220 Wall Clock

1    Overview

I modeled this design after a Urwerk UR220-SL watch. It has been scaled up to be a wall clock sized version.

This model is LARGE, at about 236x232mm. My printer has a 210x210 print bed, so any parts that are too large for it are also available in right and left half STL files. Also many parts are available as sets of files that can printed on printers with a multi-color capability.

And it's powered by an 110V AC Synchronous motor.

The STL files to print this clock are available at: https://cults3d.com/en/3d-model/gadget/220-clock-model

2    Parts list

Here are the parts that I used. You can use hex socket or Philips head screws, your choice. I paid about $1 a piece for all the ball bearings on eBay or Amazon.

Some of the “2mm” steel shafts that I’ve picked up on eBay or Amazon have been slightly oversized, just enough so the bearings won’t fit on to them. Look for a slip fit of the shaft in the bearing. DON’T force the bearings on the shaft. Excess force can jam the bearings, making them useless. My solution was to order shafts from another vendor. Maybe you will get lucky the first time.

Refer to section 6 for a list of the STL files.

2.1 Summary of non-printed parts

(6) 2x5x2.5mm MR52-ZZ ball bearings

(14) 3x6x2.5mm MR63-ZZ ball bearings

(1) 6x10x3mm MR106-ZZ ball bearings

(6) 8x14x4mm MR148-ZZ ball bearings

(2) 20x27x4mm 6704-2RS ball bearing

(1) 3x22.5mm shaft, one end rounded (Geneva Pin)

(5) 3x23mm shaft

(3) M2x35mm threaded rod

(1) AC Plug for lamp cord.

(21) Screw M2x6mm Flat Head Hex

(32) Screw M2x8mm Flat Head Hex

(22) Screw M2x10mm Flat Head Hex

(2) Screw M3x8mm Cap Head Hex

(36") Music Wire, 0.025" OD (For Hour Arm spring)

(1) Acroprint Time Clock Motor for 125 and 150 Models

(~8ft) Lamp cord.

Refer to section 5 for sources of selected parts.

3    Assembly

The STL files for this project require a printer with a minimum of a 210x210mm print bed.

3.1 Sub Assemblies

3.1.1 Spring Assembly

Included in the files is an Hour Arm Spring.STL file. This file allows you to print a plastic spring (using supports). It is painful to clean out the support material, but it does result in a working spring. However the problem I had after printing it in PLA was that under tension it would ‘take a set’, losing tension over time and the Hour Arm would not snap all the way back. I rotated the Base Spindle several times to add more tension, but after a while this stopped solving the problem.

PLA works for springs only if the normal state of the spring is zero tension, e.g. for a balance wheel in an escapement. If you clamp a piece of PLA and hold it bent for a day or so, when you take the clamps off, it bends back to its original shape a little. But the longer it is bent, the less it recovers its original shape. Someone who knows more about plastics can explain this phenomena better, but I call ‘taking a set’. The Hour Arm Spring is under constant tension, so PLA at least does not work well for long term use.

I would highly recommend making the Metal Spring Assembly. The plastic spring will allow you to debug it, but it will only work for a couple of weeks. Or you can try printing it in some material other than PLA, which might work better.

Metal Spring Assembly

To assemble the Metal Spring assembly you will need the following parts:

·     Metal Spring

·     Hour Arm Spring Metal Top

·     Hour Arm Spring Metal Bottom

·     Spring Mandrel

·     .025in (0.64mm) Piano Wire (~30 inches long.

The first step is to make the metal spring itself. There are several ways of doing this. I used my lathe, however you could also use a drill, a drill press, or a real spring winder if you own one. Figure 1 shows the steps that I went through.

Print the Spring Mandrel. Note that the diameter of the Mandrel is much smaller than the target diameter of the spring. There are several formulas available on the web for determining the mandrel diameter, based on the target spring diameter and the type and gauge of the wire. To achieve a 25mm diameter spring with 0.25in steel Music/Piano wire, I used a 15.6mm diameter mandrel.

Figure 1 steps:

Step 1 - Position one end of the wire so it will land under the chuck jaw when it is clamped.

Step 2 - Clamp it tightly in the chuck.

Step 3 - Bend the wire at a right angle and slide a brace over it. I used a piece of rod stock that I clamped into a tool holder. There was a gap between the mandrel and the brace a little larger than the diameter of the wire.

Step 4 - Hold the wire tightly. I used a pair of pliers to apply plenty of tension as I turned the chuck manually. With the wire coming from the left to keep the turns tightly packed as I turned it onto the mandrel.

Step 5 - When you get 10 or 11 turns in the mandrel, back off the brace. Be careful because the spring may unwrap violently. Don’t have your face or any other body part in the way, it stings! Notice that springs diameter is now much larger than the mandrel’s.

Step 6 - The raw spring off the mandrel.

Figure 2 shows the final spring after I cut off the raw ends, and bent the remaining ends to fit into the Hour Arm Spring Metal Top and Hour Arm Spring Metal Bottom parts.

Ideally the spring is 25.25mm in diameter to fit into the Hour Arm Spring Metal Top and Hour Arm Spring Metal Bottom parts. My spring was about 32mm in diameter, which dropped down to the target diameter when I loaded it with some tension. Also the spring should be about 16mm tall (mine was about 15mm tall), but this is taken care of when you mount the Top and Bottom parts. They stretch the spring to the correct height. But I adjusted my spring by stretching it a little.

