) Attach a 20-pound weight to the unclamped end of the cable.
	7) Tighten the clamp bolt above the weight.
	8) Cut off the excess cable at both ends, even with the bottom of the carriage.

Paper Advance Mechanism (3.2.1)
Assembled, rear view

Paper Advance Plate (3.2.1.1)
Thickness: 1/4 inch

Paper Advance Motor Assembly (3.2.1.2)
Note: Motor shown installed from wrong side.

Paper Advance Motor Mount Plate (3.2.1.2.1)
Thickness: 1/4 inch

Paper Advance Motor Mount Angles (3.2.1.2.2)

Paper Advance Shaft Support (3.2.1.3)
(2 required)
Press fit sintered bronze bearing (3.2.1.4.4), into each shaft support, ream bearing if necessary to allow 1/4" shaft to spin freely.

Paper Advance Shaft Sprocket (3.2.1.4.1)
(2 required)
1/8" wide rubber bands work well as tires on each side of each sprocket.

Motor Mount Plate (3.2.2.1)

Winding Drum (3.2.2.3)
Material: Brass
Note: To drill the nearly tangent hole in the rim of the drum, first nick the drum with a small diameter end mill coming in perpendicular to the axis of the hole to make a place to start drilling. Drill this hole before milling in from the side for the 6/32 clamp screw.

Right Pulley Mounting Plate (3.2.3.1)
Note: Left Pulley Mounting Plate is the same except
the 0.175 deep slots are on the other side.

Pulley Rim (3.2.3.2.2) (4 required)
Material: brass
Note: gentle press fit onto ball bearings 3.2.3.2.1

Pulley Shaft (3.2.3.2.3)
(4 required)
Material: brass
Note: This is 1/4" diameter, nominal. Actually, it should be of the right diameter to be a press fit with the ball bearings 3.2.3.2.1 and an easy fit in the slots in the end plates 3.2.3.1

Platten Mount Bar (3.2.4.1)
Material: 1" × 0.5" aluminum bar
Note: Round ends and upper corners so nothing on top is sharp.

Platten (3.2.4.2)
Material: Brass

Paper Hold Down Assembly (3.2.4.3)
Material: Brass
Note: When mounting each hold down to the back of the platten mounting bar, a small blob of solder or anything similar at point S allows either screw A or B to be tightened to finely adjust angle of block and thus to adjust position of the bearings at the end of the hold-down strut.

Paper Hold Down Mounting Block (3.2.4.3.1)
(2 required, one a mirror image of the other)

Paper Hold Down Strut (3.2.4.3.2)
(2 required)
Material: 1/8" Brass

Paper Hold Down Pivot Pin (3.2.4.3.3)
(2 required)
The diameter of this pin should be so as to make an extremely precise sliding fit into the hole in the strut, and the length should be just a bit more than the thickness of the strut.

Paper Guide Bar (3.2.5)
The heads of the cap screws in the front edge of this bar should protrude enough to serve as paper guides.
There are 3 holes, but only two screws should be used, the holes used depending on the paper width.

Carriage Assembly (3.2.7)

	Make 2 1.00 × 0.250 dia pins (dia +000,-0.001) to hold carriage top plate to end plates.
	Fix top plate to end plate with 4 8/32 × 3/4 cap screws, slots with pins in end plates face each other.
	Loosely mount clamp bolts in 1/4 dia holes in end plates, bolt head inside, nut outside.
	Mount solenoids loosely in holes in top plate, from inside with nuts in wells on outside.
	Mount die guide on top plate with 4 6-32 × 3/4 cap screws, check for free sliding of solenoid plungers.
	Mount bottom plate between ends of end plates, well facing up, 2 mounting holes in side facing opposite the ramps on the end plates, with 4 8-32 × 3/4 screws.
	Tighten all but the clamp bolts, attach terminal strip to side of bottom plate with 2 4-40 × 3/8 screws.

Carriage End Plates (3.2.7.1)
(2 required)
Material: 1/2 inch aluminum plate)
Note: Left end plate shown, right end plate is mirror image.
Do not install cable at this point!

Make 4 0.50 × 0.25 dia pins to fit in slots in Carriage End Plates.
The upper pin in each end plate is held by 2 6-32 × 3/8 screws. This pin sets the radius of the bend in the cable.
The lower pin in each end plate is adjusted by a 10-32 × 1/4 allen head set screw. This pin is used for fine adjustment of cable tension and carriage position.
Insert ball bushings in large holes in end plates.

Carriage Clamp Bolts (3.2.7.1.1)
(2 required)
Made from 1/4-20 × 3/4 brass bolt.
Drill through bolt 1/16 dia, just under head.
If the resulting hole is not tangent to the plane of the underside of the head, use washers to get this effect.

Carriage Top Plate (3.2.7.3.1)
(Material: 1/2 inch aluminum plate)

Carriage Die Guide (3.2.7.3.2)
(Material: 1/2 inch sq. brass bar)

Front Panel (3.3.1)
Material: 1/16 aluminum

Side Panels (3.3.2)
(2 required, mirror images)
Material: 1/16 aluminum

Front Panel Bracket (3.3.1.1)

ComputerSupportPlate (3.4)
Matrial: 1/8" Aluminum

Card Guide Bracket (3.4.1.2.1)
(2 required)

Card Guide (3.4.1.2.2)
(2 required)
Material: plastic

Card Retainer (3.4.1.2.3)
Cut and bend a piece of 1/16" aluminum in this shape.

Toggle Switch Mount (3.4.2.1)

Hinge (3.4.8)
(2 required)
Material: steel
This does not need to be a high precision item. Undrilled hinges meeting these specifications are available commercially.