I included some holes in the mandrel where you could seat the wire if it’s easier for you. You may want to drill a hole completely through the mandrel and bend the wire on the far side to lock it into place, because the wire will naturally want to pull itself out of the hole when you start winding it.

3.1.2 Hour Arm

To assemble the Hour Arm you will need the following parts:

·     Hour Arm

·     Hour Arm Tail

·     Hour Arm Cap

·     Hour Arm Spring Hub

·     Hour Pointer

·     Hour Arm Pointer Insert

·     Hour Reverse Pawl Bearing Cap

·     Hour Reverse Follower

·     Hour Reverse Pawl

·     Screw 8mm Cap (2x)

·     Ball Bearing MMR106ZZ-1

·     M2x6mm Flat Head Screw (2x)

·     M2x8mm Flat Head Screw (2x)

·     M2x10mm Flat Head Screw (4x)

·     Hour Arm Stop Pin 3x11mm

·     Metal Spring Assembly or plastic Hour Arm Spring

3.1.2.1 Reverse Pawl and Follower

Press the 6x10x3mm MR10677-1 Ball Bearing into the Hour Pointer.

Press the Hour Reverse Pawl Bearing Cap onto the Ball Bearing.

Use two 2Mx6mm Flat Head Screw secure the Reverse Pawl Bearing Cap to the Hour Pointer.

Insert the Hour Reverse Pawl through the Ball Bearing then press the Hour Reverse Follower onto the Hour Reverse Pawl. Be sure to align the Hour Reverse Pawl alignment pin with slot on the Hour Reverse Follower, as indicated by the blue dashed arrow.

Secure the Hour Reverse Follower to the Hour Reverse Pawl with a 2Mx6mm Flat Head Screw.

Press the Hour Arm Stop Pin into the Hour Point so that it’s top is flush with hole that it is inserted into.

3.1.2.2 Hour Arm Spring Hub

Press the 8x14x4mm MR-148-ZZ Ball Bearing into the Hour Arm Spring Hub. Make sure that the bearing is pressed against the bottom of the Hour Arm Spring Hub.

Drop the Hour Arm Bearing Spacer on top of the ball bearing. This will be aligned later when the Hour Arm Assembly is pressed on to the Base Spindle.

Press the 8x14x4mm MR-148-ZZ Ball Bearing into the Hour Arm Spring Hub. Make sure that the bearing is pressed against the top of the Hour Arm Bearing Spacer.

Lay the Base Spindle Cap on top of the upper MR-148-ZZ Ball Bearing. This will be attached to the Base Spring Hub by the 2Mx8mm Flat Head Screw later when the Hour Arm Assembly is pressed on to the Base Spindle.

Press the Hour Arm Tail onto the Hour Pointer (indicated by the red dashed arrows), then run a 2Mx10mm Flat Head Screw through the Hour Arm Tail, Hour Pointer, Hour Arm Spring Metal Top, and into the Hour Arm Spring Hub. Now screw the other two 2Mx10mm Flat Head Screws (indicated by the blue dashed arrows) into the Hour Arm Spring Hub, clamping everything together.

Note:   At this point the Base Spindle Cap is loose, but trapped between the Ball Bearing and the Hour Pointer. The Base Spindle Cap later when the Hour Arm Assembly is pressed on to the Base Spindle.

Note:   For clarity, the Hour Arm spring and Hour Arm Spring Metal Bottom parts are not shown, but they will be hanging below the Hour Arm Spring Hub.

Press the Hour Arm Pointer Insert into the Hour Pointer. This may need to glued if it is loose.

The Hour Arm Cap is pressed into the Hour Pointer. Do not glue this! It may be necessary to remove this later to provide easier access when the Base Spindle Cap is screwed into the Base Spindle.

Figure 5 shows the complete Hour Arm Assembly. The hex of the Hour Arm Metal Spring Bottom will be mated with the Base Spindle, and its 3 screw holes will be used to attach it to the Base Spindle with screws inserted through the bottom of the Base Spindle.

3.1.3 Minute Bar

The digits and marks on the Minute Bar fall into two types; there are 48 Minute Bar Minute Marks, and 12 Minute Bar Digit XX parts. Refer to Figure 6.

The Minute Bar Minute Marks are the small individual minute markers between each of the Minute Bar Digit XX parts.

The Minute Bar Digit XX parts typically include a digit notation and a larger minute marker, as illustrated by the blue highlighted Minute Bar Digit 60 in Figure 6. The Minute Bar Digit 15 and 45 use ‘min’ text, and the Minute Bar Digit 30 part is simply a marker.

There are a couple of ways of making the Minute Bar:

·     Print the individual Minute Marks and Minute Digits separately, then glue them to the Minute Bar.

·     Do a multi-color print with the Minute Marks and Minute Digits in one color and the Minute Bar in another. Note that any of the parts may be a different color. On the 220 SL, the Minute Bar Digit 60 is red, and the Minute Marks and the rest of the Minute Bar Digits are in a luminescent filament.

3.1.4 Minute Bar Tens Assemblies

Attached to the Tens Minute Bar there are three Minute Bar Label Assemblies; 15, 30, and 45.

The respective Minute Labels and Minute Label Digit parts may be printed separately and fitted together. Note that they are designed to fit tightly as a 2-color print, so it may take a fair amount of scraping and sanding get them to fit together.

Or they may printed as 2-color parts.

3.1.5 Gauge Assembly

There are two Gauge assemblies 1 Day and 10 Days. The 1 Day Gauge uses a green Gauge Max, and the 10 Days Gauge uses a red Gauge Max.

The parts of the Gauge assemblies may be printed separately and glued fitted together. Note that they are designed to fit tightly as a 3-color print, so it may take a fair amount of scraping and sanding get them to fit together.

Or they may printed as 3-color parts.

On the 220, the Gauge Bars are a blue luminescent filament.

3.1.6 Hour Digit Assembly

There are three Hour Digit Assemblies; Hour Digit 1-4-7-10, Hour Digit 2-5-8-11, and Hour Digit 3-6-9-12. Figure 9 illustrates the assembly of Hour Digit 1-4-7-10, however the other two assemblies are constructed using the same method.

The Hour Digit Assemblies may be printed as individual Hour Digits, then fitted and glued into the central Hour Digit 1-4-7-10 part, or they may be printed as a 2-color print. If the parts are printed separately, then Figure 9C illustrates the assembly process.

Once the Hour Digits and the Hour Digit 1-4-7-10 parts are assembled:

·     Press a 2x5x2.5 MR52ZZ ball bearing into each end, making sure that the respective bearings are seated as illustrated in Figure 9A and Figure 9B.

·     Glue the Hour Geneva Gear on to the Hour Digit 1-4-7-10 part (Figure 9C).

Note:   I found it useful to prepare the bearing seats by running a 5mm drill BACKWARDS into them with very light pressure. Be sure not to cut into the shoulder that the bearings will rest on. Running the drill forwards will cut the shoulders immediately!

3.1.7 Hour Digit Screw Assembly

Three Hour Digit Screw Assemblies are required. Cut three pieces of M2 Threaded Rod 23mm long. Screw the rod into the Hour Cap until it is firmly seated. The center of the Threaded Rod is not used, so if necessary, the center may be held with a pair of pliers without fear of crushing the threads. It also may be useful to run an M2 screw into the Hour Cap to initially cut the treads.

3.1.8 Hour Frame Assembly

The Hour Frame assembly requires multiple steps:

To begin the assembly of the Hour Frame you will need the following parts:

·     Hour Frame

·     Hour Frame Mount

·     Hour Frame Mount Hub

·     Hour Frame Bearing Spacer 3.0

·     20x27x4 6704-2RS Ball Bearing (2x)

·     M2x10 Flat Head Screw (3x)

·     M2x8 Flat Head Screw (3x)

3.1.8.1 Base Frame Assembly

Press the Hour Frame Mount Hub into the Hour Frame aligning the three screw holes. Then attach them to the Hour Frame Mount using three M2x10 Flat Head Screws.

3.1.8.2 Hour Frame Mount Assembly

Press a 20x27x4 ball bearing into the Hour Frame Mount Hub. Make sure that it is firmly seated against the shoulder in the hub. Lay the Hour Frame Bearing Space 3.0 on top of the bearing, then press the second 20x27x4 ball bearing into the Hour Frame Mount Hub. The second ball bearing should be flush with the top of the hub. Now use three M2x8 Flat Head Screws to attach the Spur Gear 1.375M 30T 5 to the Hour Frame Mount Hub.

Note:   The Hour Frame Bearing Space 3.0 should be held fairly tightly between the ball bearings, and should be aligned with the with the inner diameter of the ball bearings. If not it, then it can be aligned later, when the Hour Frame Assembly is installed.

3.1.8.3 Hour Sleeve Installation

Before their installation, prepare the Hour Sleeves by threading their center holes with either a long M2 screw or an M2 tap. It is important that when the Hour Digit Screw Assemblies are screwed into them they are tight, but not so tight that the Hour Cap gets screw slot stripped.

Install the Hour Sleeves into the Hour Frame Mount using 2 M2x6 Flat Head Screws each.

3.1.8.4 Hour Reverse Clutch Spring Installation

Attach the three Hour Reverse Clutch Springs to the Hour Frame using M2x6 Flat Head Screws.

3.1.8.5 Hour Digit Installation

Figure 15 is a cross-section view that illustrates a properly seated Hour Digit Assembly.

When installing the Hour Digit Assemblies, make sure that they increment in a counter-clockwise direction. That is if one arm of the Hour Frame is point up, then Hour Digit 1-4-7-10 Assembly must be installed at the 12 O’clock position, the Hour Digit 3-6-9-12 Assembly must be installed at the 4:30 position, and the Hour Digit 2-5-8-11 Assembly must be installed at the 7:30 position. Refer to Figure 49.

Slip the Hour Digit Assembly (section 3.1.6) onto the Hour Digit Screw Assembly (section 3.1.7). Then use a large flat head screwdriver to turn the Hour Cap of the Hour Digit Screw Assembly into the Hour Sleeve (section 3.1.8.3).

After proper installation, the Hour Digit Assembly should spin freely with minimal right/left backlash (as indicated by the green arrow).

3.2 Base Preparation

The overall dimensions of the clock are 232x236mm. The Base is divided into 3 STL files so that it may be printed on a 210x210mm print bed: Base.STL, Base Outer Frame Lf.STL and Base Outer Frame Rt.STL. The Base.STL file allows the assembly and testing of all the moving parts of the clock before the Base Outer Frame, Bezel and Base Bottom parts are printed.

3.2.1 Base Outer Frame

The Base Outer Frame Lf and Base Outer Frame Rt parts are glued to the Base. They may be attached before or after all the parts are assembled on the Base. The surfaces of the Base and the Outer Frames align and with the surfaces of the Base, so they may be glued together while laying on a flat surface.

Note that there is a hole in the bottom of the Outer Frame parts where you can use a 2mm shaft to help align the two halves if they give you trouble.

For the examples in this document, the Base Outer Frame parts are attached.

Note:   For clarity purposes, the Base Outer Frame may not be displayed in some figures.

3.2.2 Base 3x6x2.5mm Ball Bearings

Press 3x6x2.5mm Ball Bearings into the locations indicated in blue. The bearings should be flush with the bottom surface.

3.2.3 Base Spindle

Press the Base Spindle into the Base from the bottom and secure it with two M2x8 Flat Head Screws. Note, use the locations indicated in blue for the screws.

Two screws are all that are that are necessary to hold the Base Spindle in position. Later the screws can be removed and the Base Spindle can be rotated to adjust tension of the Hour Arm spring. Also the other screw locations will be difficult to access once the gear train is installed.

3.2.4 Base 8x14x4 Ball Bearing

Press the 8x14x4 MR-148-ZZ Ball Bearings into the Base. Note that these bearings will stand off from the base by 2mm.

Press Bearing Cap 14x2mm onto each of the ball bearings then secure them with M2x8 Flat Head Screws.

Press the 8x14x4 MR-148-ZZ Ball Bearing into the top side of the Base as shown in Figure 20. The top of the bearing should be flush with the top of the boss that it is pressed into. This bearing and the bearing inserted in the previous step will provide support for the Spur Gear 1.375M 40T 6.

3.2.5 Geneva Pin

The Geneva Pin is a 3x22.5mm shaft, rounding at one end. Press the Geneva Pin into the top side of the Base as illustrated in Figure 21 A. The pin should stand out approximately 6.6mm (Figure 21 B).

3.2.6 Minute Bar

Use three M2x10 Flat Head Screws to attach the Minute Bar to the base.

3.2.7 Hour Retract Cam Installation

Attach the Hour Retract Cam to the Base with 2 M2x6 Flat Head Screws. The position of the Hour Retract Cam determines when the Hour Arm retracts as it reaches the 60 minute mark. It will be adjusted to its final position in section 3.4.7.

3.2.8 Hour Arm Stop Installation

Attach the Hour Arm Stop parts to the Base with 2 M2x6 Flat Head Screws each. The position of the right Hour Arm Stop determines the 0 minute stop position of the Hour Arm when it retracts. It will be adjusted to its final position in section 3.4.7. The right Hour Arm is just cosmetic.

3.2.9 Level Indicator Installation

There are two Level Indicator assemblies for the 1 Day and 10 Days Gauges.

The parts of the Level Indicator assemblies may be printed separately or they may printed as 2-color parts.

To assemble the Level Indicator, the Level Indicator Insert should be fitted then pressed into the Level Indicator, and glued if necessary. Then press the 2x8mm shaft into the Level Indicator as shown in Figure 25A.

Now press the shafts of the Level Indicator Assembly into the holes of the 1 Day and 10 Days Gauges in the Rear Ring, shown in Figure 25B.

3.3 Gear Train

To assemble the Hour Arm you will need the following parts:

·     Winder Gear2 Straight miter gear 1M12T

·     Winder Spur gear 3 1.375M 15T

·     Winder Spur gear 4 1.375M 22T (3x)

·     Winder Spur gear 7 1.375M 15T

·     Autotrol J606-1 CW 1 RPM

·     Spur gear 3 1.375M 15T Reverse Pinon

·     Spur gear 3 1.375M 15T Reverse

·     Spur gear 1.1375M 45T 2

·     Spur gear 1.1375M 10T 3

·     Spur gear 1.1375M 50T 4

·     Spur gear 1.1375M 10T 5

·     Spur gear Drive 1.1375M 40T 6

·     Spur gear Set 1.1375M 40T 6

·     Spur gear 1.1375M 40T 6

·     Spur gear Drive Cap

·     Base Bridge

·     M2x6 Set Screw (2x)

·     Shaft 3x32mm (7x)

·     Ball Bearing MR63ZZ 3x6x2.5 (x7)

·     M2x6mm Flat Head Screw (2x)

·     M2x8mm Flat Head Screw (5x)

3.2.1 Base Bridge Assembly

Press 3x6x2.5 MR63ZZ ball bearings into each of the 7 locations in the Base Bridge. The bearings should be flush with the surface of the bridge.

3.3.2 Motor Pinion Assembly

Press the Spur gear 3 1.375M 15T Reverse Pinon onto the shaft of the Autotrol J606-1 CW 1 RPM motor. The gear should press tightly against the shoulder of the flat on the shaft.

Use two M3x6mm set screws to secure the Reverse Pinion to the motor shaft.

3.3.3 General Gear Assembly

The following gears single parts that are pressed onto 3x23mm shafts.

·     Spur Gear 1.375M 15T Reverse

·     Winder Spur Gear 4 1.375M 22T (3x)

·     Winder Spur Gear 7 1.375M 15T

In each case, the shaft should be centered in the gear, with 2.5mm sticking out on either end. 

3.3.4 Gear 2-3 Assembly

The Gear 2-3 Assembly mates the Spur Gear 1.375M 45T 2 and the Spur Gear 1.375M 10T 3 gears on a single 3x23mm shaft. Press the two gears together and glue them. Again, the shaft should be centered in the gears, with 2.5mm sticking out on either end.

3.3.5 Gear 4-5 Assembly

The Gear 4-5 Assembly mates the Spur Gear 1.375M 50T 4 and the Spur Gear 1.375M 10T 5 gears on a single 3x23mm shaft. Press the two gears together and glue them. Again, the shaft should be centered in the gears, with 2.5mm sticking out on either end.

3.3.6 Gear 6 Assembly

The Gear 6 Assembly mates the Spur Gear Drive 1.375M 40T 6 (Drive Gear), Spur Gear Set 1.375M 40T 6 (Set Gear) and Spur Gear 1.375M 10T 7 gears. The Set Gear is driven to by winder gear train to set the time, and drives the Spur Gear 1.375M 10T 7 gear to rotate the Hour Frame. The Drive Gear is used by the motor gear train to drive the time of the clock. The pawls of the Set Gear engage with the Drive Gear to enable the motor to advance the time.

Note:   When installing the Drive Gear make sure that it is oriented so the ends of the Set Gear pawls fit cleanly into the notches of the Drive Gear. If not flip it over. Also apply some petroleum jelly to the pawls to lubricate them.

Note:   When printing the Set Gear, uses supports and make sure that shaft is facing up. After removing the support material, bend each of the pawls to break them loose and free to move.

The Spur Gear Drive 1.375M 40T 6 gear is attached to the Spur Gear 1.375M 40T 6 gear with the Spur Gear Drive Cap by an M2x6 Flat Head Screw. 

The Spur Gear Drive 1.375M 10T 7 gear is attached to the Spur Gear 1.375M 40T 6 gear by an M2x6 Flat Head Screw.

Note:   The Spur Gear Drive 1.375M 10T 7 gear is attached to the Set Gear after the Set Gear has been installed into the Base.

3.3.7 Winder Gear Train Assembly

3.3.7.1           Miter and Winder Spur Gear Assembly

Press the Winder Gear 2 Straight Miter Gear 1M12T and the Winder Spur Gear 3 1.375M 15T together through the MR-148-ZZ 8x14x4 Ball Bearing at the top of the base. Then secure them with an M2x6mm Flat Head Screw.

3.3.7.2           Gear 6 Installation

Press the Gear 6 Assembly and the Spur Gear Drive 1.375M 10T 7 gear together through the MR-148-ZZ 8x14x4 Ball Bearing next to the Base Spindle. Then secure them with an M2x6mm Flat Head Screw. Refer to section 3.3.6.

3.3.7.3          Motor Installation

Install the motor as illustrated in Figure 31 using two M3x8 Hex Head Cap Screws. The pinion was installed on the motor in section 3.3.1.

Note:   Figure 31 illustrates the orientation for a motor that rotates clockwise. Insert the screws in the center hole on either side of the motor and rotate it to the position as shown in Figure 31.

For a motor that rotates counter clockwise, rotate the motor and screw it into the alternate mounting holes. In both cases, use the center holes on either side of the motor.

3.3.8 Winder Gear Train Installation

Now install the remaining winder gears:

·     Three Winder Spur Gear 4 assemblies, as described in section 3.3.3.

·     The Winder Spur Gear 7 assembly, as described in section 3.3.3.

·     Gear 6 assemblies, as described in section 3.3.6.

3.3.9 Drive Gear Train Installation

Now install the drive gears:

·     The Spur Gear 1.375M 15T Reverse gear assembly, as described in section 3.3.3.

·     The Gear 2-3 assembly, as described in section 3.3.4.

·     The Gear 4-5 assemblies, as described in section 3.3.5.

3.3.10 Base Bridge Installation

Install the Base Bridge Assembly to hold the gears of the winder and drive gear trains in place using five M2x8 Flathead screws, as illustrated in Figure 34.

3.4 Top Side Assembly

3.4.1 Minute Bar Installation

Use three M2x10 Flat Head Screws to attach the Minute Bar to the base.

3.4.2 Rear Ring Installation

Before installing the Winder Gear 1 Straight Bevel pinion 1M12PT 12 GT gear, make sure that its shaft mates with the Winder with Finger Hole part, which is installed in section 3.4.5.

Slip an 8x14x4 MR-148-ZZ ball bearing onto the Winder Gear 1 Straight Bevel pinion 1M12PT 12 GT gear, up to the shoulder. Then seat the ball bearing into the Rear Ring against the edge marked by the blue line.

While holding the gear in place, fit the Rear Ring against the Base.

Use three M2x10 Flat Head Screws to attach the Rear Ring to the base.

3.4.3 Gauge Assembly Installation

Use 2 M2x6mm screws to attach the Gauge 1 Day Assembly and Gauge 10 Days Assembly to the Rear Ring. Then press the Screw 8mm Caps in to them.

3.4.4 Minute Bar Tens Installation

Using three M2x10 Screw to attach the Minute Bar Tens part to the Base Outer Ring. Then glue the Minute Label (15, 30, 45) assemblies to the Minute Bar Tens part in their respective positions.

Refer to section 3.1.4 for more information on the Minute Label assemblies.

Note that the Base Outer Frame is attached to the Base as described in section 3.2.1.

3.4.5 Winder Installation

Press the Winder with Finger Hole onto the shaft of the Winder Gear 1 Straight bevel pinion 1M12PT 12GT gear and attach it with an M2x6 Flat Head Screw.

3.4.6 Hour Frame Installation

Slide the Hour Frame Assembly onto the Base Spindle, then press the Hour Frame Bearing Spacer onto the Base Spindle. Ensure that the bearings of the Hour Frame Assembly are seated tightly on the shoulder of the Base Spindle.

3.4.7 Hour Arm Installation

To install the Hour Arm Assembly, temporarily remove the Hour Reverse Clutch Spring at the ‘60 minute orientation’.

Press the Hour Arm Assembly onto the Base spindle. Make sure that the hex on the Hour Arm Spring Metal Bottom is rotated so that it mates with the holes in the Base Spindle for the three M2x8mm Flat Head Screws.

Use the three M2x8mm Flat Head Screws to attach the Base Spindle to the Hour Arm Spring Metal Bottom part.

Use an M2x8 Flat Head screw to attach the Base Spindle Cap to the Base Spindle.

Reinstall the Hour Reverse Clutch Spring.

The Hour Arm should rotate freely.

Figure 42 illustrates the internal configuration and positions of the properly installed Hour Arm and Hour Frame.

3.4.8 Hour Arm Adjustments

There are 3 adjustments that need to be made:

3.4.8.1 Load the Hour Arm spring

Remove the two M2x8mm screws that lock the Base Spindle to the Base.

Uses a set of needle nose pliers to rotate the Base Spindle. Place the tips of the needle nose pliers into two of the six Torque Adjustment Holes in the Base Spindle and twist the pliers to rotate it, applying torque to the Hour Arm Spring. The Hour Arm spring is adjusted correctly when, holding the clock vertically (e.g. as if hanging on a wall), there is just enough torque to swing the Hour Arm to the 0 Minute Position.

Restore the two M2x8mm screws that lock the Base Spindle to the Base.

Note:   Three of the Torque Adjustment Holes are used for the screws that attach the Base Spindle to the Hour Arm Spring Metal Bottom.

3.4.8.2 Set the Right Hour Arm Stop

The right Hour Arm Stop determines the point that the 0 minute position of the Hour Arm Assembly.

Loosen the two screws that attach the right Hour Arm Stop to the base. Then move Hour Arm Stop so the Hour Arm Assembly points directly at the 0 minute mark. Refer to the 0 Minute Position in Figure 43.

Now tighten the two screws that attach the right Hour Arm Stop to the base.

3.4.8.3 Set the Hour Retract Cam

The Hour Retract Cam determines the point that the Hour Arm Assembly snaps back to the 0 position.

Loosen the two screws that attach the Hour Retract Cam to the base. But not too loose. You want the Hour Retract Cam to hold its position when adjusting it.

Now turn the Winder to rotate the Hour Arm. When the Hour Retract Cam is correctly positioned, the Hour Arm Assembly points directly at the 60 minute mark when it releases and snaps to the 0 minute position.

Tighten the Hour Retract Cam screws.

3.5 Wiring

Depending on the files that you printed, the clock can be made with or without lighting.

3.5.1 Motor Wiring

The clock is driven by a120V AC Acroprint Time Clock Motor.

Note that there are several motors on Amazon that are one third the price and look very similar to this motor, but they do not work. I have tried three, and this is the first one that actually turns precisely at 1 RPM.

Refer to section 5 for the motor that I used.

Cut some heat shrink tubing to about a 1.5 inch length. Slip it onto the wires of a split and stripped 10 ft. (or whatever length you thing is appropriate) AC lamp cord.

Split the lamp cord about 20cm (8 inches) so a knot can be tied in the leads to act as a strain relief, refer to Figure 45B.

The AC wires will be slipped through the Power Wire Exit Hole shown in Figure 50 and Figure 45B when the Base Bottom is installed.

Insert the ends of the wires through the hole in the Base Outer Frame, refer to Figure 45A (and the Motor Power Wire Hole in Figure 50), then solder the two leads of the motor to the AC cord. Note that the polarity of the wires does not matter. Slip the heat shrink tubing over the solder connections, and shrink them with a heat gun, a soldering iron or match.

3.5.2 Lighting (Optional)

Lighting it was an afterthought. I was frustrated with the weak luminescence of the glow-in-the-dark filament that I had selected, and wanted to see if I could actively light it. It works, but it could still use some refinement.

There are two Bezels, one with and one without holes for LEDs. For the lighting I used 3mm UV LEDs. There are 34 in the Bezel and 12 in Base. Several LEDs in the bezel are hard to fit, requiring clipping the shoulder off the LEDs and running a 3mm drill in the in the holes to provide some clearance.

For the Bezel, soldered a 430 Ohm resistor to the positive side of each of the LEDs, then fitted them and superglued them in. Note that before the glue set, I pressed the LEDs into the Bezel so they were all flush or behind the surface of the bezel. I tried a couple of glues and only superglue seemed to provide a PLA to LED bond.

Once the glue was dry, I soldered the LEDs together, primarily by bending leads over, but in a couple of cases I needed to add some wire to span gaps. The Bezel has two sets of 17 LEDs/resistors wired in parallel on either side. The leads for these I routed through the Bezel Lighting Wire Holes (shown in Figure 50) to the 1A 5V power supply. I used .1 inch pin connectors to attach the Bezel LEDs to the 5V power supply, to make removal easier.

There are also 12 holes for LEDs in the Base, to back light the Minute Bar and the Minute Bar Tens assemblies. These are wired identically to the Bezel LEDs and soldered to the 5V power supply.

Figure 46 shows my wiring job. It’s ugly but it works. Note that the black and red wires coming thorugh the Bezel Lighting Wire Holes on either side plug into pins that I soldered to the power supply output. And the input to the power supply is wired on to the AC line as it passes by. This wiring can all be open because it is only 5V and it is all completely covered when the Base Bottom is attached.

Note that the STL files are designed with holes for the LEDs. But in this picture I drilled all the 3 mm holes for the LEDs.

Refer to section 5 for the sources of the LEDs and Power Supply that I used.

3.6 Bezel Installation

Use six M2x8mm flat head screws to attach the Base Bottom to the Bezel.

If the Base Bottom was printed as two halves, then the halves need to be glued together.

To help with the alignment of the two halves, there are two Alignment Pin Holes (Figure 48). Short 2mm shafts may be pressed into these holes on one side, to mate with the holes on the other side. I added the alignment holes because I found it hard to align the halves accurately without them. Be sure to glue the parts on a flat surface.

Route the power cord through the Power Wire Exit Hole shown in Figure 49 (and Figure 45B).

Use six M2x10mm flat head screws to attach the Base Bottom to the Base Outer Frame.

3.8 Final Steps

Attach a plug to the end of the power wire.

Plug it in and see it work.

To set the time, rotate the Winder in a clockwise direction to advance the Hour Arm to the current time.

I’m afraid that the Winder has only about a two minute accuracy. The best way of setting the time is to use the Winder to advance the Minute Arm slightly ahead (e.g. a minute or two) of the current time, then plug in the clock when the current time matches the time set on the clock.

4 Views

Note:   The Base Bottom is transparent in Figure 51.

For the screws, I used ones that I had left over from previous projects. So I don’t have any screw sources that I specifically used for this project. I started off with assortments of 2 and 3 mm (4 to 10 mm long), flat head, button head, and hex Socket Head Cap screws, and order another 100 from ebay, when I get low on a particular size.

From the following ebay page, you can order 2 or 2M, black or steel, cap, button or flat head screws in 4-30mm lengths for under $2 for 50. If you search, you will find a similar page for 3M screws.

https://www.ebay.com/itm/50X-M2-M3-M4-M5-Hex-Socket-Allen-Head-Screw-Bolt-Self-locking-Nylock-Nut-Locknut-/162286993963?var=&hash=item25c90f022b

Below are the links to some of the parts that I did order for this project.

I find that Uxcell, TRB and Eddies offer high quality ball bearings at reasonable prices. Metal or Rubber seals will work.

I have had very good success printing with ProtoPasta and Hatchbox PLA filaments, so I try to stick with them. Only using other brands if they don’t carry the specific color that I’m looking for. And I don’t list them here, but I also used very small amounts of red and green PLA filament.

·     ProtoPasta Back-to-basics Black PLA

https://www.proto-pasta.com/collections/all/products/back-to-basics-black-4043d-pla

·     Hatchbox PLA silver

https://www.amazon.com/HATCHBOX-3D-Filament-Dimensional-Accuracy/dp/B07HXTSVCH

·     SUNLU PLA 3D Printer Filament 1.75mm, PLA Filament Glow in The Dark 1KG Spool, Dimensional Accuracy +/- 0.02 mm, glow-in-the-dark PLA Green

This is the filament that I used, but I would not recommend it. The spool was oversized, having a large outer diameter and a large hub diameter that required me to print a larger spool holder to print with it. Also I don’t know if this is the case for all PLA Glow-in-the-dark filaments, but it only glows for a very short time (<30 seconds) after light is removed and it is not very bright. Maybe you can do better. But it did print well, adhering to the bed, and giving a relatively clean print, i.e. no whiskers.

https://www.amazon.com/Printer-Filament-SUNLU-Dimensional-Accuracy/dp/B091DS1FFT

·     2x5x2.5mm MR52 Precision Ball Bearings, Metal Shield

https://www.amazon.com/2x5x2-5mm-MR52-ZZ-Precision-Bearings-Chrome/dp/B00TVPSCVO

·     3x6x2.5mm MR63 Precision Ball Bearings, Metal Shield

https://www.amazon.com/uxcell-3mmx6mmx2-5mm-Shielded-Miniature-Bearing/dp/B075CMRGY6

·     20x27x4mm 6704 Precision Ball Bearings, Metal Shield

https://www.amazon.com/20x27x4mm-Precision-Bearings-Rubber-Seals/dp/B06Y3V9LVN

·     6x10x3mm MR106 Precision Ball Bearings, Metal Shield

https://www.amazon.com/MR106-ZZ-Bearing-Shielded-Pre-Lubricated-Grease/dp/B08M9QN999

·     8x14x4mm MR148 Precision Ball Bearings, Metal Shield

https://www.amazon.com/uxcell-MR148-2RS-Groove-Bearings-Double/dp/B082PS8MKX

·     Acroprint Time Clock Motor and Minute Cam for 125 and 150 Models

Note that there are several motors that are one third the price and look very similar to this motor, but they do not work. I have tried several, and this is the only one that actually turns precisely at 1 RPM.

The motor I received was labeled “Autotrol J606-1 CW 1 RPM”.

https://www.amazon.com/Acroprint-Clock-Motor-Minute-Models/dp/B0031SO2ZM

·     K & S Precision Metals 500 Music Wire, 0.025" OD x 36" Long

https://www.amazon.com/PRECISION-METALS-500-0-025-Music/dp/B0006MZNAY

·     UV LED, 3mm, clear round lens

Note that these LEDs come with 430 Ohm resistors for each LED, making it easy to use them with 5V.

https://www.amazon.com/EDGELEC-395-400nm-Ultraviolet-Emitting-Resistors/dp/B077XCWMBN?th=1

·     NOYITO AC to DC Precision DC 5V 1A 5W Power Supply Module AC110V 85V-265V 50-60Hz to 5V Isolated Industrial Grade Built-in Power Module (5V 1A)

https://www.amazon.com/NOYITO-Precision-85V-265V-Isolated-Industrial/dp/B07C1XCH68

6    STL Files

Unless noted, I used a .2mm first layer and all other layers were 1.5mm.

I also set the Perimeter Vertical Shell count to 3. I used the default settings for all the support options.

5 colors are used: Black, Silver, luminescent/Glow-in-the-dark Green (Glow), Red and Green.

Optionally a luminescent Blue may be used for the Gauge Bars and Level Indicator Pointer Inserts.

Several parts are too big to print on a 210x210 bed, so the parts are split into right (Rt) and left (Lf) files. The Base Bottom, Base Outer Frame and Bezel are available on Full, Lf and Rt STLs.

The Bezel is available in two versions, with LEDs and No LEDs. Both have Full, Lf and Rt STLs available.

All non-multi-color files are listed in Table 1.

The multi-color STL file sets, which are zipped into individual files, are listed in Table 2. The STLs in these zip files should only be used if you are doing multi-color prints. If you are not then use the STL files in the table below.

The origins of parts in standard STL files cause them to rest on the print bed. The origins of multi-color STL parts may be offset so they are in the correct position for multi-color printing. You only need to use the files in Table 2 if you are going to print multi-color parts.

I purchased the Bottle Applicator and Acrylic Cement (also called ‘Acrylic Solvent’) from Tap Plastics.

Bottle Applicator: https://www.tapplastics.com/product/supplies_tools/plastic_tools_supplies/hypo_type_solvent_cement_applicator/409

Acrylic Cement:

https://www.tapplastics.com/product/repair_products/plastic_adhesives/tap_acrylic_cement/130

The web page says that the Acrylic Cement is for INDUSTRIAL USE ONLY. This is because it is made up of Methylene Chloride (75-09-2), Trichloroethylene (79-01-6) and Methyl Methacrylate Monomer (80-62-6). ONLY use in a well ventilated area!!! Not only does it smell bad, but inhaling it can hurt you. So treat it with respect. Fortunately a little of it goes a long way, so the fumes from tiny drops are minimal. And don’t forget that it is also flammable!

This is probably the most volatile stuff I’ve ever used. When it comes to evaporation, it makes alcohol look like motor oil. There was an 1/8 inch of it in the bottom of the applicator and it was gone the next day. And this was with the syringe top tightly screwed on, and the cap on it. Also, after 4 months of sitting the garage a 4 oz. container of the stuff that was almost full when I put it on the shelf, was empty! I found that the seal on the container is junk. After tightening as hard as I could, I could tip the container and the stuff would still drip out. My solution, which has worked pretty well, was to store the Cement container in a coffee can with a plastic cap. My theory was that, even with the leaky Cement container, the solvent vapor pressure would equalize inside the coffee can, and slow the evaporation process. But hold the coffee can away from you when you open it, otherwise you will get an eye watering whiff of the stuff.

To fill the Bottle Applicator, just squeeze some air out of it, then stick the syringe into the bottle. It takes a minute, but the stuff will be sucked into the bottle. I found that I never needed very much. An 1/8th of an inch in the bottle, will go a long way. Besides anything you leave in the applicator will evaporate away within a day.

With all this said, a friend said that Acetone was just as effective as cement for PLA. Being a cheapskate, I will try it as soon as my current supply of Acrylic Cement is gone.

Also…

When using this Cement with the Bottle Applicator, its volatility comes into play. Normally you tip the Applicator and give it a squeeze to get a single drop of cement to come out, then relax your grip to cause an additional glue to be sucked back up the syringe. But because this stuff is so volatile, the heat from your fingers causes it to expand, so instead of a single drop, the expansion of the cement inside the bottle causes it to start dripping immediately. Even if you stop squeezing. This will flood your print with glue if the syringe is against it and make a mess. I found the best way to get a single drop was to hold the tip above a piece of cardboard, quickly tilt it to get a drop to come out, then tilt it back immediately, but no so much that the cement reaches the end of the syringe inside the bottle. The ‘tilt back’ causes the drop of cement to slide back to the working end of the syringe, without additional drips landing on your work. Note: this only works if there is just a little solvent in the bottle.